// Package api — media endpoints serve raw bytes (cover art, audio streams).
// The helpers below duplicate shape with internal/subsonic/stream.go by
// design; the two packages are kept independent so subsonic can freeze as a
// compatibility surface while /api evolves. See project memory
// `project_subsonic_legacy.md` for the rationale.

package api

import (
	"context"
	"os"
	"path/filepath"
	"strings"

	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
)

// sidecarNames is the lookup order for cover art living next to audio files.
// Matches common library conventions: cover.* wins over folder.*; JPEG wins
// over PNG when both exist.
var sidecarNames = []string{
	"cover.jpg", "cover.jpeg", "cover.png",
	"folder.jpg", "folder.jpeg", "folder.png",
}

// findSidecarCover looks for a conventional cover image in the directory that
// contains trackPath. Returns "" if no sidecar exists.
func findSidecarCover(trackPath string) string {
	dir := filepath.Dir(trackPath)
	for _, name := range sidecarNames {
		candidate := filepath.Join(dir, name)
		if info, err := os.Stat(candidate); err == nil && !info.IsDir() {
			return candidate
		}
	}
	return ""
}

// resolveAlbumCoverPath returns the filesystem path to the album's cover art.
// It prefers an explicit cover_art_path (set by the scanner in a future
// milestone) and falls back to a sidecar next to the first track in the
// album's directory. "" means no art was found.
func resolveAlbumCoverPath(ctx context.Context, q *dbq.Queries, album dbq.Album) string {
	if album.CoverArtPath != nil && *album.CoverArtPath != "" {
		if _, err := os.Stat(*album.CoverArtPath); err == nil {
			return *album.CoverArtPath
		}
	}
	tracks, err := q.ListTracksByAlbum(ctx, album.ID)
	if err != nil || len(tracks) == 0 {
		return ""
	}
	return findSidecarCover(tracks[0].FilePath)
}

// audioContentType maps the short file_format recorded on tracks (mp3, flac,
// ogg, opus, m4a, aac, wav) to a MIME type for the Content-Type header.
// Unknown formats fall back to octet-stream so the browser downloads them
// rather than attempting to decode.
func audioContentType(format string) string {
	switch strings.ToLower(format) {
	case "mp3":
		return "audio/mpeg"
	case "flac":
		return "audio/flac"
	case "ogg", "opus":
		return "audio/ogg"
	case "m4a":
		return "audio/mp4"
	case "aac":
		return "audio/aac"
	case "wav":
		return "audio/wav"
	}
	return "application/octet-stream"
}

// imageContentType maps a file extension to a MIME type for cover art.
// Unknown extensions fall back to octet-stream.
func imageContentType(path string) string {
	switch strings.ToLower(filepath.Ext(path)) {
	case ".jpg", ".jpeg":
		return "image/jpeg"
	case ".png":
		return "image/png"
	case ".webp":
		return "image/webp"
	case ".gif":
		return "image/gif"
	}
	return "application/octet-stream"
}