'use strict';

module.exports = function(Chart) {

	var helpers = Chart.helpers;

	Chart.defaults.line = {
		showLines: true,
		spanGaps: false,

		hover: {
			mode: 'label'
		},

		scales: {
			xAxes: [{
				type: 'category',
				id: 'x-axis-0'
			}],
			yAxes: [{
				type: 'linear',
				id: 'y-axis-0'
			}]
		}
	};

	function lineEnabled(dataset, options) {
		return helpers.getValueOrDefault(dataset.showLine, options.showLines);
	}

	Chart.controllers.line = Chart.DatasetController.extend({

		datasetElementType: Chart.elements.Line,

		dataElementType: Chart.elements.Point,

		update: function(reset) {
			var me = this;
			var meta = me.getMeta();
			var line = meta.dataset;
			var points = meta.data || [];
			var options = me.chart.options;
			var lineElementOptions = options.elements.line;
			var scale = me.getScaleForId(meta.yAxisID);
			var i, ilen, custom;
			var dataset = me.getDataset();
			var showLine = lineEnabled(dataset, options);

			// Update Line
			if (showLine) {
				custom = line.custom || {};

				// Compatibility: If the properties are defined with only the old name, use those values
				if ((dataset.tension !== undefined) && (dataset.lineTension === undefined)) {
					dataset.lineTension = dataset.tension;
				}

				// Utility
				line._scale = scale;
				line._datasetIndex = me.index;
				// Data
				line._children = points;
				// Model
				line._model = {
					// Appearance
					// The default behavior of lines is to break at null values, according
					// to https://github.com/chartjs/Chart.js/issues/2435#issuecomment-216718158
					// This option gives lines the ability to span gaps
					spanGaps: dataset.spanGaps ? dataset.spanGaps : options.spanGaps,
					tension: custom.tension ? custom.tension : helpers.getValueOrDefault(dataset.lineTension, lineElementOptions.tension),
					backgroundColor: custom.backgroundColor ? custom.backgroundColor : (dataset.backgroundColor || lineElementOptions.backgroundColor),
					borderWidth: custom.borderWidth ? custom.borderWidth : (dataset.borderWidth || lineElementOptions.borderWidth),
					borderColor: custom.borderColor ? custom.borderColor : (dataset.borderColor || lineElementOptions.borderColor),
					borderCapStyle: custom.borderCapStyle ? custom.borderCapStyle : (dataset.borderCapStyle || lineElementOptions.borderCapStyle),
					borderDash: custom.borderDash ? custom.borderDash : (dataset.borderDash || lineElementOptions.borderDash),
					borderDashOffset: custom.borderDashOffset ? custom.borderDashOffset : (dataset.borderDashOffset || lineElementOptions.borderDashOffset),
					borderJoinStyle: custom.borderJoinStyle ? custom.borderJoinStyle : (dataset.borderJoinStyle || lineElementOptions.borderJoinStyle),
					fill: custom.fill ? custom.fill : (dataset.fill !== undefined ? dataset.fill : lineElementOptions.fill),
					steppedLine: custom.steppedLine ? custom.steppedLine : helpers.getValueOrDefault(dataset.steppedLine, lineElementOptions.stepped),
					cubicInterpolationMode: custom.cubicInterpolationMode ? custom.cubicInterpolationMode : helpers.getValueOrDefault(dataset.cubicInterpolationMode, lineElementOptions.cubicInterpolationMode),
				};

				line.pivot();
			}

			// Update Points
			for (i=0, ilen=points.length; i<ilen; ++i) {
				me.updateElement(points[i], i, reset);
			}

			if (showLine && line._model.tension !== 0) {
				me.updateBezierControlPoints();
			}

			// Now pivot the point for animation
			for (i=0, ilen=points.length; i<ilen; ++i) {
				points[i].pivot();
			}
		},

		getPointBackgroundColor: function(point, index) {
			var backgroundColor = this.chart.options.elements.point.backgroundColor;
			var dataset = this.getDataset();
			var custom = point.custom || {};

			if (custom.backgroundColor) {
				backgroundColor = custom.backgroundColor;
			} else if (dataset.pointBackgroundColor) {
				backgroundColor = helpers.getValueAtIndexOrDefault(dataset.pointBackgroundColor, index, backgroundColor);
			} else if (dataset.backgroundColor) {
				backgroundColor = dataset.backgroundColor;
			}

