package library

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"os"
	"path/filepath"
	"sync"
	"testing"
	"time"

	"github.com/google/uuid"
	"github.com/stretchr/testify/require"
)

func TestCoverSharePaths(t *testing.T) {
	for _, rel := range []string{
		"Modeselektor - Happy Birthday! (2007-09-10)/cover.jpg",
		"Coco Bryce/Albums/(2025-11-28) Noches Sephardies/cover.jpg",
		"Thoma - Salt Spring (2019)/cover.jpeg",
		"Franz Ferdinand/2017 - Always Ascending (Single)/Cover.png",
		"Noisia/[FLAC] CCTV - Factory 5 [199502673] [2009]/cover.jpg",
		"Kerala Dust/Kerala Dust - Francesca's Frames EP (2018-04-20)/cover.jpg",
	} {
		t.Run(rel, func(t *testing.T) {
			root := t.TempDir()
			cover := filepath.Join(root, filepath.FromSlash(rel))
			require.NoError(t, os.MkdirAll(filepath.Dir(cover), 0o755))
			require.NoError(t, os.WriteFile(cover, []byte("shared image"), 0o644))
			audio := filepath.Join(filepath.Dir(cover), "01 - Track.flac")
			require.NoError(t, os.WriteFile(audio, nil, 0o644))
			c := Covers{FFmpeg: filepath.Join(root, "missing-ffmpeg")}
			img, err := c.findAudio(context.Background(), audio)
			require.NoError(t, err)
			require.Equal(t, []byte("shared image"), img)
		})
	}
}

func TestCoverFolderPriorityAndLimit(t *testing.T) {
	dir := t.TempDir()
	audio := filepath.Join(dir, "track.flac")
	require.NoError(t, os.WriteFile(audio, nil, 0o644))
	require.NoError(t, os.WriteFile(filepath.Join(dir, "folder.jpg"), []byte("folder"), 0o644))
	require.NoError(t, os.WriteFile(filepath.Join(dir, "COVER.JPEG"), []byte("cover"), 0o644))
	c := Covers{FFmpeg: filepath.Join(dir, "missing-ffmpeg")}
	img, err := c.findAudio(context.Background(), audio)
	require.NoError(t, err)
	require.Equal(t, "cover", string(img))
	f, err := os.OpenFile(filepath.Join(dir, "COVER.JPEG"), os.O_WRONLY, 0o644)
	require.NoError(t, err)
	t.Cleanup(func() { _ = f.Close() })
	require.NoError(t, f.Truncate(maxCoverBytes+1))
	require.NoError(t, f.Close())
	_, err = c.findAudio(context.Background(), audio)
	require.ErrorContains(t, err, "too large")
}

func TestCoverReadFailures(t *testing.T) {
	dir := t.TempDir()
	c := Covers{FFmpeg: filepath.Join(dir, "missing-ffmpeg")}
	audio := filepath.Join(dir, "missing.flac")
	_, err := c.findAudio(context.Background(), audio)
	require.Error(t, err)
	require.NoError(t, os.WriteFile(audio, nil, 0o644))
	_, err = c.findAudio(context.Background(), audio)
	require.Error(t, err, "missing converter must not mark an album checked")
	require.NoError(t, os.WriteFile(filepath.Join(dir, "cover.jpg"), []byte("cover"), 0o644))
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	_, err = c.findAudio(ctx, audio)
	require.ErrorIs(t, err, context.Canceled)
}

type failingCoverStore struct {
	mu         sync.Mutex
	candidates []CoverCandidate
	visited    []uuid.UUID
	checked    int
	entered    chan struct{}
	release    chan struct{}
}

func (s *failingCoverStore) AlbumsWithoutCover(_ context.Context, _ int, after uuid.UUID) ([]CoverCandidate, error) {
	// Deliberately short pages exercise pagination independently of the batch size.
	for i, a := range s.candidates {
		if a.AlbumID.String() > after.String() {
			return s.candidates[i:min(i+4, len(s.candidates))], nil
		}
	}
	return nil, nil
}

func (s *failingCoverStore) GetSource(_ context.Context, id uuid.UUID) (Source, error) {
	s.mu.Lock()
	s.visited = append(s.visited, id)
	s.mu.Unlock()
	s.entered <- struct{}{}
	<-s.release
	return Source{}, errors.New("share temporarily unavailable")
}

func (s *failingCoverStore) SetAlbumCover(context.Context, uuid.UUID, *string, []string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.checked++
	return nil
}

func TestCoverWorkersRetryFailuresWithoutLooping(t *testing.T) {
	s := &failingCoverStore{entered: make(chan struct{}, 20), release: make(chan struct{})}
	for i := byte(1); i <= 7; i++ {
		id := uuid.UUID{15: i}
		s.candidates = append(s.candidates, CoverCandidate{AlbumID: id, SourceID: id})
	}
	c := Covers{store: s, Dir: t.TempDir(), log: slog.New(slog.NewTextHandler(io.Discard, nil))}
	done := make(chan struct{})
	go func() { c.Run(context.Background()); close(done) }()
	for range 4 {
		select {
		case <-s.entered:
		case <-time.After(5 * time.Second):
			t.Fatal("expected four concurrent cover workers")
		}
	}
	close(s.release)
	select {
	case <-done:
	case <-time.After(5 * time.Second):
		t.Fatal("failed albums must not loop or prevent later pages")
	}
	require.Len(t, s.visited, 7)
	require.Zero(t, s.checked, "IO failures remain eligible for retry")
	c.Run(context.Background())
	require.Len(t, s.visited, 14, "next run retries failures")
}

type sourceCoverStore struct{ *failingCoverStore }

func (s sourceCoverStore) GetSource(context.Context, uuid.UUID) (Source, error) {
	return Source{Type: SourceLocal}, nil
}

func TestCoverRenderFailureRemainsPending(t *testing.T) {
	dir := t.TempDir()
	require.NoError(t, os.WriteFile(filepath.Join(dir, "track.flac"), nil, 0o644))
	require.NoError(t, os.WriteFile(filepath.Join(dir, "cover.jpg"), []byte("invalid image"), 0o644))
	s := sourceCoverStore{&failingCoverStore{}}
	c := Covers{
		store:  s,
		svc:    &Service{SourceService: &SourceService{cfg: Config{HostRoot: dir}}},
		FFmpeg: filepath.Join(dir, "missing-ffmpeg"),
		Dir:    t.TempDir(),
		log:    slog.New(slog.NewTextHandler(io.Discard, nil)),
	}
	c.process(context.Background(), CoverCandidate{AlbumID: uuid.New(), RelPath: "track.flac"})
	require.Zero(t, s.checked, "conversion errors must not save a missing cover")
}