var EdgeDetector = {
    prev: null,
    threshold: 0.3,
    detect: function(current) {
        var result = { rising: false, falling: false };
 
        if (this.prev === null) {
            this.prev = current;
            return result;
        }
 
        if (this.prev < this.threshold && current > this.threshold) {
            result.rising = true;
        } else if (this.prev > this.threshold && current <this.threshold) {
            result.falling = true;
        }
 
        this.prev = current;
        return result;
    },
 
    reset: function() {
        this.prev = null;
    }
};
 
 
var $AsyncScan = {
	parameters : {
		"channels"  : ["ZHeight", "TipBias", {"name":"SetPoint", "unit":"volt"}],
		"samplingRate" : 0.5, 			// unit: kHz
		"initTipBias" : 0.0,  		// unit: V
		"initSetPoint" : 1.0, 		// unit: V
		"finiTipBias" : 1.0, 		// unit: V
		"finiSetPoint" : 2.0, 		// unit: V
		"numLine" : 128
	},
 
	addChannels : function (chArray){
		for (var i in chArray){
			print('Add Ch: ' + chArray[i])
			spm.scan.channels.add(chArray[i])	
		}
		spm.scan.triggerLineScan()
		spm.sleep(50)
		spm.scan.stop()
		spm.sleep(50)
		spm.scan.stop()
	},
 
	clearChannels : function (){
		var chs = spm.scan.channels.names() 
		for (var i=0; i < chs.length; i++){
            		print('Remove Ch: '+chs[i])
            		spm.scan.channels.remove(chs[i])
            	}
	},
	calStep : function (init, fini) {
		return (fini - init) / this.parameters.numLine
	},
 
	update : function (aTipBias, aSetPoint) {
		spm.bias.tip = aTipBias;
		spm.zservo.setpoint.normValue = aSetPoint;
		print("Set Params. >> Bias (V): " + aTipBias + ", SetPoint (V): " + aSetPoint)
	},
	init: function () {
		app.setPrintOutputVisible(false)
		this.clearChannels();
		this.addChannels(this.parameters.channels);
		spm.sleep(2000)
	},
 
	fini: function () {
		this.update(this.parameters.initTipBias, this.parameters.initSetPoint)
	},
	run : function (Detector){
		this.init();
		var tipBias = this.parameters.initTipBias;
		var setPoint = this.parameters.initSetPoint;
		var stepTipBias = this.calStep(tipBias, this.parameters.finiTipBias);
		var stepSetPoint = this.calStep(setPoint, this.parameters.finiSetPoint);		
		print("Tip Bias Step: " + stepTipBias);
		print("SetPoint Step: " + stepSetPoint);
 
		this.update(tipBias, setPoint);
		spm.addChannel("aux2 in")
		spm.scan.triggerImageScan();
		spm.sleep(60);
		while (spm.scan.isImageScanning){
			var LineSync = spm.readChannel("aux2 in") 
			result = Detector.detect(LineSync.value)
			if (result.falling){
				tipBias += stepTipBias;
				setPoint += stepSetPoint;
				this.update(tipBias, setPoint);
				print("Line change")
			}
			spm.sleep(1/this.parameters.samplingRate);
		}
		this.fini()
		print("Done Image Scan")
	}
};
 
$AsyncScan.parameters.numLine = 256;
$AsyncScan.run(EdgeDetector)