nidus/internal/db/db.go

// Package db provides a lightweight SQLite-backed store for data that
// doesn't fit the plain-file model used by internal/store — currently
// calendar/address-book sharing grants. It's intentionally small: no ORM,
// just database/sql with hand-written queries, so it stays easy to
// extend when user management and the web UI are added later.
package db

import (
	"database/sql"
	"fmt"
	"os"
	"path/filepath"

	_ "modernc.org/sqlite"
)

// DB wraps a SQLite connection and exposes typed helpers for the
// application's tables.
type DB struct {
	conn *sql.DB
}

// Open opens (creating if necessary) the SQLite database at path and runs
// schema migrations. The parent directory of path is created if it
// doesn't already exist.
func Open(path string) (*DB, error) {
	if dir := filepath.Dir(path); dir != "" && dir != "." {
		if err := os.MkdirAll(dir, 0o755); err != nil {
			return nil, fmt.Errorf("creating database directory %q: %w", dir, err)
		}
	}

	conn, err := sql.Open("sqlite", path+"?_pragma=foreign_keys(1)")
	if err != nil {
		return nil, fmt.Errorf("opening database %q: %w", path, err)
	}
	// SQLite only supports one writer at a time; a single connection avoids
	// "database is locked" errors under concurrent access.
	conn.SetMaxOpenConns(1)

	d := &DB{conn: conn}
	if err := d.migrate(); err != nil {
		conn.Close()
		return nil, fmt.Errorf("migrating database: %w", err)
	}
	return d, nil
}

// Close closes the underlying connection.
func (d *DB) Close() error {
	return d.conn.Close()
}

func (d *DB) migrate() error {
	const schema = `
CREATE TABLE IF NOT EXISTS users (
	username TEXT PRIMARY KEY,
	password_hash TEXT NOT NULL,
	display_name TEXT NOT NULL DEFAULT '',
	email TEXT NOT NULL DEFAULT '',
	created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE IF NOT EXISTS calendars (
	owner TEXT NOT NULL REFERENCES users (username) ON DELETE CASCADE,
	name TEXT NOT NULL,
	color TEXT NOT NULL DEFAULT '',
	created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
	PRIMARY KEY (owner, name)
);

CREATE TABLE IF NOT EXISTS addressbooks (
	owner TEXT NOT NULL REFERENCES users (username) ON DELETE CASCADE,
	name TEXT NOT NULL,
	created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
	PRIMARY KEY (owner, name)
);

CREATE TABLE IF NOT EXISTS calendar_shares (
	id INTEGER PRIMARY KEY AUTOINCREMENT,
	owner TEXT NOT NULL,
	calendar_name TEXT NOT NULL,
	shared_with TEXT NOT NULL,
	permission TEXT NOT NULL CHECK (permission IN ('read', 'write')),
	created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
	UNIQUE (owner, calendar_name, shared_with)
);

CREATE TABLE IF NOT EXISTS addressbook_shares (
	id INTEGER PRIMARY KEY AUTOINCREMENT,
	owner TEXT NOT NULL,
	addressbook_name TEXT NOT NULL,
	shared_with TEXT NOT NULL,
	permission TEXT NOT NULL CHECK (permission IN ('read', 'write')),
	created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
	UNIQUE (owner, addressbook_name, shared_with)
);

-- Web UI login sessions. Sessions are opaque random tokens stored server
-- side (not JWTs) so they can be revoked instantly by deleting the row.
CREATE TABLE IF NOT EXISTS web_sessions (
	token TEXT PRIMARY KEY,
	username TEXT NOT NULL,
	created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
	expires_at DATETIME NOT NULL
);
CREATE INDEX IF NOT EXISTS idx_web_sessions_expires_at ON web_sessions (expires_at);
`
	_, err := d.conn.Exec(schema)
	if err != nil {
		return err
	}
	return d.migrateAddColumns()
}

// migrateAddColumns adds columns to already-existing tables that predate
// their introduction. CREATE TABLE IF NOT EXISTS above only creates a
// table's initial shape, so columns added later (like calendars.color)
// need an explicit ALTER TABLE for databases created before this change.
func (d *DB) migrateAddColumns() error {
	hasColumn := func(table, column string) (bool, error) {
		rows, err := d.conn.Query(`SELECT name FROM pragma_table_info(?)`, table)
		if err != nil {
			return false, err
		}
		defer rows.Close()
		for rows.Next() {
			var name string
			if err := rows.Scan(&name); err != nil {
				return false, err
			}
			if name == column {
				return true, nil
			}
		}
		return false, rows.Err()
	}

	ok, err := hasColumn("calendars", "color")
	if err != nil {
		return fmt.Errorf("checking calendars.color column: %w", err)
	}
	if !ok {
		if _, err := d.conn.Exec(`ALTER TABLE calendars ADD COLUMN color TEXT NOT NULL DEFAULT ''`); err != nil {
			return fmt.Errorf("adding calendars.color column: %w", err)
		}
	}
	return nil
}