			return backgroundColor;
		},

		getPointBorderColor: function(point, index) {
			var borderColor = this.chart.options.elements.point.borderColor;
			var dataset = this.getDataset();
			var custom = point.custom || {};

			if (custom.borderColor) {
				borderColor = custom.borderColor;
			} else if (dataset.pointBorderColor) {
				borderColor = helpers.getValueAtIndexOrDefault(dataset.pointBorderColor, index, borderColor);
			} else if (dataset.borderColor) {
				borderColor = dataset.borderColor;
			}

			return borderColor;
		},

		getPointBorderWidth: function(point, index) {
			var borderWidth = this.chart.options.elements.point.borderWidth;
			var dataset = this.getDataset();
			var custom = point.custom || {};

			if (!isNaN(custom.borderWidth)) {
				borderWidth = custom.borderWidth;
			} else if (!isNaN(dataset.pointBorderWidth)) {
				borderWidth = helpers.getValueAtIndexOrDefault(dataset.pointBorderWidth, index, borderWidth);
			} else if (!isNaN(dataset.borderWidth)) {
				borderWidth = dataset.borderWidth;
			}

			return borderWidth;
		},

		updateElement: function(point, index, reset) {
			var me = this;
			var meta = me.getMeta();
			var custom = point.custom || {};
			var dataset = me.getDataset();
			var datasetIndex = me.index;
			var value = dataset.data[index];
			var yScale = me.getScaleForId(meta.yAxisID);
			var xScale = me.getScaleForId(meta.xAxisID);
			var pointOptions = me.chart.options.elements.point;
			var x, y;
			var labels = me.chart.data.labels || [];
			var includeOffset = (labels.length === 1 || dataset.data.length === 1) || me.chart.isCombo;

			// Compatibility: If the properties are defined with only the old name, use those values
			if ((dataset.radius !== undefined) && (dataset.pointRadius === undefined)) {
				dataset.pointRadius = dataset.radius;
			}
			if ((dataset.hitRadius !== undefined) && (dataset.pointHitRadius === undefined)) {
				dataset.pointHitRadius = dataset.hitRadius;
			}

			x = xScale.getPixelForValue(typeof value === 'object' ? value : NaN, index, datasetIndex, includeOffset);
			y = reset ? yScale.getBasePixel() : me.calculatePointY(value, index, datasetIndex);

			// Utility
			point._xScale = xScale;
			point._yScale = yScale;
			point._datasetIndex = datasetIndex;
			point._index = index;

			// Desired view properties
			point._model = {
				x: x,
				y: y,
				skip: custom.skip || isNaN(x) || isNaN(y),
				// Appearance
				radius: custom.radius || helpers.getValueAtIndexOrDefault(dataset.pointRadius, index, pointOptions.radius),
				pointStyle: custom.pointStyle || helpers.getValueAtIndexOrDefault(dataset.pointStyle, index, pointOptions.pointStyle),
				backgroundColor: me.getPointBackgroundColor(point, index),
				borderColor: me.getPointBorderColor(point, index),
				borderWidth: me.getPointBorderWidth(point, index),
				tension: meta.dataset._model ? meta.dataset._model.tension : 0,
				steppedLine: meta.dataset._model ? meta.dataset._model.steppedLine : false,
				// Tooltip
				hitRadius: custom.hitRadius || helpers.getValueAtIndexOrDefault(dataset.pointHitRadius, index, pointOptions.hitRadius)
			};
		},

		calculatePointY: function(value, index, datasetIndex) {
			var me = this;
			var chart = me.chart;
			var meta = me.getMeta();
			var yScale = me.getScaleForId(meta.yAxisID);
			var sumPos = 0;
			var sumNeg = 0;
			var i, ds, dsMeta;

			if (yScale.options.stacked) {
				for (i = 0; i < datasetIndex; i++) {
					ds = chart.data.datasets[i];
					dsMeta = chart.getDatasetMeta(i);
					if (dsMeta.type === 'line' && dsMeta.yAxisID === yScale.id && chart.isDatasetVisible(i)) {
						var stackedRightValue = Number(yScale.getRightValue(ds.data[index]));
						if (stackedRightValue < 0) {
							sumNeg += stackedRightValue || 0;
						} else {
							sumPos += stackedRightValue || 0;
						}
					}
				}

				var rightValue = Number(yScale.getRightValue(value));
				if (rightValue < 0) {
					return yScale.getPixelForValue(sumNeg + rightValue);
				}
				return yScale.getPixelForValue(sumPos + rightValue);
			}

			return yScale.getPixelForValue(value);
		},

		updateBezierControlPoints: function() {
			var me = this;
			var meta = me.getMeta();
			var area = me.chart.chartArea;
			var points = (meta.data || []);
			var i, ilen, point, model, controlPoints;

