package backend

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

	"music-server/internal/db/repository"
	"music-server/internal/testutil/fakedb"

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

func writeFile(t *testing.T, path, content string) {
	t.Helper()
	require.NoError(t, os.MkdirAll(filepath.Dir(path), 0o755))
	require.NoError(t, os.WriteFile(path, []byte(content), 0o644))
}

// addSoundtrackWithSongs creates a soundtrack folder with song files and matching database rows.
func addSoundtrackWithSongs(t *testing.T, store *fakedb.Store, musicDir, name string, timesPlayed int32, songs ...string) repository.Soundtrack {
	t.Helper()
	dir := musicDir + "/" + name + "/"
	st := store.AddSoundtrack(repository.Soundtrack{SoundtrackName: name, Path: dir, TimesPlayed: timesPlayed})
	for _, song := range songs {
		fileName := song + ".mp3"
		writeFile(t, dir+fileName, song)
		store.AddTestSong(repository.Song{SoundtrackID: st.ID, SongName: song, Path: dir + fileName, FileName: &fileName})
	}
	return st
}

func TestMusicServiceEmptyQueue(t *testing.T) {
	m := NewMusicService(fakedb.New(), t.TempDir())

	_, err := m.NextSong()
	assert.ErrorIs(t, err, ErrQueueEmpty)
	_, err = m.PreviousSong()
	assert.ErrorIs(t, err, ErrQueueEmpty)
	_, err = m.Song(0)
	assert.ErrorIs(t, err, ErrQueueEmpty)
	assert.Equal(t, SongInfo{}, m.SongInfo(context.Background()))
	assert.Empty(t, m.PlayedSongs(context.Background()))
	assert.NoError(t, m.AddLatestPlayed(context.Background()))
	assert.NoError(t, m.SetPlayed(context.Background(), -1))
}

func TestMusicServiceNoSoundtracks(t *testing.T) {
	m := NewMusicService(fakedb.New(), t.TempDir())
	ctx := context.Background()

	_, err := m.RandomSong(ctx)
	assert.ErrorIs(t, err, ErrNoSongs)
	_, err = m.RandomSongLowChance(ctx)
	assert.ErrorIs(t, err, ErrNoSongs)
	_, err = m.RandomSongClassic(ctx)
	assert.ErrorIs(t, err, ErrNoSongs)
}

func TestMusicServiceSoundtracksWithoutSongs(t *testing.T) {
	store := fakedb.New()
	store.AddSoundtrack(repository.Soundtrack{SoundtrackName: "Empty"})
	m := NewMusicService(store, t.TempDir())

	_, err := m.RandomSong(context.Background())
	assert.ErrorIs(t, err, ErrNoSongs)
}

func TestMusicServiceQueue(t *testing.T) {
	store := fakedb.New()
	musicDir := t.TempDir()
	addSoundtrackWithSongs(t, store, musicDir, "Game A", 0, "Song 1", "Song 2")
	m := NewMusicService(store, t.TempDir())
	ctx := context.Background()

	first, err := m.RandomSong(ctx)
	require.NoError(t, err)
	m.AddLatestToQueue()
	second, err := m.RandomSong(ctx)
	require.NoError(t, err)
	m.AddLatestToQueue()

	info := m.SongInfo(ctx)
	assert.Equal(t, "Game A", info.Soundtrack)
	soundtrack, _ := store.Soundtrack("Game A")
	assert.Equal(t, soundtrack.Uuid, info.SoundtrackUuid)
	assert.Contains(t, []string{first, second}, songPathByUUID(store, info.SongUuid))
	assert.Equal(t, 1, info.SongNo)
	assert.True(t, info.CurrentlyPlaying)

	path, err := m.PreviousSong()
	require.NoError(t, err)
	assert.Equal(t, first, path)
	path, err = m.PreviousSong()
	require.NoError(t, err)
	assert.Equal(t, first, path, "previous stays on the first song")

	path, err = m.NextSong()
	require.NoError(t, err)
	assert.Equal(t, second, path)
	path, err = m.NextSong()
	require.NoError(t, err)
	assert.Equal(t, second, path, "next stays on the last song")

	path, err = m.Song(99)
	require.NoError(t, err)
	assert.Equal(t, second, path, "song number is clamped")

	played := m.PlayedSongs(ctx)
	require.Len(t, played, 2)
	assert.False(t, played[0].CurrentlyPlaying)
	assert.True(t, played[1].CurrentlyPlaying)

	require.NoError(t, m.Reset(ctx))
	_, err = m.NextSong()
	assert.ErrorIs(t, err, ErrQueueEmpty)
}

func TestMusicServiceAddLatestToQueueWithoutFetch(t *testing.T) {
	m := NewMusicService(fakedb.New(), t.TempDir())
	m.AddLatestToQueue()
	_, err := m.NextSong()
	assert.ErrorIs(t, err, ErrQueueEmpty)
}

func TestMusicServiceMarkPlayed(t *testing.T) {
	store := fakedb.New()
	st := addSoundtrackWithSongs(t, store, t.TempDir(), "Game A", 0, "Song 1")
	m := NewMusicService(store, t.TempDir())
	ctx := context.Background()

