dev@37: import {Injectable, Inject} from '@angular/core';
dev@52: import {Subject} from "rxjs/Subject";
dev@52: import {Observable} from "rxjs";
dev@37: 
dev@37: @Injectable()
dev@37: export class AudioPlayerService {
dev@37: 
dev@52:   private currentObjectUrl: string;
dev@52:   private playingStateChange: Subject<boolean>;
dev@52:   playingStateChange$: Observable<boolean>;
dev@52:   private seeked: Subject<number>;
dev@52:   seeked$: Observable<number>;
dev@52: 
dev@37:   constructor(@Inject(HTMLAudioElement) private audioElement: HTMLAudioElement /* TODO probably shouldn't play audio this way */,
dev@37:               @Inject('AudioContext') private audioContext: AudioContext) {
dev@52:     this.currentObjectUrl = '';
dev@52:     this.playingStateChange = new Subject<boolean>();
dev@52:     this.playingStateChange$ = this.playingStateChange.asObservable();
dev@52:     this.seeked = new Subject<number>();
dev@52:     this.seeked$ = this.seeked.asObservable();
dev@52:     this.audioElement.addEventListener('ended', () => {
dev@52:       this.playingStateChange.next(this.isPlaying());
dev@52:     });
dev@52:     this.audioElement.addEventListener('seeked', () => {
dev@52:       this.seeked.next(this.audioElement.currentTime);
dev@52:     });
dev@37:   }
dev@37: 
dev@37:   getCurrentTime(): number {
dev@37:     return this.audioElement.currentTime;
dev@37:   }
dev@37: 
dev@37:   isPlaying(): boolean {
dev@37:     return !this.audioElement.paused;
dev@37:   }
dev@37: 
dev@37:   decodeAudioData(buffer: ArrayBuffer): Promise<AudioBuffer> {
dev@37:     return new Promise((res, rej) => this.audioContext.decodeAudioData(buffer, res, rej));
dev@37:   }
dev@37: 
dev@37:   loadAudioFromUrl(url: string): void {
dev@52:     if (this.currentObjectUrl)
dev@52:       URL.revokeObjectURL(this.currentObjectUrl);
dev@52:     this.currentObjectUrl = url;
dev@37:     this.audioElement.pause();
dev@37:     this.audioElement.src = url;
dev@37:   }
dev@37: 
dev@37:   togglePlaying(): void {
dev@37:     this.isPlaying() ? this.audioElement.pause() : this.audioElement.play();
dev@52:     this.playingStateChange.next(this.isPlaying());
dev@37:   }
dev@37: 
dev@37:   setVolume(value: number): void {
dev@37:     this.audioElement.volume = value; // TODO check bounds?
dev@37:   }
dev@37: 
dev@37:   seekBy(seconds: number): void {
dev@37:     // TODO some kind of error handling?
dev@37:     this.audioElement.currentTime += seconds;
dev@37:   }
dev@37: 
dev@37:   seekToStart(): void {
dev@37:     this.audioElement.currentTime = 0;
dev@37:   }
dev@37: 
dev@37:   seekToEnd(): void {
dev@37:     this.audioElement.currentTime = this.getDuration();
dev@37:   }
dev@37: 
dev@37:   getDuration(): number {
dev@37:     return this.audioElement.duration;
dev@37:   }
dev@37: }