import Tone from "../core/Tone";
import "../signal/Signal";
import "../signal/Multiply";
import "../signal/WaveShaper";

/**
 *  @class  GreaterThanZero outputs 1 when the input is strictly greater than zero
 *
 *  @constructor
 *  @extends {Tone.SignalBase}
 *  @example
 * var gt0 = new Tone.GreaterThanZero();
 * var sig = new Tone.Signal(0.01).connect(gt0);
 * //the output of gt0 is 1.
 * sig.value = 0;
 * //the output of gt0 is 0.
 */
Tone.GreaterThanZero = function(){

	Tone.SignalBase.call(this);

	/**
	 *  @type {Tone.WaveShaper}
	 *  @private
	 */
	this._thresh = this.output = new Tone.WaveShaper(function(val){
		if (val <= 0){
			return 0;
		} else {
			return 1;
		}
	}, 127);

	/**
	 *  scale the first thresholded signal by a large value.
	 *  this will help with values which are very close to 0
	 *  @type {Tone.Multiply}
	 *  @private
	 */
	this._scale = this.input = new Tone.Multiply(10000);

	//connections
	this._scale.connect(this._thresh);
};

Tone.extend(Tone.GreaterThanZero, Tone.SignalBase);

/**
 *  dispose method
 *  @returns {Tone.GreaterThanZero} this
 */
Tone.GreaterThanZero.prototype.dispose = function(){
	Tone.SignalBase.prototype.dispose.call(this);
	this._scale.dispose();
	this._scale = null;
	this._thresh.dispose();
	this._thresh = null;
	return this;
};

export default Tone.GreaterThanZero;