package playback

import "github.com/delucks/go-subsonic"

type queue struct {
	currentSong int
	songQueue   []*subsonic.Child
}

func newQueue() *queue {
	return &queue{
		currentSong: 0,
		songQueue:   []*subsonic.Child{},
	}
}

func (q *queue) Set(songs []*subsonic.Child) {
	q.currentSong = 0
	q.songQueue = songs
}

func (q *queue) Clear() {
	q.currentSong = 0
	q.songQueue = []*subsonic.Child{}
}

// returns true if queue was empty before addition.
func (q *queue) Add(songs ...*subsonic.Child) bool {
	shouldStartPlaying := len(q.songQueue) == 0
	q.songQueue = append(q.songQueue, songs...)

	if shouldStartPlaying {
		q.currentSong = 0

		return true
	}

	return false
}

// returns a song if position has changed.
func (q *queue) SetPosition(position int) *subsonic.Child {
	if position == q.currentSong || position < 0 || len(q.songQueue) < position {
		return nil
	}

	q.currentSong = position

	return q.GetCurrentSong()
}

func (q *queue) GetPosition() int {
	return q.currentSong
}

func (q *queue) GetCurrentSong() *subsonic.Child {
	if len(q.songQueue) == 0 {
		return nil
	}

	return q.songQueue[q.currentSong]
}

func (q *queue) HasPrev() bool {
	return 0 < q.currentSong
}

func (q *queue) HasNext() bool {
	return q.currentSong < len(q.songQueue)-1
}

func (q *queue) Next() *subsonic.Child {
	if len(q.songQueue) > q.currentSong+1 {
		q.currentSong++

		return q.GetCurrentSong()
	}

	return nil
}

func (q *queue) Prev() *subsonic.Child {
	if q.currentSong > 0 {
		q.currentSong--

		return q.GetCurrentSong()
	}

	return nil
}

func (q *queue) Get() []*subsonic.Child {
	return q.songQueue
}