// Package fakedb provides an in-memory repository.Querier for tests.
package fakedb

import (
	"cmp"
	"context"
	"math/rand/v2"
	"slices"
	"sync"
	"time"

	"music-server/internal/db/repository"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

// Store is an in-memory implementation of the queries used by the application.
// Calling a query it does not implement panics through the nil embedded interface.
type Store struct {
	repository.Querier

	mu          sync.Mutex
	nextID      int32
	Soundtracks []repository.Soundtrack
	Songs       []repository.Song
	Sessions    map[string]repository.Session

	// Err, when set, is returned by every implemented query.
	Err error
}

// New returns an empty Store.
func New() *Store {
	return &Store{Sessions: map[string]repository.Session{}}
}

func (s *Store) lock() func() {
	s.mu.Lock()
	return s.mu.Unlock
}

// AddSoundtrack inserts a soundtrack and returns it with its ID and UUID set.
func (s *Store) AddSoundtrack(st repository.Soundtrack) repository.Soundtrack {
	defer s.lock()()
	s.nextID++
	st.ID = s.nextID
	if st.Uuid == uuid.Nil {
		st.Uuid = uuid.New()
	}
	s.Soundtracks = append(s.Soundtracks, st)
	return st
}

// AddTestSong inserts a song and returns it with its UUID set.
func (s *Store) AddTestSong(song repository.Song) repository.Song {
	defer s.lock()()
	if song.Uuid == uuid.Nil {
		song.Uuid = uuid.New()
	}
	s.Songs = append(s.Songs, song)
	return song
}

// Soundtrack returns the soundtrack with the given name.
func (s *Store) Soundtrack(name string) (repository.Soundtrack, bool) {
	defer s.lock()()
	for _, st := range s.Soundtracks {
		if st.SoundtrackName == name {
			return st, true
		}
	}
	return repository.Soundtrack{}, false
}

// SongsOf returns the songs of a soundtrack sorted by path.
func (s *Store) SongsOf(soundtrackID int32) []repository.Song {
	defer s.lock()()
	var songs []repository.Song
	for _, song := range s.Songs {
		if song.SoundtrackID == soundtrackID {
			songs = append(songs, song)
		}
	}
	slices.SortFunc(songs, func(a, b repository.Song) int { return cmp.Compare(a.Path, b.Path) })
	return songs
}

func (s *Store) soundtrackIndex(id int32) int {
	return slices.IndexFunc(s.Soundtracks, func(st repository.Soundtrack) bool { return st.ID == id })
}

func (s *Store) updateSoundtrack(id int32, f func(*repository.Soundtrack)) error {
	defer s.lock()()
	if s.Err != nil {
		return s.Err
	}
	if i := s.soundtrackIndex(id); i >= 0 {
		f(&s.Soundtracks[i])
	}
	return nil
}

func sortedByName(soundtracks []repository.Soundtrack) []repository.Soundtrack {
	slices.SortFunc(soundtracks, func(a, b repository.Soundtrack) int { return cmp.Compare(a.SoundtrackName, b.SoundtrackName) })
	return soundtracks
}

func (s *Store) FindAllSoundtracks(context.Context) ([]repository.Soundtrack, error) {
	defer s.lock()()
	if s.Err != nil {
		return nil, s.Err
	}
	var active []repository.Soundtrack
	for _, st := range s.Soundtracks {
		if st.Deleted == nil {
			active = append(active, st)
		}
	}
	return sortedByName(active), nil
}

func (s *Store) GetAllSoundtracksIncludingDeleted(context.Context) ([]repository.Soundtrack, error) {
	defer s.lock()()
	if s.Err != nil {
		return nil, s.Err
	}
	return sortedByName(slices.Clone(s.Soundtracks)), nil
}

func (s *Store) InsertSoundtrack(_ context.Context, arg repository.InsertSoundtrackParams) (repository.InsertSoundtrackRow, error) {
	if s.Err != nil {
		return repository.InsertSoundtrackRow{}, s.Err
	}
	st := s.AddSoundtrack(repository.Soundtrack{
		SoundtrackName: arg.SoundtrackName,
		Path:           arg.Path,
		Hash:           arg.Hash,
		Uuid:           arg.Uuid,
		Added:          time.Now(),
	})
	return repository.InsertSoundtrackRow{ID: st.ID, Uuid: st.Uuid}, nil
}

func (s *Store) ResetSoundtrackIdSeq(context.Context) (int64, error) {
	return int64(s.nextID), s.Err
}

func (s *Store) UpdateSoundtrackHash(_ context.Context, arg repository.UpdateSoundtrackHashParams) error {
	return s.updateSoundtrack(arg.ID, func(st *repository.Soundtrack) { st.Hash = arg.Hash })
}

func (s *Store) UpdateSoundtrackName(_ context.Context, arg repository.UpdateSoundtrackNameParams) error {
	return s.updateSoundtrack(arg.ID, func(st *repository.Soundtrack) { st.SoundtrackName, st.Path = arg.Name, arg.Path })
}

func (s *Store) SetSoundtrackFingerprint(_ context.Context, arg repository.SetSoundtrackFingerprintParams) error {
	return s.updateSoundtrack(arg.ID, func(st *repository.Soundtrack) { st.Fingerprint = arg.Fingerprint })
}

func (s *Store) RemoveSoundtrackDeletionDate(_ context.Context, id int32) error {
	return s.updateSoundtrack(id, func(st *repository.Soundtrack) { st.Deleted = nil })
}

