minstrel/internal/subsonic/stream.go

package subsonic

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgtype"
	"github.com/jackc/pgx/v5/pgxpool"

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

// mediaHandlers serves the bytes-on-the-wire endpoints: stream, download,
// getCoverArt, scrobble. They share a pool and an in-memory now-playing map
// because M1 has no event ingestion yet (see M2).
type mediaHandlers struct {
	pool       *pgxpool.Pool
	nowPlaying *nowPlayingMap
}

func newMediaHandlers(pool *pgxpool.Pool) *mediaHandlers {
	return &mediaHandlers{pool: pool, nowPlaying: newNowPlayingMap()}
}

// handleStream serves the raw track bytes. http.ServeContent gives us Range,
// If-Modified-Since, and ETag handling for free — the Subsonic spec requires
// Range support so clients can seek.
func (m *mediaHandlers) handleStream(w http.ResponseWriter, r *http.Request) {
	m.serveTrack(w, r, false)
}

// handleDownload is stream with a filename and attachment disposition so
// browsers save rather than stream.
func (m *mediaHandlers) handleDownload(w http.ResponseWriter, r *http.Request) {
	m.serveTrack(w, r, true)
}

func (m *mediaHandlers) serveTrack(w http.ResponseWriter, r *http.Request, attachment bool) {
	idStr := r.URL.Query().Get("id")
	if idStr == "" {
		WriteFail(w, r, ErrMissingParameter, "Missing required parameter: id")
		return
	}
	id, ok := parseUUID(idStr)
	if !ok {
		WriteFail(w, r, ErrDataNotFound, "Track not found")
		return
	}
	q := dbq.New(m.pool)
	track, err := q.GetTrackByID(r.Context(), id)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			WriteFail(w, r, ErrDataNotFound, "Track not found")
			return
		}
		WriteFail(w, r, ErrGeneric, "Failed to load track")
		return
	}

	f, err := os.Open(track.FilePath)
	if err != nil {
		// File vanished between scan and now — treat as not found so clients
		// can recover gracefully rather than assume a 5xx network blip.
		WriteFail(w, r, ErrDataNotFound, "Track file not found")
		return
	}
	defer func() { _ = f.Close() }()

	info, err := f.Stat()
	if err != nil {
		WriteFail(w, r, ErrGeneric, "Failed to stat track file")
		return
	}

	w.Header().Set("Content-Type", contentTypeForFormat(track.FileFormat))
	w.Header().Set("Accept-Ranges", "bytes")
	if attachment {
		w.Header().Set("Content-Disposition",
			fmt.Sprintf(`attachment; filename=%q`, filepath.Base(track.FilePath)))
	}
	http.ServeContent(w, r, filepath.Base(track.FilePath), info.ModTime(), f)
}

// handleGetCoverArt resolves an id (album, track, or cover-art id — all of
// which we key off the album UUID) to an image file. Scanner does not yet
// populate albums.cover_art_path, so the common path is the sidecar lookup.
func (m *mediaHandlers) handleGetCoverArt(w http.ResponseWriter, r *http.Request) {
	idStr := r.URL.Query().Get("id")
	if idStr == "" {
		WriteFail(w, r, ErrMissingParameter, "Missing required parameter: id")
		return
	}
	id, ok := parseUUID(idStr)
	if !ok {
		WriteFail(w, r, ErrDataNotFound, "Cover art not found")
		return
	}

	q := dbq.New(m.pool)
	album, albumErr := q.GetAlbumByID(r.Context(), id)
	if albumErr != nil {
		// Fall back: maybe the id is a track. Resolve through its album_id.
		track, terr := q.GetTrackByID(r.Context(), id)
		if terr != nil {
			WriteFail(w, r, ErrDataNotFound, "Cover art not found")
			return
		}
		album, albumErr = q.GetAlbumByID(r.Context(), track.AlbumID)
		if albumErr != nil {
			WriteFail(w, r, ErrDataNotFound, "Cover art not found")
			return
		}
	}

	if path := resolveAlbumCoverPath(r.Context(), q, album); path != "" {
		serveImage(w, r, path)
		return
	}
	WriteFail(w, r, ErrDataNotFound, "Cover art not found")
}

