export function Slope() {

	const _ = L.Control.Elevation.Utils;

	let opts  = this.options;
	let slope = {};

	slope.label          = opts.slopeLabel || '%';

	return {
		name: 'slope',
		meta: 'slope',
		unit: slope.label,
		deltaMax: this.options.slopedDeltaMax,
		clampRange: this.options.slopeRange,
		decimals: 2,
		pointToAttr: (_, i) => { // slope in % = ( dy / dx ) * 100;
			let dx    = (this._data[i].dist - this._data[i > 0 ? i - 1 : i].dist) * 1000;
			let dy    = this._data[i][this.options.yAttr] - this._data[i > 0 ? i - 1 : i][this.options.yAttr];
			return dx !== 0 ? (dy / dx) * 100 : NaN; 
		},
		onPointAdded: (_, i) => {
			let dz = this._data[i][this.options.yAttr] - this._data[i > 0 ? i - 1 : i][this.options.yAttr];
			if (dz > 0)      this.track_info.ascent  = (this.track_info.ascent || 0) + dz;  // Total Ascent
			else if (dz < 0) this.track_info.descent = (this.track_info.descent || 0) - dz; // Total Descent
		},
		stats: { max: _.iMax, min: _.iMin, avg: _.iAvg, },
		scale: {
			axis       : "y",
			position   : "right",
			scale      : { min: -1, max: +1 },
			tickPadding: 16,
			labelX     : 25,
			labelY     : -8,
		},
		path: {
			label        : 'Slope',
			yAttr        : 'slope',
			scaleX       : 'distance',
			scaleY       : 'slope',
			color        : '#F00',
			strokeColor  : '#000',
			strokeOpacity: "0.5",
			fillOpacity  : "0.25",
		},
		tooltip: {
			chart: (item) => L._("m: ") + item.slope + slope.label,
			marker: (item) => Math.round(item.slope) + slope.label,
			order: 40,
		},
		summary: {
			"minslope": {
				label: "Min Slope: ",
				value: (track, unit) => Math.round(track.slope_min || 0) + '&nbsp;' + unit,
				order: 40
			},
			"maxslope": {
				label: "Max Slope: ",
				value: (track, unit) => Math.round(track.slope_max || 0) + '&nbsp;' + unit,
				order: 41
			},
			"avgslope": {
				label: "Avg Slope: ",
				value: (track, unit) => Math.round(track.slope_avg || 0) + '&nbsp;' + unit,
				order: 42
			},
			"ascent"  : {
				label: "Total Ascent: ",
				value: (track, unit) => Math.round(track.ascent || 0) + '&nbsp;' + (this.options.imperial ? 'ft' : 'm'),
				order: 43
			},
			"descent"  : {
				label: "Total Descent: ",
				value: (track, unit) => Math.round(track.descent || 0) + '&nbsp;' + (this.options.imperial ? 'ft' : 'm'),
				order: 45
			},
		}
	};
}