docs: update changelog for v1.5.0

Introduces the `godeez download track <ID>` command, allowing users to download individual songs directly.

Single tracks are saved into a "Singles" folder by default to keep them organized. The README has been updated with documentation and examples for this new functionality.

.example-config

@@ -1,4 +0,0 @@
-arl_cookie = '1d9e90abb452a61b1b7463f0953e1b303c4e2e7e5fd404fde9b385f4de01c340ac0f62f1c8c1550405b0b9beded0e28c481e96a6148e8f4548351add5d7db746b2785ecf83b1768e5dd8cc73b1ad30c18d07c9cb37f5c6b9cd7a78a4de2aff11'
-license_token = 'AAAAA1bcDFgHJKLmnOPqrsTUvwXYZ12o3lmNOjR2xWiQRT3v5zxL4mKoWjxL82jD7sWx93KfYGsN2IkdPxsUw9PTas7oFbgR3nY9qpZmVyHFJKLPxT7sWmqErXyTn5iKoNpRtV7bPdQZ8qLmWoJpU2nKrXz6vW'
-secret_key = 'hTv1IAw19qWy9i3f'
-iv = '0001020304050607'

.github/scripts/release-notes.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+#
+# Extracts the CHANGELOG.md section for a version and formats it as the GitHub
+# release body. Usage: release-notes.sh v1.5.0
+#
+# Exits non-zero when the version has no section, so a tag can never be
+# published with empty or stale release notes.
+
+set -euo pipefail
+
+if [ $# -ne 1 ]; then
+	echo "usage: $0 <version>" >&2
+	exit 2
+fi
+
+version="${1#v}"
+changelog="${CHANGELOG_FILE:-CHANGELOG.md}"
+
+if [ ! -f "$changelog" ]; then
+	echo "$changelog not found" >&2
+	exit 1
+fi
+
+notes=$(awk -v ver="$version" '
+	BEGIN { heading = "## [" ver "]" }
+	index($0, heading) == 1 { found = 1; next }
+	found && index($0, "## [") == 1 { exit }
+	found { print }
+' "$changelog")
+
+if [ -z "${notes//[[:space:]]/}" ]; then
+	echo "no $changelog section found for version $version" >&2
+	exit 1
+fi
+
+printf "## What's new in v%s\n%s\n" "$version" "$notes"

.github/workflows/ci.yml

@@ -0,0 +1,40 @@
+name: ci
+
+on:
+  push:
+    branches: ['**']
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      - name: Check formatting
+        run: |
+          unformatted=$(gofmt -l .)
+          if [ -n "$unformatted" ]; then
+            echo "Not gofmt'd:"
+            echo "$unformatted"
+            exit 1
+          fi
+
+      - run: go vet ./...
+
+      - run: go test ./...
+
+      - run: go build ./...
+
+      # Catches a broken release config before a tag is pushed.
+      - uses: goreleaser/goreleaser-action@v6
+        with:
+          version: '~> v2'
+          args: check

.github/workflows/release.yml

@@ -0,0 +1,33 @@
+name: release
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+permissions:
+  contents: write
+
+jobs:
+  goreleaser:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      # Fails the release if CHANGELOG.md has no section for this tag.
+      - name: Build release notes from CHANGELOG.md
+        run: .github/scripts/release-notes.sh "${{ github.ref_name }}" > "${RUNNER_TEMP}/release-notes.md"
+
+      - uses: goreleaser/goreleaser-action@v6
+        with:
+          version: '~> v2'
+          args: release --clean --release-notes=${{ runner.temp }}/release-notes.md
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -0,0 +1,3 @@
+.DS_Store
+build.sh
+builds/

.goreleaser.yaml

@@ -0,0 +1,47 @@
+version: 2
+
+project_name: godeez
+
+before:
+  hooks:
+    - go mod tidy
+
+builds:
+  - id: godeez
+    main: .
+    binary: godeez
+    env:
+      - CGO_ENABLED=0
+    flags:
+      - -trimpath
+    ldflags:
+      - -s -w
+      - -X github.com/mathismqn/godeez/internal/buildinfo.version={{ .Version }}
+      - -X github.com/mathismqn/godeez/internal/buildinfo.commit={{ .FullCommit }}
+      - -X github.com/mathismqn/godeez/internal/buildinfo.date={{ .CommitDate }}
+    goos:
+      - linux
+      - darwin
+      - windows
+    goarch:
+      - amd64
+      - arm64
+
+archives:
+  - formats:
+      - binary
+    name_template: '{{ .ProjectName }}_{{ .Version }}_{{ .Os }}_{{ .Arch }}'
+
+checksum:
+  name_template: checksums.txt
+  algorithm: sha256
+
+snapshot:
+  version_template: '{{ incpatch .Version }}-snapshot'
+
+# Release notes are written by hand in CHANGELOG.md
+changelog:
+  disable: true
+
+release:
+  prerelease: auto

CHANGELOG.md

@@ -0,0 +1,111 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [1.5.0] - 2026-08-05
+
+### Added
+
+- Add new `login` and `logout` commands to authenticate with your Deezer email and password. Credentials are stored in the system keyring. Requires `DEEZER_MOBILE_API_KEY` and `DEEZER_MOBILE_GW_KEY` to be set.
+- Add new `update` command to replace the binary in place with the latest release, with `--check` to only report availability and `--force` to reinstall.
+- Add new `version` command to print the version, commit, build date, and platform.
+- Notify when a newer version is available after a download completes.
+- Add WAV download quality (`--quality=wav`): the FLAC stream is converted locally to lossless WAV.
+
+### Changed
+
+- `DEEZER_ARL` is now optional. When it is unset, the credentials stored by `godeez login` are used instead, and expired sessions are renewed automatically.
+- Release binaries are now named `godeez_<version>_<os>_<arch>` (previously `godeez-<version>-<os>-<arch>`) and are published alongside a `checksums.txt` file.
+
+### Fixed
+
+- Interrupted downloads no longer leave partial files behind.
+- Avoid overwriting an existing file when another track resolves to the same name.
+- Report a clear error when the database is already in use by another process.
+- Migrate the legacy database when `~/.godeez` and `~/Music/GoDeez` are on different filesystems.
+- Write metadata tags even when the cover art or track duration is missing.
+
+## [1.4.0] - 2026-03-01
+
+### Added
+
+- Automatic database migration from `~/.godeez/tracks.db` to `~/Music/GoDeez/.tracks.db`.
+
+### Changed
+
+- Configuration now uses `DEEZER_ARL` environment variable (replaces `config.toml`).
+- Database moved from `~/.godeez/tracks.db` to `~/Music/GoDeez/.tracks.db`.
+- Show warning count in download summary.
+
+### Removed
+
+- `config.toml` configuration file and `~/.godeez` directory.
+- `--config` flag from CLI.
+- `secret_key` and `output_dir` configuration options.
+- Watcher feature (`watch` subcommands).
+
+### Fixed
+
+- Track number zero-padding for correct file sorting.
+
+## [1.3.0] - 2025-09-11
+
+### Added
+
+- Add new `track` command to download individual tracks.
+- Add `--genre` flag to fetch and embed genre information into file metadata tags.
+
+### Fixed
+
+- Handle empty media resources gracefully to prevent crashes.
+
+## [1.2.0] - 2025-08-18
+
+### Added
+
+- Add new `artist` command to download an artist’s top tracks.
+- Add `--limit` flag for the `artist` command to restrict the number of tracks.
+- Add `--strict` flag for downloads: fail if the requested quality is unavailable.
+
+### Changed
+
+- Set default download quality to MP3 320 kbps.
+
+### Removed
+
+- Remove `--quality=best` option. Fallback to lower quality is now the default behavior; use the `--strict` flag to prevent fallback.
+
+### Fixed
+
+- Handle error when `SNG_CONTRIBUTORS` metadata is empty.
+
+## [1.1.1] - 2025-06-16
+
+### Fixed
+
+- Restore ability to download tracks without a Deezer Premium account (limited to MP3 128 kbps for free accounts).
+
+## [1.1.0] - 2025-05-19
+
+### Added
+
+- Support downloading full albums and playlists with more than 40 tracks (previous limit removed).
+- Fetch and embed BPM and musical key into metadata tags.
+- Add local database system (`tracks.db`) to track downloaded files and avoid re-downloading, even if files are renamed or moved.
+- Improve CLI output formatting for a cleaner and more informative user experience.
+
+### Changed
+
+- Replace the `godeez` file in the user’s home directory with a `.godeez/` directory, which now stores both `config.toml` and `tracks.db`.  
+  👉 If upgrading, move your existing config into `.godeez/config.toml`.
+- Simplify `config.toml`: remove the need for `iv` and `license_token`.
+- Automatically delete corrupted or incomplete files on download failure.
+
+## [1.0.0] - 2024-10-15
+
+### Added
+
+- Initial release of **GoDeez** with basic Deezer album and playlist downloading capabilities.

README.md

@@ -2,86 +2,160 @@
   
 # GoDeez
 
+[![GitHub release](https://img.shields.io/github/v/release/mathismqn/godeez)](https://github.com/mathismqn/godeez/releases)
+[![License](https://img.shields.io/github/license/mathismqn/godeez)](https://github.com/mathismqn/godeez/blob/main/LICENSE)
+[![Last commit](https://img.shields.io/github/last-commit/mathismqn/godeez)](https://github.com/mathismqn/godeez/commits/main)
+
 A simple Go tool for downloading music from [Deezer](https://www.deezer.com).
 
 [Features](#features) •
 [Installation](#installation) •
+[Updating](#updating) •
 [Configuration](#configuration) •
-[Usage](#usage) •
+[Usage](#usage)
-[Contributing](#contributing) •
-[License](#license)
 
 </div>
 
 ## Features
 
-* Download playlists and albums from Deezer
+- Download playlists, albums, artists' top tracks, and individual tracks
-* Select audio quality: MP3 128kbps, MP3 320kbps, or FLAC
+- Choose audio quality: MP3 128 kbps, MP3 320 kbps (default), or lossless FLAC/WAV (⚠️ non-premium accounts are limited to 128 kbps)
-* Automatically adds metadata tags to downloaded files
+- Authenticate with an ARL cookie or with your Deezer email and password
-* Cross-platform support (works on Windows, macOS, and Linux)
+- Automatically embed metadata tags (artist, album, title, artwork, etc.)
-* Simple and easy-to-use CLI
+- Fetch and tag tracks with BPM, musical key, and genre
+- Works on Windows, macOS, and Linux
 
 ## Installation
 
-To install **GoDeez**, simply download the latest binary for your platform from the Releases page.
+Prebuilt binaries are available for every release.
 
 1. Go to the [Releases](https://github.com/mathismqn/godeez/releases) page.
-2. Download the appropriate binary for your operating system (Windows, macOS, or Linux).
+2. Download the appropriate binary for your operating system and architecture, named `godeez_<version>_<os>_<arch>`.
-3. Move the binary to a directory included in $PATH for easy access (optional but recommended).
+3. (Optional) Move the binary to a directory on your `$PATH` for easier access.
 
 Example (Linux/macOS):
+
 ```bash
-# Move the downloaded binary to /usr/local/bin for easy access from anywhere
+# Make it executable and move it to /usr/local/bin for access from anywhere
-mv godeez-1.0.0-linux-amd64 /usr/local/bin/godeez
+chmod +x godeez_1.5.0_linux_amd64
+mv godeez_1.5.0_linux_amd64 /usr/local/bin/godeez
+```
+
+Each release also includes a `checksums.txt`, so you can verify your download:
+
+```bash
+sha256sum -c checksums.txt --ignore-missing
+```
+
+### macOS
+
+The macOS binaries are not signed with an Apple Developer certificate, so
+Gatekeeper blocks them on first run. You only need to clear the quarantine flag
+once:
+
+```bash
+xattr -d com.apple.quarantine /usr/local/bin/godeez
+```
+
+## Updating
+
+**GoDeez** can update itself to the latest release:
+
+```bash
+# Check for a new version
+godeez update --check
+
+# Download, verify, and install it
+godeez update
+
+# Reinstall even if already up to date
+godeez update --force
+```
+
+The new binary is verified against the release's published SHA256 checksum
+before it replaces the current one. If **GoDeez** lives in a directory you do
+not own (such as `/usr/local/bin` on some systems), run `sudo godeez update`.
+
+To disable new-version notifications:
+
+```bash
+export GODEEZ_NO_UPDATE_CHECK=1
+```
+
+To check which version you are running:
+
+```bash
+godeez version
 ```
 
 ## Configuration
 
-The first time you run **GoDeez**, a configuration file named .godeez will be automatically generated in your home directory ($HOME on Linux/macOS, %USERPROFILE% on Windows).
+**GoDeez** authenticates to Deezer in one of two ways: with an **ARL cookie** copied from your browser, or with your **email and password**. The ARL cookie works out of the box and is the recommended option; email/password login requires two extra keys that **GoDeez** does not ship (see below).
 
-This configuration file contains several important variables that you need to fill out manually. Below are the steps for retrieving and setting each variable.
+### ARL cookie
 
-### Steps to configure
+Set your ARL cookie as an environment variable:
 
-1. Run the application for the first time: This generates the .godeez configuration file in your home directory.
+```bash
-2. Edit the configuration file: Open the .godeez file with a text editor to set the required variables.
+export DEEZER_ARL="your_arl_cookie_here"
+```
 
-### Variables to configure
+To make it persistent, add the line above to your shell profile (`~/.bashrc`, `~/.zshrc`, etc.).
 
-Here are the key variables you need to set in the .godeez file:
+#### How to retrieve your ARL cookie
 
-1. `arl_cookie`
+1. Open your browser and log in to your [Deezer](https://www.deezer.com) account.
-* **What is it?**: The arl_cookie is a session cookie used for authentication with Deezer. Without this cookie, the downloader cannot access your account to retrieve playlists, albums, or songs.
+2. Open the **Developer Tools** (right-click on the page and select **Inspect**, or press <kbd>F12</kbd>).
-* **How to retrieve it**:
+3. Navigate to the **Application** tab (Chrome/Edge) or **Storage** tab (Firefox).
-	1.	Open your browser and log in to your Deezer account.
+4. In the left panel, look for **Cookies** and select **https://www.deezer.com**.
-	2.	Open the Developer Tools (right-click on the page and select “Inspect” or press F12).
+5. Find the `arl` cookie and copy its value.
-	3.	Navigate to the Application tab (in Chrome/Edge) or Storage tab (in Firefox).
-	4.	In the left panel, look for Cookies and select `https://www.deezer.com`.
-	5.	Find the arl cookie and copy its value.
 
-2. `license_token`
+> **Note:** The ARL cookie may expire after some time. If you get authentication errors, retrieve a fresh cookie using the steps above.
-* **What is it?**: The license_token is required to access Deezer’s media URLs for downloading songs. This token is found in the network requests your browser makes when playing a song.
-* **How to retrieve it**:
-  1.	Open Developer Tools in your browser (right-click on the page and select “Inspect” or press F12).
-	2.	Go to the Network tab.
-	3.	Start playing a song on Deezer and look for a request to `https://media.deezer.com/v1/get_url`.
-	4.	Select the request and in the Request Data section, find the license_token.
-	5.	Copy the license_token value.
 
-3. `secret_key`
+### Email and password
-* **What is it?**: The secret_key is a cryptographic value used alongside the iv to decrypt Deezer’s media files.
-* **How to retrieve it?**: While we cannot provide the specific secret_key in this documentation, it can be found online through various sources or developer communities that focus on Deezer.
 
-4. `iv`
+Instead of copying a cookie, you can log in once with your Deezer account:
-* **What is it?**: This is another cryptographic variable needed to decrypt media streams from Deezer.
+
-* **How to retrieve it?**: The iv can be found in the [.example-config](https://github.com/mathismqn/godeez/blob/main/.example-config) file included with this project.
+```bash
+godeez login
+```
+
+You will be prompted for your email and password. On success, **GoDeez** stores your credentials in your system keyring under the service name `godeez`. From then on, **GoDeez** authenticates on its own and renews the session when it expires.
+
+To remove the stored credentials:
+
+```bash
+godeez logout
+```
+
+#### Gateway keys
+
+Email/password login goes through Deezer's mobile gateway, which requires two keys:
+
+```bash
+export DEEZER_MOBILE_API_KEY="your_api_key_here"
+export DEEZER_MOBILE_GW_KEY="your_gateway_key"   # exactly 16 characters
+```
+
+**GoDeez** does not bundle these keys, so you have to supply your own. For background on what they are and where they live in Deezer's clients, see [this write-up](https://gist.github.com/svbnet/b79b705a4c19d74896670c1ac7ad627e). If either variable is missing, `godeez login` exits with an error.
+
+> **Note:** `DEEZER_ARL` takes precedence over stored credentials. If it is set, **GoDeez** always uses the cookie and never falls back to your login, so unset it (and remove it from your shell profile) before running `godeez login`.
+
+> **Note:** The keyring entry holds your password alongside the ARL because the password is reused to renew expired sessions. On Linux, the keyring requires a running secret service; without one, `godeez login` fails with `system keyring is unavailable`.
+
+### Output directory
+
+Downloaded files are saved to `~/Music/GoDeez`. The download database (`.tracks.db`) is stored in the same directory as your music.
+
+> **Upgrading from v1.3.0?** The `~/.godeez` directory and `config.toml` are no longer used. Set the `DEEZER_ARL` environment variable instead. Your existing database will be migrated automatically on first run.
 
 ## Usage
 
-### CLI Overview
+### CLI overview
 
-When you run **godeez** without any additional commands, you’ll see a general help menu:
+Running `godeez` without arguments shows the help menu:
-```bash
+
+```text
 GoDeez is a tool to download music from Deezer
 
 Usage:
@@ -89,47 +163,85 @@ Usage:
 
 Available Commands:
   completion  Generate the autocompletion script for the specified shell
-  download    Download songs from Deezer
+  download    Download tracks from Deezer
   help        Help about any command
+  login       Log in to Deezer with your email and password
+  logout      Remove stored Deezer credentials
+  update      Update GoDeez to the latest version
+  version     Print the current version of GoDeez
 
 Flags:
-      --config string   config file (default is $HOME/.godeez)
+  -h, --help   help for godeez
-  -h, --help            help for godeez
 
 Use "godeez [command] --help" for more information about a command.
 ```
-This provides an overview of the available commands and flags.
 
-To download music, you need to use the download command. Here’s how the CLI looks when you run `godeez download`:
+### Download commands
-```bash
+
-Download songs from Deezer
+```text
+Download tracks from Deezer
 
 Usage:
   godeez download [command]
 
 Available Commands:
-  album       Download songs from one or more albums
+  album       Download tracks from an album
-  playlist    Download songs from one or more playlists
+  artist      Download an artist's top tracks
+  playlist    Download tracks from a playlist
+  track       Download a single track
 
 Flags:
-  -h, --help             help for download
+      --bpm                fetch BPM/key and add to file tags
-  -o, --output string    output directory (default is current directory)
+      --genre              fetch genre and add to file tags
-  -q, --quality string   download quality [mp3_128, mp3_320, flac, best] (default is best)
+  -h, --help               help for download
-
+  -q, --quality string     download quality [mp3_128, mp3_320, flac, wav] (default "mp3_320")
-Global Flags:
+      --strict             fail the download if the requested quality is unavailable
-      --config string   config file (default is $HOME/.godeez)
+  -t, --timeout duration   timeout for each download (e.g. 10s, 1m, 2m30s) (default 2m0s)
 
 Use "godeez download [command] --help" for more information about a command.
 ```
 
+> **Note:** The `artist` command takes an extra `-l, --limit` flag to choose how many top tracks to download (default 10, maximum 100).
+
+### Examples
+
+```bash
+# Download an album
+godeez download album 12345678
+
+# Download a playlist
+godeez download playlist 87654321
+
+# Download an artist's top tracks (limit to 5 tracks)
+godeez download artist 11223344 --limit 5
+
+# Download a single track
+godeez download track 98765432
+
+# Download with specific quality, BPM, and genre data
+godeez download track 98765432 --quality flac --bpm --genre
+```
+
 ## Contributing
 
-Contributions help make **GoDeez** a better tool for everyone, and any help is greatly appreciated.
+Contributions make **GoDeez** better for everyone, and any help is greatly appreciated — whether it's a bug fix, a new feature, or a documentation improvement.
-Whether it’s a bug fix, a new feature, or improving documentation, your input is valuable.
 
-If you have an idea for improvement, feel free to fork the repository and submit a pull request. You can also open an issue if you spot a bug or have a feature suggestion.
+To contribute, fork the repository and open a pull request. To report a bug or suggest a feature, open an issue instead.
-Every bit of support counts, so don’t forget to give the project a star if you enjoy using it. Thank you for helping make this project better!
+
+## Support the project
+
+If **GoDeez** helps you enjoy your music collection, please consider giving it a star ⭐
+
+**Why star the project?**
+
+- Helps more music lovers discover it
+- Shows appreciation for the work and keeps me motivated
+- Takes one click, and it means a lot
 
 ## License
 
 This project is licensed under the MIT License. See the [LICENSE](https://github.com/mathismqn/godeez/blob/main/LICENSE) file for details.
+
+---
+
+> ⚠️ This tool is provided for educational and personal use only. Please ensure your usage complies with Deezer's Terms of Service.

cmd/download.go

@@ -1,158 +1,89 @@
 package cmd
 
 import (
+	"context"
+	"errors"
 	"fmt"
-	"os"
-	"path"
 	"strings"
+	"time"
 
-	"github.com/flytam/filenamify"
+	"github.com/mathismqn/godeez/internal/config"
 	"github.com/mathismqn/godeez/internal/deezer"
-	"github.com/mathismqn/godeez/internal/tags"
+	"github.com/mathismqn/godeez/internal/download"
+	"github.com/mathismqn/godeez/internal/store"
 	"github.com/spf13/cobra"
 )
 
-var outputDir string
+func newDownloadCmd() *cobra.Command {
-var quality string
+	cmd := &cobra.Command{
-
+		Use:         "download",
-var downloadCmd = &cobra.Command{
+		Short:       "Download tracks from Deezer",
-	Use:   "download",
+		Annotations: map[string]string{updateNoticeAnnotation: "true"},
-	Short: "Download songs from Deezer",
-}
-
-func init() {
-	RootCmd.AddCommand(downloadCmd)
-	downloadCmd.PersistentFlags().StringVarP(&outputDir, "output", "o", "", "output directory (default is current directory)")
-	downloadCmd.PersistentFlags().StringVarP(&quality, "quality", "q", "", "download quality [mp3_128, mp3_320, flac, best] (default is best)")
-}
-
-func validateInput() {
-	if quality == "" {
-		quality = "best"
 	}
 
-	validQualities := map[string]bool{
+	opts := &download.Options{}
-		"mp3_128": true,
+	cmd.PersistentFlags().StringVarP(&opts.Quality, "quality", "q", "mp3_320", "download quality [mp3_128, mp3_320, flac, wav]")
-		"mp3_320": true,
+	cmd.PersistentFlags().DurationVarP(&opts.Timeout, "timeout", "t", 2*time.Minute, "timeout for each download (e.g. 10s, 1m, 2m30s)")
-		"flac":    true,
+	cmd.PersistentFlags().BoolVar(&opts.BPM, "bpm", false, "fetch BPM/key and add to file tags")
-		"best":    true,
+	cmd.PersistentFlags().BoolVar(&opts.Genre, "genre", false, "fetch genre and add to file tags")
-	}
+	cmd.PersistentFlags().BoolVar(&opts.Strict, "strict", false, "fail the download if the requested quality is unavailable")
-	if !validQualities[quality] {
+
-		fmt.Fprintf(os.Stderr, "Error: invalid quality option: %s\n", quality)
+	cmd.AddCommand(
-		os.Exit(1)
+		newDownloadSubCmd(deezer.KindAlbum, opts),
-	}
+		newDownloadSubCmd(deezer.KindPlaylist, opts),
+		newDownloadSubCmd(deezer.KindArtist, opts),
+		newDownloadSubCmd(deezer.KindTrack, opts),
+	)
+
+	return cmd
 }
 
