var overlayControl = gantt.ext.overlay;
var today = new Date();
var return_first;

var sCurvePayload = {
	period: 'week',
	project_id: proyekId,
  gantt_id: ganttId
};

function callback(response) {
	return_first = response;
}

function getSCurveData(){
	$.ajax({
		headers: {
			"Content-Type": "application/json",
			"Authorization": `Bearer ${token}`
		},
		url: `${base_url}project/get-s-curve`,
		type: "POST",
		data:JSON.stringify(sCurvePayload),
		success: function (data) {
			callback(data)
		}
	});
};

function toggleOverlay() {
	if(overlayControl.isOverlayVisible(lineOverlay)){
		gantt.config.readonly = false;
		overlayControl.hideOverlay(lineOverlay);
		gantt.$root.classList.remove("overlay_visible");
	}else{
		gantt.config.readonly = true;
		overlayControl.showOverlay(lineOverlay);
		gantt.$root.classList.add("overlay_visible");
	}
}

function getChartScaleRange(){
	var tasksRange = gantt.getSubtaskDates();
	var cells = [];
	var scale = gantt.getScale();
	if(!tasksRange.start_date){
		return scale.trace_x;
	}

	scale.trace_x.forEach(function(date){
		if(date >= tasksRange.start_date && date <= tasksRange.end_date){
			cells.push(date);
		}
	});
	return cells;
}

function getProgressLine(){
	// As long as the progress data length is same with chart scale range (period) then it's fine.
	getSCurveData();
	var cumulativePlannedDurations = return_first.data[0].data.percentagePlan;
	var cumulativeRealDurations = return_first.data[0].data.percentageReal;
	return {planned: cumulativePlannedDurations, real: cumulativeRealDurations};
}

function getScalePaddings(){
	var scale = gantt.getScale();
	var dataRange = gantt.getSubtaskDates();

	var chartScale = getChartScaleRange();
	var newWidth = scale.col_width;
	var padding = {
		left:0,
		right:0
	};

	if(dataRange.start_date){
		var yScaleLabelsWidth = 48;
		// fine tune values in order to align chart with the scale range
		padding.left = gantt.posFromDate(dataRange.start_date) - yScaleLabelsWidth;
		padding.right = scale.full_width - gantt.posFromDate(dataRange.end_date) - yScaleLabelsWidth;
		padding.top = gantt.config.row_height - 12;
		padding.bottom = gantt.config.row_height - 12;
	}
	return padding;
}

var myChart;
var lineOverlay = overlayControl.addOverlay(function(container) {

	var scaleLabels = [];

	var chartScale = getChartScaleRange();

	chartScale.forEach(function(date){
		scaleLabels.push(dateToStr(date));
	});

	var values = getProgressLine();

	var canvas = document.createElement("canvas");
	container.appendChild(canvas);
	canvas.style.height = container.offsetHeight + "px";
	canvas.style.width = container.offsetWidth + "px";

	var ctx = canvas.getContext("2d");
	if(myChart){
		myChart.destroy();
	}
	myChart = new Chart(ctx, {
		type: "line",
		data: {
			datasets: [
				{
					label: "Planned progress",
					backgroundColor: "#0000cc",
					borderColor: "#0000cc",
					data: values.planned,
					fill: false,
					cubicInterpolationMode: 'monotone'
				},
				{
					label: "Real progress",
					backgroundColor: "#006600",
					borderColor: "#006600",
					data: values.real,
					fill: false,
					cubicInterpolationMode: 'monotone'
				}
			]
		},
		options: {
			responsive: true,
			maintainAspectRatio: false,
			layout: {
				padding: getScalePaddings()
			},
			onResize: function(chart, newSize) {
				var dataRange = gantt.getSubtaskDates();
				if(dataRange.start_date){
					// align chart with the scale range
					chart.options.layout.padding = getScalePaddings();
				}
			},
			legend: {
				display: false
			},
			tooltips: {
				mode: "index",
				intersect: false,
				callbacks: {
					label: function(tooltipItem, data) {
						var dataset = data.datasets[tooltipItem.datasetIndex];
						return dataset.label + ": " + dataset.data[tooltipItem.index] + "%";
					}
				}
			},
			hover: {
				mode: "nearest",
				intersect: true
			},
			scales: {
				xAxes: [{
					labels: scaleLabels,
					gridLines:{
						display: false
					},
					ticks: {
						display: false
					}
				},
					{
						position:"top",
						labels: scaleLabels,
						gridLines:{
							display: false
						},
						ticks: {
							display: false
						}
					}
				],
				yAxes: [{
					display: true,
					gridLines: {
						display:false
					},
					ticks: {
						display: true,
						min: 0,
						max: 100,
						stepSize: 10,
						callback: function(current) {
							if (current > 100) {return "";}
							return current + "%";
						}
					}
				},
				]
			}
		}
	});
	return canvas;
});