var me = {}

me.onMoving = function (ins, rate, downHight){
	ins.requestAnimationFrame(function () {
		ins.selectComponent('.mescroll-wxs-content').setStyle({
			'will-change': 'transform',
			'transform': 'translateY(' + downHight + 'px)',
			'transition': ''
		})
		var progress = ins.selectComponent('.mescroll-wxs-progress')
		progress && progress.setStyle({transform: 'rotate(' + 360 * rate + 'deg)'})
	})
}

me.showLoading = function (ins){
	me.downHight = me.optDown.offset
	ins.requestAnimationFrame(function () {
		ins.selectComponent('.mescroll-wxs-content').setStyle({
			'will-change': 'auto',
			'transform': 'translateY(' + me.downHight + 'px)',
			'transition': 'transform 300ms'
		})
	})
}

me.endDownScroll = function (ins){
	me.downHight = 0;
	me.isDownScrolling = false;
	ins.requestAnimationFrame(function () {
		ins.selectComponent('.mescroll-wxs-content').setStyle({
			'will-change': 'auto',
			'transform': 'translateY(0)', // 不可以写空串,否则scroll-view渲染不完整 (延时350ms会调clearTransform置空)
			'transition': 'transform 300ms'
		})
	})
}

me.clearTransform = function (ins){
	ins.requestAnimationFrame(function () {
		ins.selectComponent('.mescroll-wxs-content').setStyle({
			'will-change': '',
			'transform': '',
			'transition': ''
		})
	})
}


function propObserver(wxsProp) {
	me.optDown = wxsProp.optDown
	me.scrollTop = wxsProp.scrollTop
	me.bodyHeight = wxsProp.bodyHeight
	me.isDownScrolling = wxsProp.isDownScrolling
	me.isUpScrolling = wxsProp.isUpScrolling
	me.isUpBoth = wxsProp.isUpBoth
	me.isScrollBody = wxsProp.isScrollBody
	me.startTop = wxsProp.scrollTop 
}


function callObserver(callProp, oldValue, ins) {
	if (me.disabled()) return;
	if(callProp.callType){
		if(callProp.callType === 'showLoading'){
			me.showLoading(ins)
		}else if(callProp.callType === 'endDownScroll'){
			me.endDownScroll(ins)
		}else if(callProp.callType === 'clearTransform'){
			me.clearTransform(ins)
		}
	}
}

function touchstartEvent(e, ins) {
	me.downHight = 0; 
	me.startPoint = me.getPoint(e); 
	me.startTop = me.getScrollTop(); 
	me.startAngle = 0; 
	me.lastPoint = me.startPoint;
	me.maxTouchmoveY = me.getBodyHeight() - me.optDown.bottomOffset; 
	me.inTouchend = false;
	
	me.callMethod(ins, {type: 'setWxsProp'}) 
}

function touchmoveEvent(e, ins) {
	var isPrevent = true 
	
	if (me.disabled()) return isPrevent;
	
	var scrollTop = me.getScrollTop();
	var curPoint = me.getPoint(e);
	
	var moveY = curPoint.y - me.startPoint.y;
	
	if (moveY > 0 && (
			(me.isScrollBody && scrollTop <= 0)
			||
			(!me.isScrollBody && (scrollTop <= 0 || (scrollTop <= me.optDown.startTop && scrollTop === me.startTop)) )
		)) {
		if (!me.inTouchend && !me.isDownScrolling && !me.optDown.isLock && (!me.isUpScrolling || (me.isUpScrolling &&
				me.isUpBoth))) {
	
			if(!me.startAngle) me.startAngle = me.getAngle(me.lastPoint, curPoint); 
			if (me.startAngle < me.optDown.minAngle) return isPrevent;
	
			if (me.maxTouchmoveY > 0 && curPoint.y >= me.maxTouchmoveY) {
				me.inTouchend = true;
				touchendEvent(e, ins);
				return isPrevent;
			}
			
			isPrevent = false
	
			var diff = curPoint.y - me.lastPoint.y;
	
			if (me.downHight < me.optDown.offset) {
				if (me.movetype !== 1) {
					me.movetype = 1; 
					me.callMethod(ins, {type: 'setLoadType', downLoadType: 1})
					me.isMoveDown = true; 
				}
				me.downHight += diff * me.optDown.inOffsetRate; 
	
			} else {
				if (me.movetype !== 2) {
					me.movetype = 2; 
					me.callMethod(ins, {type: 'setLoadType', downLoadType: 2})
					me.isMoveDown = true;
				}
				if (diff > 0) {
					me.downHight += diff * me.optDown.outOffsetRate; 
				} else {
					me.downHight += diff;
				}
			}
			
			me.downHight = Math.round(me.downHight) 
			var rate = me.downHight / me.optDown.offset;
			me.onMoving(ins, rate, me.downHight)
		}
	}
	
	me.lastPoint = curPoint; 
	
	return isPrevent 
}

function touchendEvent(e, ins) {
	if (me.isMoveDown) {
		if (me.downHight >= me.optDown.offset) {
			me.downHight = me.optDown.offset;
			me.callMethod(ins, {type: 'triggerDownScroll'})
		} else {
			me.downHight = 0;
			me.callMethod(ins, {type: 'endDownScroll'})
		}
		me.movetype = 0;
		me.isMoveDown = false;
	} else if (!me.isScrollBody && me.getScrollTop() === me.startTop) {
		var isScrollUp = me.getPoint(e).y - me.startPoint.y < 0; 
		if (isScrollUp) {
			var angle = me.getAngle(me.getPoint(e), me.startPoint);
			if (angle > 80) {
				me.callMethod(ins, {type: 'triggerUpScroll'})
			}
		}
	}
	me.callMethod(ins, {type: 'setWxsProp'}) 
}

me.disabled = function(){
	return !me.optDown || !me.optDown.use || me.optDown.native
}

me.getPoint = function(e) {
	if (!e) {
		return {x: 0,y: 0}
	}
	if (e.touches && e.touches[0]) {
		return {x: e.touches[0].pageX,y: e.touches[0].pageY}
	} else if (e.changedTouches && e.changedTouches[0]) {
		return {x: e.changedTouches[0].pageX,y: e.changedTouches[0].pageY}
	} else {
		return {x: e.clientX,y: e.clientY}
	}
}

me.getAngle = function (p1, p2) {
	var x = Math.abs(p1.x - p2.x);
	var y = Math.abs(p1.y - p2.y);
	var z = Math.sqrt(x * x + y * y);
	var angle = 0;
	if (z !== 0) {
		angle = Math.asin(y / z) / Math.PI * 180;
	}
	return angle
}

me.getScrollTop = function() {
	return me.scrollTop || 0
}

me.getBodyHeight = function() {
	return me.bodyHeight || 0;
}

me.callMethod = function(ins, param) {
	if(ins) ins.callMethod('wxsCall', param)
}

module.exports = {
	propObserver: propObserver,
	callObserver: callObserver,
	touchstartEvent: touchstartEvent,
	touchmoveEvent: touchmoveEvent,
	touchendEvent: touchendEvent
}