export function PCMPlayer(option)
{
	this.init(option);
}

PCMPlayer.prototype.init=function(option)
{
	var defaults={
	encoding: '16bitInt',
	channels:1,
	sampleRate:8000,
	flushingTime:1000
	};
	this.option=Object.assign({},defaults,option);
	this.samples=new Float32Array();
	this.flush=this.flush.bind(this);
	this.interval=setInterval(this.flush,this.option.flushingTime);
	this.maxValue=this.getMaxValue();
	this.typedArray=this.getTypedArray();
	this.createContext();
};

PCMPlayer.prototype.getMaxValue=function()
{
	var encodings={
		'8bitInt': 128,
		'16bitInt':32768,
		'32bitInt':2147483648,
		'32bitFloat':1
	}

	return encodings[this.option.encoding]?encodings[this.option.encoding]:encodings['16bitInt'];
};

PCMPlayer.prototype.getTypedArray=function()
{
	var typedArrays={
		'8bitInt': Int8Array,
		'16bitInt':Int16Array,
		'32bitInt':Int32Array,
		'32bitFloat':Float32Array
	}

	return typedArrays[this.option.encoding]?typedArrays[this.option.encoding]:typedArrays['16bitInt'];
};

PCMPlayer.prototype.createContext=function()
{
	this.audioCtx=new (window.AudioContext||window.webkitAudioContext)();
	this.gainNode=this.audioCtx.createGain();
	this.gainNode.gain.value=1;
	this.gainNode.connect(this.audioCtx.destination);
	this.startTime=this.audioCtx.currentTime;
};

PCMPlayer.prototype.isTypedArray=function(data)
{
	return (data.byteLength&&data.buffer&&data.buffer.constructor==ArrayBuffer);
};

PCMPlayer.prototype.feed=function(data)
{
	if(!this.isTypedArray(data)) return;
	data=this.getFormatedValue(data);
	var tmp=new Float32Array(this.samples.length+data.length);
	tmp.set(this.samples,0);
	tmp.set(data,this.samples.length);
	this.samples=tmp;
};

PCMPlayer.prototype.getFormatedValue=function(data)
{
	var data=new this.typedArray(data.buffer),
		float32=new Float32Array(data.length),
		i;

	for(i=0; i<data.length; i++)
	{
		float32[i]=data[i]/this.maxValue;
	}
	return float32;
};

PCMPlayer.prototype.volume=function(volume)
{
	this.gainNode.gain.value=volume;
};

PCMPlayer.prototype.destroy=function()
{
	if(this.interval)
	{
		clearInterval(this.interval);
	}
	this.samples=null;
	this.audioCtx.close();
	this.audioCtx=null;
};

PCMPlayer.prototype.flush=function()
{
	if(!this.samples.length) return;
	var bufferSource=this.audioCtx.createBufferSource(),
		length=this.samples.length/this.option.channels,
		audioBuffer=this.audioCtx.createBuffer(this.option.channels,length,this.option.sampleRate),
		audioData,
		channel,
		offset,
		i,
		decrement;

	for(channel=0; channel<this.option.channels; channel++)
	{
		audioData=audioBuffer.getChannelData(channel);
		offset=channel;
		decrement=50;
		for(i=0; i<length; i++)
		{
			audioData[i]=this.samples[offset];
			/* fadein */
			if(i<50)
			{
				audioData[i]=(audioData[i]*i)/50;
			}
			/* fadeout*/
			if(i>=(length-51))
			{
				audioData[i]=(audioData[i]*decrement--)/50;
			}
			offset+=this.option.channels;
		}
	}

	if(this.startTime<this.audioCtx.currentTime)
	{
		this.startTime=this.audioCtx.currentTime;
	}
	//console.log('start vs current '+this.startTime+' vs '+this.audioCtx.currentTime+' duration: '+audioBuffer.duration);
	bufferSource.buffer=audioBuffer;
	bufferSource.connect(this.gainNode);
	bufferSource.start(this.startTime);
	this.startTime+=audioBuffer.duration;
	this.samples=new Float32Array();
};

PCMPlayer.prototype.getTimestamp=function()
{
	if(this.audioCtx)
	{
		return this.audioCtx.currentTime;
	}
	else
	{
		return 0;
	}
};

PCMPlayer.prototype.play=function(data)
{
	if(!this.isTypedArray(data))
	{
		return;
	}

	data=this.getFormatedValue(data);
	if(!data.length)
	{
		return;
	}

	var bufferSource=this.audioCtx.createBufferSource(),
		length=data.length/this.option.channels,
		audioBuffer=this.audioCtx.createBuffer(this.option.channels,length,this.option.sampleRate),
		audioData,
		channel,
		offset,
		i,
		decrement;

	for(channel=0; channel<this.option.channels; channel++)
	{
		audioData=audioBuffer.getChannelData(channel);
		offset=channel;
		decrement=50;
		for(i=0; i<length; i++)
		{
			audioData[i]=data[offset];
			/* fadein */
			if(i<50)
			{
				audioData[i]=(audioData[i]*i)/50;
			}
			/* fadeout*/
			if(i>=(length-51))
			{
				audioData[i]=(audioData[i]*decrement--)/50;
			}
			offset+=this.option.channels;
		}
	}

	if(this.startTime<this.audioCtx.currentTime)
	{
		this.startTime=this.audioCtx.currentTime;
	}
	//console.log('start vs current '+this.startTime+' vs '+this.audioCtx.currentTime+' duration: '+audioBuffer.duration);
	bufferSource.buffer=audioBuffer;
	bufferSource.connect(this.gainNode);
	bufferSource.start(this.startTime);
	this.startTime+=audioBuffer.duration;
};

PCMPlayer.prototype.pause=function()
{
	if(this.audioCtx.state==='running')
	{
		this.audioCtx.suspend()
	}
}

PCMPlayer.prototype.resume=function()
{
	if(this.audioCtx.state==='suspended')
	{
		this.audioCtx.resume()
	}
}