-func downloadContent(contentType string, args []string) {
+func newDownloadSubCmd(kind deezer.Kind, opts *download.Options) *cobra.Command {
-	nArgs := len(args)
+	cmd := &cobra.Command{
-	separator := "--------------------------------------------------"
+		Use:   fmt.Sprintf("%s <%s_id>", kind, kind),
-
+		Short: downloadShort(kind),
-	for i, id := range args {
+		Args:  cobra.ExactArgs(1),
-		fmt.Println(separator)
+		PreRunE: func(cmd *cobra.Command, args []string) error {
-		fmt.Printf("[%d/%d] Getting data for %s %s...", i+1, nArgs, contentType, id)
+			opts.Quality = strings.ToLower(opts.Quality)
-
+			return opts.Validate(kind)
-		var resource deezer.Resource
+		},
-		var songs []*deezer.Song
+		RunE: func(cmd *cobra.Command, args []string) error {
-
+			cfg, err := config.Load()
-		switch contentType {
-		case "album":
-			album := &deezer.Album{}
-			if err := deezer.GetData(album, id); err != nil {
-				fmt.Printf("\r[%d/%d] Getting data for album %s... FAILED\n", i+1, nArgs, id)
-				fmt.Fprintf(os.Stderr, "Error: could not get album data: %v\n", err)
-				continue
-			}
-			resource = album
-			songs = album.GetSongs()
-		case "playlist":
-			playlist := &deezer.Playlist{}
-			if err := deezer.GetData(playlist, id); err != nil {
-				fmt.Printf("\r[%d/%d] Getting data for playlist %s... FAILED\n", i+1, nArgs, id)
-				fmt.Fprintf(os.Stderr, "Error: could not get playlist data: %v\n", err)
-				continue
-			}
-			if playlist.Data.Status == 1 && playlist.Data.CollabKey == "" {
-				fmt.Printf("\r[%d/%d] Getting data for playlist %s... FAILED\n", i+1, nArgs, id)
-				fmt.Fprintf(os.Stderr, "Error: playlist is private and no valid arl cookie was provided\n")
-				continue
-			}
-
-			resource = playlist
-			songs = playlist.GetSongs()
-		}
-
-		fmt.Printf("\r[%d/%d] Getting data for %s %s... DONE\n", i+1, nArgs, contentType, id)
-
-		output := resource.GetOutputPath(outputDir)
-		if _, err := os.Stat(output); os.IsNotExist(err) {
-			if err := os.MkdirAll(output, 0755); err != nil {
-				fmt.Fprintf(os.Stderr, "Error: could not create output directory: %v\n", err)
-				continue
-			}
-		}
-
-		title := resource.GetTitle()
-		fmt.Printf("Starting download of %s: %s\n", contentType, title)
-
-		for _, song := range songs {
-			songTitle := song.Title
-			if song.Version != "" {
-				songTitle = fmt.Sprintf("%s %s", song.Title, song.Version)
-			}
-
-			fmt.Printf("    Downloading %s...", songTitle)
-
-			media, err := song.GetMediaData(quality)
 			if err != nil {
-				fmt.Printf("\r    Downloading %s... FAILED\n", songTitle)
+				return err
-				fmt.Fprintf(os.Stderr, "Error: could not get media data: %v\n", err)
-				if err.Error() == "invalid license token" {
-					os.Exit(1)
-				}
-				continue
 			}
+			config.MigrateLegacy(cfg.OutputDir)
 
-			if len(media.Data) == 0 || len(media.Data[0].Media) == 0 || len(media.Data[0].Media[0].Sources) == 0 {
+			st, err := store.Open(cfg.OutputDir)
-				fmt.Printf("\r    Downloading %s... FAILED\n", songTitle)
-				fmt.Fprintf(os.Stderr, "Error: could not get media sources\n")
-				continue
-			}
-
-			url := media.Data[0].Media[0].Sources[0].URL
-			for _, source := range media.Data[0].Media[0].Sources {
-				if source.Provider == "ak" {
-					url = source.URL
-					break
-				}
-			}
-
-			ext := "mp3"
-			if media.Data[0].Media[0].Format == "FLAC" {
-				ext = "flac"
-			}
-			trackNumber := ""
-			if contentType == "album" {
-				trackNumber = song.TrackNumber + "."
-			}
-
-			fileName := fmt.Sprintf("%s %s - %s.%s", trackNumber, songTitle, strings.Join(song.Contributors.MainArtists, ", "), ext)
-			fileName, _ = filenamify.Filenamify(fileName, filenamify.Options{})
-			filePath := path.Join(output, fileName)
-
-			err = media.Download(url, filePath, song.ID)
 			if err != nil {
-				fmt.Printf("\r    Downloading %s... FAILED\n", songTitle)
+				return err
-				fmt.Fprintf(os.Stderr, "Error: could not download song: %v\n", err)
-				continue
 			}
-			fmt.Printf("\r    Downloading %s... DONE\n", songTitle)
+			defer st.Close()
 
-			if err := tags.AddTags(resource, song, filePath); err != nil {
+			err = download.New(cfg, st, kind).Run(cmd.Context(), *opts, args[0])
-				fmt.Fprintf(os.Stderr, "Error: could not add tags to song: %v\n", err)
+			if errors.Is(err, context.Canceled) {
+				return nil
 			}
-		}
+			return err
+		},
 	}
 
-	fmt.Println(separator)
+	if kind == deezer.KindArtist {
-	fmt.Println("All downloads completed")
+		cmd.Flags().IntVarP(&opts.Limit, "limit", "l", 10, "number of tracks to download")
+	}
+
+	return cmd
+}
+
+func downloadShort(kind deezer.Kind) string {
+	switch kind {
+	case deezer.KindArtist:
+		return "Download an artist's top tracks"
+	case deezer.KindTrack:
+		return "Download a single track"
+	case deezer.KindAlbum:
+		return "Download tracks from an album"
+	default:
+		return fmt.Sprintf("Download tracks from a %s", kind)
+	}
 }

cmd/download_album.go

@@ -1,17 +0,0 @@
-package cmd
-
-import "github.com/spf13/cobra"
-
-var albumCmd = &cobra.Command{
-	Use:   "album [album_id...]",
-	Short: "Download songs from one or more albums",
-	Args:  cobra.MinimumNArgs(1),
-	Run: func(cmd *cobra.Command, args []string) {
-		validateInput()
-		downloadContent("album", args)
-	},
-}
-
-func init() {
-	downloadCmd.AddCommand(albumCmd)
-}

cmd/download_playlist.go

@@ -1,17 +0,0 @@
-package cmd
-
-import "github.com/spf13/cobra"
-
-var playlistCmd = &cobra.Command{
-	Use:   "playlist [playlist_id...]",
-	Short: "Download songs from one or more playlists",
-	Args:  cobra.MinimumNArgs(1),
-	Run: func(cmd *cobra.Command, args []string) {
-		validateInput()
-		downloadContent("playlist", args)
-	},
-}
-
-func init() {
-	downloadCmd.AddCommand(playlistCmd)
-}

cmd/login.go

@@ -0,0 +1,96 @@
+package cmd
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+	"github.com/spf13/cobra"
+	"golang.org/x/term"
+)
+
+func newLoginCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "login",
+		Short: "Log in to Deezer with your email and password",
+		Args:  cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if err := deezer.CheckGatewayEnv(); err != nil {
+				return err
+			}
+
+			err := runLogin(cmd.Context())
+			if errors.Is(err, context.Canceled) {
+				return nil
+			}
+
+			return err
+		},
+	}
+}
+
+func runLogin(ctx context.Context) error {
+	email, password, err := promptCredentials(ctx)
+	if err != nil {
+		return err
+	}
+
+	_, username, err := deezer.Login(ctx, email, password)
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("Successfully logged in as %s.\n", username)
+
+	return nil
+}
+
+func promptCredentials(ctx context.Context) (string, string, error) {
+	oldState, stateErr := term.GetState(int(os.Stdin.Fd()))
+
+	type credentials struct {
+		email    string
+		password string
+		err      error
+	}
+	resultChan := make(chan credentials, 1)
+	go func() {
+		var c credentials
+		c.email, c.password, c.err = readCredentials()
+		resultChan <- c
+	}()
+
+	select {
+	case c := <-resultChan:
+		return c.email, c.password, c.err
+	case <-ctx.Done():
+		if stateErr == nil {
+			term.Restore(int(os.Stdin.Fd()), oldState)
+		}
+		fmt.Println()
+
+		return "", "", ctx.Err()
+	}
+}
+
+func readCredentials() (string, string, error) {
+	fmt.Print("Email: ")
+	line, err := bufio.NewReader(os.Stdin).ReadString('\n')
+	if err != nil {
+		return "", "", err
+	}
+	email := strings.TrimSpace(line)
+
+	fmt.Print("Password: ")
+	passwordBytes, err := term.ReadPassword(int(os.Stdin.Fd()))
+	fmt.Println()
+	if err != nil {
+		return "", "", err
+	}
+
+	return email, string(passwordBytes), nil
+}

cmd/logout.go

@@ -0,0 +1,25 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+	"github.com/spf13/cobra"
+)
+
+func newLogoutCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "logout",
+		Short: "Remove stored Deezer credentials",
+		Args:  cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if err := deezer.ClearCredentials(); err != nil {
+				return err
+			}
+
+			fmt.Println("Successfully logged out.")
+
+			return nil
+		},
+	}
+}

cmd/root.go

@@ -1,78 +1,89 @@
 package cmd
 
 import (
+	"context"
 	"fmt"
 	"os"
-	"path"
+	"slices"
 
-	"github.com/mathismqn/godeez/internal/config"
+	"github.com/mathismqn/godeez/internal/buildinfo"
+	"github.com/mathismqn/godeez/internal/update"
 	"github.com/spf13/cobra"
-	"github.com/spf13/viper"
+	"golang.org/x/term"
 )
 
-var cfgFile string
+const updateNoticeAnnotation = "godeez:update-notice"
 
-var RootCmd = &cobra.Command{
+func Execute(ctx context.Context) error {
-	Use:   "godeez",
+	root := newRootCmd()
-	Short: "GoDeez is a tool to download music from Deezer",
+
-	Run: func(cmd *cobra.Command, args []string) {
+	var notice <-chan string
-		cmd.Help()
+	if wantsUpdateNotice(root) {
-	},
+		notice = update.StartCheck(ctx)
+	}
+
+	err := root.ExecuteContext(ctx)
+
+	printUpdateNotice(notice)
+
+	return err
 }
 
-func init() {
+func newRootCmd() *cobra.Command {
-	RootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.godeez)")
+	root := &cobra.Command{
-	cobra.OnInitialize(initConfig)
+		Use:          "godeez",
+		Short:        "GoDeez is a tool to download music from Deezer",
+		SilenceUsage: true,
+	}
+
+	root.AddCommand(
+		newDownloadCmd(),
+		newLoginCmd(),
+		newLogoutCmd(),
+		newUpdateCmd(),
+		newVersionCmd(),
+	)
+
+	return root
 }
 
-func initConfig() {
+func wantsUpdateNotice(root *cobra.Command) bool {
-	if cfgFile != "" {
+	if !term.IsTerminal(int(os.Stderr.Fd())) {
-		viper.SetConfigFile(cfgFile)
+		return false
-	} else {
+	}
-		homedir, err := os.UserHomeDir()
+
-		if err != nil {
+	args := os.Args[1:]
-			fmt.Fprintf(os.Stderr, "Error: could not get home directory: %v\n", err)
+	if slices.Contains(args, "-h") || slices.Contains(args, "--help") {
-			os.Exit(1)
+		return false
+	}
+
+	target, _, err := root.Find(args)
+	if err != nil || target == nil {
+		return false
+	}
+
+	if target.Run == nil && target.RunE == nil {
+		return false
+	}
+
+	for cmd := target; cmd != nil; cmd = cmd.Parent() {
+		if cmd.Annotations[updateNoticeAnnotation] == "true" {
+			return true
+		}
+	}
+
+	return false
+}
+
+func printUpdateNotice(notice <-chan string) {
+	select {
+	case latest := <-notice:
+		if latest == "" {
+			return
 		}
 
-		path := path.Join(homedir, ".godeez")
+		fmt.Fprintf(os.Stderr, "\n  ┌ Update available: %s → %s\n  └ Run `godeez update` to install\n",
-		if _, err := os.Stat(path); os.IsNotExist(err) {
+			buildinfo.Version(), latest)
-			fmt.Printf("Config file not found, creating one at %s\n", path)
+	default:
-
-			content := []byte("arl_cookie = ''\nlicense_token = ''\nsecret_key = ''\niv = '0001020304050607'\n")
-			if err := os.WriteFile(path, content, 0644); err != nil {
-				fmt.Fprintf(os.Stderr, "Error: could not create config file: %v\n", err)
-				os.Exit(1)
-			}
-		}
-
-		viper.AddConfigPath(homedir)
-		viper.SetConfigName(".godeez")
-	}
-
-	viper.SetConfigType("toml")
-	viper.AutomaticEnv()
-	if err := viper.ReadInConfig(); err != nil {
-		fmt.Fprintf(os.Stderr, "Error: could not read config file: %v\n", err)
-		os.Exit(1)
-	}
-
-	cfg := &config.Cfg
-	if err := viper.Unmarshal(&cfg); err != nil {
-		fmt.Fprintf(os.Stderr, "Error: could not unmarshal config file: %v\n", err)
-		os.Exit(1)
-	}
-
-	if cfg.LicenseToken == "" {
-		fmt.Fprintln(os.Stderr, "Error: license_token is not set in config file")
-		os.Exit(1)
-	}
-	if cfg.SecretKey == "" {
-		fmt.Fprintln(os.Stderr, "Error: secret_key is not set in config file")
-		os.Exit(1)
-	}
-	if cfg.IV == "" {
-		fmt.Fprintln(os.Stderr, "Error: iv is not set in config file")
-		os.Exit(1)
 	}
 }

cmd/update.go

@@ -0,0 +1,76 @@
+package cmd
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+	"github.com/mathismqn/godeez/internal/update"
+	"github.com/spf13/cobra"
+)
+
+type updateOptions struct {
+	checkOnly bool
+	force     bool
+}
+
+func newUpdateCmd() *cobra.Command {
+	opts := &updateOptions{}
+	cmd := &cobra.Command{
+		Use:   "update",
+		Short: "Update GoDeez to the latest version",
+		Args:  cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			err := runUpdate(cmd.Context(), opts)
+			if errors.Is(err, context.Canceled) {
+				return nil
+			}
+
+			return err
+		},
+	}
+
+	cmd.Flags().BoolVar(&opts.checkOnly, "check", false, "only report whether an update is available")
+	cmd.Flags().BoolVar(&opts.force, "force", false, "reinstall even if already up to date")
+
+	return cmd
+}
+
+func runUpdate(ctx context.Context, opts *updateOptions) error {
+	if err := update.CheckUpdatable(); err != nil {
+		return err
+	}
+
+	u := update.New()
+	u.Out = os.Stdout
+	current := buildinfo.Version()
+
+	release, err := u.Latest(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to check for updates: %w", err)
+	}
+
+	latest := release.Version()
+	fmt.Printf("Current: %s\nLatest:  %s\n", current, latest)
+
+	if !update.IsNewer(current, latest) && !opts.force {
+		fmt.Println("Already up to date.")
+
+		return nil
+	}
+
+	if opts.checkOnly {
+		fmt.Printf("Run `godeez update` to install %s.\n", latest)
+
+		return nil
+	}
+
+	if err := u.Apply(ctx, release); err != nil {
+		return err
+	}
+	fmt.Printf("Updated to %s.\n", latest)
+
+	return nil
+}

cmd/version.go

@@ -0,0 +1,30 @@
+package cmd
+
+import (
+	"fmt"
+	"runtime"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+	"github.com/spf13/cobra"
+)
+
+func newVersionCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "version",
+		Short: "Print the current version of GoDeez",
+		Args:  cobra.NoArgs,
+		Run: func(cmd *cobra.Command, args []string) {
+			fmt.Printf("godeez %s\n", buildinfo.Version())
+
+			if commit := buildinfo.Commit(); commit != "" {
+				fmt.Printf("  commit:   %s\n", commit)
+			}
+			if date := buildinfo.Date(); date != "" {
+				fmt.Printf("  built:    %s\n", date)
+			}
+
+			fmt.Printf("  go:       %s\n", runtime.Version())
+			fmt.Printf("  platform: %s/%s\n", runtime.GOOS, runtime.GOARCH)
+		},
+	}
+}

go.mod

@@ -1,40 +1,40 @@
 module github.com/mathismqn/godeez
 
-go 1.23.1
+go 1.25.0
 
 require (
-	github.com/spf13/cobra v1.8.1
+	github.com/mewkiz/flac v1.0.13
-	github.com/spf13/viper v1.19.0
+	github.com/spf13/cobra v1.10.2
+	github.com/zalando/go-keyring v0.2.8
+	golang.org/x/mod v0.38.0
+	golang.org/x/term v0.45.0
 )
 
 require (
-	github.com/fsnotify/fsnotify v1.7.0 // indirect
+	github.com/andybalholm/cascadia v1.3.4 // indirect
-	github.com/hashicorp/hcl v1.0.0 // indirect
+	github.com/danieljoos/wincred v1.2.3 // indirect
-	github.com/magiconair/properties v1.8.7 // indirect
+	github.com/fatih/color v1.19.0 // indirect
-	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/godbus/dbus/v5 v5.2.2 // indirect
-	github.com/pelletier/go-toml/v2 v2.2.2 // indirect
+	github.com/icza/bitio v1.1.0 // indirect
-	github.com/sagikazarmark/locafero v0.4.0 // indirect
+	github.com/mattn/go-colorable v0.1.15 // indirect
-	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
+	github.com/mattn/go-isatty v0.0.24 // indirect
-	github.com/sourcegraph/conc v0.3.0 // indirect
+	github.com/mewkiz/pkg v0.0.0-20250417130911-3f050ff8c56d // indirect
-	github.com/spf13/afero v1.11.0 // indirect
+	github.com/mewpkg/term v0.0.0-20241026122259-37a80af23985 // indirect
-	github.com/spf13/cast v1.6.0 // indirect
+	golang.org/x/net v0.57.0 // indirect
-	github.com/subosito/gotenv v1.6.0 // indirect
+	golang.org/x/sys v0.47.0 // indirect
-	go.uber.org/atomic v1.9.0 // indirect
+	golang.org/x/text v0.40.0 // indirect
-	go.uber.org/multierr v1.9.0 // indirect
-	golang.org/x/exp v0.0.0-20230905200255-921286631fa9 // indirect
-	golang.org/x/sys v0.26.0 // indirect
-	golang.org/x/text v0.19.0 // indirect
-	gopkg.in/ini.v1 v1.67.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
 
 require (
+	github.com/PuerkitoBio/goquery v1.12.0
 	github.com/bogem/id3v2/v2 v2.1.4
+	github.com/briandowns/spinner v1.23.2
 	github.com/flytam/filenamify v1.2.0
 	github.com/go-flac/flacpicture/v2 v2.0.2
 	github.com/go-flac/flacvorbis/v2 v2.0.2
-	github.com/go-flac/go-flac/v2 v2.0.1
+	github.com/go-flac/go-flac/v2 v2.0.4
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/spf13/pflag v1.0.10 // indirect
-	golang.org/x/crypto v0.28.0
+	go.etcd.io/bbolt v1.5.0
+	golang.org/x/crypto v0.54.0
 )

go.sum

@@ -1,113 +1,99 @@
+github.com/PuerkitoBio/goquery v1.12.0 h1:pAcL4g3WRXekcB9AU/y1mbKez2dbY2AajVhtkO8RIBo=
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internal/audio/wav.go

@@ -0,0 +1,189 @@
+package audio
+
+import (
+	"bufio"
+	"context"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"os"
+	"path/filepath"
+
+	"github.com/mathismqn/godeez/internal/fsutil"
+	"github.com/mewkiz/flac"
+)
+
+const (
+	headerSize       = 44
+	formatPCM        = 1
+	ctxCheckInterval = 64
+	maxDataSize      = math.MaxUint32 - (headerSize - 8)
+)
+
+func FLACToWAV(ctx context.Context, srcPath, dstPath string) error {
+	stream, err := flac.Open(srcPath)
+	if err != nil {
+		return err
+	}
+	defer stream.Close()
+
+	info := stream.Info
+	bytesPerSample, err := bytesPerSample(info.BitsPerSample)
+	if err != nil {
+		return err
+	}
+	if info.NChannels < 1 || info.NChannels > 2 {
+		return fmt.Errorf("unsupported channel count: %d", info.NChannels)
+	}
+	if size := int64(info.NSamples) * int64(info.NChannels) * int64(bytesPerSample); size > maxDataSize {
+		return fmt.Errorf("audio data of %d bytes exceeds the wav format limit", size)
+	}
+
+	file, err := os.CreateTemp(filepath.Dir(dstPath), fsutil.PartPattern)
+	if err != nil {
+		return err
+	}
+	tmpPath := file.Name()
+	done := false
+	defer func() {
+		if !done {
+			file.Close()
+			os.Remove(tmpPath)
+		}
+	}()
+
+	w := bufio.NewWriter(file)
+	if err := writeHeader(w, info.SampleRate, info.NChannels, info.BitsPerSample, 0); err != nil {
+		return err
+	}
+
+	dataSize, err := writeSamples(ctx, w, stream, int(info.NChannels), bytesPerSample)
+	if err != nil {
+		return err
+	}
+	if dataSize > maxDataSize {
+		return fmt.Errorf("audio data of %d bytes exceeds the wav format limit", dataSize)
+	}
+	if dataSize%2 != 0 {
+		if err := w.WriteByte(0); err != nil {
+			return err
+		}
+	}
+	if err := w.Flush(); err != nil {
+		return err
+	}
+	if err := patchSizes(file, dataSize); err != nil {
+		return err
+	}
+
+	if err := file.Sync(); err != nil {
+		return err
+	}
+	if err := file.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tmpPath, dstPath); err != nil {
+		return err
+	}
+	done = true
+
+	return nil
+}
+
+func bytesPerSample(bitsPerSample uint8) (int, error) {
+	switch bitsPerSample {
+	case 8, 16, 24:
+		return int(bitsPerSample) / 8, nil
+	default:
+		return 0, fmt.Errorf("unsupported bit depth: %d", bitsPerSample)
+	}
+}
+
+func writeHeader(w io.Writer, sampleRate uint32, nChannels, bitsPerSample uint8, dataSize uint32) error {
+	blockAlign := uint32(nChannels) * uint32(bitsPerSample) / 8
+
+	header := make([]byte, 0, headerSize)
+	header = append(header, "RIFF"...)
+	header = binary.LittleEndian.AppendUint32(header, uint32(headerSize-8)+dataSize)
+	header = append(header, "WAVE"...)
+	header = append(header, "fmt "...)
+	header = binary.LittleEndian.AppendUint32(header, 16)
+	header = binary.LittleEndian.AppendUint16(header, formatPCM)
+	header = binary.LittleEndian.AppendUint16(header, uint16(nChannels))
+	header = binary.LittleEndian.AppendUint32(header, sampleRate)
+	header = binary.LittleEndian.AppendUint32(header, sampleRate*blockAlign)
+	header = binary.LittleEndian.AppendUint16(header, uint16(blockAlign))
+	header = binary.LittleEndian.AppendUint16(header, uint16(bitsPerSample))
+	header = append(header, "data"...)
+	header = binary.LittleEndian.AppendUint32(header, dataSize)
+
+	_, err := w.Write(header)
+
+	return err
+}
+
+func writeSamples(ctx context.Context, w io.Writer, stream *flac.Stream, nChannels, bytesPerSample int) (int64, error) {
+	var dataSize int64
+	buf := make([]byte, 4)
+
+	for i := 0; ; i++ {
+		if i%ctxCheckInterval == 0 {
+			select {
+			case <-ctx.Done():
+				return dataSize, ctx.Err()
+			default:
+			}
+		}
+
+		frame, err := stream.ParseNext()
+		if err != nil {
+			if errors.Is(err, io.EOF) {
+				break
+			}
+			return dataSize, err
+		}
+		if len(frame.Subframes) != nChannels {
+			return dataSize, fmt.Errorf("frame %d has %d channels, want %d", frame.Num, len(frame.Subframes), nChannels)
+		}
+
+		for i := range frame.Subframes[0].Samples {
+			for _, subframe := range frame.Subframes {
+				putSample(buf, subframe.Samples[i], bytesPerSample)
+				if _, err := w.Write(buf[:bytesPerSample]); err != nil {
+					return dataSize, err
+				}
+				dataSize += int64(bytesPerSample)
+			}
+		}
+	}
+
+	return dataSize, nil
+}
+
+func putSample(buf []byte, sample int32, bytesPerSample int) {
+	if bytesPerSample == 1 {
+		buf[0] = byte(sample + 128)
+		return
+	}
+
+	value := uint32(sample)
+	for i := range bytesPerSample {
+		buf[i] = byte(value >> (8 * i))
+	}
+}
+
+func patchSizes(file *os.File, dataSize int64) error {
+	buf := make([]byte, 4)
+
+	binary.LittleEndian.PutUint32(buf, uint32(headerSize-8+dataSize+dataSize%2))
+	if _, err := file.WriteAt(buf, 4); err != nil {
+		return err
+	}
+
+	binary.LittleEndian.PutUint32(buf, uint32(dataSize))
+	_, err := file.WriteAt(buf, headerSize-4)
+
+	return err
+}

