export class StreamingAudioChannel
{
	public static maxChannels:number = 4;

	public static _channels:Array<StreamingAudioChannel> = new Array<StreamingAudioChannel>();

	private _sourceOpenDelegate:(event) => void;
	private _updateEndDelegate:(event) => void;
	private _sourceBuffer:SourceBuffer;
	private _sourceDirty:boolean;
	private _isPlaying:boolean = false;
	private _isLooping:boolean = false;
	private _isQueuing:boolean;
	private _isOpening:boolean;
	private _buffer:ArrayBuffer;
	private _offset:number;
	private _volume:number;
	private _startTime:number = 0;
	private _duration:number;
	
	private _audio:HTMLAudioElement;
	
	private _mediaSource:MediaSource;
	private _urlString:string;

	public get duration():number
	{
		return this._duration;
	}

	public get currentTime():number
	{
		return this._audio.currentTime - this._startTime;
	}


	public get volume():number
	{
		return this._volume;
	}

	public set volume(value:number)
	{
		if (this._volume == value)
			return;

		this._volume = value;

		this._audio.volume = this._volume;
	}

	public isPlaying():boolean
	{
		return this._isPlaying;
	}

	public isLooping():boolean
	{
		return this._isLooping;
	}

	public isDecoding():boolean
	{
		return false;
	}

	constructor()
	{
		this._sourceOpenDelegate = (event) => this._sourceOpen(event);
		this._updateEndDelegate = (event) => this._updateEnd(event);

		this._audio = new Audio();
		this._audio.ontimeupdate = (event) => this._onTimeUpdate(event);

		this._updateSource();

	}
	
	public play(buffer:ArrayBuffer, offset:number = 0, loop:boolean = false):void
	{
		this._isPlaying = true;

		if (this._isLooping || this._isLooping != loop) {
			this._isLooping = loop;
			this._sourceDirty = true;
		}

		if (this._sourceDirty)
			this._updateSource();

		this._buffer = buffer;
		this._offset = offset;

		if (!this._isQueuing && !this._isOpening)
			this._queueBuffer();
	}

	public stop():void
	{
		this._audio.pause();
		this._isPlaying = false;
		this._isLooping = false;
	}
	
	private _sourceOpen(event):void
	{
		this._isOpening = false;

		//TODO: find out how in the name of all that is holy how this can be executed more than once on a MediaSource object
		if (this._mediaSource.activeSourceBuffers.length) {
			console.log("ERR: double sourceopen event called")
			return;
		}

		this._sourceBuffer = this._mediaSource.addSourceBuffer('audio/mpeg');
		this._sourceBuffer.addEventListener("updateend", this._updateEndDelegate);

		if (this._isPlaying)
			this._queueBuffer();
	}

	private _queueBuffer():void
	{
		this._isQueuing = true;

		this._startTime = this._sourceBuffer.timestampOffset;
		this._sourceBuffer.appendBuffer(this._buffer);
	}

	private _updateEnd(event):void
	{
		this._isQueuing = false;

		if (this._isLooping)
			this._mediaSource.endOfStream();

		this._duration = this._sourceBuffer.timestampOffset - this._startTime;

		this._audio.currentTime = this._startTime + this._offset;
		this._audio.play();
	}

	private _onTimeUpdate(event):void
	{
		//TODO: more accurate end detection
		if (!this._isLooping && this._duration < this._audio.currentTime - this._startTime + 0.1)
			this.stop();
	}

	private _updateSource():void
	{
		if(this._mediaSource)
			this._disposeSource();

		this._isQueuing = false;
		this._isOpening = true;

		this._mediaSource = new MediaSource();
		this._mediaSource.addEventListener("sourceopen", this._sourceOpenDelegate);
		this._urlString = URL.createObjectURL(this._mediaSource);
		this._audio.src = this._urlString;
		this._audio.loop = this._isLooping;

		this._sourceDirty = false;
	}

	private _disposeSource():void
	{
		if (!this._isOpening) {
			if (this._sourceBuffer.timestampOffset)
				this._sourceBuffer.remove(0, this._sourceBuffer.timestampOffset);

			this._sourceBuffer.removeEventListener("updateend", this._updateEndDelegate);
			this._mediaSource.removeSourceBuffer(this._sourceBuffer);
			delete this._sourceBuffer;
			this._sourceBuffer = null;
		}

		this._mediaSource.removeEventListener("sourceopen", this._sourceOpenDelegate);
		URL.revokeObjectURL(this._urlString);
		delete this._mediaSource;
		this._mediaSource = null;
	}
}