export default class AudioManager{

	static get BUFFER_SIZE(){ return 8192; }


	constructor(){

		/* (1) Build Audio Context */
		this.ctx = new (window.AudioContext || window.webkitAudioContext)();
		this.gain   = this.ctx.createGain();

		/* (3) Create input (typically recorder) */
		this.input = null;

		/* (4) Create network I/O controllers (WebSocket) */
		this.network = {
			out: this.ctx.createScriptProcessor(AudioManager.BUFFER_SIZE, 1, 1),
			in:  null // will contain NETWORK:IN source node
		};

		/* (5) Bind network routines */
		this.network.out.onaudioprocess = this.send.bind(this);

		/* (5) Specify node chains */
		this.node = {
			input:  [ this.ctx.createAnalyser() ],  // INPUT connects to it
			netout: []                             // INPUT chains through it until NETOUT
		};

		/* (6) Create output + bind gain */
		this.output = this.ctx.destination;

		/* (7) Initialise websocket */
		this.ws = null;



	}


	/* (1) Binds an input stream
	*
	---------------------------------------------------------*/
	bind(){

		let current_node = null;


		/* (1) Bind INPUT ------> NETWORK:OUT circuit
		---------------------------------------------------------*/
		current_node = this.input;

		/* (1) Connect INPUT to input list */
		for( let node of this.node.input )
			current_node.connect(node);

		/* (2) Chain INPUT to input chain */
		for( let node of this.node.netout ){
			current_node.connect(node);
			current_node = node;
		}

		/* (3) Finally connect to NETWORK:OUT */
		current_node.connect(this.network.out);


		/* (2) Bind NETWORK:IN ------> OUTPUT circuit
		---------------------------------------------------------*/
		// WILL BE DONE ON receive()

		/* (1) Finally connect to OUTPUT */
		// current_node.connect(this.gain);
		this.gain.connect(this.output);

	}


	/* (2) Binds an input stream
	*
	---------------------------------------------------------*/
	bindRecorderStream(_stream){

		/* (1) Bind audio stream */
		this.input = this.ctx.createMediaStreamSource(_stream);

	}


	/* (3) Sharing process implementation
	*
	---------------------------------------------------------*/
	send(_audioprocess){
		/*DEBUG*///console.warn('time of', 16*2048/8, 'bytes in ',  new Date().getTime()-window.timer);
		/*DEBUG*///window.timer = new Date().getTime();

		let buf32 = new Float32Array(AudioManager.BUFFER_SIZE);
		// _audioprocess.inputBuffer.copyFromChannel(buf32, 0);
		_audioprocess.inputBuffer.copyFromChannel(buf32, 0);

		let buf16 = this.f32toi16(buf32);

		this.ws.send(buf16);

	}

	receive(_buffer){

		/* (1) Convert to Float32Array */
		let buf32 = this.i16tof32(_buffer);

		/* (2) Create source node */
		this.network.in = new AudioBufferSourceNode(this.ctx, {
			playbackRate: 1.1
		});

		/* (3) Create buffer and dump data */
		let input_buffer = this.ctx.createBuffer(1, AudioManager.BUFFER_SIZE, this.ctx.sampleRate);
		input_buffer.getChannelData(0).set(buf32);

		/* (4) Pass buffer to source node */
		this.network.in.buffer = input_buffer;

		/* (5) Connect and play audio */
		this.network.in.connect(this.gain);
		this.network.in.start(0);

	}


	/* (4) Convert Float32Array to Int16Array
	*
	* @buf32<Float32Array>				Input
	*
	* @return buf16<Int16Array>			Converted output
	*
	---------------------------------------------------------*/
	f32toi16(buf32){

		/* (1) Initialise output */
		let buf16 = new Int16Array(buf32.length);

		/* (2) Initialize loop */
		let i = 0, l = buf32.length;

		/* (3) Convert each value */
		for( ; i < l ; i++ )
			buf16[i] = (buf32[i] < 0) ? 0x8000 * buf32[i] : 0x7FFF * buf32[i];

		return buf16;
	}


	/* (2) Convert Int16Array to Float32Array
	*
	* @buf16<Int16Array>				Input
	*
	* @return buf32<Float32Array>		Converted output
	*
	---------------------------------------------------------*/
	i16tof32(buf16){

		/* (1) Initialise output */
		let buf32 = new Float32Array(buf16.length);

		/* (2) Initialize loop */
		let i = 0, l = buf16.length;

		/* (3) Convert each value */
		for( ; i < l ; i++ )
			buf32[i] = (buf16[i] >= 0x8000) ? -(0x10000 * buf16[i])/0x8000 : buf16[i] / 0x7FFF;

		return buf32;
	}



	/* (8) Connect websocket
	*
	* @address<String>					Websocket address
	*
	---------------------------------------------------------*/
	wsconnect(_addr){

		/* (1) Create websocket connection */
		this.ws = new WebSocket(_addr);

		/* (2) Manage websocket responses */
		this.ws.onmessage = function(_msg){

			if( !(_msg.data instanceof Blob) )
				return console.warn('[NaB] Not A Blob');

			let fr = new FileReader();

			fr.onload = function(){

				let buf16 = new Int16Array(fr.result);
				this.receive(buf16);

			}.bind(this);

			fr.readAsArrayBuffer(_msg.data);

		}.bind(this);

	}



	/* (x) Access microphone + launch all
	*
	---------------------------------------------------------*/
	launch(wsAddress='wss://ws.douscord.xdrm.io/audio/2'){

		/* (1) Start websocket */
		this.wsconnect(wsAddress);

		window.recorder = null;

		if( navigator.mediaDevices && navigator.mediaDevices.getUserMedia ){

			navigator.mediaDevices.getUserMedia({ audio: true })
			.then( stream => {

				recorder         = new MediaRecorder(stream);
				this.bindRecorderStream(stream);
				this.bind();

				recorder.onstart   = () => console.warn('start');
				recorder.onstop    = () => {
					recorder.stream.getTracks().map( t => t.stop() );
				};

				// start recording
				recorder.start();

			})
			.catch( e => console.warn('error getting audio stream', e) );

		}else
			console.warn('getUserMedia() not supported');

	}


}