internal/audio/wav_test.go

@@ -0,0 +1,291 @@
+package audio
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/mewkiz/flac"
+	"github.com/mewkiz/flac/frame"
+	"github.com/mewkiz/flac/meta"
+)
+
+func testSamples(nChannels, bitsPerSample, nSamples int) [][]int32 {
+	max := int32(1)<<(bitsPerSample-1) - 1
+	min := -int32(1) << (bitsPerSample - 1)
+
+	channels := make([][]int32, nChannels)
+	for c := range channels {
+		samples := make([]int32, nSamples)
+		for i := range samples {
+			switch i {
+			case 0:
+				samples[i] = min
+			case 1:
+				samples[i] = max
+			case 2:
+				samples[i] = 0
+			default:
+				samples[i] = int32(i*(c+1)) % max
+				if i%3 == 0 {
+					samples[i] = -samples[i]
+				}
+			}
+		}
+		channels[c] = samples
+	}
+
+	return channels
+}
+
+func writeTestFLAC(t *testing.T, path string, sampleRate uint32, bitsPerSample uint8, channels [][]int32) {
+	t.Helper()
+
+	nSamples := len(channels[0])
+	info := &meta.StreamInfo{
+		BlockSizeMin:  uint16(nSamples),
+		BlockSizeMax:  uint16(nSamples),
+		SampleRate:    sampleRate,
+		NChannels:     uint8(len(channels)),
+		BitsPerSample: bitsPerSample,
+		NSamples:      uint64(nSamples),
+	}
+
+	file, err := os.Create(path)
+	if err != nil {
+		t.Fatalf("create flac: %v", err)
+	}
+	defer file.Close()
+
+	enc, err := flac.NewEncoder(file, info)
+	if err != nil {
+		t.Fatalf("new encoder: %v", err)
+	}
+
+	subframes := make([]*frame.Subframe, len(channels))
+	for c, samples := range channels {
+		subframes[c] = &frame.Subframe{
+			SubHeader: frame.SubHeader{Pred: frame.PredVerbatim},
+			Samples:   samples,
+			NSamples:  nSamples,
+		}
+	}
+
+	channelsLayout := frame.ChannelsMono
+	if len(channels) == 2 {
+		channelsLayout = frame.ChannelsLR
+	}
+
+	f := &frame.Frame{
+		Header: frame.Header{
+			HasFixedBlockSize: true,
+			BlockSize:         uint16(nSamples),
+			SampleRate:        sampleRate,
+			Channels:          channelsLayout,
+			BitsPerSample:     bitsPerSample,
+		},
+		Subframes: subframes,
+	}
+
+	if err := enc.WriteFrame(f); err != nil {
+		t.Fatalf("write frame: %v", err)
+	}
+	if err := enc.Close(); err != nil {
+		t.Fatalf("close encoder: %v", err)
+	}
+}
+
+func expectedPCM(channels [][]int32, bytesPerSample int) []byte {
+	var buf bytes.Buffer
+
+	for i := range channels[0] {
+		for _, samples := range channels {
+			sample := samples[i]
+			switch bytesPerSample {
+			case 1:
+				buf.WriteByte(byte(sample + 128))
+			case 2:
+				buf.Write([]byte{byte(sample), byte(sample >> 8)})
+			case 3:
+				buf.Write([]byte{byte(sample), byte(sample >> 8), byte(sample >> 16)})
+			}
+		}
+	}
+
+	return buf.Bytes()
+}
+
+func TestFLACToWAV(t *testing.T) {
+	tests := []struct {
+		name          string
+		sampleRate    uint32
+		bitsPerSample uint8
+		nChannels     int
+		nSamples      int
+	}{
+		{"16 bit stereo", 44100, 16, 2, 512},
+		{"16 bit mono", 44100, 16, 1, 512},
+		{"24 bit stereo", 48000, 24, 2, 333},
+		{"8 bit mono", 22050, 8, 1, 128},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dir := t.TempDir()
+			src := filepath.Join(dir, "in.flac")
+			dst := filepath.Join(dir, "out.wav")
+
+			channels := testSamples(tt.nChannels, int(tt.bitsPerSample), tt.nSamples)
+			writeTestFLAC(t, src, tt.sampleRate, tt.bitsPerSample, channels)
+
+			if err := FLACToWAV(context.Background(), src, dst); err != nil {
+				t.Fatalf("FLACToWAV() error = %v", err)
+			}
+
+			got, err := os.ReadFile(dst)
+			if err != nil {
+				t.Fatalf("read wav: %v", err)
+			}
+
+			bytesPerSample := int(tt.bitsPerSample) / 8
+			blockAlign := uint16(tt.nChannels * bytesPerSample)
+			want := expectedPCM(channels, bytesPerSample)
+			dataSize := uint32(len(want))
+			pad := dataSize % 2
+
+			if len(got) != headerSize+len(want)+int(pad) {
+				t.Fatalf("file size = %d, want %d", len(got), headerSize+len(want)+int(pad))
+			}
+			if string(got[0:4]) != "RIFF" || string(got[8:12]) != "WAVE" {
+				t.Errorf("magic = %q %q, want \"RIFF\" \"WAVE\"", got[0:4], got[8:12])
+			}
+			if size := binary.LittleEndian.Uint32(got[4:8]); size != headerSize-8+dataSize+pad {
+				t.Errorf("riff size = %d, want %d", size, headerSize-8+dataSize+pad)
+			}
+			if string(got[12:16]) != "fmt " {
+				t.Errorf("fmt chunk id = %q, want \"fmt \"", got[12:16])
+			}
+			if size := binary.LittleEndian.Uint32(got[16:20]); size != 16 {
+				t.Errorf("fmt chunk size = %d, want 16", size)
+			}
+			if format := binary.LittleEndian.Uint16(got[20:22]); format != formatPCM {
+				t.Errorf("format = %d, want %d", format, formatPCM)
+			}
+			if n := binary.LittleEndian.Uint16(got[22:24]); n != uint16(tt.nChannels) {
+				t.Errorf("channels = %d, want %d", n, tt.nChannels)
+			}
+			if rate := binary.LittleEndian.Uint32(got[24:28]); rate != tt.sampleRate {
+				t.Errorf("sample rate = %d, want %d", rate, tt.sampleRate)
+			}
+			if rate := binary.LittleEndian.Uint32(got[28:32]); rate != tt.sampleRate*uint32(blockAlign) {
+				t.Errorf("byte rate = %d, want %d", rate, tt.sampleRate*uint32(blockAlign))
+			}
+			if align := binary.LittleEndian.Uint16(got[32:34]); align != blockAlign {
+				t.Errorf("block align = %d, want %d", align, blockAlign)
+			}
+			if bits := binary.LittleEndian.Uint16(got[34:36]); bits != uint16(tt.bitsPerSample) {
+				t.Errorf("bits per sample = %d, want %d", bits, tt.bitsPerSample)
+			}
+			if string(got[36:40]) != "data" {
+				t.Errorf("data chunk id = %q, want \"data\"", got[36:40])
+			}
+			if size := binary.LittleEndian.Uint32(got[40:44]); size != dataSize {
+				t.Errorf("data chunk size = %d, want %d", size, dataSize)
+			}
+			if !bytes.Equal(got[headerSize:headerSize+len(want)], want) {
+				t.Error("pcm payload does not match the source samples")
+			}
+		})
+	}
+}
+
+func TestFLACToWAVErrors(t *testing.T) {
+	dir := t.TempDir()
+
+	notFLAC := filepath.Join(dir, "not.flac")
+	if err := os.WriteFile(notFLAC, []byte("this is not a flac file"), 0644); err != nil {
+		t.Fatalf("write file: %v", err)
+	}
+
+	valid := filepath.Join(dir, "valid.flac")
+	writeTestFLAC(t, valid, 44100, 16, testSamples(2, 16, 64))
+	data, err := os.ReadFile(valid)
+	if err != nil {
+		t.Fatalf("read flac: %v", err)
+	}
+	truncated := filepath.Join(dir, "truncated.flac")
+	if err := os.WriteFile(truncated, data[:len(data)/2], 0644); err != nil {
+		t.Fatalf("write file: %v", err)
+	}
+
+	tests := []struct {
+		name string
+		path string
+	}{
+		{"not a flac file", notFLAC},
+		{"missing file", filepath.Join(dir, "missing.flac")},
+		{"truncated file", truncated},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dst := filepath.Join(t.TempDir(), "out.wav")
+			if err := FLACToWAV(context.Background(), tt.path, dst); err == nil {
+				t.Error("FLACToWAV() error = nil, want error")
+			}
+			if _, err := os.Stat(dst); err == nil {
+				t.Error("FLACToWAV() left an output file behind")
+			}
+		})
+	}
+}
+
+func TestFLACToWAVCanceled(t *testing.T) {
+	dir := t.TempDir()
+	src := filepath.Join(dir, "in.flac")
+	dst := filepath.Join(dir, "out.wav")
+	writeTestFLAC(t, src, 44100, 16, testSamples(2, 16, 512))
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	if err := FLACToWAV(ctx, src, dst); err == nil {
+		t.Error("FLACToWAV() error = nil, want context.Canceled")
+	}
+	if _, err := os.Stat(dst); err == nil {
+		t.Error("FLACToWAV() left an output file behind")
+	}
+	matches, _ := filepath.Glob(filepath.Join(dir, ".godeez-*.part"))
+	if len(matches) > 0 {
+		t.Errorf("FLACToWAV() left %d part files behind", len(matches))
+	}
+}
+
+func TestBytesPerSample(t *testing.T) {
+	tests := []struct {
+		bitsPerSample uint8
+		want          int
+		wantErr       bool
+	}{
+		{8, 1, false},
+		{16, 2, false},
+		{24, 3, false},
+		{4, 0, true},
+		{12, 0, true},
+		{20, 0, true},
+		{32, 0, true},
+	}
+
+	for _, tt := range tests {
+		got, err := bytesPerSample(tt.bitsPerSample)
+		if (err != nil) != tt.wantErr {
+			t.Errorf("bytesPerSample(%d) error = %v, wantErr %v", tt.bitsPerSample, err, tt.wantErr)
+		}
+		if got != tt.want {
+			t.Errorf("bytesPerSample(%d) = %d, want %d", tt.bitsPerSample, got, tt.want)
+		}
+	}
+}

internal/buildinfo/buildinfo.go

@@ -0,0 +1,74 @@
+package buildinfo
+
+import (
+	"fmt"
+	"runtime"
+	"runtime/debug"
+	"strings"
+
+	"golang.org/x/mod/module"
+	"golang.org/x/mod/semver"
+)
+
+// devVersion is the version reported by builds that were not produced by a
+// release. Both the update check and `godeez update` refuse to run on them.
+const devVersion = "dev"
+
+var (
+	version = devVersion
+	commit  = ""
+	date    = ""
+)
+
+func Version() string {
+	if version != devVersion {
+		return version
+	}
+
+	if info, ok := debug.ReadBuildInfo(); ok {
+		if v := releaseVersion(info.Main.Version); v != "" {
+			return v
+		}
+	}
+
+	return devVersion
+}
+
+func releaseVersion(v string) string {
+	if !semver.IsValid(v) {
+		return ""
+	}
+	if semver.Build(v) != "" || module.IsPseudoVersion(v) {
+		return ""
+	}
+
+	return strings.TrimPrefix(v, "v")
+}
+
+func IsDev() bool {
+	return Version() == devVersion
+}
+
+func Commit() string {
+	if commit != "" {
+		return commit
+	}
+
+	if info, ok := debug.ReadBuildInfo(); ok {
+		for _, s := range info.Settings {
+			if s.Key == "vcs.revision" {
+				return s.Value
+			}
+		}
+	}
+
+	return ""
+}
+
+func Date() string {
+	return date
+}
+
+func UserAgent() string {
+	return fmt.Sprintf("godeez/%s (%s/%s)", Version(), runtime.GOOS, runtime.GOARCH)
+}

internal/config/config.go

@@ -1,10 +1,33 @@
 package config
 
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/mathismqn/godeez/internal/fsutil"
+)
+
 type Config struct {
-	LicenseToken string `mapstructure:"license_token"`
+	ARLCookie string
-	ArlCookie    string `mapstructure:"arl_cookie"`
+	OutputDir string
-	SecretKey    string `mapstructure:"secret_key"`
-	IV           string `mapstructure:"iv"`
 }
 
-var Cfg Config
+func Load() (*Config, error) {
+	arl := os.Getenv("DEEZER_ARL")
+
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get home directory: %w", err)
+	}
+
+	outputDir := filepath.Join(homeDir, "Music", "GoDeez")
+	if err := fsutil.EnsureDir(outputDir); err != nil {
+		return nil, fmt.Errorf("failed to create output directory: %w", err)
+	}
+
+	return &Config{
+		ARLCookie: arl,
+		OutputDir: outputDir,
+	}, nil
+}

internal/config/migrate.go

@@ -0,0 +1,65 @@
+package config
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+)
+
+func MigrateLegacy(outputDir string) {
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		return
+	}
+
+	oldDir := filepath.Join(homeDir, ".godeez")
+	oldDB := filepath.Join(oldDir, "tracks.db")
+	newDB := filepath.Join(outputDir, ".tracks.db")
+	if _, err := os.Stat(oldDB); err == nil {
+		if _, err := os.Stat(newDB); os.IsNotExist(err) {
+			if err := os.Rename(oldDB, newDB); err != nil {
+				if err := copyFile(oldDB, newDB); err != nil {
+					return
+				}
+				os.Remove(oldDB)
+			}
+		}
+	}
+
+	os.Remove(oldDir)
+}
+
+func copyFile(src, dst string) error {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	out, err := os.CreateTemp(filepath.Dir(dst), ".tracks.db-*.tmp")
+	if err != nil {
+		return err
+	}
+	tmp := out.Name()
+
+	if _, err := io.Copy(out, in); err != nil {
+		out.Close()
+		os.Remove(tmp)
+		return err
+	}
+	if err := out.Sync(); err != nil {
+		out.Close()
+		os.Remove(tmp)
+		return err
+	}
+	if err := out.Close(); err != nil {
+		os.Remove(tmp)
+		return err
+	}
+	if err := os.Rename(tmp, dst); err != nil {
+		os.Remove(tmp)
+		return err
+	}
+
+	return nil
+}

internal/crypto/crypto.go

@@ -1,41 +0,0 @@
-package crypto
-
-import (
-	"crypto/cipher"
-	"crypto/md5"
-	"encoding/hex"
-	"fmt"
-
-	"github.com/mathismqn/godeez/internal/config"
-	"golang.org/x/crypto/blowfish"
-)
-
-func GetBlowfishKey(songID string) []byte {
-	hash := md5.Sum([]byte(songID))
-	hashHex := fmt.Sprintf("%x", hash)
-
-	key := []byte(config.Cfg.SecretKey)
-	for i := 0; i < len(hash); i++ {
-		key[i] = key[i] ^ hashHex[i] ^ hashHex[i+16]
-	}
-
-	return key
-}
-
-func DecryptBlowfish(data, key []byte) ([]byte, error) {
-	block, err := blowfish.NewCipher(key)
-	if err != nil {
-		return nil, err
-	}
-
-	iv, err := hex.DecodeString(config.Cfg.IV)
-	if err != nil {
-		return nil, err
-	}
-
-	mode := cipher.NewCBCDecrypter(block, iv)
-	decrypted := make([]byte, len(data))
-	mode.CryptBlocks(decrypted, data)
-
-	return decrypted, nil
-}

internal/deezer/album.go

@@ -3,46 +3,47 @@ package deezer
 import (
 	"encoding/json"
 	"fmt"
-	"path"
+	"path/filepath"
 
 	"github.com/flytam/filenamify"
 )
 
 type Album struct {
-	Data struct {
+	Results struct {
-		Title               string `json:"ALB_TITLE"`
+		Data struct {
-		Artist              string `json:"ART_NAME"`
+			Title               string `json:"ALB_TITLE"`
-		OriginalReleaseDate string `json:"ORIGINAL_RELEASE_DATE"`
+			Artist              string `json:"ART_NAME"`
-		PhysicalReleaseDate string `json:"PHYSICAL_RELEASE_DATE"`
+			OriginalReleaseDate string `json:"ORIGINAL_RELEASE_DATE"`
-		Label               string `json:"LABEL_NAME"`
+			PhysicalReleaseDate string `json:"PHYSICAL_RELEASE_DATE"`
-		ProducerLine        string `json:"PRODUCER_LINE"`
+			Label               string `json:"LABEL_NAME"`
-	} `json:"DATA"`
+			ProducerLine        string `json:"PRODUCER_LINE"`
-	Songs struct {
+			Copyright           string `json:"COPYRIGHT"`
-		Data []*Song `json:"data"`
+			Duration            string `json:"DURATION"`
-	} `json:"SONGS"`
+		} `json:"DATA"`
+		Tracks struct {
+			Data []*Track `json:"data"`
+		} `json:"SONGS"`
+	} `json:"results"`
 }
 
-func (a *Album) GetURL(id string) string {
+func (a *Album) Title() string {
-	return "https://www.deezer.com/en/album/" + id
+	return a.Results.Data.Title
 }
 
-func (a *Album) UnmarshalData(data []byte) error {
+func (a *Album) Tracks() []*Track {
+	return a.Results.Tracks.Data
+}
+
+func (a *Album) SetTracks(t []*Track) {
+	a.Results.Tracks.Data = t
+}
+
+func (a *Album) OutputDir(outputDir string) string {
+	base := fmt.Sprintf("%s - %s", a.Results.Data.Artist, a.Results.Data.Title)
+	base, _ = filenamify.Filenamify(base, filenamify.Options{})
+	return filepath.Join(outputDir, base)
+}
+
+func (a *Album) decode(data []byte) error {
 	return json.Unmarshal(data, a)
 }
-
-func (a *Album) GetSongs() []*Song {
-	return a.Songs.Data
-}
-
-func (a *Album) GetOutputPath(outputDir string) string {
-	base := fmt.Sprintf("%s - %s", a.Data.Artist, a.Data.Title)
-	base, _ = filenamify.Filenamify(base, filenamify.Options{})
-	outputPath := path.Join(outputDir, base)
-	outputPath, _ = filenamify.Filenamify(outputPath, filenamify.Options{})
-
-	return outputPath
-}
-
-func (a *Album) GetTitle() string {
-	return a.Data.Title
-}

internal/deezer/artist.go

@@ -0,0 +1,40 @@
+package deezer
+
+import (
+	"encoding/json"
+	"path/filepath"
+
+	"github.com/flytam/filenamify"
+)
+
+type Artist struct {
+	Results struct {
+		Data struct {
+			Name string `json:"ART_NAME"`
+		} `json:"DATA"`
+		Tracks struct {
+			Data []*Track `json:"data"`
+		} `json:"TOP"`
+	} `json:"results"`
+}
+
+func (a *Artist) Title() string {
+	return a.Results.Data.Name
+}
+
+func (a *Artist) Tracks() []*Track {
+	return a.Results.Tracks.Data
+}
+
+func (a *Artist) SetTracks(t []*Track) {
+	a.Results.Tracks.Data = t
+}
+
+func (a *Artist) OutputDir(outputDir string) string {
+	base, _ := filenamify.Filenamify(a.Results.Data.Name, filenamify.Options{})
+	return filepath.Join(outputDir, base)
+}
+
+func (a *Artist) decode(data []byte) error {
+	return json.Unmarshal(data, a)
+}

internal/deezer/blowfish.go

@@ -0,0 +1,39 @@
+package deezer
+
+import (
+	"crypto/cipher"
+	"crypto/md5"
+	"encoding/hex"
+
+	"golang.org/x/crypto/blowfish"
+)
+
+var (
+	blowfishIV        = []byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07}
+	blowfishSecretKey = []byte("g4el58wc0zvf9na1")
+)
+
+func BlowfishKey(trackID string) []byte {
+	hash := md5.Sum([]byte(trackID))
+	hashHex := hex.EncodeToString(hash[:])
+
+	key := make([]byte, len(blowfishSecretKey))
+	copy(key, blowfishSecretKey)
+	for i := range len(hash) {
+		key[i] = key[i] ^ hashHex[i] ^ hashHex[i+16]
+	}
+
+	return key
+}
+
+func DecryptBlowfish(data, key []byte) ([]byte, error) {
+	block, err := blowfish.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	decrypted := make([]byte, len(data))
+	cipher.NewCBCDecrypter(block, blowfishIV).CryptBlocks(decrypted, data)
+
+	return decrypted, nil
+}

internal/deezer/blowfish_test.go

@@ -0,0 +1,56 @@
+package deezer
+
+import (
+	"bytes"
+	"crypto/cipher"
+	"encoding/hex"
+	"testing"
+
+	"golang.org/x/crypto/blowfish"
+)
+
+func TestBlowfishKey(t *testing.T) {
+	tests := []struct {
+		trackID string
+		want    string
+	}{
+		{"3135556", "6c6c666b39662c37652575603c643439"},
+		{"123456789", "6d34656061377f31322a7336393f626b"},
+		{"1", "3464656e343a7d3a672c236a33696061"},
+	}
+
+	for _, tt := range tests {
+		got := hex.EncodeToString(BlowfishKey(tt.trackID))
+		if got != tt.want {
+			t.Errorf("BlowfishKey(%q) = %s, want %s", tt.trackID, got, tt.want)
+		}
+	}
+}
+
+func TestDecryptBlowfishRoundTrip(t *testing.T) {
+	key := BlowfishKey("3135556")
+	plaintext := bytes.Repeat([]byte("01234567"), 16)
+
+	block, err := blowfish.NewCipher(key)
+	if err != nil {
+		t.Fatalf("NewCipher: %v", err)
+	}
+
+	encrypted := make([]byte, len(plaintext))
+	cipher.NewCBCEncrypter(block, blowfishIV).CryptBlocks(encrypted, plaintext)
+
+	decrypted, err := DecryptBlowfish(encrypted, key)
+	if err != nil {
+		t.Fatalf("DecryptBlowfish: %v", err)
+	}
+
+	if !bytes.Equal(decrypted, plaintext) {
+		t.Errorf("round trip mismatch: got %x, want %x", decrypted, plaintext)
+	}
+}
+
+func TestDecryptBlowfishInvalidKey(t *testing.T) {
+	if _, err := DecryptBlowfish(make([]byte, 8), nil); err == nil {
+		t.Error("expected error for nil key")
+	}
+}

internal/deezer/client.go

@@ -0,0 +1,222 @@
+package deezer
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+type Client struct {
+	Session *Session
+}
+
+func NewClient(ctx context.Context, arlCookie string) (*Client, error) {
+	session, err := resolveSession(ctx, arlCookie)
+	if err != nil {
+		return nil, fmt.Errorf("failed to authenticate: %w", err)
+	}
+
+	return &Client{
+		Session: session,
+	}, nil
+}
+
+func resolveSession(ctx context.Context, arlCookie string) (*Session, error) {
+	if arlCookie != "" {
+		return authenticate(ctx, arlCookie)
+	}
+
+	var session *Session
+	validate := func(ctx context.Context, arl string) error {
+		s, err := authenticate(ctx, arl)
+		if err != nil {
+			return err
+		}
+		session = s
+
+		return nil
+	}
+
+	arl, err := resolveARL(ctx, validate)
+	if err != nil {
+		return nil, err
+	}
+
+	if session == nil {
+		session, err = authenticate(ctx, arl)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return session, nil
+}
+
+func (c *Client) FetchResource(ctx context.Context, kind Kind, id string) (Resource, error) {
+	resource, err := kind.newResource()
+	if err != nil {
+		return nil, err
+	}
+
+	payload := map[string]any{
+		"nb":     10000,
+		"start":  0,
+		"lang":   "en",
+		"tab":    0,
+		"tags":   true,
+		"header": true,
+	}
+	payload[kind.idKey()] = id
+
+	jsonData, err := json.Marshal(payload)
+	if err != nil {
+		return nil, err
+	}
+
+	url := fmt.Sprintf("https://www.deezer.com/ajax/gw-light.php?method=deezer.page%s&input=3&api_version=1.0&api_token=%s", kind.pageMethod(), c.Session.apiToken)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBuffer(jsonData))
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.Session.HTTPClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	bodyStr := string(body)
+	for _, check := range []struct {
+		marker string
+		errMsg string
+	}{
+		{`"DATA_ERROR":"playlist::getData"`, "invalid playlist ID"},
+		{`"DATA_ERROR":"album::getData"`, "invalid album ID"},
+		{`"DATA_ERROR":"artist::getData"`, "invalid artist ID"},
+		{`"DATA_ERROR":"song::getData"`, "invalid track ID"},
+	} {
+		if strings.Contains(bodyStr, check.marker) {
+			return nil, errors.New(check.errMsg)
+		}
+	}
+
+	if strings.Contains(bodyStr, `"results":{}`) {
+		return nil, errors.New("unexpected response")
+	}
+
+	if err := resource.decode(body); err != nil {
+		return nil, err
+	}
+
+	return resource, nil
+}
+
+func (c *Client) FetchMedia(ctx context.Context, track *Track, quality string) (*Media, error) {
+	qualityFormats := map[string]string{
+		"mp3_128": `[{"cipher":"BF_CBC_STRIPE","format":"MP3_128"}]`,
+		"mp3_320": `[{"cipher":"BF_CBC_STRIPE","format":"MP3_320"},{"cipher":"BF_CBC_STRIPE","format":"MP3_128"}]`,
+		"flac":    `[{"cipher":"BF_CBC_STRIPE","format":"FLAC"},{"cipher":"BF_CBC_STRIPE","format":"MP3_320"},{"cipher":"BF_CBC_STRIPE","format":"MP3_128"}]`,
+	}
+
+	reqBody := fmt.Sprintf(`{"license_token":"%s","media":[{"type":"FULL","formats":%s}],"track_tokens":["%s"]}`, c.Session.licenseToken, qualityFormats[quality], track.TrackToken)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, "https://media.deezer.com/v1/get_url", bytes.NewBuffer([]byte(reqBody)))
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.Session.HTTPClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusBadRequest {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var media Media
+	if err := json.Unmarshal(body, &media); err != nil {
+		return nil, err
+	}
+
+	if len(media.Errors) > 0 {
+		if media.Errors[0].Code == 1000 {
+			return nil, errors.New("invalid license token")
+		}
+		return nil, errors.New(media.Errors[0].Message)
+	}
+
+	if len(media.Data) > 0 && len(media.Data[0].Errors) > 0 {
+		if media.Data[0].Errors[0].Code == 2002 {
+			return nil, errors.New("invalid track token")
+		}
+		return nil, errors.New(media.Data[0].Errors[0].Message)
+	}
+
+	if len(media.Data) == 0 || len(media.Data[0].Media) == 0 || len(media.Data[0].Media[0].Sources) == 0 {
+		return nil, errors.New("no sources found")
+	}
+
+	return &media, nil
+}
+
+func (c *Client) FetchCoverImage(ctx context.Context, track *Track) ([]byte, error) {
+	url := fmt.Sprintf("https://e-cdn-images.dzcdn.net/images/cover/%s/500x500-000000-80-0-0.jpg", track.Cover)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.Session.HTTPClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	return io.ReadAll(resp.Body)
+}
+
+func (c *Client) MediaStream(ctx context.Context, media *Media) (io.ReadCloser, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, media.URL(), nil)
+	if err != nil {
+		return nil, err
+	}
+
+	streamingClient := *c.Session.HTTPClient
+	streamingClient.Timeout = 0
+
+	resp, err := streamingClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	return resp.Body, nil
+}