			// Only consider points that are drawn in case the spanGaps option is used
			if (meta.dataset._model.spanGaps) {
				points = points.filter(function(pt) {
					return !pt._model.skip;
				});
			}

			function capControlPoint(pt, min, max) {
				return Math.max(Math.min(pt, max), min);
			}

			if (meta.dataset._model.cubicInterpolationMode === 'monotone') {
				helpers.splineCurveMonotone(points);
			} else {
				for (i = 0, ilen = points.length; i < ilen; ++i) {
					point = points[i];
					model = point._model;
					controlPoints = helpers.splineCurve(
						helpers.previousItem(points, i)._model,
						model,
						helpers.nextItem(points, i)._model,
						meta.dataset._model.tension
					);
					model.controlPointPreviousX = controlPoints.previous.x;
					model.controlPointPreviousY = controlPoints.previous.y;
					model.controlPointNextX = controlPoints.next.x;
					model.controlPointNextY = controlPoints.next.y;
				}
			}

			if (me.chart.options.elements.line.capBezierPoints) {
				for (i = 0, ilen = points.length; i < ilen; ++i) {
					model = points[i]._model;
					model.controlPointPreviousX = capControlPoint(model.controlPointPreviousX, area.left, area.right);
					model.controlPointPreviousY = capControlPoint(model.controlPointPreviousY, area.top, area.bottom);
					model.controlPointNextX = capControlPoint(model.controlPointNextX, area.left, area.right);
					model.controlPointNextY = capControlPoint(model.controlPointNextY, area.top, area.bottom);
				}
			}
		},

		draw: function() {
			var me = this;
			var chart = me.chart;
			var meta = me.getMeta();
			var points = meta.data || [];
			var area = chart.chartArea;
			var ilen = points.length;
			var i = 0;

			Chart.canvasHelpers.clipArea(chart.ctx, area);

			if (lineEnabled(me.getDataset(), chart.options)) {
				meta.dataset.draw();
			}

			Chart.canvasHelpers.unclipArea(chart.ctx);

			// Draw the points
			for (; i<ilen; ++i) {
				points[i].draw(area);
			}
		},

		setHoverStyle: function(point) {
			// Point
			var dataset = this.chart.data.datasets[point._datasetIndex];
			var index = point._index;
			var custom = point.custom || {};
			var model = point._model;

			model.radius = custom.hoverRadius || helpers.getValueAtIndexOrDefault(dataset.pointHoverRadius, index, this.chart.options.elements.point.hoverRadius);
			model.backgroundColor = custom.hoverBackgroundColor || helpers.getValueAtIndexOrDefault(dataset.pointHoverBackgroundColor, index, helpers.getHoverColor(model.backgroundColor));
			model.borderColor = custom.hoverBorderColor || helpers.getValueAtIndexOrDefault(dataset.pointHoverBorderColor, index, helpers.getHoverColor(model.borderColor));
			model.borderWidth = custom.hoverBorderWidth || helpers.getValueAtIndexOrDefault(dataset.pointHoverBorderWidth, index, model.borderWidth);
		},

		removeHoverStyle: function(point) {
			var me = this;
			var dataset = me.chart.data.datasets[point._datasetIndex];
			var index = point._index;
			var custom = point.custom || {};
			var model = point._model;

			// Compatibility: If the properties are defined with only the old name, use those values
			if ((dataset.radius !== undefined) && (dataset.pointRadius === undefined)) {
				dataset.pointRadius = dataset.radius;
			}

			model.radius = custom.radius || helpers.getValueAtIndexOrDefault(dataset.pointRadius, index, me.chart.options.elements.point.radius);
			model.backgroundColor = me.getPointBackgroundColor(point, index);
			model.borderColor = me.getPointBorderColor(point, index);
			model.borderWidth = me.getPointBorderWidth(point, index);
		}
	});
};
