package backend

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

	"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 strPtr(s string) *string { return &s }

func TestReconcileSongs(t *testing.T) {
	keep := repository.Song{Uuid: uuid.New(), Path: "/m/a.mp3", SongName: "a", FileName: strPtr("a.mp3"), Hash: "ha"}
	changed := repository.Song{Uuid: uuid.New(), Path: "/m/b.mp3", SongName: "b", FileName: strPtr("b.mp3"), Hash: "old"}
	renamed := repository.Song{Uuid: uuid.New(), Path: "/m/c.mp3", SongName: "c", FileName: strPtr("c.mp3"), Hash: "hc"}
	removed := repository.Song{Uuid: uuid.New(), Path: "/m/d.mp3", SongName: "d", FileName: strPtr("d.mp3"), Hash: "hd"}

	files := []songFile{
		{name: "a", fileName: "a.mp3", path: "/m/a.mp3", hash: "ha"},
		{name: "b", fileName: "b.mp3", path: "/m/b.mp3", hash: "new"},
		{name: "c2", fileName: "c2.mp3", path: "/m/c2.mp3", hash: "hc"},
		{name: "e", fileName: "e.mp3", path: "/m/e.mp3", hash: "he"},
	}

	ops := reconcileSongs([]repository.Song{keep, changed, renamed, removed}, files)

	assert.Equal(t, []songFile{files[3]}, ops.insert)
	assert.Equal(t, []uuid.UUID{removed.Uuid}, ops.delete)
	assert.ElementsMatch(t, []songUpdate{
		{uuid: changed.Uuid, file: files[1]},
		{uuid: renamed.Uuid, file: files[2]},
	}, ops.update)
}

func TestReconcileSongsDuplicateHashes(t *testing.T) {
	// Two identical files: each existing song may only be matched once.
	existing := repository.Song{Uuid: uuid.New(), Path: "/m/a.mp3", SongName: "a", FileName: strPtr("a.mp3"), Hash: "h"}
	files := []songFile{
		{name: "a", fileName: "a.mp3", path: "/m/a.mp3", hash: "h"},
		{name: "copy", fileName: "copy.mp3", path: "/m/copy.mp3", hash: "h"},
	}
	ops := reconcileSongs([]repository.Song{existing}, files)
	assert.Empty(t, ops.update)
	assert.Empty(t, ops.delete)
	assert.Equal(t, []songFile{files[1]}, ops.insert)
}

func TestClassify(t *testing.T) {
	existing := []repository.Soundtrack{
		{ID: 1, SoundtrackName: "Game A", Hash: "ha"},
		{ID: 2, SoundtrackName: "Game B", Hash: "hb"},
	}
	tests := []struct {
		name, hash string
		status     SoundtrackStatus
		id         int32
	}{
		{"Game A", "ha", NotChanged, 1},
		{"Game A", "changed", SoundtrackChanged, 1},
		{"Game B renamed", "hb", TitleChanged, 2},
		{"Game C", "hc", NewSoundtrack, 0},
	}
	for _, tt := range tests {
		status, match := classify(existing, tt.name, tt.hash)
		assert.Equal(t, tt.status, status, tt.name)
		if tt.id == 0 {
			assert.Nil(t, match)
		} else {
			assert.Equal(t, tt.id, match.ID)
		}
	}
}

func TestFingerprint(t *testing.T) {
	dir := t.TempDir()
	writeFile(t, filepath.Join(dir, "a.mp3"), "one")
	writeFile(t, filepath.Join(dir, "sub", "b.mp3"), "two")

	first, err := fingerprint(dir)
	require.NoError(t, err)
	again, err := fingerprint(dir)
	require.NoError(t, err)
	assert.Equal(t, first, again)

	writeFile(t, filepath.Join(dir, "sub", "b.mp3"), "changed size")
	changed, err := fingerprint(dir)
	require.NoError(t, err)
	assert.NotEqual(t, first, changed, "changes in sub folders are detected")