internal/deezer/credentials.go

@@ -0,0 +1,61 @@
+package deezer
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/zalando/go-keyring"
+)
+
+const (
+	keyringService = "godeez"
+	keyringUser    = "default"
+)
+
+type Credentials struct {
+	Email    string `json:"email"`
+	Password string `json:"password"`
+	ARL      string `json:"arl,omitempty"`
+}
+
+func loadCredentials() (*Credentials, error) {
+	secret, err := keyring.Get(keyringService, keyringUser)
+	if err != nil {
+		if errors.Is(err, keyring.ErrNotFound) {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	var creds Credentials
+	if err := json.Unmarshal([]byte(secret), &creds); err != nil {
+		return nil, err
+	}
+
+	return &creds, nil
+}
+
+func saveCredentials(creds *Credentials) error {
+	data, err := json.Marshal(creds)
+	if err != nil {
+		return err
+	}
+
+	if err := keyring.Set(keyringService, keyringUser, string(data)); err != nil {
+		return fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	return nil
+}
+
+func ClearCredentials() error {
+	if err := keyring.Delete(keyringService, keyringUser); err != nil {
+		if errors.Is(err, keyring.ErrNotFound) {
+			return nil
+		}
+		return fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	return nil
+}

internal/deezer/ecb.go

@@ -0,0 +1,42 @@
+package deezer
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"fmt"
+)
+
+func zeroPad(data []byte) []byte {
+	bs := aes.BlockSize
+	padded := make([]byte, len(data)+(bs-len(data)%bs)%bs)
+	copy(padded, data)
+
+	return padded
+}
+
+func ecbEncrypt(key, data []byte) ([]byte, error) {
+	return ecbTransform(key, data, (cipher.Block).Encrypt)
+}
+
+func ecbDecrypt(key, data []byte) ([]byte, error) {
+	return ecbTransform(key, data, (cipher.Block).Decrypt)
+}
+
+func ecbTransform(key, data []byte, op func(cipher.Block, []byte, []byte)) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	bs := block.BlockSize()
+	if len(data)%bs != 0 {
+		return nil, fmt.Errorf("data length %d is not a multiple of the AES block size", len(data))
+	}
+
+	out := make([]byte, len(data))
+	for i := 0; i < len(data); i += bs {
+		op(block, out[i:i+bs], data[i:i+bs])
+	}
+
+	return out, nil
+}

internal/deezer/ecb_test.go

@@ -0,0 +1,72 @@
+package deezer
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestZeroPad(t *testing.T) {
+	tests := []struct {
+		length int
+		want   int
+	}{
+		{0, 0},
+		{1, 16},
+		{15, 16},
+		{16, 16},
+		{17, 32},
+	}
+
+	for _, tt := range tests {
+		padded := zeroPad(make([]byte, tt.length))
+		if len(padded) != tt.want {
+			t.Errorf("zeroPad(len %d) = len %d, want %d", tt.length, len(padded), tt.want)
+		}
+	}
+}
+
+func TestZeroPadPreservesData(t *testing.T) {
+	data := []byte("secret")
+	padded := zeroPad(data)
+
+	if !bytes.Equal(padded[:len(data)], data) {
+		t.Errorf("zeroPad changed data: got %q", padded[:len(data)])
+	}
+	for _, b := range padded[len(data):] {
+		if b != 0 {
+			t.Errorf("padding is not zero: %v", padded)
+		}
+	}
+}
+
+func TestECBRoundTrip(t *testing.T) {
+	key := []byte("0123456789abcdef")
+	plaintext := zeroPad([]byte("some secret data"))
+
+	encrypted, err := ecbEncrypt(key, plaintext)
+	if err != nil {
+		t.Fatalf("ecbEncrypt: %v", err)
+	}
+	if bytes.Equal(encrypted, plaintext) {
+		t.Fatal("encrypted data equals plaintext")
+	}
+
+	decrypted, err := ecbDecrypt(key, encrypted)
+	if err != nil {
+		t.Fatalf("ecbDecrypt: %v", err)
+	}
+	if !bytes.Equal(decrypted, plaintext) {
+		t.Errorf("round trip mismatch: got %q, want %q", decrypted, plaintext)
+	}
+}
+
+func TestECBRejectsPartialBlock(t *testing.T) {
+	key := []byte("0123456789abcdef")
+
+	if _, err := ecbEncrypt(key, make([]byte, 15)); err == nil {
+		t.Error("expected error for data not a multiple of the block size")
+	}
+	if _, err := ecbDecrypt(key, make([]byte, 17)); err == nil {
+		t.Error("expected error for data not a multiple of the block size")
+	}
+}

internal/deezer/gateway.go

@@ -0,0 +1,269 @@
+package deezer
+
+import (
+	"bytes"
+	"context"
+	"crypto/aes"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"math/rand/v2"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"time"
+)
+
+const (
+	gatewayBaseURL   = "https://api.deezer.com/1.0/gateway.php"
+	gatewayUserAgent = "Deezer/6.1.22.49 (Android; 9; Tablet; us) innotek GmbH VirtualBox"
+	nonceAlphabet    = "012345689abdef"
+)
+
+const (
+	deviceOS       = "Android"
+	deviceName     = "VirtualBox"
+	deviceType     = "tablet"
+	deviceModel    = "VirtualBox"
+	devicePlatform = "innotek GmbH_x86_64_9"
+	deviceSerial   = ""
+)
+
+type mobileClient struct {
+	httpClient *http.Client
+	apiKey     string
+	gwKey      []byte
+	sid        string
+}
+
+func CheckGatewayEnv() error {
+	_, _, err := gatewayEnv()
+	return err
+}
+
+func gatewayEnv() (string, string, error) {
+	apiKey := os.Getenv("DEEZER_MOBILE_API_KEY")
+	gwKey := os.Getenv("DEEZER_MOBILE_GW_KEY")
+	if apiKey == "" || gwKey == "" {
+		return "", "", errors.New("DEEZER_MOBILE_API_KEY and DEEZER_MOBILE_GW_KEY must be set to use email/password login")
+	}
+
+	if len(gwKey) != aes.BlockSize {
+		return "", "", fmt.Errorf("DEEZER_MOBILE_GW_KEY must be exactly %d bytes long", aes.BlockSize)
+	}
+
+	return apiKey, gwKey, nil
+}
+
+func newMobileClient() (*mobileClient, error) {
+	apiKey, gwKey, err := gatewayEnv()
+	if err != nil {
+		return nil, err
+	}
+
+	return &mobileClient{
+		httpClient: &http.Client{Timeout: 20 * time.Second},
+		apiKey:     apiKey,
+		gwKey:      []byte(gwKey),
+	}, nil
+}
+
+func (m *mobileClient) login(ctx context.Context, email, password string) (*Credentials, string, error) {
+	token, tokenKey, userKey, err := m.authenticate(ctx)
+	if err != nil {
+		return nil, "", err
+	}
+
+	if err := m.checkToken(ctx, token, tokenKey); err != nil {
+		return nil, "", err
+	}
+
+	arl, username, err := m.userAuth(ctx, email, password, userKey)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return &Credentials{Email: email, Password: password, ARL: arl}, username, nil
+}
+
+func (m *mobileClient) authenticate(ctx context.Context) (string, string, string, error) {
+	body, err := m.gatewayRequest(ctx, "mobile_auth", http.MethodGet, "uniq_id", genUniqID(), nil)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	var res struct {
+		Results struct {
+			Token string `json:"TOKEN"`
+		} `json:"results"`
+	}
+	if err := json.Unmarshal(body, &res); err != nil {
+		return "", "", "", err
+	}
+
+	if strings.Contains(string(body), "Undefined or invalid API key") {
+		return "", "", "", errors.New("DEEZER_MOBILE_API_KEY is invalid")
+	}
+	if strings.Contains(string(body), "GATEWAY_ERROR") || res.Results.Token == "" {
+		return "", "", "", errors.New("unexpected response from gateway")
+	}
+
+	encrypted, err := hex.DecodeString(res.Results.Token)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	decrypted, err := ecbDecrypt(m.gwKey, encrypted)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	if len(decrypted) < 96 {
+		return "", "", "", errors.New("unexpected response from gateway")
+	}
+
+	token := string(decrypted[0:64])
+	tokenKey := string(decrypted[64:80])
+	userKey := string(decrypted[80:96])
+
+	return token, tokenKey, userKey, nil
+}
+
+func (m *mobileClient) checkToken(ctx context.Context, token, tokenKey string) error {
+	encrypted, err := ecbEncrypt([]byte(tokenKey), []byte(token))
+	if err != nil {
+		return err
+	}
+	authToken := hex.EncodeToString(encrypted)
+
+	body, err := m.gatewayRequest(ctx, "api_checkToken", http.MethodGet, "auth_token", authToken, nil)
+	if err != nil {
+		return err
+	}
+
+	var res struct {
+		Results string `json:"results"`
+	}
+	if err := json.Unmarshal(body, &res); err != nil {
+		return err
+	}
+	if res.Results == "" {
+		return errors.New("unexpected response from gateway")
+	}
+	m.sid = res.Results
+
+	return nil
+}
+
+func (m *mobileClient) userAuth(ctx context.Context, email, password, userKey string) (string, string, error) {
+	encryptedPassword, err := ecbEncrypt([]byte(userKey), zeroPad([]byte(password)))
+	if err != nil {
+		return "", "", err
+	}
+
+	payload := map[string]string{
+		"mail":                              email,
+		"password":                          hex.EncodeToString(encryptedPassword),
+		"device_serial":                     deviceSerial,
+		"platform":                          devicePlatform,
+		"custo_version_id":                  "",
+		"custo_partner":                     "",
+		"model":                             deviceModel,
+		"device_name":                       deviceName,
+		"device_os":                         deviceOS,
+		"device_type":                       deviceType,
+		"google_play_services_availability": "1",
+		"consent_string":                    "",
+	}
+
+	jsonBody, err := json.Marshal(payload)
+	if err != nil {
+		return "", "", err
+	}
+
+	body, err := m.gatewayRequest(ctx, "mobile_userAuth", http.MethodPost, "", "", jsonBody)
+	if err != nil {
+		return "", "", err
+	}
+
+	if strings.Contains(string(body), "USER_AUTH_ERROR") {
+		return "", "", errors.New("invalid email or password")
+	}
+
+	var res struct {
+		Results struct {
+			ARL      string `json:"ARL"`
+			UserID   int    `json:"USER_ID"`
+			BlogName string `json:"BLOG_NAME"`
+		} `json:"results"`
+	}
+	if err := json.Unmarshal(body, &res); err != nil {
+		return "", "", err
+	}
+
+	if res.Results.ARL == "" || res.Results.UserID == 0 {
+		return "", "", errors.New("unexpected response from gateway")
+	}
+
+	return res.Results.ARL, res.Results.BlogName, nil
+}
+
+func (m *mobileClient) gatewayRequest(ctx context.Context, method, httpMethod, paramKey, paramValue string, jsonBody []byte) ([]byte, error) {
+	u, err := url.Parse(gatewayBaseURL)
+	if err != nil {
+		return nil, err
+	}
+
+	q := u.Query()
+	q.Set("method", method)
+	q.Set("api_key", m.apiKey)
+	q.Set("output", "3")
+	if httpMethod == http.MethodPost {
+		q.Set("input", "3")
+	}
+	if m.sid != "" {
+		q.Set("sid", m.sid)
+	}
+	if paramKey != "" {
+		q.Set(paramKey, paramValue)
+	}
+	u.RawQuery = q.Encode()
+
+	var reqBody io.Reader
+	if jsonBody != nil {
+		reqBody = bytes.NewReader(jsonBody)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, httpMethod, u.String(), reqBody)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("User-Agent", gatewayUserAgent)
+	if jsonBody != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	resp, err := m.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	return io.ReadAll(resp.Body)
+}
+
+func genUniqID() string {
+	b := make([]byte, 32)
+	for i := range b {
+		b[i] = nonceAlphabet[rand.IntN(len(nonceAlphabet))]
+	}
+
+	return string(b)
+}

internal/deezer/kind.go

@@ -0,0 +1,57 @@
+package deezer
+
+import "fmt"
+
+type Kind string
+
+const (
+	KindAlbum    Kind = "album"
+	KindPlaylist Kind = "playlist"
+	KindArtist   Kind = "artist"
+	KindTrack    Kind = "track"
+)
+
+func (k Kind) pageMethod() string {
+	switch k {
+	case KindAlbum:
+		return "Album"
+	case KindPlaylist:
+		return "Playlist"
+	case KindArtist:
+		return "Artist"
+	case KindTrack:
+		return "Track"
+	}
+
+	return ""
+}
+
+func (k Kind) idKey() string {
+	switch k {
+	case KindAlbum:
+		return "alb_id"
+	case KindPlaylist:
+		return "playlist_id"
+	case KindArtist:
+		return "art_id"
+	case KindTrack:
+		return "sng_id"
+	}
+
+	return ""
+}
+
+func (k Kind) newResource() (Resource, error) {
+	switch k {
+	case KindAlbum:
+		return &Album{}, nil
+	case KindPlaylist:
+		return &Playlist{}, nil
+	case KindArtist:
+		return &Artist{}, nil
+	case KindTrack:
+		return &Single{}, nil
+	}
+
+	return nil, fmt.Errorf("unsupported resource type: %s", k)
+}

internal/deezer/login.go

@@ -0,0 +1,54 @@
+package deezer
+
+import (
+	"context"
+	"errors"
+	"fmt"
+)
+
+func resolveARL(ctx context.Context, validate func(ctx context.Context, arl string) error) (string, error) {
+	creds, err := loadCredentials()
+	if err != nil {
+		return "", err
+	}
+
+	if creds != nil && creds.ARL != "" {
+		verr := validate(ctx, creds.ARL)
+		if verr == nil {
+			return creds.ARL, nil
+		}
+
+		if !errors.Is(verr, ErrInvalidARL) {
+			return "", fmt.Errorf("stored session could not be validated: %w", verr)
+		}
+	}
+
+	if creds != nil && creds.Email != "" && creds.Password != "" {
+		arl, _, err := Login(ctx, creds.Email, creds.Password)
+		if err != nil {
+			return "", fmt.Errorf("stored session expired and could not be renewed automatically: %w", err)
+		}
+
+		return arl, nil
+	}
+
+	return "", errors.New("run 'godeez login' or export DEEZER_ARL environment variable")
+}
+
+func Login(ctx context.Context, email, password string) (string, string, error) {
+	client, err := newMobileClient()
+	if err != nil {
+		return "", "", err
+	}
+
+	creds, username, err := client.login(ctx, email, password)
+	if err != nil {
+		return "", "", err
+	}
+
+	if err := saveCredentials(creds); err != nil {
+		return "", "", err
+	}
+
+	return creds.ARL, username, nil
+}

internal/deezer/media.go

@@ -1,98 +1,27 @@
 package deezer
 
-import (
-	"fmt"
-	"net/http"
-	"os"
-
-	"github.com/mathismqn/godeez/internal/crypto"
-)
-
 type Media struct {
-	Errors []MediaError `json:"errors"`
+	Errors []mediaError `json:"errors"`
 	Data   []struct {
 		Media []struct {
-			Type    string   `json:"media_type"`
+			Format  string `json:"format"`
-			Cipher  Cipher   `json:"cipher"`
+			Sources []struct {
-			Format  string   `json:"format"`
+				URL string `json:"url"`
-			Sources []Source `json:"sources"`
+			} `json:"sources"`
 		}
-		Errors []MediaError `json:"errors"`
+		Errors []mediaError `json:"errors"`
 	} `json:"data"`
 }
 
-type MediaError struct {
+type mediaError struct {
 	Code    int    `json:"code"`
 	Message string `json:"message"`
 }
 
-type Cipher struct {
+func (m *Media) URL() string {
-	Type string `json:"type"`
+	return m.Data[0].Media[0].Sources[0].URL
 }
 
-type Source struct {
+func (m *Media) Format() string {
-	URL      string `json:"url"`
+	return m.Data[0].Media[0].Format
-	Provider string `json:"provider"`
-}
-
-const ChunkSize = 2048
-
-func (m *Media) Download(url, path, songID string) error {
-	resp, err := http.Get(url)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK {
-		return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
-	}
-
-	file, err := os.Create(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	key := crypto.GetBlowfishKey(songID)
-	buffer := make([]byte, ChunkSize)
-
-	for chunk := 0; ; chunk++ {
-		totalRead := 0
-		for totalRead < ChunkSize {
-			n, err := resp.Body.Read(buffer[totalRead:])
-			if err != nil {
-				if err.Error() == "EOF" {
-					break
-				}
-				return err
-			}
-
-			if n > 0 {
-				totalRead += n
-			}
-		}
-
-		if totalRead == 0 {
-			break
-		}
-
-		if chunk%3 == 0 && totalRead == ChunkSize {
-			buffer, err = crypto.DecryptBlowfish(buffer, key)
-			if err != nil {
-				return err
-			}
-		}
-
-		_, err = file.Write(buffer[:totalRead])
-		if err != nil {
-			return err
-		}
-
-		if totalRead < ChunkSize {
-			break
-		}
-	}
-
-	return nil
 }

internal/deezer/playlist.go

@@ -2,42 +2,41 @@ package deezer
 
 import (
 	"encoding/json"
-	"path"
+	"path/filepath"
 
 	"github.com/flytam/filenamify"
 )
 
 type Playlist struct {
-	Data struct {
+	Results struct {
-		Title     string `json:"TITLE"`
+		Data struct {
-		Status    int    `json:"STATUS"`
+			Title    string `json:"TITLE"`
-		CollabKey string `json:"COLLAB_KEY"`
+			Creator  string `json:"PARENT_USERNAME"`
-	} `json:"DATA"`
+			Duration int    `json:"DURATION"`
-	Songs struct {
+		} `json:"DATA"`
-		Data []*Song `json:"data"`
+		Tracks struct {
-	} `json:"SONGS"`
+			Data []*Track `json:"data"`
+		} `json:"SONGS"`
+	} `json:"results"`
 }
 
-func (p *Playlist) GetURL(id string) string {
+func (p *Playlist) Title() string {
-	return "https://www.deezer.com/en/playlist/" + id
+	return p.Results.Data.Title
 }
 
-func (p *Playlist) UnmarshalData(data []byte) error {
+func (p *Playlist) Tracks() []*Track {
+	return p.Results.Tracks.Data
+}
+
+func (p *Playlist) SetTracks(t []*Track) {
+	p.Results.Tracks.Data = t
+}
+
+func (p *Playlist) OutputDir(outputDir string) string {
+	base, _ := filenamify.Filenamify(p.Results.Data.Title, filenamify.Options{})
+	return filepath.Join(outputDir, base)
+}
+
+func (p *Playlist) decode(data []byte) error {
 	return json.Unmarshal(data, p)
 }
-
-func (p *Playlist) GetSongs() []*Song {
-	return p.Songs.Data
-}
-
-func (p *Playlist) GetOutputPath(outputDir string) string {
-	p.Data.Title, _ = filenamify.Filenamify(p.Data.Title, filenamify.Options{})
-	outputPath := path.Join(outputDir, p.Data.Title)
-	outputPath, _ = filenamify.Filenamify(outputPath, filenamify.Options{})
-
-	return outputPath
-}
-
-func (p *Playlist) GetTitle() string {
-	return p.Data.Title
-}

internal/deezer/resource.go

@@ -1,57 +1,9 @@
 package deezer
 
-import (
-	"fmt"
-	"io"
-	"net/http"
-	"regexp"
-
-	"github.com/mathismqn/godeez/internal/config"
-)
-
 type Resource interface {
-	GetURL(id string) string
+	Title() string
-	UnmarshalData(data []byte) error
+	Tracks() []*Track
-	GetSongs() []*Song
+	SetTracks(tracks []*Track)
-	GetOutputPath(outputDir string) string
+	OutputDir(outputDir string) string
-	GetTitle() string
+	decode(data []byte) error
-}
-
-func GetData(r Resource, id string) error {
-	url := r.GetURL(id)
-
-	client := &http.Client{}
-	req, err := http.NewRequest("GET", url, nil)
-	if err != nil {
-		return err
-	}
-
-	if config.Cfg.ArlCookie != "" {
-		req.AddCookie(&http.Cookie{
-			Name:  "arl",
-			Value: config.Cfg.ArlCookie,
-		})
-	}
-
-	resp, err := client.Do(req)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK {
-		if resp.StatusCode == http.StatusNotFound {
-			return fmt.Errorf("resource not found")
-		}
-		return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
-	}
-
-	body, _ := io.ReadAll(resp.Body)
-	re := regexp.MustCompile(`window\.__DZR_APP_STATE__ = (\{.*\})`)
-	matches := re.FindStringSubmatch(string(body))
-	if len(matches) != 2 {
-		return fmt.Errorf("error parsing response")
-	}
-
-	return r.UnmarshalData([]byte(matches[1]))
 }

internal/deezer/session.go

@@ -0,0 +1,87 @@
+package deezer
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/cookiejar"
+	"time"
+)
+
+var ErrInvalidARL = errors.New("invalid or expired ARL cookie")
+
+type Session struct {
+	apiToken     string
+	licenseToken string
+	HTTPClient   *http.Client
+	Premium      bool
+}
+
+func authenticate(ctx context.Context, arlCookie string) (*Session, error) {
+	jar, err := cookiejar.New(nil)
+	if err != nil {
+		return nil, err
+	}
+	client := &http.Client{
+		Timeout: 20 * time.Second,
+		Jar:     jar,
+	}
+
+	url := "https://www.deezer.com/ajax/gw-light.php?method=deezer.getUserData&input=3&api_version=1.0&api_token="
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	req.AddCookie(&http.Cookie{
+		Name:  "arl",
+		Value: arlCookie,
+	})
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var res struct {
+		Results struct {
+			APIToken string `json:"checkForm"`
+			User     struct {
+				ID      int `json:"USER_ID"`
+				Options struct {
+					LicenseToken  string `json:"license_token"`
+					MobileOffline bool   `json:"mobile_offline"`
+					WebOffline    bool   `json:"web_offline"`
+				} `json:"OPTIONS"`
+			} `json:"USER"`
+		} `json:"results"`
+	}
+	if err := json.Unmarshal(body, &res); err != nil {
+		return nil, err
+	}
+
+	if res.Results.User.ID == 0 {
+		return nil, ErrInvalidARL
+	}
+
+	opts := res.Results.User.Options
+	return &Session{
+		apiToken:     res.Results.APIToken,
+		licenseToken: opts.LicenseToken,
+		HTTPClient:   client,
+		Premium:      opts.MobileOffline || opts.WebOffline,
+	}, nil
+}

internal/deezer/single.go

@@ -0,0 +1,36 @@
+package deezer
+
+import (
+	"encoding/json"
+	"path/filepath"
+)
+
+type Single struct {
+	Results struct {
+		Data *Track `json:"DATA"`
+	} `json:"results"`
+}
+
+func (s *Single) Title() string {
+	if s.Results.Data == nil {
+		return ""
+	}
+	return s.Results.Data.FullTitle()
+}
+
+func (s *Single) Tracks() []*Track {
+	if s.Results.Data == nil {
+		return nil
+	}
+	return []*Track{s.Results.Data}
+}
+
+func (s *Single) SetTracks(tracks []*Track) {}
+
+func (s *Single) OutputDir(outputDir string) string {
+	return filepath.Join(outputDir, "Singles")
+}
+
+func (s *Single) decode(data []byte) error {
+	return json.Unmarshal(data, s)
+}