	_, err := m.RandomSong(ctx)
	require.NoError(t, err)
	m.AddLatestToQueue()

	require.NoError(t, m.AddLatestPlayed(ctx))
	require.NoError(t, m.SetPlayed(ctx, 0))
	require.NoError(t, m.SetPlayed(ctx, 5), "out of range is ignored")

	updated, _ := store.Soundtrack("Game A")
	assert.Equal(t, int32(2), updated.TimesPlayed)
	assert.Equal(t, int32(2), store.SongsOf(st.ID)[0].TimesPlayed)
}

func TestMusicServiceRemovesBrokenSongs(t *testing.T) {
	store := fakedb.New()
	musicDir := t.TempDir()
	st := addSoundtrackWithSongs(t, store, musicDir, "Game A", 0, "Good")
	missing := "Missing.mp3"
	store.AddTestSong(repository.Song{SoundtrackID: st.ID, SongName: "Missing", Path: st.Path + missing, FileName: &missing})
	wav := "Wave.wav"
	writeFile(t, st.Path+wav, "wav")
	store.AddTestSong(repository.Song{SoundtrackID: st.ID, SongName: "Wave", Path: st.Path + wav, FileName: &wav})
	m := NewMusicService(store, t.TempDir())

	for range 20 {
		path, err := m.RandomSong(context.Background())
		require.NoError(t, err)
		assert.Equal(t, st.Path+"Good.mp3", path)
	}
	songs := store.SongsOf(st.ID)
	require.Len(t, songs, 1)
	assert.Equal(t, "Good", songs[0].SongName)
}

func TestMusicServiceRandomSongClassic(t *testing.T) {
	store := fakedb.New()
	st := addSoundtrackWithSongs(t, store, t.TempDir(), "Game A", 0, "Good")
	missing := "Missing.mp3"
	store.AddTestSong(repository.Song{SoundtrackID: st.ID, SongName: "Missing", Path: st.Path + missing, FileName: &missing})
	m := NewMusicService(store, t.TempDir())

	for range 20 {
		path, err := m.RandomSongClassic(context.Background())
		require.NoError(t, err)
		assert.Equal(t, st.Path+"Good.mp3", path)
	}
	assert.Len(t, store.SongsOf(st.ID), 1)
}

func TestLowChanceWeights(t *testing.T) {
	soundtracks := []repository.Soundtrack{
		{SoundtrackName: "Often", TimesPlayed: 30},
		{SoundtrackName: "Average", TimesPlayed: 20},
		{SoundtrackName: "Rarely", TimesPlayed: 10},
	}
	weights := lowChanceWeights(soundtracks)
	assert.Equal(t, []int{1, 1, 10}, []int{weights[0].weight, weights[1].weight, weights[2].weight})
}

func TestAveragePlayed(t *testing.T) {
	assert.Equal(t, int32(0), averagePlayed(nil))
	assert.Equal(t, int32(20), averagePlayed([]repository.Soundtrack{{TimesPlayed: 10}, {TimesPlayed: 30}}))
}

func TestSoundtrackNames(t *testing.T) {
	store := fakedb.New()
	store.AddSoundtrack(repository.Soundtrack{SoundtrackName: "B"})
	store.AddSoundtrack(repository.Soundtrack{SoundtrackName: "A"})
	m := NewMusicService(store, t.TempDir())

	names, err := m.SoundtrackNames(context.Background())
	require.NoError(t, err)
	assert.Equal(t, []string{"A", "B"}, names)

	random, err := m.SoundtrackNamesRandom(context.Background())
	require.NoError(t, err)
	assert.ElementsMatch(t, []string{"A", "B"}, random)
	assert.Equal(t, []string{"A", "B"}, names, "shuffling must not change the cached order")
}

func TestSoundCheckSong(t *testing.T) {
	dir := t.TempDir()
	m := NewMusicService(fakedb.New(), dir)
	_, err := m.SoundCheckSong()
	assert.ErrorIs(t, err, ErrNoSongs)

	writeFile(t, filepath.Join(dir, "check.mp3"), "x")
	path, err := m.SoundCheckSong()
	require.NoError(t, err)
	assert.Equal(t, filepath.Join(dir, "check.mp3"), path)

	_, err = NewMusicService(fakedb.New(), filepath.Join(dir, "missing")).SoundCheckSong()
	assert.Error(t, err)
}

func songPathByUUID(store *fakedb.Store, id uuid.UUID) string {
	for _, song := range store.Songs {
		if song.Uuid == id {
			return song.Path
		}
	}
	return ""
}

func TestMarkPlayedUsesSongUUID(t *testing.T) {
	// Two songs with the same name in one soundtrack: only the played one is counted.
	store := fakedb.New()
	st := addSoundtrackWithSongs(t, store, t.TempDir(), "Game A", 0, "Song")
	fileName := "Song (copy).mp3"
	writeFile(t, st.Path+fileName, "copy")
	store.AddTestSong(repository.Song{SoundtrackID: st.ID, SongName: "Song", Path: st.Path + fileName, FileName: &fileName})
	m := NewMusicService(store, t.TempDir())
	ctx := context.Background()

	_, err := m.RandomSong(ctx)
	require.NoError(t, err)
	m.AddLatestToQueue()
	require.NoError(t, m.AddLatestPlayed(ctx))

	songs := store.SongsOf(st.ID)
	require.Len(t, songs, 2)
	assert.ElementsMatch(t, []int32{0, 1}, []int32{songs[0].TimesPlayed, songs[1].TimesPlayed})
}