// resolveAlbumCoverPath returns the filesystem path to the album's cover art,
// preferring an explicit cover_art_path (set by the scanner in a future
// milestone) and falling back to a sidecar image next to any track in the
// album 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)
}

// sidecarNames are the conventional names for album art living next to audio
// files. Order matches how most library tools write them — cover.* wins over
// folder.*, and JPEG wins over PNG when both are present.
var sidecarNames = []string{
	"cover.jpg", "cover.jpeg", "cover.png",
	"folder.jpg", "folder.jpeg", "folder.png",
}

// findSidecarCover looks for a cover image in the directory containing the
// given track file. 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 ""
}

func serveImage(w http.ResponseWriter, r *http.Request, path string) {
	f, err := os.Open(path)
	if err != nil {
		WriteFail(w, r, ErrDataNotFound, "Cover art not found")
		return
	}
	defer func() { _ = f.Close() }()
	info, err := f.Stat()
	if err != nil {
		WriteFail(w, r, ErrGeneric, "Failed to stat cover art")
		return
	}
	w.Header().Set("Content-Type", imageContentType(path))
	http.ServeContent(w, r, filepath.Base(path), info.ModTime(), f)
}

func imageContentType(path string) string {
	switch strings.ToLower(filepath.Ext(path)) {
	case ".jpg", ".jpeg":
		return "image/jpeg"
	case ".png":
		return "image/png"
	case ".gif":
		return "image/gif"
	case ".webp":
		return "image/webp"
	default:
		return "application/octet-stream"
	}
}

// handleScrobble records a now-playing hint when submission=false. M1 has no
// event ingestion, so submission=true is a no-op that still returns ok — the
// real play/skip/seek/complete events land in M2.
func (m *mediaHandlers) handleScrobble(w http.ResponseWriter, r *http.Request) {
	params := r.URL.Query()
	idStr := params.Get("id")
	if idStr == "" {
		WriteFail(w, r, ErrMissingParameter, "Missing required parameter: id")
		return
	}
	trackID, ok := parseUUID(idStr)
	if !ok {
		WriteFail(w, r, ErrDataNotFound, "Track not found")
		return
	}

	// Per spec, submission defaults to true. Only false means "this is now
	// playing, don't record a play event." Anything else is an M2 no-op.
	submission := strings.ToLower(params.Get("submission"))
	if submission == "false" {
		if user, ok := UserFromContext(r.Context()); ok {
			m.nowPlaying.Set(uuidToID(user.ID), trackID)
		}
	}

	Write(w, r, struct{ Envelope }{Envelope: NewEnvelope("ok")})
}

// nowPlayingMap is a tiny in-memory store keyed by user id. M1 doesn't expose
// a getNowPlaying endpoint yet; this structure exists so scrobble has a place
// to write and M2 has something to read.
type nowPlayingMap struct {
	mu sync.RWMutex
	m  map[string]nowPlayingEntry
}

type nowPlayingEntry struct {
	TrackID pgtype.UUID
	At      time.Time
}

func newNowPlayingMap() *nowPlayingMap {
	return &nowPlayingMap{m: make(map[string]nowPlayingEntry)}
}

func (n *nowPlayingMap) Set(userID string, trackID pgtype.UUID) {
	n.mu.Lock()
	defer n.mu.Unlock()
	n.m[userID] = nowPlayingEntry{TrackID: trackID, At: time.Now()}
}

func (n *nowPlayingMap) Get(userID string) (nowPlayingEntry, bool) {
	n.mu.RLock()
	defer n.mu.RUnlock()
	e, ok := n.m[userID]
	return e, ok
}