internal/deezer/song.go

@@ -1,95 +0,0 @@
-package deezer
-
-import (
-	"bytes"
-	"encoding/json"
-	"fmt"
-	"io"
-	"net/http"
-
-	"github.com/mathismqn/godeez/internal/config"
-)
-
-type Song struct {
-	ID           string `json:"SNG_ID"`
-	Artist       string `json:"ART_NAME"`
-	Title        string `json:"SNG_TITLE"`
-	Version      string `json:"VERSION"`
-	Cover        string `json:"ALB_PICTURE"`
-	Contributors struct {
-		MainArtists []string `json:"main_artist"`
-		Composers   []string `json:"composer"`
-		Authors     []string `json:"author"`
-	} `json:"SNG_CONTRIBUTORS"`
-	Duration    string `json:"DURATION"`
-	Gain        string `json:"GAIN"`
-	ISRC        string `json:"ISRC"`
-	TrackNumber string `json:"TRACK_NUMBER"`
-	TrackToken  string `json:"TRACK_TOKEN"`
-}
-
-func (s *Song) GetMediaData(quality string) (*Media, error) {
-	var formats string
-
-	switch quality {
-	case "mp3_128":
-		formats = `[{"cipher":"BF_CBC_STRIPE","format":"MP3_128"}]`
-	case "mp3_320":
-		formats = `[{"cipher":"BF_CBC_STRIPE","format":"MP3_320"}]`
-	case "flac":
-		formats = `[{"cipher":"BF_CBC_STRIPE","format":"FLAC"}]`
-	case "best":
-		formats = `[{"cipher":"BF_CBC_STRIPE","format":"FLAC"},{"cipher":"BF_CBC_STRIPE","format":"MP3_320"},{"cipher":"BF_CBC_STRIPE","format":"MP3_128"}]`
-	}
-
-	reqBody := fmt.Sprintf(`{"license_token":"%s","media":[{"type":"FULL","formats":%s}],"track_tokens":["%s"]}`, config.Cfg.LicenseToken, formats, s.TrackToken)
-	resp, err := http.Post("https://media.deezer.com/v1/get_url", "application/json", bytes.NewBuffer([]byte(reqBody)))
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusBadRequest {
-		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
-	}
-
-	body, _ := io.ReadAll(resp.Body)
-
-	var media Media
-	err = json.Unmarshal(body, &media)
-	if err != nil {
-		return nil, err
-	}
-
-	if len(media.Errors) > 0 {
-		if media.Errors[0].Code == 1000 {
-			return nil, fmt.Errorf("invalid license token")
-		}
-
-		return nil, fmt.Errorf("%s", media.Errors[0].Message)
-	}
-	if len(media.Data) > 0 && len(media.Data[0].Errors) > 0 {
-		if media.Data[0].Errors[0].Code == 2002 {
-			return nil, fmt.Errorf("invalid track token")
-		}
-
-		return nil, fmt.Errorf("%s", media.Data[0].Errors[0].Message)
-	}
-
-	return &media, nil
-}
-
-func (s *Song) GetCoverImage() ([]byte, error) {
-	url := fmt.Sprintf("https://e-cdn-images.dzcdn.net/images/cover/%s/500x500-000000-80-0-0.jpg", s.Cover)
-	resp, err := http.Get(url)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
-	}
-
-	return io.ReadAll(resp.Body)
-}

internal/deezer/track.go

@@ -0,0 +1,91 @@
+package deezer
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+
+	"github.com/flytam/filenamify"
+)
+
+type Contributors struct {
+	MainArtists []string `json:"main_artist"`
+	Composers   []string `json:"composer"`
+	Authors     []string `json:"author"`
+}
+
+func (c *Contributors) UnmarshalJSON(data []byte) error {
+	if string(data) == "[]" {
+		*c = Contributors{}
+		return nil
+	}
+
+	type Alias Contributors
+	aux := (*Alias)(c)
+
+	return json.Unmarshal(data, aux)
+}
+
+type Track struct {
+	ID           string       `json:"SNG_ID"`
+	Artist       string       `json:"ART_NAME"`
+	Title        string       `json:"SNG_TITLE"`
+	Version      string       `json:"VERSION"`
+	Cover        string       `json:"ALB_PICTURE"`
+	Contributors Contributors `json:"SNG_CONTRIBUTORS"`
+	Duration     string       `json:"DURATION"`
+	Gain         string       `json:"GAIN"`
+	ISRC         string       `json:"ISRC"`
+	TrackNumber  string       `json:"TRACK_NUMBER"`
+	TrackToken   string       `json:"TRACK_TOKEN"`
+}
+
+func (t *Track) FullTitle() string {
+	if t.Version != "" {
+		return t.Title + " " + t.Version
+	}
+	return t.Title
+}
+
+func (t *Track) Filename(kind Kind, format string) string {
+	ext := "mp3"
+	switch format {
+	case "FLAC":
+		ext = "flac"
+	case "WAV":
+		ext = "wav"
+	}
+
+	prefix := ""
+	if kind == KindAlbum {
+		if n, err := strconv.Atoi(t.TrackNumber); err == nil {
+			prefix = fmt.Sprintf("%02d. ", n)
+		} else {
+			prefix = t.TrackNumber + ". "
+		}
+	}
+
+	base := fmt.Sprintf("%s%s - %s", prefix, t.Artist, t.FullTitle())
+	base, _ = filenamify.Filenamify(base, filenamify.Options{MaxLength: 255})
+	base = truncateBytes(base, 255-len(ext)-1-len("-id3v2"))
+
+	return base + "." + ext
+}
+
+func truncateBytes(s string, maxLen int) string {
+	if maxLen <= 0 {
+		return ""
+	}
+	if len(s) <= maxLen {
+		return s
+	}
+
+	last := 0
+	for i := range s {
+		if i > maxLen {
+			return s[:last]
+		}
+		last = i
+	}
+	return s[:last]
+}

internal/deezer/track_test.go

@@ -0,0 +1,116 @@
+package deezer
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+func TestFullTitle(t *testing.T) {
+	tests := []struct {
+		title   string
+		version string
+		want    string
+	}{
+		{"Song", "", "Song"},
+		{"Song", "(Remix)", "Song (Remix)"},
+	}
+
+	for _, tt := range tests {
+		track := &Track{Title: tt.title, Version: tt.version}
+		if got := track.FullTitle(); got != tt.want {
+			t.Errorf("FullTitle() = %q, want %q", got, tt.want)
+		}
+	}
+}
+
+func TestFilename(t *testing.T) {
+	tests := []struct {
+		name        string
+		track       Track
+		kind        Kind
+		mediaFormat string
+		want        string
+	}{
+		{
+			name:        "album with numeric track number",
+			track:       Track{Artist: "Artist", Title: "Song", TrackNumber: "1"},
+			kind:        KindAlbum,
+			mediaFormat: "MP3_320",
+			want:        "01. Artist - Song.mp3",
+		},
+		{
+			name:        "album with non-numeric track number",
+			track:       Track{Artist: "Artist", Title: "Song", TrackNumber: "A"},
+			kind:        KindAlbum,
+			mediaFormat: "MP3_320",
+			want:        "A. Artist - Song.mp3",
+		},
+		{
+			name:        "playlist has no prefix",
+			track:       Track{Artist: "Artist", Title: "Song", TrackNumber: "1"},
+			kind:        KindPlaylist,
+			mediaFormat: "MP3_128",
+			want:        "Artist - Song.mp3",
+		},
+		{
+			name:        "flac extension",
+			track:       Track{Artist: "Artist", Title: "Song"},
+			kind:        KindTrack,
+			mediaFormat: "FLAC",
+			want:        "Artist - Song.flac",
+		},
+		{
+			name:        "wav extension",
+			track:       Track{Artist: "Artist", Title: "Song"},
+			kind:        KindTrack,
+			mediaFormat: "WAV",
+			want:        "Artist - Song.wav",
+		},
+		{
+			name:        "version appended",
+			track:       Track{Artist: "Artist", Title: "Song", Version: "(Live)"},
+			kind:        KindTrack,
+			mediaFormat: "MP3_320",
+			want:        "Artist - Song (Live).mp3",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.track.Filename(tt.kind, tt.mediaFormat); got != tt.want {
+				t.Errorf("Filename() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestFilenameSanitizesSeparators(t *testing.T) {
+	track := Track{Artist: "AC/DC", Title: "Song"}
+	got := track.Filename(KindTrack, "MP3_320")
+
+	if strings.ContainsRune(got, '/') {
+		t.Errorf("Filename() contains a path separator: %q", got)
+	}
+	if !strings.HasSuffix(got, ".mp3") {
+		t.Errorf("Filename() = %q, want .mp3 suffix", got)
+	}
+}
+
+func TestContributorsUnmarshalJSON(t *testing.T) {
+	var c Contributors
+	if err := json.Unmarshal([]byte("[]"), &c); err != nil {
+		t.Fatalf("unmarshal empty array: %v", err)
+	}
+	if len(c.MainArtists) != 0 || len(c.Composers) != 0 || len(c.Authors) != 0 {
+		t.Errorf("expected empty contributors, got %+v", c)
+	}
+
+	data := `{"main_artist":["A","B"],"composer":["C"],"author":["D"]}`
+	if err := json.Unmarshal([]byte(data), &c); err != nil {
+		t.Fatalf("unmarshal object: %v", err)
+	}
+	if len(c.MainArtists) != 2 || c.MainArtists[0] != "A" || len(c.Composers) != 1 || len(c.Authors) != 1 {
+		t.Errorf("unexpected contributors: %+v", c)
+	}
+}

internal/download/bpm.go

@@ -0,0 +1,155 @@
+package download
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/PuerkitoBio/goquery"
+)
+
+var (
+	bpmRegex  = regexp.MustCompile(`tempo of <span[^>]*>(\d+) BPM`)
+	keyRegex  = regexp.MustCompile(`with a <span[^>]*>([A-G](?:♯|#|♭|b)?(?:/[A-G](?:♯|#|♭|b)?)?)</span> key`)
+	modeRegex = regexp.MustCompile(`a  <span[^>]*>([a-z]+)</span> mode`)
+)
+
+func fetchBPM(ctx context.Context, httpClient *http.Client, artist, title, duration string) (bpmKey, error) {
+	trackURL, err := findTrackURL(ctx, httpClient, artist, title, duration)
+	if err != nil {
+		return bpmKey{}, err
+	}
+
+	html, err := fetchBPMPage(ctx, httpClient, trackURL)
+	if err != nil {
+		return bpmKey{}, err
+	}
+
+	return parseBPM(html)
+}
+
+func findTrackURL(ctx context.Context, httpClient *http.Client, artist, title, duration string) (string, error) {
+	const rootURL = "https://songbpm.com"
+
+	values := url.Values{}
+	values.Add("query", fmt.Sprintf("%s %s", artist, title))
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, rootURL+"/searches", bytes.NewBufferString(values.Encode()))
+	if err != nil {
+		return "", err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.Header.Set("Origin", rootURL)
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	doc, err := goquery.NewDocumentFromReader(resp.Body)
+	if err != nil {
+		return "", err
+	}
+
+	wantDuration, err := strconv.Atoi(duration)
+	if err != nil {
+		return "", fmt.Errorf("invalid duration: %w", err)
+	}
+
+	lowerTitle := strings.ToLower(title)
+	lowerArtist := strings.ToLower(artist)
+
+	var matchURL string
+	doc.Find("a.flex.flex-col").EachWithBreak(func(_ int, sel *goquery.Selection) bool {
+		text := strings.ToLower(sel.Text())
+		if !strings.Contains(text, lowerTitle) || !strings.Contains(text, lowerArtist) {
+			return true
+		}
+
+		durationStr := strings.TrimSpace(sel.Find("div.flex-1.flex-col.items-center").Eq(1).Find("span.text-2xl").Text())
+		parts := strings.Split(durationStr, ":")
+		if len(parts) != 2 {
+			return true
+		}
+		minutes, err := strconv.Atoi(parts[0])
+		if err != nil {
+			return true
+		}
+		seconds, err := strconv.Atoi(parts[1])
+		if err != nil {
+			return true
+		}
+
+		const toleranceSec = 2
+		foundDuration := minutes*60 + seconds
+		if foundDuration < wantDuration-toleranceSec || foundDuration > wantDuration+toleranceSec {
+			return true
+		}
+
+		matchURL = sel.AttrOr("href", "")
+		return false
+	})
+
+	if matchURL == "" {
+		return "", errors.New("no data found")
+	}
+
+	return rootURL + matchURL, nil
+}
+
+func fetchBPMPage(ctx context.Context, httpClient *http.Client, pageURL string) (string, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, pageURL, nil)
+	if err != nil {
+		return "", err
+	}
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+
+	return string(body), nil
+}
+
+func parseBPM(html string) (bpmKey, error) {
+	bpmMatch := bpmRegex.FindStringSubmatch(html)
+	keyMatch := keyRegex.FindStringSubmatch(html)
+	modeMatch := modeRegex.FindStringSubmatch(html)
+
+	if len(bpmMatch) != 2 || len(keyMatch) != 2 || len(modeMatch) != 2 {
+		return bpmKey{}, errors.New("no data found")
+	}
+
+	bpm := bpmMatch[1]
+	key := strings.SplitN(keyMatch[1], "/", 2)[0]
+	key = strings.ReplaceAll(key, "\u266f", "#")
+	key = strings.ReplaceAll(key, "\u266d", "b")
+
+	if modeMatch[1] == "minor" {
+		key += "m"
+	}
+
+	return bpmKey{BPM: bpm, Key: key}, nil
+}

internal/download/bpm_test.go

@@ -0,0 +1,42 @@
+package download
+
+import "testing"
+
+func bpmHTML(bpm, key, mode string) string {
+	return `tempo of <span class="x">` + bpm + ` BPM</span>` +
+		` with a <span class="x">` + key + `</span> key` +
+		` and a  <span class="x">` + mode + `</span> mode`
+}
+
+func TestParseBPM(t *testing.T) {
+	tests := []struct {
+		name    string
+		html    string
+		wantBPM string
+		wantKey string
+	}{
+		{"major key", bpmHTML("128", "A", "major"), "128", "A"},
+		{"minor key gets m suffix", bpmHTML("90", "F", "minor"), "90", "Fm"},
+		{"unicode sharp normalized", bpmHTML("124", "C♯", "major"), "124", "C#"},
+		{"unicode flat normalized", bpmHTML("100", "B♭", "minor"), "100", "Bbm"},
+		{"enharmonic pair keeps first", bpmHTML("110", "A♯/B♭", "major"), "110", "A#"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseBPM(tt.html)
+			if err != nil {
+				t.Fatalf("parseBPM: %v", err)
+			}
+			if got.BPM != tt.wantBPM || got.Key != tt.wantKey {
+				t.Errorf("parseBPM() = %+v, want BPM %q Key %q", got, tt.wantBPM, tt.wantKey)
+			}
+		})
+	}
+}
+
+func TestParseBPMNoData(t *testing.T) {
+	if _, err := parseBPM("<html>nothing here</html>"); err == nil {
+		t.Error("expected error for page without BPM data")
+	}
+}

internal/download/download.go

@@ -0,0 +1,118 @@
+package download
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/config"
+	"github.com/mathismqn/godeez/internal/deezer"
+	"github.com/mathismqn/godeez/internal/fsutil"
+	"github.com/mathismqn/godeez/internal/store"
+)
+
+type Downloader struct {
+	appConfig    *config.Config
+	store        *store.Store
+	kind         deezer.Kind
+	deezerClient *deezer.Client
+
+	hashIndexOnce sync.Once
+	hashIndex     *hashIndex
+	hashIndexErr  error
+}
+
+func New(appConfig *config.Config, st *store.Store, kind deezer.Kind) *Downloader {
+	return &Downloader{
+		appConfig: appConfig,
+		store:     st,
+		kind:      kind,
+	}
+}
+
+func (d *Downloader) Run(ctx context.Context, opts Options, id string) error {
+	if err := d.initDeezerClient(ctx, opts); err != nil {
+		return err
+	}
+
+	resource, outputDir, err := d.prepareResource(ctx, id, opts)
+	if err != nil {
+		return err
+	}
+
+	return d.downloadAllTracks(ctx, resource, opts, outputDir)
+}
+
+func (d *Downloader) initDeezerClient(ctx context.Context, opts Options) error {
+	var err error
+	d.deezerClient, err = deezer.NewClient(ctx, d.appConfig.ARLCookie)
+	if err != nil {
+		return err
+	}
+
+	if !d.deezerClient.Session.Premium && opts.sourceQuality() != "mp3_128" {
+		return fmt.Errorf("premium account required for '%s' quality", opts.Quality)
+	}
+
+	return nil
+}
+
+func (d *Downloader) prepareResource(ctx context.Context, id string, opts Options) (deezer.Resource, string, error) {
+	resource, err := d.deezerClient.FetchResource(ctx, d.kind, id)
+	if err != nil {
+		return nil, "", fmt.Errorf("failed to fetch resource: %w", err)
+	}
+
+	tracks := resource.Tracks()
+	if len(tracks) == 0 {
+		if d.kind == deezer.KindTrack {
+			return nil, "", fmt.Errorf("track with ID %s not found", id)
+		}
+		return nil, "", fmt.Errorf("%s has no tracks", d.kind)
+	}
+
+	if d.kind == deezer.KindArtist && len(tracks) > opts.Limit {
+		resource.SetTracks(tracks[:opts.Limit])
+	}
+
+	outputDir := resource.OutputDir(d.appConfig.OutputDir)
+	if err := fsutil.EnsureDir(outputDir); err != nil {
+		return nil, "", fmt.Errorf("failed to create output directory: %w", err)
+	}
+	sweepPartFiles(outputDir)
+
+	return resource, outputDir, nil
+}
+
+func (d *Downloader) downloadAllTracks(ctx context.Context, resource deezer.Resource, opts Options, outputDir string) error {
+	tracks := resource.Tracks()
+	startTime := time.Now()
+
+	if d.kind != deezer.KindTrack {
+		fmt.Printf("%s\n\nStarting download...\n\n", resourceInfo(resource))
+	}
+
+	progress := newProgressTracker(len(tracks), d.kind)
+
+	for i, track := range tracks {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+
+		sp := progress.startDownload(i, track)
+		result := d.downloadTrack(ctx, resource, track, opts, outputDir)
+		sp.Stop()
+
+		if result.err != nil && errors.Is(result.err, context.Canceled) {
+			return result.err
+		}
+
+		progress.handleResult(i, track, result)
+	}
+
+	progress.printSummary(outputDir, time.Since(startTime))
+
+	return nil
+}

internal/download/genre.go

@@ -0,0 +1,131 @@
+package download
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/PuerkitoBio/goquery"
+)
+
+var electronicKeywords = toLower([]string{
+	"Ambient", "Bass", "Big Room", "Breakbeat", "Dance", "Disco", "Downtempo",
+	"Drum And Bass", "Dub", "Dubstep", "EDM", "Electro", "Electronic", "Electronica",
+	"Eurodance", "Gabber", "Garage", "Hardcore", "Hardstyle", "House", "Industrial",
+	"Jungle", "Moombahton", "Synthpop", "Synthwave", "Techno", "Trance", "Trap",
+	"Trip Hop", "Vaporwave",
+})
+
+var nonElectronicKeywords = toLower([]string{
+	"Blues", "Chillout", "Classical", "Country", "Folk", "Funk", "Hip Hop", "Jazz",
+	"Latin", "Metal", "Pop", "R&B", "Rap", "Reggae", "Rock", "Soul",
+})
+
+func toLower(ss []string) []string {
+	out := make([]string, len(ss))
+	for i, s := range ss {
+		out[i] = strings.ToLower(s)
+	}
+	return out
+}
+
+func fetchGenre(ctx context.Context, httpClient *http.Client, artist, title string) (string, error) {
+	// Escape the path segments: names containing '/', '?', or '#' would
+	// otherwise change the URL structure and fetch the wrong page.
+	reqURL := fmt.Sprintf("https://www.last.fm/music/%s/%s/+tags", url.PathEscape(artist), url.PathEscape(title))
+
+	doc, err := fetchGenrePage(ctx, httpClient, reqURL)
+	if err != nil {
+		return "", err
+	}
+
+	tags := parseGenreTags(doc)
+	if len(tags) > 2 {
+		tags = tags[:2]
+	}
+
+	filtered := filterTags(tags)
+	if len(filtered) == 0 {
+		return "", errors.New("no data found")
+	}
+
+	return formatTags(filtered), nil
+}
+
+func fetchGenrePage(ctx context.Context, httpClient *http.Client, pageURL string) (*goquery.Document, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, pageURL, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	return goquery.NewDocumentFromReader(resp.Body)
+}
+
+func parseGenreTags(doc *goquery.Document) []string {
+	var tags []string
+	doc.Find("ol.big-tags .big-tags-item-name a").Each(func(_ int, s *goquery.Selection) {
+		if tag := strings.TrimSpace(s.Text()); tag != "" {
+			tags = append(tags, tag)
+		}
+	})
+	return tags
+}
+
+func matchesKeyword(tag string, keywords []string) bool {
+	tagLower := strings.ToLower(tag)
+	for _, kw := range keywords {
+		if strings.Contains(tagLower, kw) {
+			return true
+		}
+	}
+	return false
+}
+
+func filterTags(tags []string) []string {
+	var electronic, nonElectronic []string
+
+	for _, tag := range tags {
+		if matchesKeyword(tag, electronicKeywords) {
+			electronic = append(electronic, tag)
+		} else if matchesKeyword(tag, nonElectronicKeywords) {
+			nonElectronic = append(nonElectronic, tag)
+		}
+	}
+
+	if len(electronic) > 0 {
+		return append(electronic, nonElectronic...)
+	}
+	return electronic
+}
+
+func formatTags(tags []string) string {
+	formatted := make([]string, 0, len(tags))
+	for _, tag := range tags {
+		tag = strings.TrimSpace(tag)
+		if tag == "" {
+			continue
+		}
+		words := strings.Fields(tag)
+		for i, w := range words {
+			r, size := utf8.DecodeRuneInString(w)
+			words[i] = string(unicode.ToUpper(r)) + strings.ToLower(w[size:])
+		}
+		formatted = append(formatted, strings.Join(words, " "))
+	}
+	return strings.Join(formatted, " / ")
+}

internal/download/genre_test.go

@@ -0,0 +1,51 @@
+package download
+
+import (
+	"slices"
+	"testing"
+)
+
+func TestMatchesKeyword(t *testing.T) {
+	if !matchesKeyword("Deep House", electronicKeywords) {
+		t.Error("expected Deep House to match electronic keywords")
+	}
+	if !matchesKeyword("classic rock", nonElectronicKeywords) {
+		t.Error("expected classic rock to match non-electronic keywords")
+	}
+	if matchesKeyword("Spoken Word", electronicKeywords) {
+		t.Error("did not expect Spoken Word to match electronic keywords")
+	}
+}
+
+func TestFilterTags(t *testing.T) {
+	got := filterTags([]string{"Deep House", "Rock", "Spoken Word"})
+	want := []string{"Deep House", "Rock"}
+	if !slices.Equal(got, want) {
+		t.Errorf("filterTags() = %v, want %v", got, want)
+	}
+
+	if got := filterTags([]string{"Rock", "Jazz"}); len(got) != 0 {
+		t.Errorf("filterTags() = %v, want empty", got)
+	}
+
+	if got := filterTags(nil); len(got) != 0 {
+		t.Errorf("filterTags(nil) = %v, want empty", got)
+	}
+}
+
+func TestFormatTags(t *testing.T) {
+	tests := []struct {
+		tags []string
+		want string
+	}{
+		{[]string{"deep house"}, "Deep House"},
+		{[]string{"TECHNO", "trance"}, "Techno / Trance"},
+		{[]string{" house ", ""}, "House"},
+	}
+
+	for _, tt := range tests {
+		if got := formatTags(tt.tags); got != tt.want {
+			t.Errorf("formatTags(%v) = %q, want %q", tt.tags, got, tt.want)
+		}
+	}
+}

internal/download/hash.go

@@ -0,0 +1,69 @@
+package download
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+)
+
+func hashFile(path string) (string, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	h := sha256.New()
+	if _, err := io.Copy(h, file); err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(h.Sum(nil)), nil
+}
+
+type hashIndex struct {
+	files map[string]string
+}
+
+func newHashIndex(ctx context.Context, root string) (*hashIndex, error) {
+	index := &hashIndex{files: make(map[string]string)}
+
+	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		if err != nil || d.IsDir() {
+			return nil
+		}
+
+		hash, err := hashFile(path)
+		if err != nil {
+			return nil
+		}
+
+		index.files[hash] = path
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return index, nil
+}
+
+func (h *hashIndex) find(hash string) (string, bool) {
+	path, ok := h.files[hash]
+	return path, ok
+}
+
+func (d *Downloader) initHashIndex(ctx context.Context) error {
+	d.hashIndexOnce.Do(func() {
+		d.hashIndex, d.hashIndexErr = newHashIndex(ctx, d.appConfig.OutputDir)
+	})
+
+	return d.hashIndexErr
+}

