index.js

var setterGetterify = require('setter-getterify');
var DCBias = require('openmusic-dcbias');

function SamplePlayer(context) {
	var node = context.createGain();
	var nodeProperties = {
		buffer: null,
		loop: false,
		loopStart: 0,
		loopEnd: 0,
		pitchBend: null
	};

	var bufferSourcesCount = 0;
	var bufferSources = {};
	var bufferSourceProperties = {};
	var pitchBend = DCBias(context);

	nodeProperties.pitchBend = pitchBend.gain;
	pitchBend.gain.setValueAtTime(0, context.currentTime);

	setterGetterify(node, nodeProperties, {
		afterSetting: onNodePropertySet
	});

	
	// TODO: player can be mono or poly i.e. only one buffer can play at a given time or many can overlap

	node.start = function(when, offset, duration) {
		
		var buffer = nodeProperties['buffer'];
		if(!buffer) {
			console.info('OpenMusic SamplePlayer: no buffer to play, so byeee!');
			return;
		}

		when = when !== undefined ? when : 0;
		offset = offset !== undefined ? offset : 0;
		
		// TODO This is mega ugly but urgh what is going on urgh
		// if I just pass 'undefined' as duration Chrome doesn't play anything
		if(window.webkitAudioContext) {
			console.log('correcting for chrome aghh');
			var sampleLength = buffer.length;
			duration = duration !== undefined ? duration : sampleLength - offset;
		}

		// Mono: invalidate all scheduled bufferSources to make sure only one is played (retrig mode)
		// TODO implement invalidation code ...

		pitchBend.start();

		// Poly: it's fine, just add a new one to the list
		var bs = makeBufferSource();

		// console.log('start', 'when', when, 'offset', offset, 'duration', duration);
		bs.start(when, offset, duration);
		
	};

	node.stop = function(when) {
		// For ease of development, we'll just stop to all the sources and empty the queue
		// If you need to re-schedule them, you'll need to call start() again.
		var keys = Object.keys(bufferSources);
		keys.forEach(function(k) {
			var source = bufferSources[k];
			source.stop(when);
			removeFromQueue(source);
		});
		
		pitchBend.stop(when);
	};

	node.cancelScheduledEvents = function(when) {
		// TODO: when/if there is automation
	};

	return node;
	
	//~~~

	function makeBufferSource() {

		var source = context.createBufferSource();
		source.addEventListener('ended', onBufferEnded);
		source.connect(node);
		source.id = bufferSourcesCount++;
		bufferSources[source.id] = source;

		pitchBend.connect(source.playbackRate);

		Object.keys(nodeProperties).forEach(function(name) {
			source[name] = nodeProperties[name];
		});

		return source;
		
	}

	function onBufferEnded(e) {
		var source = e.target;
		source.stop();
		source.disconnect();
		pitchBend.disconnect(source.playbackRate);
		// also remove from list
		removeFromQueue(source);
	}

	function onNodePropertySet(property, value) {
		var keys = Object.keys(bufferSources);
		keys.forEach(function(k) {
			var src = bufferSources[k];
			src.loopStart = nodeProperties.loopStart;
			src.loopEnd = nodeProperties.loopEnd;
			src.loop = nodeProperties.loop;
		});
	}

	function removeFromQueue(source) {
		delete bufferSources[source.id];
	}

}

module.exports = SamplePlayer;