	// Moving the folder keeps the fingerprint, so renames are detected by name lookup failing.
	moved := filepath.Join(t.TempDir(), "moved")
	require.NoError(t, os.Rename(dir, moved))
	afterMove, err := fingerprint(moved)
	require.NoError(t, err)
	assert.Equal(t, changed, afterMove)
}

func TestIsSong(t *testing.T) {
	dir := t.TempDir()
	for _, name := range []string{"a.mp3", "b.MP3", "c.wav", "cover.jpg"} {
		writeFile(t, filepath.Join(dir, name), "x")
	}
	require.NoError(t, os.Mkdir(filepath.Join(dir, "folder.mp3"), 0o755))
	entries, err := os.ReadDir(dir)
	require.NoError(t, err)

	var songs []string
	for _, e := range entries {
		if isSong(e) {
			songs = append(songs, e.Name())
		}
	}
	assert.Equal(t, []string{"a.mp3", "b.MP3"}, songs)
	assert.Equal(t, "b", songName("b.MP3"))
}

// syncFixture is a music folder with a SyncService backed by an in-memory database.
type syncFixture struct {
	t     *testing.T
	dir   string
	store *fakedb.Store
	sync  *SyncService
}

func newSyncFixture(t *testing.T) *syncFixture {
	dir := t.TempDir()
	store := fakedb.New()
	return &syncFixture{t: t, dir: dir, store: store, sync: NewSyncService(store, dir, nil)}
}

func (f *syncFixture) write(rel, content string) {
	writeFile(f.t, filepath.Join(f.dir, rel), content)
}

func (f *syncFixture) run(full bool) SyncResponse {
	f.t.Helper()
	require.True(f.t, f.sync.Start(full))
	f.sync.Wait()
	require.False(f.t, f.sync.IsSyncing())
	return f.sync.Result()
}

func (f *syncFixture) soundtrack(name string) repository.Soundtrack {
	f.t.Helper()
	st, ok := f.store.Soundtrack(name)
	require.True(f.t, ok, "soundtrack %q not found", name)
	return st
}

func TestSyncAddsSoundtracksAndSongs(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01 Title.mp3", "a1")
	f.write("Game A/02 Battle.MP3", "a2")
	f.write("Game A/cover.jpg", "img")
	f.write("Game B/01 Intro.mp3", "b1")
	f.write("old/ignored.mp3", "x")
	f.write("loose file.mp3", "x")

	result := f.run(false)
	assert.Equal(t, []string{"Game A", "Game B"}, result.SoundtracksAdded)
	assert.Empty(t, result.CatchedErrors)

	a := f.soundtrack("Game A")
	assert.Equal(t, f.dir+"/Game A/", a.Path)
	assert.NotEmpty(t, a.Hash)
	assert.NotEmpty(t, a.Fingerprint)
	songs := f.store.SongsOf(a.ID)
	require.Len(t, songs, 2)
	assert.Equal(t, "01 Title", songs[0].SongName)
	assert.Equal(t, "02 Battle", songs[1].SongName)
	assert.Equal(t, a.Uuid, songs[0].SoundtrackUuid)
	assert.NotEmpty(t, songs[0].Hash)

	_, ok := f.store.Soundtrack("old")
	assert.False(t, ok, "skipped folders are not synced")
}

func TestSyncSkipsUnchangedSoundtracksByFingerprint(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01.mp3", "a1")
	f.run(false)

	// If the folder were hashed again, the stored hash would be replaced.
	a := f.soundtrack("Game A")
	require.NoError(t, f.store.UpdateSoundtrackHash(context.Background(), repository.UpdateSoundtrackHashParams{Hash: "stale", ID: a.ID}))

	result := f.run(false)
	assert.Empty(t, result.SoundtracksAdded)
	assert.Empty(t, result.SoundtracksChangedContent)
	assert.Equal(t, "stale", f.soundtrack("Game A").Hash)

	result = f.run(true)
	assert.NotEqual(t, "stale", f.soundtrack("Game A").Hash, "a full sync always hashes")
	assert.Empty(t, result.SoundtracksChangedTitle, "a full sync does not report unchanged titles")
}

func TestSyncDetectsChangedContent(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01.mp3", "a1")
	f.write("Game A/02.mp3", "a2")
	f.run(false)
	a := f.soundtrack("Game A")
	before := f.store.SongsOf(a.ID)