internal/download/hash_test.go

@@ -0,0 +1,71 @@
+package download
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestHashFile(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "file.txt")
+	if err := os.WriteFile(path, []byte("hello world"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := hashFile(path)
+	if err != nil {
+		t.Fatalf("hashFile: %v", err)
+	}
+
+	want := "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+	if got != want {
+		t.Errorf("hashFile() = %s, want %s", got, want)
+	}
+}
+
+func TestHashFileMissing(t *testing.T) {
+	if _, err := hashFile(filepath.Join(t.TempDir(), "missing")); err == nil {
+		t.Error("expected error for missing file")
+	}
+}
+
+func TestHashIndexFind(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "sub", "track.mp3")
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(path, []byte("hello world"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	index, err := newHashIndex(context.Background(), dir)
+	if err != nil {
+		t.Fatalf("newHashIndex: %v", err)
+	}
+
+	hash := "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+	found, ok := index.find(hash)
+	if !ok || found != path {
+		t.Errorf("find(%s) = %q, %v; want %q, true", hash, found, ok, path)
+	}
+
+	if _, ok := index.find("deadbeef"); ok {
+		t.Error("find() reported a match for an unknown hash")
+	}
+}
+
+func TestHashIndexCanceledContext(t *testing.T) {
+	dir := t.TempDir()
+	if err := os.WriteFile(filepath.Join(dir, "a"), []byte("x"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	if _, err := newHashIndex(ctx, dir); err == nil {
+		t.Error("expected error for canceled context")
+	}
+}

internal/download/info.go

@@ -0,0 +1,111 @@
+package download
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+)
+
+func resourceInfo(resource deezer.Resource) string {
+	switch r := resource.(type) {
+	case *deezer.Album:
+		return albumInfo(r)
+	case *deezer.Playlist:
+		return playlistInfo(r)
+	case *deezer.Artist:
+		return artistInfo(r)
+	case *deezer.Single:
+		return singleInfo(r)
+	}
+
+	return ""
+}
+
+func albumInfo(a *deezer.Album) string {
+	duration, err := strconv.Atoi(a.Results.Data.Duration)
+	if err != nil {
+		duration = 0
+	}
+
+	return fmt.Sprintf(
+		`================= [ Album Info ] =================
+Title:    %s
+Artist:   %s
+Tracks:   %d
+Duration: %s
+==================================================`,
+		a.Results.Data.Title,
+		a.Results.Data.Artist,
+		len(a.Results.Tracks.Data),
+		time.Duration(duration)*time.Second,
+	)
+}
+
+func playlistInfo(p *deezer.Playlist) string {
+	return fmt.Sprintf(
+		`=============== [ Playlist Info ] ===============
+Title:    %s
+Creator:  %s
+Tracks:   %d
+Duration: %s
+=================================================`,
+		p.Results.Data.Title,
+		p.Results.Data.Creator,
+		len(p.Results.Tracks.Data),
+		time.Duration(p.Results.Data.Duration)*time.Second,
+	)
+}
+
+func artistInfo(a *deezer.Artist) string {
+	tracks := a.Results.Tracks.Data
+	count := len(tracks)
+
+	totalSec := 0
+	for _, t := range tracks {
+		if d, err := strconv.Atoi(t.Duration); err == nil {
+			totalSec += d
+		}
+	}
+
+	limit := min(3, count)
+
+	var b strings.Builder
+	fmt.Fprintf(&b, "============= [ Artist Info ] =============\n")
+	fmt.Fprintf(&b, "Artist:   %s\n", a.Results.Data.Name)
+	fmt.Fprintf(&b, "Tracks:   %d\n", count)
+	fmt.Fprintf(&b, "Playtime: %s\n", time.Duration(totalSec)*time.Second)
+	fmt.Fprintf(&b, "-------------------------------------------\n")
+	fmt.Fprintf(&b, "Top %d most popular tracks:\n", limit)
+	for i := 0; i < limit; i++ {
+		t := tracks[i]
+		fmt.Fprintf(&b, "    %2d. %s – %s\n", i+1, t.Artist, t.FullTitle())
+	}
+	fmt.Fprintf(&b, "===========================================\n")
+
+	return b.String()
+}
+
+func singleInfo(s *deezer.Single) string {
+	if s.Results.Data == nil {
+		return "Track: No data available"
+	}
+
+	duration, err := strconv.Atoi(s.Results.Data.Duration)
+	if err != nil {
+		duration = 0
+	}
+
+	return fmt.Sprintf(
+		`================= [ Track Info ] =================
+Title:    %s
+Artist:   %s
+Duration: %s
+==================================================`,
+		s.Results.Data.FullTitle(),
+		s.Results.Data.Artist,
+		time.Duration(duration)*time.Second,
+	)
+}

internal/download/metadata.go

@@ -0,0 +1,79 @@
+package download
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+)
+
+type bpmKey struct {
+	BPM string
+	Key string
+}
+
+type metadataResult struct {
+	bpmKey   bpmKey
+	genre    string
+	warnings []string
+}
+
+func fetchMetadata(ctx context.Context, httpClient *http.Client, track *deezer.Track, opts Options) metadataResult {
+	if !opts.BPM && !opts.Genre {
+		return metadataResult{}
+	}
+
+	type bpmResult struct {
+		value bpmKey
+		err   error
+	}
+	type genreResult struct {
+		value string
+		err   error
+	}
+
+	bpmChan := make(chan bpmResult, 1)
+	genreChan := make(chan genreResult, 1)
+
+	if opts.BPM {
+		go func() {
+			result, err := fetchBPM(ctx, httpClient, track.Artist, track.Title, track.Duration)
+			bpmChan <- bpmResult{value: result, err: err}
+		}()
+	}
+
+	if opts.Genre {
+		go func() {
+			genre, err := fetchGenre(ctx, httpClient, track.Artist, track.FullTitle())
+			genreChan <- genreResult{value: genre, err: err}
+		}()
+	}
+
+	var result metadataResult
+
+	if opts.BPM {
+		r := <-bpmChan
+		if r.err != nil {
+			if !errors.Is(r.err, context.Canceled) {
+				result.warnings = append(result.warnings, fmt.Sprintf("failed to fetch BPM and key: %v", r.err))
+			}
+		} else {
+			result.bpmKey = r.value
+		}
+	}
+
+	if opts.Genre {
+		r := <-genreChan
+		if r.err != nil {
+			if !errors.Is(r.err, context.Canceled) {
+				result.warnings = append(result.warnings, fmt.Sprintf("failed to fetch genre: %v", r.err))
+			}
+		} else {
+			result.genre = r.value
+		}
+	}
+
+	return result
+}

internal/download/options.go

@@ -0,0 +1,55 @@
+package download
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+)
+
+var validQualities = map[string]bool{
+	"mp3_128": true,
+	"mp3_320": true,
+	"flac":    true,
+	"wav":     true,
+}
+
+type Options struct {
+	Quality string
+	Timeout time.Duration
+	Limit   int
+	BPM     bool
+	Genre   bool
+	Strict  bool
+}
+
+func (o *Options) sourceQuality() string {
+	if o.Quality == "wav" {
+		return "flac"
+	}
+	return o.Quality
+}
+
+func (o *Options) convertsToWAV() bool {
+	return o.Quality == "wav"
+}
+
+func (o *Options) Validate(kind deezer.Kind) error {
+	if !validQualities[o.Quality] {
+		return fmt.Errorf("invalid quality option: %s", o.Quality)
+	}
+	if o.Timeout <= 0 {
+		return errors.New("timeout must be a positive duration")
+	}
+	if kind == deezer.KindArtist {
+		if o.Limit <= 0 {
+			return errors.New("limit must be a positive integer")
+		}
+		if o.Limit > 100 {
+			return errors.New("limit must not exceed 100")
+		}
+	}
+
+	return nil
+}

internal/download/options_test.go

@@ -0,0 +1,71 @@
+package download
+
+import (
+	"testing"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+)
+
+func TestOptionsSourceQuality(t *testing.T) {
+	tests := []struct {
+		quality string
+		want    string
+		wantWAV bool
+	}{
+		{"mp3_128", "mp3_128", false},
+		{"mp3_320", "mp3_320", false},
+		{"flac", "flac", false},
+		{"wav", "flac", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.quality, func(t *testing.T) {
+			opts := Options{Quality: tt.quality}
+
+			if got := opts.sourceQuality(); got != tt.want {
+				t.Errorf("sourceQuality() = %q, want %q", got, tt.want)
+			}
+			if got := opts.convertsToWAV(); got != tt.wantWAV {
+				t.Errorf("convertsToWAV() = %v, want %v", got, tt.wantWAV)
+			}
+		})
+	}
+}
+
+func TestOptionsValidate(t *testing.T) {
+	valid := Options{Quality: "mp3_320", Timeout: time.Minute, Limit: 10}
+
+	tests := []struct {
+		name    string
+		mutate  func(o *Options)
+		kind    deezer.Kind
+		wantErr bool
+	}{
+		{"valid", func(o *Options) {}, deezer.KindAlbum, false},
+		{"mp3_128", func(o *Options) { o.Quality = "mp3_128" }, deezer.KindAlbum, false},
+		{"flac", func(o *Options) { o.Quality = "flac" }, deezer.KindAlbum, false},
+		{"wav", func(o *Options) { o.Quality = "wav" }, deezer.KindAlbum, false},
+		{"invalid quality", func(o *Options) { o.Quality = "ogg" }, deezer.KindAlbum, true},
+		{"uppercase quality", func(o *Options) { o.Quality = "MP3_320" }, deezer.KindAlbum, true},
+		{"zero timeout", func(o *Options) { o.Timeout = 0 }, deezer.KindAlbum, true},
+		{"negative timeout", func(o *Options) { o.Timeout = -time.Second }, deezer.KindAlbum, true},
+		{"artist zero limit", func(o *Options) { o.Limit = 0 }, deezer.KindArtist, true},
+		{"artist limit too high", func(o *Options) { o.Limit = 101 }, deezer.KindArtist, true},
+		{"artist limit at max", func(o *Options) { o.Limit = 100 }, deezer.KindArtist, false},
+		{"album ignores zero limit", func(o *Options) { o.Limit = 0 }, deezer.KindAlbum, false},
+		{"track ignores zero limit", func(o *Options) { o.Limit = 0 }, deezer.KindTrack, false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			opts := valid
+			tt.mutate(&opts)
+
+			err := opts.Validate(tt.kind)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Validate(%s) error = %v, wantErr %v", tt.kind, err, tt.wantErr)
+			}
+		})
+	}
+}

internal/download/progress.go

@@ -0,0 +1,119 @@
+package download
+
+import (
+	"fmt"
+	"math/rand/v2"
+	"os"
+	"time"
+
+	"github.com/briandowns/spinner"
+	"github.com/mathismqn/godeez/internal/deezer"
+)
+
+type downloadResult struct {
+	skipped  bool
+	path     string
+	warnings []string
+	err      error
+}
+
+type downloadStats struct {
+	downloaded int
+	skipped    int
+	failed     int
+	warnings   int
+}
+
+type progressTracker struct {
+	stats       downloadStats
+	totalTracks int
+	kind        deezer.Kind
+}
+
+func newProgressTracker(totalTracks int, kind deezer.Kind) *progressTracker {
+	return &progressTracker{
+		totalTracks: totalTracks,
+		kind:        kind,
+	}
+}
+
+func (pt *progressTracker) startDownload(index int, track *deezer.Track) *spinner.Spinner {
+	trackProgress := fmt.Sprintf("[%d/%d]", index+1, pt.totalTracks)
+
+	sp := spinner.New(spinner.CharSets[14], 100*time.Millisecond)
+	sp.Writer = os.Stdout
+	sp.Prefix = trackProgress + " "
+	sp.Suffix = fmt.Sprintf(" Downloading: %s - %s", track.Artist, track.FullTitle())
+	sp.Start()
+
+	return sp
+}
+
+func (pt *progressTracker) handleResult(index int, track *deezer.Track, result downloadResult) {
+	trackProgress := fmt.Sprintf("[%d/%d]", index+1, pt.totalTracks)
+	trackTitle := track.FullTitle()
+
+	if result.skipped {
+		pt.stats.skipped++
+		fmt.Printf("%s ↷ Skipped: %s - %s\n    Already exists at: %s\n",
+			trackProgress, track.Artist, trackTitle, result.path)
+		return
+	}
+
+	if result.err != nil {
+		pt.stats.failed++
+		fmt.Printf("%s ✖ Failed: %s - %s:\n    Error: %v\n",
+			trackProgress, track.Artist, trackTitle, result.err)
+		return
+	}
+
+	pt.stats.downloaded++
+	if len(result.warnings) > 0 {
+		pt.stats.warnings++
+	}
+
+	symbol := "✔"
+	if len(result.warnings) > 0 {
+		symbol = "⚠"
+	}
+	fmt.Printf("%s %s Downloaded: %s - %s\n", trackProgress, symbol, track.Artist, trackTitle)
+
+	for _, w := range result.warnings {
+		fmt.Printf("    Warning: %s\n", w)
+	}
+}
+
+func (pt *progressTracker) printSummary(outputDir string, elapsed time.Duration) {
+	if pt.kind != deezer.KindTrack {
+		warningsLine := ""
+		if pt.stats.warnings > 0 {
+			warningsLine = fmt.Sprintf("\nWarnings:       %d", pt.stats.warnings)
+		}
+		fmt.Printf(`
+================== [ Summary ] ==================
+Downloaded:     %d
+Skipped:        %d
+Failed:         %d%s
+Elapsed time:   %s
+Files saved to: %s
+=================================================
+`,
+			pt.stats.downloaded,
+			pt.stats.skipped,
+			pt.stats.failed,
+			warningsLine,
+			elapsed.Round(time.Second),
+			outputDir,
+		)
+
+		if pt.stats.downloaded > 0 {
+			pt.showSupportMessage()
+		}
+	}
+}
+
+func (*progressTracker) showSupportMessage() {
+	if rand.Float64() < 0.1 {
+		fmt.Println("\n⭐ Enjoying GoDeez? Star it on GitHub: https://github.com/mathismqn/godeez")
+	}
+}

internal/download/skip.go

@@ -0,0 +1,36 @@
+package download
+
+import (
+	"context"
+
+	"github.com/mathismqn/godeez/internal/fsutil"
+)
+
+func (d *Downloader) shouldSkipDownload(ctx context.Context, trackID, mediaFormat string) (string, bool) {
+	existing, err := d.store.DownloadInfo(trackID)
+	if err != nil || existing.Quality != mediaFormat {
+		return "", false
+	}
+
+	if fsutil.Exists(existing.Path) {
+		return existing.Path, true
+	}
+
+	if existing.Hash == "" {
+		return "", false
+	}
+
+	if err := d.initHashIndex(ctx); err != nil {
+		return "", false
+	}
+
+	foundPath, ok := d.hashIndex.find(existing.Hash)
+	if !ok {
+		return "", false
+	}
+
+	existing.Path = foundPath
+	_ = d.store.PutDownloadInfo(existing)
+
+	return foundPath, true
+}

internal/download/stream.go

@@ -0,0 +1,105 @@
+package download
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+	"github.com/mathismqn/godeez/internal/fsutil"
+)
+
+const chunkSize = 2048
+
+func sweepPartFiles(dir string) {
+	matches, err := filepath.Glob(filepath.Join(dir, fsutil.PartPattern))
+	if err != nil {
+		return
+	}
+	for _, match := range matches {
+		os.Remove(match)
+	}
+}
+
+func (d *Downloader) streamToFile(ctx context.Context, stream io.ReadCloser, outputPath string, key []byte) error {
+	tmpPath, err := d.streamToTempFile(ctx, stream, filepath.Dir(outputPath), key)
+	if err != nil {
+		return err
+	}
+
+	if err := os.Rename(tmpPath, outputPath); err != nil {
+		os.Remove(tmpPath)
+		return err
+	}
+
+	return nil
+}
+
+func (d *Downloader) streamToTempFile(ctx context.Context, stream io.ReadCloser, dir string, key []byte) (string, error) {
+	defer stream.Close()
+
+	file, err := os.CreateTemp(dir, fsutil.PartPattern)
+	if err != nil {
+		return "", err
+	}
+	tmpPath := file.Name()
+	done := false
+	defer func() {
+		if !done {
+			file.Close()
+			os.Remove(tmpPath)
+		}
+	}()
+
+	buffer := make([]byte, chunkSize)
+	for chunk := 0; ; chunk++ {
+		select {
+		case <-ctx.Done():
+			return "", ctx.Err()
+		default:
+		}
+
+		totalRead := 0
+		for totalRead < chunkSize {
+			n, err := stream.Read(buffer[totalRead:])
+			totalRead += n
+			if err != nil {
+				if errors.Is(err, io.EOF) {
+					break
+				}
+				return "", err
+			}
+		}
+
+		if totalRead == 0 {
+			break
+		}
+
+		if chunk%3 == 0 && totalRead == chunkSize {
+			buffer, err = deezer.DecryptBlowfish(buffer, key)
+			if err != nil {
+				return "", err
+			}
+		}
+
+		if _, err = file.Write(buffer[:totalRead]); err != nil {
+			return "", err
+		}
+
+		if totalRead < chunkSize {
+			break
+		}
+	}
+
+	if err := file.Sync(); err != nil {
+		return "", err
+	}
+	if err := file.Close(); err != nil {
+		return "", err
+	}
+	done = true
+
+	return tmpPath, nil
+}

internal/download/tagmeta.go

@@ -0,0 +1,40 @@
+package download
+
+import (
+	"strings"
+
+	"github.com/mathismqn/godeez/internal/deezer"
+	"github.com/mathismqn/godeez/internal/tag"
+)
+
+func buildTagMetadata(resource deezer.Resource, track *deezer.Track, cover []byte, bpm bpmKey, genre string) tag.Metadata {
+	m := tag.Metadata{
+		Title:       track.FullTitle(),
+		Artists:     strings.Join(track.Contributors.MainArtists, ", "),
+		Composers:   strings.Join(track.Contributors.Composers, ", "),
+		Lyricists:   strings.Join(track.Contributors.Authors, ", "),
+		Genre:       genre,
+		BPM:         bpm.BPM,
+		Key:         bpm.Key,
+		TrackNumber: track.TrackNumber,
+		Duration:    track.Duration,
+		Gain:        track.Gain,
+		ISRC:        track.ISRC,
+		Cover:       cover,
+	}
+
+	if album, ok := resource.(*deezer.Album); ok {
+		data := album.Results.Data
+		m.Album = &tag.AlbumMetadata{
+			Artist:              data.Artist,
+			Title:               data.Title,
+			Label:               data.Label,
+			OriginalReleaseDate: data.OriginalReleaseDate,
+			ReleaseDate:         data.PhysicalReleaseDate,
+			ProducerLine:        data.ProducerLine,
+			Copyright:           data.Copyright,
+		}
+	}
+
+	return m
+}

internal/download/track.go

@@ -0,0 +1,137 @@
+package download
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/audio"
+	"github.com/mathismqn/godeez/internal/deezer"
+	"github.com/mathismqn/godeez/internal/fsutil"
+	"github.com/mathismqn/godeez/internal/store"
+	"github.com/mathismqn/godeez/internal/tag"
+)
+
+func (d *Downloader) downloadTrack(ctx context.Context, resource deezer.Resource, track *deezer.Track, opts Options, outputDir string) downloadResult {
+	media, err := d.deezerClient.FetchMedia(ctx, track, opts.sourceQuality())
+	if err != nil {
+		return downloadResult{err: fmt.Errorf("failed to fetch media: %w", err)}
+	}
+
+	mediaFormat := media.Format()
+	outputFormat := mediaFormat
+	if opts.convertsToWAV() {
+		if mediaFormat != "FLAC" {
+			return downloadResult{err: fmt.Errorf("wav requires a flac source, but only '%s' is available", strings.ToLower(mediaFormat))}
+		}
+		outputFormat = "WAV"
+	}
+
+	if opts.Strict && strings.ToLower(outputFormat) != opts.Quality {
+		return downloadResult{err: fmt.Errorf("requested quality '%s' not available", opts.Quality)}
+	}
+
+	if skipPath, skip := d.shouldSkipDownload(ctx, track.ID, outputFormat); skip {
+		return downloadResult{skipped: true, path: skipPath}
+	}
+
+	metadataChan := make(chan metadataResult, 1)
+	go func() {
+		metadataChan <- fetchMetadata(ctx, d.deezerClient.Session.HTTPClient, track, opts)
+	}()
+
+	dlCtx, cancel := context.WithTimeout(ctx, opts.Timeout)
+	defer cancel()
+
+	stream, err := d.deezerClient.MediaStream(dlCtx, media)
+	if err != nil {
+		return downloadResult{err: fmt.Errorf("failed to get media stream: %w", err)}
+	}
+
+	fileName := track.Filename(d.kind, outputFormat)
+	outputPath := d.uniqueOutputPath(track.ID, filepath.Join(outputDir, fileName))
+
+	key := deezer.BlowfishKey(track.ID)
+	if opts.convertsToWAV() {
+		tmpPath, err := d.streamToTempFile(dlCtx, stream, outputDir, key)
+		if err != nil {
+			return downloadResult{err: fmt.Errorf("failed to stream to file: %w", err)}
+		}
+		defer fsutil.Remove(tmpPath)
+
+		if err := audio.FLACToWAV(ctx, tmpPath, outputPath); err != nil {
+			return downloadResult{err: fmt.Errorf("failed to convert to wav: %w", err)}
+		}
+	} else if err := d.streamToFile(dlCtx, stream, outputPath, key); err != nil {
+		return downloadResult{err: fmt.Errorf("failed to stream to file: %w", err)}
+	}
+
+	var warnings []string
+
+	if opts.Quality != strings.ToLower(outputFormat) {
+		warnings = append(warnings, fmt.Sprintf("requested quality '%s' not available, using '%s' instead", opts.Quality, strings.ToLower(outputFormat)))
+	}
+
+	cover, err := d.deezerClient.FetchCoverImage(ctx, track)
+	if err != nil && !errors.Is(err, context.Canceled) {
+		warnings = append(warnings, fmt.Sprintf("failed to fetch cover image: %v", err))
+	}
+
+	metadata := <-metadataChan
+
+	if err := ctx.Err(); err != nil {
+		fsutil.Remove(outputPath)
+		return downloadResult{err: err}
+	}
+
+	warnings = append(warnings, metadata.warnings...)
+	warnings = append(warnings, d.finalizeDownload(resource, track, outputPath, outputFormat, metadata.genre, cover, metadata.bpmKey)...)
+
+	return downloadResult{warnings: warnings}
+}
+
+func (d *Downloader) uniqueOutputPath(trackID, path string) string {
+	owned := ""
+	if info, err := d.store.DownloadInfo(trackID); err == nil {
+		owned = info.Path
+	}
+
+	ext := filepath.Ext(path)
+	stem := strings.TrimSuffix(path, ext)
+	candidate := path
+	for i := 2; candidate != owned && fsutil.Exists(candidate); i++ {
+		candidate = fmt.Sprintf("%s (%d)%s", stem, i, ext)
+	}
+
+	return candidate
+}
+
+func (d *Downloader) finalizeDownload(resource deezer.Resource, track *deezer.Track, outputPath, outputFormat, genre string, cover []byte, bpmKey bpmKey) []string {
+	var warnings []string
+
+	if err := tag.Write(outputPath, buildTagMetadata(resource, track, cover, bpmKey, genre)); err != nil {
+		warnings = append(warnings, fmt.Sprintf("failed to add tags: %v", err))
+	}
+
+	hash, err := hashFile(outputPath)
+	if err != nil {
+		warnings = append(warnings, fmt.Sprintf("failed to get file hash: %v", err))
+	}
+
+	info := &store.DownloadInfo{
+		TrackID:    track.ID,
+		Quality:    outputFormat,
+		Path:       outputPath,
+		Hash:       hash,
+		Downloaded: time.Now(),
+	}
+
+	if err := d.store.PutDownloadInfo(info); err != nil {
+		warnings = append(warnings, fmt.Sprintf("failed to save download info: %v", err))
+	}
+
+	return warnings
+}

internal/fsutil/fsutil.go

@@ -0,0 +1,34 @@
+package fsutil
+
+import (
+	"fmt"
+	"os"
+)
+
+const PartPattern = ".godeez-*.part"
+
+func EnsureDir(path string) error {
+	info, err := os.Stat(path)
+	if os.IsNotExist(err) {
+		return os.MkdirAll(path, 0755)
+	}
+	if err != nil {
+		return err
+	}
+	if !info.IsDir() {
+		return fmt.Errorf("file already exists at %s", path)
+	}
+	return nil
+}
+
+func Exists(path string) bool {
+	info, err := os.Stat(path)
+	return err == nil && !info.IsDir()
+}
+
+func Remove(path string) error {
+	if !Exists(path) {
+		return nil
+	}
+	return os.Remove(path)
+}

