feat: download single tracks (#5)

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.

internal/deezer/client.go

@@ -45,6 +45,8 @@ func (c *Client) FetchResource(ctx context.Context, resource Resource, id string
 		payload["alb_id"] = id
 	case *Artist:
 		payload["art_id"] = id
+	case *Track:
+		payload["sng_id"] = id
 	default:
 		return fmt.Errorf("unsupported resource type: %T", r)
 	}
@@ -84,6 +86,9 @@ func (c *Client) FetchResource(ctx context.Context, resource Resource, id string
 	if strings.Contains(string(body), `"DATA_ERROR":"artist::getData"`) {
 		return fmt.Errorf("invalid artist ID")
 	}
+	if strings.Contains(string(body), `"DATA_ERROR":"song::getData"`) {
+		return fmt.Errorf("invalid track ID")
+	}
 	if strings.Contains(string(body), `"results":{}`) {
 		return fmt.Errorf("unexpected response")
 	}

internal/deezer/track.go

@@ -0,0 +1,81 @@
+package deezer
+
+import (
+	"encoding/json"
+	"fmt"
+	"path"
+	"time"
+
+	"github.com/flytam/filenamify"
+)
+
+type Track struct {
+	Results struct {
+		Data *Song `json:"DATA"`
+	} `json:"results"`
+}
+
+func (t *Track) String() string {
+	if t.Results.Data == nil {
+		return "Track: No data available"
+	}
+
+	duration := "Unknown"
+	if t.Results.Data.Duration != "" {
+		if d, err := time.ParseDuration(t.Results.Data.Duration + "s"); err == nil {
+			duration = d.String()
+		}
+	}
+
+	return fmt.Sprintf(
+		`================= [ Track Info ] =================
+Title:    %s
+Artist:   %s
+Duration: %s
+==================================================`,
+		t.Results.Data.GetTitle(),
+		t.Results.Data.Artist,
+		duration,
+	)
+}
+
+func (t *Track) GetType() string {
+	return "Track"
+}
+
+func (t *Track) GetTitle() string {
+	if t.Results.Data == nil {
+		return ""
+	}
+	return t.Results.Data.GetTitle()
+}
+
+func (t *Track) GetSongs() []*Song {
+	if t.Results.Data == nil {
+		return []*Song{}
+	}
+	return []*Song{t.Results.Data}
+}
+
+func (t *Track) SetSongs(songs []*Song) {
+	if len(songs) > 0 {
+		t.Results.Data = songs[0]
+	}
+}
+
+func (t *Track) GetOutputDir(outputDir string) string {
+	if t.Results.Data == nil {
+		return outputDir
+	}
+
+	// For single tracks, create a simple "Singles" folder
+	base := "Singles"
+	base, _ = filenamify.Filenamify(base, filenamify.Options{})
+	outputDir = path.Join(outputDir, base)
+
+	return outputDir
+}
+
+func (t *Track) Unmarshal(data []byte) error {
+	return json.Unmarshal(data, t)
+}

internal/downloader/client.go

@@ -63,6 +63,8 @@ func (c *Client) Run(ctx context.Context, opts Options, id string) error {
 		resource = &deezer.Playlist{}
 	case "artist":
 		resource = &deezer.Artist{}
+	case "track":
+		resource = &deezer.Track{}
 	default:
 		return fmt.Errorf("unsupported resource type: %s", c.resourceType)
 	}