func (s *Store) AddSoundtrackPlayed(_ context.Context, id int32) error {
	now := time.Now()
	return s.updateSoundtrack(id, func(st *repository.Soundtrack) { st.TimesPlayed++; st.LastPlayed = &now })
}

func (s *Store) MarkSoundtracksDeletedExcept(_ context.Context, ids []int32) error {
	defer s.lock()()
	if s.Err != nil {
		return s.Err
	}
	now := time.Now()
	for i := range s.Soundtracks {
		if s.Soundtracks[i].Deleted == nil && !slices.Contains(ids, s.Soundtracks[i].ID) {
			s.Soundtracks[i].Deleted = &now
		}
	}
	return nil
}

func (s *Store) ClearSoundtracks(context.Context) error {
	defer s.lock()()
	s.Soundtracks = nil
	return s.Err
}

func (s *Store) ClearSongs(context.Context) error {
	defer s.lock()()
	s.Songs = nil
	return s.Err
}

func (s *Store) FindSongsFromSoundtrack(_ context.Context, soundtrackID int32) ([]repository.Song, error) {
	if s.Err != nil {
		return nil, s.Err
	}
	return s.SongsOf(soundtrackID), nil
}

func (s *Store) FetchAllSongs(context.Context) ([]repository.Song, error) {
	defer s.lock()()
	return slices.Clone(s.Songs), s.Err
}

func (s *Store) AddSong(_ context.Context, arg repository.AddSongParams) error {
	if s.Err != nil {
		return s.Err
	}
	s.AddTestSong(repository.Song{
		SoundtrackID:   arg.SoundtrackID,
		SongName:       arg.SongName,
		Path:           arg.Path,
		FileName:       arg.FileName,
		Hash:           arg.Hash,
		Uuid:           arg.Uuid,
		SoundtrackUuid: arg.SoundtrackUuid,
	})
	return nil
}

func (s *Store) UpdateSongByUUID(_ context.Context, arg repository.UpdateSongByUUIDParams) error {
	defer s.lock()()
	for i := range s.Songs {
		if s.Songs[i].Uuid == arg.Uuid {
			s.Songs[i].SongName, s.Songs[i].FileName, s.Songs[i].Path, s.Songs[i].Hash = arg.SongName, arg.FileName, arg.Path, arg.Hash
		}
	}
	return s.Err
}

func (s *Store) AddSongPlayed(_ context.Context, arg repository.AddSongPlayedParams) error {
	defer s.lock()()
	for i := range s.Songs {
		if s.Songs[i].SoundtrackID == arg.SoundtrackID && s.Songs[i].SongName == arg.SongName {
			s.Songs[i].TimesPlayed++
		}
	}
	return s.Err
}

func (s *Store) RemoveBrokenSong(_ context.Context, arg repository.RemoveBrokenSongParams) error {
	defer s.lock()()
	s.Songs = slices.DeleteFunc(s.Songs, func(song repository.Song) bool {
		return song.SoundtrackID == arg.SoundtrackID && song.Path == arg.Path
	})
	return s.Err
}

func (s *Store) RemoveBrokenSongs(_ context.Context, uuids []uuid.UUID) error {
	defer s.lock()()
	s.Songs = slices.DeleteFunc(s.Songs, func(song repository.Song) bool { return slices.Contains(uuids, song.Uuid) })
	return s.Err
}

func (s *Store) GetRandomActiveSong(context.Context) (repository.GetRandomActiveSongRow, error) {
	defer s.lock()()
	if s.Err != nil {
		return repository.GetRandomActiveSongRow{}, s.Err
	}
	var rows []repository.GetRandomActiveSongRow
	for _, song := range s.Songs {
		if i := s.soundtrackIndex(song.SoundtrackID); i >= 0 && s.Soundtracks[i].Deleted == nil {
			rows = append(rows, repository.GetRandomActiveSongRow{Song: song, SoundtrackPath: s.Soundtracks[i].Path})
		}
	}
	if len(rows) == 0 {
		return repository.GetRandomActiveSongRow{}, pgx.ErrNoRows
	}
	return rows[rand.IntN(len(rows))], nil
}

func (s *Store) CreateSession(_ context.Context, arg repository.CreateSessionParams) (repository.Session, error) {
	defer s.lock()()
	if s.Err != nil {
		return repository.Session{}, s.Err
	}
	session := repository.Session{
		Token:      arg.Token,
		IpAddress:  arg.IpAddress,
		UserAgent:  arg.UserAgent,
		ClientType: arg.ClientType,
		ExpiresAt:  arg.ExpiresAt,
	}
	s.Sessions[arg.Token] = session
	return session, nil
}

func (s *Store) GetSession(_ context.Context, token string) (repository.Session, error) {
	defer s.lock()()
	if s.Err != nil {
		return repository.Session{}, s.Err
	}
	session, ok := s.Sessions[token]
	if !ok {
		return repository.Session{}, pgx.ErrNoRows
	}
	return session, nil
}

func (s *Store) DeleteSession(ctx context.Context, token string) error {
	if err := ctx.Err(); err != nil {
		return err
	}
	defer s.lock()()
	delete(s.Sessions, token)
	return s.Err
}

func (s *Store) DeleteExpiredSessions(context.Context) error {
	defer s.lock()()
	for token, session := range s.Sessions {
		if session.ExpiresAt.Time.Before(time.Now()) {
			delete(s.Sessions, token)
		}
	}
	return s.Err
}

// HasSession reports whether a session with the given token exists.
func (s *Store) HasSession(token string) bool {
	defer s.lock()()
	_, ok := s.Sessions[token]
	return ok
}