internal/store/download_info.go

@@ -0,0 +1,57 @@
+package store
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"time"
+
+	"go.etcd.io/bbolt"
+)
+
+type DownloadInfo struct {
+	TrackID    string    `json:"song_id"`
+	Quality    string    `json:"quality"`
+	Path       string    `json:"path"`
+	Hash       string    `json:"hash"`
+	Downloaded time.Time `json:"downloaded_at"`
+}
+
+var trackBucket = []byte("tracks")
+
+func (s *Store) DownloadInfo(trackID string) (*DownloadInfo, error) {
+	var info DownloadInfo
+
+	if err := s.db.View(func(tx *bbolt.Tx) error {
+		b := tx.Bucket(trackBucket)
+		if b == nil {
+			return errors.New("bucket not found")
+		}
+
+		data := b.Get([]byte(trackID))
+		if data == nil {
+			return errors.New("not found")
+		}
+		return json.Unmarshal(data, &info)
+	}); err != nil {
+		return nil, err
+	}
+
+	return &info, nil
+}
+
+func (s *Store) PutDownloadInfo(d *DownloadInfo) error {
+	return s.db.Update(func(tx *bbolt.Tx) error {
+		b, err := tx.CreateBucketIfNotExists(trackBucket)
+		if err != nil {
+			return fmt.Errorf("failed to create bucket: %w", err)
+		}
+
+		data, err := json.Marshal(d)
+		if err != nil {
+			return err
+		}
+
+		return b.Put([]byte(d.TrackID), data)
+	})
+}

internal/store/store.go

@@ -0,0 +1,31 @@
+package store
+
+import (
+	"errors"
+	"fmt"
+	"path/filepath"
+	"time"
+
+	"go.etcd.io/bbolt"
+	bolterrors "go.etcd.io/bbolt/errors"
+)
+
+type Store struct {
+	db *bbolt.DB
+}
+
+func Open(dir string) (*Store, error) {
+	db, err := bbolt.Open(filepath.Join(dir, ".tracks.db"), 0600, &bbolt.Options{Timeout: 5 * time.Second})
+	if err != nil {
+		if errors.Is(err, bolterrors.ErrTimeout) {
+			return nil, errors.New("database is already in use by another process")
+		}
+		return nil, fmt.Errorf("failed to open database: %w", err)
+	}
+
+	return &Store{db: db}, nil
+}
+
+func (s *Store) Close() error {
+	return s.db.Close()
+}

internal/store/store_test.go

@@ -0,0 +1,63 @@
+package store
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+func TestOpenPutGet(t *testing.T) {
+	dir := t.TempDir()
+
+	s, err := Open(dir)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	defer s.Close()
+
+	if _, err := os.Stat(filepath.Join(dir, ".tracks.db")); err != nil {
+		t.Errorf("expected .tracks.db to exist: %v", err)
+	}
+
+	info := &DownloadInfo{
+		TrackID:    "123",
+		Quality:    "MP3_320",
+		Path:       "/music/track.mp3",
+		Hash:       "abc",
+		Downloaded: time.Now().Truncate(time.Second),
+	}
+	if err := s.PutDownloadInfo(info); err != nil {
+		t.Fatalf("PutDownloadInfo: %v", err)
+	}
+
+	got, err := s.DownloadInfo("123")
+	if err != nil {
+		t.Fatalf("DownloadInfo: %v", err)
+	}
+	if got.TrackID != info.TrackID || got.Quality != info.Quality || got.Path != info.Path || got.Hash != info.Hash {
+		t.Errorf("DownloadInfo() = %+v, want %+v", got, info)
+	}
+}
+
+func TestDownloadInfoNotFound(t *testing.T) {
+	s, err := Open(t.TempDir())
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	defer s.Close()
+
+	if _, err := s.DownloadInfo("missing"); err == nil {
+		t.Error("expected error for unknown track ID")
+	}
+}
+
+func TestClose(t *testing.T) {
+	s, err := Open(t.TempDir())
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	if err := s.Close(); err != nil {
+		t.Errorf("Close: %v", err)
+	}
+}

internal/tag/flac.go

@@ -0,0 +1,85 @@
+package tag
+
+import (
+	"os"
+	"strings"
+
+	"github.com/go-flac/flacpicture/v2"
+	"github.com/go-flac/flacvorbis/v2"
+	"github.com/go-flac/go-flac/v2"
+)
+
+type flacTagger struct {
+	file  *flac.File
+	cmts  *flacvorbis.MetaDataBlockVorbisComment
+	index int
+	path  string
+}
+
+func (t *flacTagger) write(m Metadata) error {
+	if m.Album != nil {
+		date := m.Album.ReleaseDate
+		if parts := strings.Split(date, "-"); len(parts) == 3 {
+			date = parts[0]
+		}
+
+		t.addTag("TRACKNUMBER", m.TrackNumber)
+		t.addTag("ALBUMARTIST", m.Album.Artist)
+		t.addTag("ALBUM", m.Album.Title)
+		t.addTag("PUBLISHER", m.Album.Label)
+		t.addTag("ORIGINALDATE", m.Album.OriginalReleaseDate)
+		t.addTag("DATE", date)
+		t.addTag("COMMENT", m.Album.ProducerLine)
+		t.addTag("COPYRIGHT", m.Album.Copyright)
+	}
+
+	t.addTag("ARTIST", m.Artists)
+	t.addTag("TITLE", m.Title)
+	t.addTag("COMPOSER", m.Composers)
+	t.addTag("LYRICIST", m.Lyricists)
+	t.addTag("GENRE", m.Genre)
+	t.addTag("REPLAYGAIN_TRACK_GAIN", m.Gain)
+	t.addTag("ISRC", m.ISRC)
+	t.addTag("BPM", m.BPM)
+	t.addTag("KEY", m.Key)
+	t.addTag("INITIALKEY", m.Key)
+
+	cmtsMeta := t.cmts.Marshal()
+	if t.index > 0 {
+		t.file.Meta[t.index] = &cmtsMeta
+	} else {
+		t.file.Meta = append(t.file.Meta, &cmtsMeta)
+	}
+
+	if len(m.Cover) > 0 {
+		if picture, err := flacpicture.NewFromImageData(flacpicture.PictureTypeFrontCover, "Front cover", m.Cover, "image/jpeg"); err == nil {
+			pictureMeta := picture.Marshal()
+			t.file.Meta = append(t.file.Meta, &pictureMeta)
+		}
+	}
+
+	tmpPath := t.path + ".tmp"
+	if err := t.file.Save(tmpPath); err != nil {
+		os.Remove(tmpPath)
+		return err
+	}
+	return os.Rename(tmpPath, t.path)
+}
+
+func (t *flacTagger) addTag(name, value string) {
+	if value != "" {
+		t.cmts.Add(name, value)
+	}
+}
+
+func extractFLACComment(file *flac.File) (*flacvorbis.MetaDataBlockVorbisComment, int) {
+	for idx, meta := range file.Meta {
+		if meta.Type == flac.VorbisComment {
+			cmt, err := flacvorbis.ParseFromMetaDataBlock(*meta)
+			if err == nil {
+				return cmt, idx
+			}
+		}
+	}
+	return nil, 0
+}

internal/tag/id3v2.go

@@ -0,0 +1,87 @@
+package tag
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/bogem/id3v2/v2"
+)
+
+type id3v2Tagger struct {
+	tag *id3v2.Tag
+}
+
+func (t *id3v2Tagger) write(m Metadata) error {
+	defer t.tag.Close()
+
+	applyID3Frames(t.tag, m)
+
+	return t.tag.Save()
+}
+
+func applyID3Frames(tag *id3v2.Tag, m Metadata) {
+	if m.Album != nil {
+		year := m.Album.ReleaseDate
+		if parts := strings.Split(year, "-"); len(parts) == 3 {
+			year = parts[0]
+		}
+
+		addID3Text(tag, "TRCK", m.TrackNumber)
+		addID3Text(tag, "TPE2", m.Album.Artist)
+		addID3Text(tag, "TALB", m.Album.Title)
+		addID3Text(tag, "TPUB", m.Album.Label)
+		addID3Text(tag, "TDOR", m.Album.OriginalReleaseDate)
+		addID3Text(tag, "TYER", year)
+		addID3Comment(tag, m.Album.ProducerLine)
+		addID3Text(tag, "TCOP", m.Album.Copyright)
+	}
+
+	addID3Text(tag, "TPE1", m.Artists)
+	addID3Text(tag, "TIT2", m.Title)
+	addID3Text(tag, "TCOM", m.Composers)
+	addID3Text(tag, "TEXT", m.Lyricists)
+	addID3Text(tag, "TCON", m.Genre)
+	if duration, err := strconv.Atoi(m.Duration); err == nil {
+		addID3Text(tag, "TLEN", strconv.Itoa(duration*1000))
+	}
+	addID3Text(tag, "TBPM", m.BPM)
+	addID3Text(tag, "TKEY", m.Key)
+	addID3TXXX(tag, "GAIN", m.Gain)
+	addID3TXXX(tag, "ISRC", m.ISRC)
+
+	if len(m.Cover) > 0 {
+		tag.AddAttachedPicture(id3v2.PictureFrame{
+			Encoding:    tag.DefaultEncoding(),
+			MimeType:    "image/jpeg",
+			PictureType: id3v2.PTFrontCover,
+			Description: "Cover",
+			Picture:     m.Cover,
+		})
+	}
+}
+
+func addID3Text(tag *id3v2.Tag, name, value string) {
+	if value != "" {
+		tag.AddTextFrame(name, tag.DefaultEncoding(), value)
+	}
+}
+
+func addID3Comment(tag *id3v2.Tag, value string) {
+	if value != "" {
+		tag.AddCommentFrame(id3v2.CommentFrame{
+			Encoding: tag.DefaultEncoding(),
+			Language: "eng",
+			Text:     value,
+		})
+	}
+}
+
+func addID3TXXX(tag *id3v2.Tag, description, value string) {
+	if value != "" {
+		tag.AddUserDefinedTextFrame(id3v2.UserDefinedTextFrame{
+			Encoding:    tag.DefaultEncoding(),
+			Description: description,
+			Value:       value,
+		})
+	}
+}

internal/tag/tag.go

@@ -0,0 +1,72 @@
+package tag
+
+import (
+	"path/filepath"
+
+	"github.com/bogem/id3v2/v2"
+	"github.com/go-flac/flacvorbis/v2"
+	"github.com/go-flac/go-flac/v2"
+)
+
+type AlbumMetadata struct {
+	Artist              string
+	Title               string
+	Label               string
+	OriginalReleaseDate string
+	ReleaseDate         string
+	ProducerLine        string
+	Copyright           string
+}
+
+type Metadata struct {
+	Title       string
+	Artists     string
+	Composers   string
+	Lyricists   string
+	Genre       string
+	BPM         string
+	Key         string
+	TrackNumber string
+	Duration    string
+	Gain        string
+	ISRC        string
+	Cover       []byte
+	Album       *AlbumMetadata
+}
+
+type tagger interface {
+	write(m Metadata) error
+}
+
+func newTagger(filePath string) (tagger, error) {
+	switch filepath.Ext(filePath) {
+	case ".mp3":
+		tag, err := id3v2.Open(filePath, id3v2.Options{Parse: true})
+		if err != nil {
+			return nil, err
+		}
+		return &id3v2Tagger{tag: tag}, nil
+	case ".wav":
+		return &wavTagger{path: filePath}, nil
+	}
+
+	file, err := flac.ParseFile(filePath)
+	if err != nil {
+		return nil, err
+	}
+
+	cmts, idx := extractFLACComment(file)
+	if cmts == nil {
+		cmts = flacvorbis.New()
+	}
+
+	return &flacTagger{file: file, cmts: cmts, index: idx, path: filePath}, nil
+}
+
+func Write(filePath string, m Metadata) error {
+	t, err := newTagger(filePath)
+	if err != nil {
+		return err
+	}
+	return t.write(m)
+}

internal/tag/wav.go

@@ -0,0 +1,256 @@
+package tag
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/bogem/id3v2/v2"
+)
+
+type wavTagger struct {
+	path string
+}
+
+type wavChunk struct {
+	id      string
+	payload []byte
+}
+
+type infoField struct {
+	id    string
+	value string
+}
+
+func (t *wavTagger) write(m Metadata) error {
+	id3Chunk, err := buildID3Chunk(m)
+	if err != nil {
+		return err
+	}
+
+	var chunks []wavChunk
+	if info := buildInfoChunk(m); info != nil {
+		chunks = append(chunks, wavChunk{id: "LIST", payload: info})
+	}
+	if id3Chunk != nil {
+		chunks = append(chunks, wavChunk{id: "id3 ", payload: id3Chunk})
+	}
+
+	return rewriteWAV(t.path, chunks)
+}
+
+func buildID3Chunk(m Metadata) ([]byte, error) {
+	tag := id3v2.NewEmptyTag()
+	applyID3Frames(tag, m)
+	if !tag.HasFrames() {
+		return nil, nil
+	}
+
+	var buf bytes.Buffer
+	if _, err := tag.WriteTo(&buf); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func buildInfoChunk(m Metadata) []byte {
+	fields := []infoField{
+		{"INAM", m.Title},
+		{"IART", m.Artists},
+		{"IGNR", m.Genre},
+		{"ITRK", m.TrackNumber},
+	}
+
+	if m.Album != nil {
+		date := m.Album.ReleaseDate
+		if parts := strings.Split(date, "-"); len(parts) == 3 {
+			date = parts[0]
+		}
+
+		fields = append(fields,
+			infoField{"IPRD", m.Album.Title},
+			infoField{"ICRD", date},
+			infoField{"ICMT", m.Album.ProducerLine},
+			infoField{"ICOP", m.Album.Copyright},
+		)
+	}
+
+	var buf bytes.Buffer
+	buf.WriteString("INFO")
+
+	for _, field := range fields {
+		if field.value == "" {
+			continue
+		}
+		writeChunk(&buf, field.id, append([]byte(field.value), 0))
+	}
+
+	if buf.Len() == 4 {
+		return nil
+	}
+
+	return buf.Bytes()
+}
+
+func writeChunk(w io.Writer, id string, payload []byte) {
+	header := make([]byte, 0, 8)
+	header = append(header, id...)
+	header = binary.LittleEndian.AppendUint32(header, uint32(len(payload)))
+
+	w.Write(header)
+	w.Write(payload)
+	if len(payload)%2 != 0 {
+		w.Write([]byte{0})
+	}
+}
+
+func rewriteWAV(path string, chunks []wavChunk) error {
+	src, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer src.Close()
+
+	header := make([]byte, 12)
+	if _, err := io.ReadFull(src, header); err != nil {
+		return err
+	}
+	if string(header[0:4]) != "RIFF" || string(header[8:12]) != "WAVE" {
+		return errors.New("not a wav file")
+	}
+
+	tmpPath := path + ".tmp"
+	dst, err := os.Create(tmpPath)
+	if err != nil {
+		return err
+	}
+	done := false
+	defer func() {
+		if !done {
+			dst.Close()
+			os.Remove(tmpPath)
+		}
+	}()
+
+	if _, err := dst.Write(header); err != nil {
+		return err
+	}
+
+	size, err := copyChunks(dst, src)
+	if err != nil {
+		return err
+	}
+
+	for _, chunk := range chunks {
+		var buf bytes.Buffer
+		writeChunk(&buf, chunk.id, chunk.payload)
+		if _, err := dst.Write(buf.Bytes()); err != nil {
+			return err
+		}
+		size += int64(buf.Len())
+	}
+
+	riffSize := make([]byte, 4)
+	binary.LittleEndian.PutUint32(riffSize, uint32(size))
+	if _, err := dst.WriteAt(riffSize, 4); err != nil {
+		return err
+	}
+
+	if err := dst.Sync(); err != nil {
+		return err
+	}
+	if err := dst.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tmpPath, path); err != nil {
+		return err
+	}
+	done = true
+
+	return nil
+}
+
+func copyChunks(dst io.Writer, src io.Reader) (int64, error) {
+	size := int64(4)
+	head := make([]byte, 8)
+
+	for {
+		if _, err := io.ReadFull(src, head); err != nil {
+			if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
+				return size, nil
+			}
+			return size, err
+		}
+
+		id := string(head[0:4])
+		payloadSize := int64(binary.LittleEndian.Uint32(head[4:8]))
+
+		if id == "id3 " || id == "ID3 " {
+			if err := skipPayload(src, payloadSize); err != nil {
+				return size, err
+			}
+			continue
+		}
+
+		if id == "LIST" {
+			payload := make([]byte, payloadSize)
+			if _, err := io.ReadFull(src, payload); err != nil {
+				return size, err
+			}
+			if err := skipPad(src, payloadSize); err != nil {
+				return size, err
+			}
+			if bytes.HasPrefix(payload, []byte("INFO")) {
+				continue
+			}
+
+			var buf bytes.Buffer
+			writeChunk(&buf, id, payload)
+			if _, err := dst.Write(buf.Bytes()); err != nil {
+				return size, err
+			}
+			size += int64(buf.Len())
+
+			continue
+		}
+
+		if _, err := dst.Write(head); err != nil {
+			return size, err
+		}
+		if _, err := io.CopyN(dst, src, payloadSize); err != nil {
+			return size, err
+		}
+		size += 8 + payloadSize
+
+		if payloadSize%2 != 0 {
+			if _, err := dst.Write([]byte{0}); err != nil {
+				return size, err
+			}
+			size++
+			if err := skipPad(src, payloadSize); err != nil {
+				return size, err
+			}
+		}
+	}
+}
+
+func skipPayload(src io.Reader, payloadSize int64) error {
+	if _, err := io.CopyN(io.Discard, src, payloadSize); err != nil {
+		return err
+	}
+	return skipPad(src, payloadSize)
+}
+
+func skipPad(src io.Reader, payloadSize int64) error {
+	if payloadSize%2 == 0 {
+		return nil
+	}
+	if _, err := io.CopyN(io.Discard, src, 1); err != nil && !errors.Is(err, io.EOF) {
+		return err
+	}
+	return nil
+}

internal/tag/wav_test.go

@@ -0,0 +1,246 @@
+package tag
+
+import (
+	"bytes"
+	"encoding/binary"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func minimalWAV(audio []byte) []byte {
+	var body bytes.Buffer
+	body.WriteString("WAVE")
+
+	fmtPayload := make([]byte, 0, 16)
+	fmtPayload = binary.LittleEndian.AppendUint16(fmtPayload, 1)
+	fmtPayload = binary.LittleEndian.AppendUint16(fmtPayload, 2)
+	fmtPayload = binary.LittleEndian.AppendUint32(fmtPayload, 44100)
+	fmtPayload = binary.LittleEndian.AppendUint32(fmtPayload, 176400)
+	fmtPayload = binary.LittleEndian.AppendUint16(fmtPayload, 4)
+	fmtPayload = binary.LittleEndian.AppendUint16(fmtPayload, 16)
+	writeChunk(&body, "fmt ", fmtPayload)
+	writeChunk(&body, "data", audio)
+
+	var out bytes.Buffer
+	out.WriteString("RIFF")
+	binary.Write(&out, binary.LittleEndian, uint32(body.Len()))
+	out.Write(body.Bytes())
+
+	return out.Bytes()
+}
+
+func parseChunks(t *testing.T, data []byte) map[string][]byte {
+	t.Helper()
+
+	if string(data[0:4]) != "RIFF" || string(data[8:12]) != "WAVE" {
+		t.Fatalf("bad riff header: %q %q", data[0:4], data[8:12])
+	}
+	if size := binary.LittleEndian.Uint32(data[4:8]); int(size) != len(data)-8 {
+		t.Errorf("riff size = %d, want %d", size, len(data)-8)
+	}
+
+	chunks := make(map[string][]byte)
+	for offset := 12; offset < len(data); {
+		if offset%2 != 0 {
+			t.Errorf("chunk at offset %d is not word aligned", offset)
+		}
+		if offset+8 > len(data) {
+			t.Fatalf("truncated chunk header at offset %d", offset)
+		}
+
+		id := string(data[offset : offset+4])
+		size := int(binary.LittleEndian.Uint32(data[offset+4 : offset+8]))
+		if offset+8+size > len(data) {
+			t.Fatalf("chunk %q at offset %d overruns the file", id, offset)
+		}
+		if _, ok := chunks[id]; ok {
+			t.Errorf("duplicate %q chunk", id)
+		}
+		chunks[id] = data[offset+8 : offset+8+size]
+
+		offset += 8 + size + size%2
+	}
+
+	return chunks
+}
+
+func testMetadata() Metadata {
+	return Metadata{
+		Title:       "Song",
+		Artists:     "Artist",
+		Genre:       "Rock",
+		BPM:         "120",
+		Key:         "Am",
+		TrackNumber: "3",
+		Duration:    "215",
+		Gain:        "-7.5",
+		ISRC:        "FR1234567890",
+		Cover:       []byte{0xff, 0xd8, 0xff, 0xe0, 0x00},
+		Album: &AlbumMetadata{
+			Artist:       "Album Artist",
+			Title:        "Album",
+			Label:        "Label",
+			ReleaseDate:  "2024-05-01",
+			ProducerLine: "Producer line",
+			Copyright:    "Copyright",
+		},
+	}
+}
+
+func writeTestWAV(t *testing.T, audio []byte) string {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "track.wav")
+	if err := os.WriteFile(path, minimalWAV(audio), 0644); err != nil {
+		t.Fatalf("write wav: %v", err)
+	}
+
+	return path
+}
+
+func TestWriteWAV(t *testing.T) {
+	audio := bytes.Repeat([]byte{0x11, 0x22, 0x33, 0x44}, 16)
+	path := writeTestWAV(t, audio)
+	original := parseChunks(t, minimalWAV(audio))
+
+	if err := Write(path, testMetadata()); err != nil {
+		t.Fatalf("Write() error = %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read wav: %v", err)
+	}
+	chunks := parseChunks(t, data)
+
+	if !bytes.Equal(chunks["data"], original["data"]) {
+		t.Error("data chunk was modified")
+	}
+	if !bytes.Equal(chunks["fmt "], original["fmt "]) {
+		t.Error("fmt chunk was modified")
+	}
+
+	id3, ok := chunks["id3 "]
+	if !ok {
+		t.Fatal("missing id3 chunk")
+	}
+	if string(id3[0:3]) != "ID3" {
+		t.Errorf("id3 chunk does not start with an ID3 header: %q", id3[0:3])
+	}
+	for _, want := range []string{"Song", "Artist", "Album", "120", "Am", "FR1234567890", "Rock"} {
+		if !bytes.Contains(id3, []byte(want)) {
+			t.Errorf("id3 chunk is missing %q", want)
+		}
+	}
+	if !bytes.Contains(id3, []byte{0xff, 0xd8, 0xff, 0xe0}) {
+		t.Error("id3 chunk is missing the cover art")
+	}
+
+	list, ok := chunks["LIST"]
+	if !ok {
+		t.Fatal("missing LIST chunk")
+	}
+	if string(list[0:4]) != "INFO" {
+		t.Errorf("LIST form = %q, want \"INFO\"", list[0:4])
+	}
+	for _, want := range []struct{ id, value string }{
+		{"INAM", "Song"},
+		{"IART", "Artist"},
+		{"IGNR", "Rock"},
+		{"ITRK", "3"},
+		{"IPRD", "Album"},
+		{"ICRD", "2024"},
+		{"ICMT", "Producer line"},
+		{"ICOP", "Copyright"},
+	} {
+		if !bytes.Contains(list, append([]byte(want.id), append([]byte{byte(len(want.value) + 1), 0, 0, 0}, want.value...)...)) {
+			t.Errorf("LIST chunk is missing %s = %q", want.id, want.value)
+		}
+	}
+}
+
+func TestWriteWAVIsIdempotent(t *testing.T) {
+	audio := bytes.Repeat([]byte{0x01, 0x02}, 32)
+	path := writeTestWAV(t, audio)
+
+	if err := Write(path, testMetadata()); err != nil {
+		t.Fatalf("first Write() error = %v", err)
+	}
+	first, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read wav: %v", err)
+	}
+	firstChunks := parseChunks(t, first)
+
+	if err := Write(path, testMetadata()); err != nil {
+		t.Fatalf("second Write() error = %v", err)
+	}
+	second, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read wav: %v", err)
+	}
+	secondChunks := parseChunks(t, second)
+
+	if len(first) != len(second) {
+		t.Errorf("re-tagging changed the file size: %d bytes then %d bytes", len(first), len(second))
+	}
+	if len(firstChunks) != len(secondChunks) {
+		t.Errorf("chunk count = %d, want %d", len(secondChunks), len(firstChunks))
+	}
+	for id, payload := range firstChunks {
+		got, ok := secondChunks[id]
+		if !ok {
+			t.Errorf("re-tagging dropped the %q chunk", id)
+			continue
+		}
+		if len(got) != len(payload) {
+			t.Errorf("%q chunk size = %d, want %d", id, len(got), len(payload))
+		}
+	}
+	if !bytes.Equal(secondChunks["data"], audio) {
+		t.Error("data chunk was modified")
+	}
+	if !bytes.Equal(secondChunks["fmt "], firstChunks["fmt "]) {
+		t.Error("fmt chunk was modified")
+	}
+	if !bytes.Equal(secondChunks["LIST"], firstChunks["LIST"]) {
+		t.Error("LIST chunk was modified")
+	}
+}
+
+func TestWriteWAVOddSizedChunks(t *testing.T) {
+	audio := bytes.Repeat([]byte{0x07}, 33)
+	path := writeTestWAV(t, audio)
+
+	if err := Write(path, testMetadata()); err != nil {
+		t.Fatalf("Write() error = %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read wav: %v", err)
+	}
+
+	chunks := parseChunks(t, data)
+	if !bytes.Equal(chunks["data"], audio) {
+		t.Error("data chunk was modified")
+	}
+	if _, ok := chunks["id3 "]; !ok {
+		t.Error("missing id3 chunk")
+	}
+}
+
+func TestWriteWAVRejectsNonWAV(t *testing.T) {
+	path := filepath.Join(t.TempDir(), "track.wav")
+	if err := os.WriteFile(path, []byte("this is not a wav file at all"), 0644); err != nil {
+		t.Fatalf("write file: %v", err)
+	}
+
+	if err := Write(path, testMetadata()); err == nil {
+		t.Error("Write() error = nil, want error")
+	}
+	if _, err := os.Stat(path + ".tmp"); err == nil {
+		t.Error("Write() left a temp file behind")
+	}
+}