	require.NoError(t, os.Remove(filepath.Join(f.dir, "Game A/02.mp3")))
	require.NoError(t, os.Rename(filepath.Join(f.dir, "Game A/01.mp3"), filepath.Join(f.dir, "Game A/01 renamed.mp3")))
	f.write("Game A/03.mp3", "a3")

	result := f.run(false)
	assert.Equal(t, []string{"Game A"}, result.SoundtracksChangedContent)

	after := f.store.SongsOf(a.ID)
	require.Len(t, after, 2)
	assert.Equal(t, "01 renamed", after[0].SongName)
	assert.Equal(t, before[0].Uuid, after[0].Uuid, "renamed song keeps its identity and play count")
	assert.Equal(t, "03", after[1].SongName)
}

func TestSyncDetectsRenamedSoundtrack(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01.mp3", "a1")
	f.run(false)
	a := f.soundtrack("Game A")
	require.NoError(t, f.store.AddSongPlayedByUUID(context.Background(), f.store.SongsOf(a.ID)[0].Uuid))

	require.NoError(t, os.Rename(filepath.Join(f.dir, "Game A"), filepath.Join(f.dir, "Game A Remastered")))
	result := f.run(false)

	assert.Equal(t, map[string]string{"Game A": "Game A Remastered"}, result.SoundtracksChangedTitle)
	assert.Empty(t, result.SoundtracksRemoved)
	assert.Empty(t, result.SoundtracksAdded)

	renamed := f.soundtrack("Game A Remastered")
	assert.Equal(t, a.ID, renamed.ID)
	assert.Equal(t, f.dir+"/Game A Remastered/", renamed.Path)
	songs := f.store.SongsOf(a.ID)
	require.Len(t, songs, 1)
	assert.Equal(t, f.dir+"/Game A Remastered/01.mp3", songs[0].Path)
	assert.Equal(t, int32(1), songs[0].TimesPlayed)
}

func TestSyncRemovedAndReAdded(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01.mp3", "a1")
	f.write("Game B/01.mp3", "b1")
	f.run(false)

	backup := filepath.Join(t.TempDir(), "Game B")
	require.NoError(t, os.Rename(filepath.Join(f.dir, "Game B"), backup))
	result := f.run(false)
	assert.Equal(t, []string{"Game B"}, result.SoundtracksRemoved)
	assert.NotNil(t, f.soundtrack("Game B").Deleted)

	// Polling the result must not change it.
	assert.Equal(t, result, f.sync.Result())
	assert.Equal(t, result, f.sync.Result())

	require.NoError(t, os.Rename(backup, filepath.Join(f.dir, "Game B")))
	result = f.run(false)
	assert.Equal(t, []string{"Game B"}, result.SoundtracksReAdded)
	assert.Empty(t, result.SoundtracksRemoved)
	assert.Nil(t, f.soundtrack("Game B").Deleted)

	// A full sync reports re-added soundtracks too.
	require.NoError(t, os.Rename(filepath.Join(f.dir, "Game B"), backup))
	f.run(false)
	require.NoError(t, os.Rename(backup, filepath.Join(f.dir, "Game B")))
	result = f.run(true)
	assert.Equal(t, []string{"Game B"}, result.SoundtracksReAdded)
	assert.Nil(t, f.soundtrack("Game B").Deleted)
}

func TestSyncUpdatesMovedMusicPath(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01.mp3", "a1")
	f.run(false)

	newDir := filepath.Join(t.TempDir(), "music")
	require.NoError(t, os.Rename(f.dir, newDir))
	f.dir = newDir
	f.sync = NewSyncService(f.store, newDir, nil)
	f.run(false)

	a := f.soundtrack("Game A")
	assert.Equal(t, newDir+"/Game A/", a.Path)
	assert.Equal(t, newDir+"/Game A/01.mp3", f.store.SongsOf(a.ID)[0].Path)
}

func TestSyncIDFileCleanup(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01.mp3", "a1")
	f.write("Game A/.5.id", "")
	f.write("Game B/01.mp3", "b1")
	f.write("Game B/.6.id", "")