internal/tags/flac.go

@@ -1,87 +0,0 @@
-package tags
-
-import (
-	"os"
-	"strings"
-
-	"github.com/go-flac/flacpicture/v2"
-	"github.com/go-flac/flacvorbis/v2"
-	"github.com/go-flac/go-flac/v2"
-	"github.com/mathismqn/godeez/internal/deezer"
-)
-
-type FLACTagger struct {
-	File  *flac.File
-	Cmts  *flacvorbis.MetaDataBlockVorbisComment
-	Index int
-}
-
-func (t *FLACTagger) AddTags(resource deezer.Resource, song *deezer.Song, cover []byte, path string) error {
-	if album, ok := resource.(*deezer.Album); ok {
-		dateParts := strings.Split(album.Data.PhysicalReleaseDate, "-")
-		if len(dateParts) == 3 {
-			album.Data.PhysicalReleaseDate = dateParts[0]
-		}
-
-		t.addTag("ALBUM", album.Data.Title)
-		t.addTag("ALBUMARTIST", album.Data.Artist)
-		t.addTag("PUBLISHER", album.Data.Label)
-		t.addTag("ORIGINALDATE", album.Data.OriginalReleaseDate)
-		t.addTag("DATE", album.Data.PhysicalReleaseDate)
-		t.addTag("COMMENT", album.Data.ProducerLine)
-		t.addTag("TRACKNUMBER", song.TrackNumber)
-	}
-
-	t.addTag("TITLE", song.Title)
-	t.addTag("ARTIST", strings.Join(song.Contributors.MainArtists, ", "))
-	t.addTag("COMPOSER", strings.Join(song.Contributors.Composers, ", "))
-	t.addTag("LYRICIST", strings.Join(song.Contributors.Authors, ", "))
-	t.addTag("REPLAYGAIN_TRACK_GAIN", song.Gain)
-	t.addTag("ISRC", song.ISRC)
-
-	cmtsmeta := t.Cmts.Marshal()
-	if t.Index > 0 {
-		t.File.Meta[t.Index] = &cmtsmeta
-	} else {
-		t.File.Meta = append(t.File.Meta, &cmtsmeta)
-	}
-
-	picture, err := flacpicture.NewFromImageData(flacpicture.PictureTypeFrontCover, "Front cover", cover, "image/jpeg")
-	if err != nil {
-		return err
-	}
-	picturemeta := picture.Marshal()
-	t.File.Meta = append(t.File.Meta, &picturemeta)
-
-	return t.saveTags(path)
-}
-
-func (t *FLACTagger) addTag(name, value string) {
-	if value != "" {
-		t.Cmts.Add(name, value)
-	}
-}
-
-func (t *FLACTagger) saveTags(path string) error {
-	tempPath := path + ".tmp"
-	t.File.Save(tempPath)
-
-	return os.Rename(tempPath, path)
-}
-
-func extractFLACComment(file *flac.File) (*flacvorbis.MetaDataBlockVorbisComment, int, error) {
-	var cmt *flacvorbis.MetaDataBlockVorbisComment
-	var cmtIdx int
-	var err error
-	for idx, meta := range file.Meta {
-		if meta.Type == flac.VorbisComment {
-			cmt, err = flacvorbis.ParseFromMetaDataBlock(*meta)
-			cmtIdx = idx
-			if err != nil {
-				return nil, 0, err
-			}
-		}
-	}
-
-	return cmt, cmtIdx, nil
-}

internal/tags/id3v2.go

@@ -1,67 +0,0 @@
-package tags
-
-import (
-	"fmt"
-	"strconv"
-	"strings"
-
-	"github.com/bogem/id3v2/v2"
-	"github.com/mathismqn/godeez/internal/deezer"
-)
-
-type ID3v2Tagger struct {
-	Tag *id3v2.Tag
-}
-
-func (t *ID3v2Tagger) AddTags(resource deezer.Resource, song *deezer.Song, cover []byte, path string) error {
-	defer t.Tag.Close()
-
-	duration, _ := strconv.Atoi(song.Duration)
-	song.Duration = fmt.Sprintf("%d", duration*1000)
-
-	if album, ok := resource.(*deezer.Album); ok {
-		t.addTag("TALB", album.Data.Title)
-		t.addTag("TPE2", album.Data.Artist)
-		t.addTag("TPUB", album.Data.Label)
-		t.addTag("TDOR", album.Data.OriginalReleaseDate)
-		t.addTag("TYER", album.Data.PhysicalReleaseDate)
-		t.addTag("COMM", album.Data.ProducerLine)
-		t.addTag("TRCK", song.TrackNumber)
-	}
-
-	t.addTag("TIT2", song.Title)
-	t.addTag("TPE1", strings.Join(song.Contributors.MainArtists, ", "))
-	t.addTag("TCOM", strings.Join(song.Contributors.Composers, ", "))
-	t.addTag("TEXT", strings.Join(song.Contributors.Authors, ", "))
-	t.addTag("TLEN", song.Duration)
-	t.addTXXXTag("GAIN", song.Gain)
-	t.addTXXXTag("ISRC", song.ISRC)
-
-	frame := id3v2.PictureFrame{
-		Encoding:    t.Tag.DefaultEncoding(),
-		MimeType:    "image/jpeg",
-		PictureType: id3v2.PTFrontCover,
-		Description: "Cover",
-		Picture:     cover,
-	}
-	t.Tag.AddAttachedPicture(frame)
-
-	return t.Tag.Save()
-}
-
-func (t *ID3v2Tagger) addTag(name, value string) {
-	if value != "" {
-		t.Tag.AddTextFrame(name, t.Tag.DefaultEncoding(), value)
-	}
-}
-
-func (t *ID3v2Tagger) addTXXXTag(description, value string) {
-	if value != "" {
-		udf := id3v2.UserDefinedTextFrame{
-			Encoding:    t.Tag.DefaultEncoding(),
-			Description: description,
-			Value:       value,
-		}
-		t.Tag.AddUserDefinedTextFrame(udf)
-	}
-}

internal/tags/tag.go

@@ -1,52 +0,0 @@
-package tags
-
-import (
-	"path"
-
-	"github.com/bogem/id3v2/v2"
-	"github.com/go-flac/flacvorbis/v2"
-	"github.com/go-flac/go-flac/v2"
-	"github.com/mathismqn/godeez/internal/deezer"
-)
-
-type Tagger interface {
-	AddTags(resource deezer.Resource, song *deezer.Song, cover []byte, path string) error
-}
-
-func NewTagger(filePath string) (Tagger, error) {
-	ext := path.Ext(filePath)
-	if ext == ".mp3" {
-		tag, err := id3v2.Open(filePath, id3v2.Options{Parse: true})
-		if err != nil {
-			return nil, err
-		}
-		return &ID3v2Tagger{Tag: tag}, nil
-	}
-
-	file, err := flac.ParseFile(filePath)
-	if err != nil {
-		return nil, err
-	}
-	cmts, idx, err := extractFLACComment(file)
-	if err != nil {
-		return nil, err
-	}
-	if cmts == nil && idx > 0 {
-		cmts = flacvorbis.New()
-	}
-
-	return &FLACTagger{File: file, Cmts: cmts, Index: idx}, nil
-}
-
-func AddTags(resource deezer.Resource, song *deezer.Song, filePath string) error {
-	tagger, err := NewTagger(filePath)
-	if err != nil {
-		return err
-	}
-	cover, err := song.GetCoverImage()
-	if err != nil {
-		return err
-	}
-
-	return tagger.AddTags(resource, song, cover, filePath)
-}

internal/update/apply.go

@@ -0,0 +1,211 @@
+package update
+
+import (
+	"bufio"
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+	"github.com/mathismqn/godeez/internal/fsutil"
+)
+
+var managedPrefixes = []string{
+	"/nix/store",
+	"/opt/homebrew",
+	"/usr/local/Cellar",
+	"/home/linuxbrew",
+	"/snap",
+	"/var/lib/flatpak",
+}
+
+func resolveTarget() (string, error) {
+	if buildinfo.IsDev() {
+		return "", fmt.Errorf("development build cannot self-update; install a release from https://github.com/%s/%s/releases",
+			repoOwner, repoName)
+	}
+
+	exe, err := os.Executable()
+	if err != nil {
+		return "", fmt.Errorf("failed to locate the running binary: %w", err)
+	}
+
+	target := exe
+	if resolved, err := filepath.EvalSymlinks(exe); err == nil {
+		target = resolved
+	}
+
+	for _, prefix := range managedPrefixes {
+		if target == prefix || strings.HasPrefix(target, prefix+"/") {
+			return "", fmt.Errorf("%s was installed by a package manager; update it with that instead", target)
+		}
+	}
+
+	return target, nil
+}
+
+func CheckUpdatable() error {
+	_, err := resolveTarget()
+
+	return err
+}
+
+func checkWritable(dir string) error {
+	f, err := os.CreateTemp(dir, tmpPattern)
+	if err != nil {
+		hint := "re-run with sudo"
+		if runtime.GOOS == "windows" {
+			hint = "re-run from an elevated prompt"
+		}
+
+		return fmt.Errorf("cannot write to %s: %w; %s", dir, err, hint)
+	}
+
+	name := f.Name()
+	f.Close()
+	os.Remove(name)
+
+	return nil
+}
+
+func (u *Updater) Apply(ctx context.Context, release *Release) error {
+	target, err := resolveTarget()
+	if err != nil {
+		return err
+	}
+
+	dir := filepath.Dir(target)
+	if err := checkWritable(dir); err != nil {
+		return err
+	}
+
+	asset, err := release.assetForRuntime()
+	if err != nil {
+		return err
+	}
+
+	want, err := u.fetchChecksum(ctx, release, asset.Name)
+	if err != nil {
+		return err
+	}
+
+	u.step("Downloading %s", asset.Name)
+	tmp, sum, err := u.download(ctx, dir, asset)
+	if err != nil {
+		return err
+	}
+	defer fsutil.Remove(tmp)
+
+	u.step("Verifying checksum")
+	if sum != want {
+		return fmt.Errorf("checksum mismatch for %s: expected %s, got %s", asset.Name, want, sum)
+	}
+
+	if err := os.Chmod(tmp, 0755); err != nil {
+		return err
+	}
+
+	u.step("Replacing %s", target)
+
+	return u.replaceBinary(target, tmp)
+}
+
+func (u *Updater) fetchChecksum(ctx context.Context, release *Release, assetName string) (string, error) {
+	asset, ok := release.asset(checksumsAsset)
+	if !ok {
+		return "", fmt.Errorf("release %s does not publish %s", release.TagName, checksumsAsset)
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, apiTimeout)
+	defer cancel()
+
+	body, err := u.get(ctx, asset.URL, nil)
+	if err != nil {
+		return "", err
+	}
+	defer body.Close()
+
+	return parseChecksums(io.LimitReader(body, maxResponseSize), assetName)
+}
+
+func parseChecksums(r io.Reader, name string) (string, error) {
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		fields := strings.Fields(scanner.Text())
+		if len(fields) != 2 {
+			continue
+		}
+		if strings.TrimPrefix(fields[1], "*") == name {
+			return strings.ToLower(fields[0]), nil
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return "", err
+	}
+
+	return "", fmt.Errorf("no checksum listed for %s", name)
+}
+
+func (u *Updater) download(ctx context.Context, dir string, asset Asset) (string, string, error) {
+	ctx, cancel := context.WithTimeout(ctx, downloadTimeout)
+	defer cancel()
+
+	body, err := u.get(ctx, asset.URL, nil)
+	if err != nil {
+		return "", "", err
+	}
+	defer body.Close()
+
+	f, err := os.CreateTemp(dir, tmpPattern)
+	if err != nil {
+		return "", "", err
+	}
+	tmp := f.Name()
+
+	hash := sha256.New()
+	if _, err := io.Copy(io.MultiWriter(f, hash), body); err != nil {
+		f.Close()
+		fsutil.Remove(tmp)
+
+		return "", "", fmt.Errorf("failed to download %s: %w", asset.Name, err)
+	}
+	if err := f.Close(); err != nil {
+		fsutil.Remove(tmp)
+
+		return "", "", err
+	}
+
+	return tmp, hex.EncodeToString(hash.Sum(nil)), nil
+}
+
+func (u *Updater) replaceBinary(target, tmp string) error {
+	if runtime.GOOS != "windows" {
+		return os.Rename(tmp, target)
+	}
+
+	old := target + ".old"
+	os.Remove(old)
+
+	if err := os.Rename(target, old); err != nil {
+		return fmt.Errorf("failed to move the current binary aside: %w", err)
+	}
+
+	if err := os.Rename(tmp, target); err != nil {
+		if rollbackErr := os.Rename(old, target); rollbackErr != nil {
+			return fmt.Errorf("failed to install the new binary: %w; the previous one could not be restored from %s: %v",
+				err, old, rollbackErr)
+		}
+
+		return fmt.Errorf("failed to install the new binary: %w", err)
+	}
+
+	os.Remove(old)
+
+	return nil
+}

internal/update/apply_test.go

@@ -0,0 +1,43 @@
+package update
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestParseChecksums(t *testing.T) {
+	checksums := `ABCDEF0123  godeez_1.0.0_darwin_arm64
+deadbeef  *godeez_1.0.0_linux_amd64
+malformed-line
+one two three
+cafebabe  godeez_1.0.0_windows_amd64.exe
+`
+
+	tests := []struct {
+		name  string
+		asset string
+		want  string
+	}{
+		{"plain name lowercased", "godeez_1.0.0_darwin_arm64", "abcdef0123"},
+		{"star-prefixed name", "godeez_1.0.0_linux_amd64", "deadbeef"},
+		{"windows asset", "godeez_1.0.0_windows_amd64.exe", "cafebabe"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseChecksums(strings.NewReader(checksums), tt.asset)
+			if err != nil {
+				t.Fatalf("parseChecksums: %v", err)
+			}
+			if got != tt.want {
+				t.Errorf("parseChecksums() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestParseChecksumsMissing(t *testing.T) {
+	if _, err := parseChecksums(strings.NewReader("abc  other_asset\n"), "godeez_1.0.0_darwin_arm64"); err == nil {
+		t.Error("expected error for missing asset name")
+	}
+}

internal/update/check.go

@@ -0,0 +1,118 @@
+package update
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+	"github.com/mathismqn/godeez/internal/fsutil"
+)
+
+const noCheckEnv = "GODEEZ_NO_UPDATE_CHECK"
+
+const (
+	cacheTTL     = 24 * time.Hour
+	checkTimeout = 3 * time.Second
+)
+
+type cacheEntry struct {
+	CheckedAt     time.Time `json:"checked_at"`
+	LatestVersion string    `json:"latest_version"`
+}
+
+func cachePath() (string, error) {
+	dir, err := os.UserCacheDir()
+	if err != nil {
+		return "", err
+	}
+
+	return filepath.Join(dir, "godeez", "update.json"), nil
+}
+
+func readCache() (cacheEntry, bool) {
+	path, err := cachePath()
+	if err != nil {
+		return cacheEntry{}, false
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return cacheEntry{}, false
+	}
+
+	var entry cacheEntry
+	if err := json.Unmarshal(data, &entry); err != nil {
+		return cacheEntry{}, false
+	}
+	if entry.LatestVersion == "" || time.Since(entry.CheckedAt) > cacheTTL {
+		return cacheEntry{}, false
+	}
+
+	return entry, true
+}
+
+func writeCache(version string) error {
+	path, err := cachePath()
+	if err != nil {
+		return err
+	}
+	if err := fsutil.EnsureDir(filepath.Dir(path)); err != nil {
+		return err
+	}
+
+	data, err := json.Marshal(cacheEntry{CheckedAt: time.Now(), LatestVersion: version})
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(path, data, 0644)
+}
+
+func check(ctx context.Context) (string, error) {
+	if entry, ok := readCache(); ok {
+		return latestIfNewer(entry.LatestVersion), nil
+	}
+
+	release, err := New().Latest(ctx)
+	if err != nil {
+		return "", err
+	}
+
+	latest := release.Version()
+	_ = writeCache(latest)
+
+	return latestIfNewer(latest), nil
+}
+
+func latestIfNewer(latest string) string {
+	if IsNewer(buildinfo.Version(), latest) {
+		return latest
+	}
+
+	return ""
+}
+
+func StartCheck(ctx context.Context) <-chan string {
+	ch := make(chan string, 1)
+
+	if os.Getenv(noCheckEnv) != "" || buildinfo.IsDev() {
+		close(ch)
+		return ch
+	}
+
+	go func() {
+		defer close(ch)
+
+		ctx, cancel := context.WithTimeout(ctx, checkTimeout)
+		defer cancel()
+
+		if latest, err := check(ctx); err == nil && latest != "" {
+			ch <- latest
+		}
+	}()
+
+	return ch
+}

internal/update/release.go

@@ -0,0 +1,83 @@
+package update
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"runtime"
+)
+
+const (
+	repoOwner        = "mathismqn"
+	repoName         = "godeez"
+	latestReleaseURL = "https://api.github.com/repos/" + repoOwner + "/" + repoName + "/releases/latest"
+	checksumsAsset   = "checksums.txt"
+	maxResponseSize  = 1 << 20
+)
+
+var githubAPIHeaders = map[string]string{
+	"Accept":               "application/vnd.github+json",
+	"X-GitHub-Api-Version": "2022-11-28",
+}
+
+type Release struct {
+	TagName string  `json:"tag_name"`
+	Assets  []Asset `json:"assets"`
+}
+
+type Asset struct {
+	Name string `json:"name"`
+	URL  string `json:"browser_download_url"`
+}
+
+func (u *Updater) Latest(ctx context.Context) (*Release, error) {
+	ctx, cancel := context.WithTimeout(ctx, apiTimeout)
+	defer cancel()
+
+	body, err := u.get(ctx, latestReleaseURL, githubAPIHeaders)
+	if err != nil {
+		return nil, err
+	}
+	defer body.Close()
+
+	var release Release
+	if err := json.NewDecoder(io.LimitReader(body, maxResponseSize)).Decode(&release); err != nil {
+		return nil, fmt.Errorf("failed to decode release: %w", err)
+	}
+	if release.TagName == "" {
+		return nil, errors.New("release has no tag name")
+	}
+
+	return &release, nil
+}
+
+func (r *Release) Version() string {
+	return trimV(r.TagName)
+}
+
+func (r *Release) asset(name string) (Asset, bool) {
+	for _, a := range r.Assets {
+		if a.Name == name {
+			return a, true
+		}
+	}
+
+	return Asset{}, false
+}
+
+func (r *Release) assetForRuntime() (Asset, error) {
+	name := fmt.Sprintf("%s_%s_%s_%s", repoName, r.Version(), runtime.GOOS, runtime.GOARCH)
+	if runtime.GOOS == "windows" {
+		name += ".exe"
+	}
+
+	asset, ok := r.asset(name)
+	if !ok {
+		return Asset{}, fmt.Errorf("release %s has no binary for %s/%s (expected %s)",
+			r.TagName, runtime.GOOS, runtime.GOARCH, name)
+	}
+
+	return asset, nil
+}

internal/update/update.go

@@ -0,0 +1,56 @@
+package update
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/buildinfo"
+)
+
+const (
+	apiTimeout      = 30 * time.Second
+	downloadTimeout = 5 * time.Minute
+	tmpPattern      = ".godeez-update-*"
+)
+
+type Updater struct {
+	client *http.Client
+	Out    io.Writer
+}
+
+func New() *Updater {
+	return &Updater{
+		client: &http.Client{},
+		Out:    io.Discard,
+	}
+}
+
+func (u *Updater) step(format string, args ...any) {
+	fmt.Fprintf(u.Out, format+"...\n", args...)
+}
+
+func (u *Updater) get(ctx context.Context, url string, headers map[string]string) (io.ReadCloser, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("User-Agent", buildinfo.UserAgent())
+	for name, value := range headers {
+		req.Header.Set(name, value)
+	}
+
+	resp, err := u.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode != http.StatusOK {
+		resp.Body.Close()
+
+		return nil, fmt.Errorf("unexpected status code %d from %s", resp.StatusCode, url)
+	}
+
+	return resp.Body, nil
+}

internal/update/version.go

@@ -0,0 +1,35 @@
+package update
+
+import (
+	"strings"
+
+	"golang.org/x/mod/semver"
+)
+
+func trimV(v string) string {
+	return strings.TrimPrefix(strings.TrimSpace(v), "v")
+}
+
+func canonical(v string) string {
+	v = strings.TrimSpace(v)
+	if v == "" {
+		return ""
+	}
+	if !strings.HasPrefix(v, "v") {
+		v = "v" + v
+	}
+	if !semver.IsValid(v) {
+		return ""
+	}
+
+	return v
+}
+
+func IsNewer(current, latest string) bool {
+	c, l := canonical(current), canonical(latest)
+	if c == "" || l == "" {
+		return false
+	}
+
+	return semver.Compare(l, c) > 0
+}

internal/update/version_test.go

@@ -0,0 +1,65 @@
+package update
+
+import "testing"
+
+func TestIsNewer(t *testing.T) {
+	tests := []struct {
+		current string
+		latest  string
+		want    bool
+	}{
+		{"1.0.0", "1.0.1", true},
+		{"v1.0.0", "v1.1.0", true},
+		{"1.0.0", "v2.0.0", true},
+		{"1.0.0", "1.0.0", false},
+		{"1.1.0", "1.0.0", false},
+		{" 1.0.0 ", "1.0.1", true},
+		{"1.0.0", "1.0.1-rc.1", true},
+		{"1.0.0-rc.1", "1.0.0", true},
+		{"dev", "1.0.0", false},
+		{"1.0.0", "not-a-version", false},
+		{"", "1.0.0", false},
+		{"1.0.0", "", false},
+	}
+
+	for _, tt := range tests {
+		if got := IsNewer(tt.current, tt.latest); got != tt.want {
+			t.Errorf("IsNewer(%q, %q) = %v, want %v", tt.current, tt.latest, got, tt.want)
+		}
+	}
+}
+
+func TestTrimV(t *testing.T) {
+	tests := []struct {
+		in   string
+		want string
+	}{
+		{"v1.2.3", "1.2.3"},
+		{"1.2.3", "1.2.3"},
+		{" v1.2.3 ", "1.2.3"},
+	}
+
+	for _, tt := range tests {
+		if got := trimV(tt.in); got != tt.want {
+			t.Errorf("trimV(%q) = %q, want %q", tt.in, got, tt.want)
+		}
+	}
+}
+
+func TestCanonical(t *testing.T) {
+	tests := []struct {
+		in   string
+		want string
+	}{
+		{"1.2.3", "v1.2.3"},
+		{"v1.2.3", "v1.2.3"},
+		{"", ""},
+		{"garbage", ""},
+	}
+
+	for _, tt := range tests {
+		if got := canonical(tt.in); got != tt.want {
+			t.Errorf("canonical(%q) = %q, want %q", tt.in, got, tt.want)
+		}
+	}
+}

main.go

@@ -1,7 +1,19 @@
 package main
 
-import "github.com/mathismqn/godeez/cmd"
+import (
+	"context"
+	"os"
+	"os/signal"
+
+	"github.com/mathismqn/godeez/cmd"
+)
 
 func main() {
-	cmd.RootCmd.Execute()
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
+	defer stop()
+
+	if err := cmd.Execute(ctx); err != nil {
+		stop()
+		os.Exit(1)
+	}
 }