	// Simulate an upgraded database: hashes are known but no fingerprints yet.
	for _, name := range []string{"Game A", "Game B"} {
		hash, err := dirHash(filepath.Join(f.dir, name) + "/")
		require.NoError(t, err)
		f.store.AddSoundtrack(repository.Soundtrack{SoundtrackName: name, Path: f.dir + "/" + name + "/", Hash: hash})
	}
	f.write("Game B/02.mp3", "b2") // Game B changes, Game A does not

	f.run(false)
	assert.FileExists(t, filepath.Join(f.dir, "Game A/.5.id"), "unchanged soundtracks keep their .id files")
	assert.NoFileExists(t, filepath.Join(f.dir, "Game B/.6.id"), "changed soundtracks are cleaned up")

	result := f.run(true)
	assert.NoFileExists(t, filepath.Join(f.dir, "Game A/.5.id"), "a full sync cleans up everything")
	assert.Empty(t, result.CatchedErrors)

	// The stored fingerprint matches the folder without .id files, so the next sync skips it.
	a := f.soundtrack("Game A")
	fp, err := fingerprint(a.Path)
	require.NoError(t, err)
	assert.Equal(t, fp, a.Fingerprint)
}

func TestSyncFullRemovesBrokenSongs(t *testing.T) {
	f := newSyncFixture(t)
	f.write("Game A/01.mp3", "a1")
	f.run(false)
	gone := f.store.AddTestSong(repository.Song{SoundtrackID: 999, SongName: "gone", Path: "/does/not/exist.mp3"})

	f.run(false)
	assert.Len(t, f.store.Songs, 2, "changes-only sync leaves other songs alone")

	f.run(true)
	for _, song := range f.store.Songs {
		assert.NotEqual(t, gone.Uuid, song.Uuid)
	}
}

func TestSyncUnreadableMusicPath(t *testing.T) {
	store := fakedb.New()
	existing := store.AddSoundtrack(repository.Soundtrack{SoundtrackName: "Game A"})
	s := NewSyncService(store, filepath.Join(t.TempDir(), "missing"), nil)

	require.True(t, s.Start(false))
	s.Wait()
	result := s.Result()
	require.Len(t, result.CatchedErrors, 1)
	assert.Contains(t, result.CatchedErrors[0], "ReadDir")
	st, _ := store.Soundtrack(existing.SoundtrackName)
	assert.Nil(t, st.Deleted, "nothing is marked deleted when the music path cannot be read")
}

func TestSyncStartOnlyOnce(t *testing.T) {
	release := make(chan struct{})
	s := NewSyncService(fakedb.New(), t.TempDir(), func(context.Context) { <-release })

	require.True(t, s.Start(false))
	assert.True(t, s.IsSyncing())
	assert.False(t, s.Start(true), "a second sync cannot start while one is running")

	close(release)
	s.Wait()
	assert.False(t, s.IsSyncing())
	assert.True(t, s.Start(false))
	s.Wait()
}

func TestSyncProgressBeforeFirstSync(t *testing.T) {
	s := NewSyncService(fakedb.New(), t.TempDir(), nil)
	assert.Equal(t, "0", s.Progress().Progress)
	assert.Equal(t, SyncResponse{}, s.Result())
}

func TestSyncCallsOnCompleteBeforeFinishing(t *testing.T) {
	var syncingDuringCallback bool
	var s *SyncService
	s = NewSyncService(fakedb.New(), t.TempDir(), func(context.Context) { syncingDuringCallback = s.IsSyncing() })
	require.True(t, s.Start(false))
	s.Wait()
	assert.True(t, syncingDuringCallback, "caches are refreshed before requests are let through again")
}

func TestResetDB(t *testing.T) {
	store := fakedb.New()
	store.AddSoundtrack(repository.Soundtrack{SoundtrackName: "A"})
	store.AddTestSong(repository.Song{SongName: "a"})
	s := NewSyncService(store, t.TempDir(), nil)
	require.NoError(t, s.ResetDB(context.Background()))
	assert.Empty(t, store.Soundtracks)
	assert.Empty(t, store.Songs)
}

func TestFormatDuration(t *testing.T) {
	assert.Equal(t, "01:02:03", formatDuration(time.Hour+2*time.Minute+3*time.Second))
}