# component/crosshair.js

    import * as d3 from "d3";
    import { colorParse } from "../colorHelper.js";

    /**
     * Reusable 3D Crosshair Component
     *
     * @module
     */
    export default function() {

    	/* Default Properties */
    	let dimensions = { x: 40, y: 40, z: 40 };
    	let colors = ["blue", "red", "green"];
    	let classed = "d3X3dCrosshair";
    	let radius = 0.1;

    	/* Scales */
    	let xScale;
    	let yScale;
    	let zScale;

    	/**
    	 * Constructor
    	 *
    	 * @constructor
    	 * @alias crosshair
    	 * @param {d3.selection} selection - The chart holder D3 selection.
    	 */
    	const my = function(selection) {
    		selection.each(function(data) {

    			const element = d3.select(this)
    				.classed(classed, true)
    				.attr("id", (d) => d.key);

    			const xOff = dimensions["x"] / 2;
    			const yOff = dimensions["y"] / 2;
    			const zOff = dimensions["z"] / 2;
    			const xVal = xScale(data.x);
    			const yVal = yScale(data.y);
    			const zVal = zScale(data.z);

    			const positionVectors = {
    				x: [xOff, yVal, zVal],
    				y: [xVal, yOff, zVal],
    				z: [xVal, yVal, zOff]
    			};

    			function getPositionVector(axisDir) {
    				return positionVectors[axisDir].join(" ");
    			}

    			const rotationVectors = {
    				x: [1, 1, 0, Math.PI],
    				y: [0, 0, 0, 0],
    				z: [0, 1, 1, Math.PI]
    			};

    			function getRotationVector(axisDir) {
    				return rotationVectors[axisDir].join(" ");
    			}

    			const colorScale = d3.scaleOrdinal()
    				.domain(Object.keys(dimensions))
    				.range(colors);

    			// Origin Ball
    			const ballSelect = element.selectAll(".ball")
    				.data([data]);

    			let ball = ballSelect.enter()
    				.append("Transform")
    				.attr("translation", (d) => (xScale(d.x) + " " + yScale(d.y) + " " + zScale(d.z)))
    				.classed("ball", true)
    				.append("Shape");

    			ball.append("Appearance")
    				.append("Material")
    				.attr("diffuseColor", colorParse("blue"));

    			ball.append("Sphere")
    				.attr("radius", 0.3);

    			ball.merge(ballSelect);

    			ballSelect.transition()
    				.ease(d3.easeQuadOut)
    				.attr("translation", (d) => (xScale(d.x) + " " + yScale(d.y) + " " + zScale(d.z)));

    			// Crosshair Lines
    			const lineSelect = element.selectAll(".line")
    				.data(Object.keys(dimensions));

    			const line = lineSelect.enter()
    				.append("Transform")
    				.classed("line", true)
    				.attr("translation", (d) => getPositionVector(d))
    				.attr("rotation", (d) => getRotationVector(d))
    				.append("Shape");

    			line.append("cylinder")
    				.attr("radius", radius)
    				.attr("height", (d) => dimensions[d]);

    			line.append("Appearance")
    				.append("Material")
    				.attr("diffuseColor", (d) => colorParse(colorScale(d)));

    			line.merge(lineSelect);

    			lineSelect.transition()
    				.ease(d3.easeQuadOut)
    				.attr("translation", (d) => getPositionVector(d));
    		});
    	};

    	/**
    	 * Dimensions Getter / Setter
    	 *
    	 * @param {{x: number, y: number, z: number}} _v - 3D object dimensions.
    	 * @returns {*}
    	 */
    	my.dimensions = function(_v) {
    		if (!arguments.length) return dimensions;
    		dimensions = _v;
    		return this;
    	};

    	/**
    	 * X Scale Getter / Setter
    	 *
    	 * @param {d3.scale} _v - D3 scale.
    	 * @returns {*}
    	 */
    	my.xScale = function(_v) {
    		if (!arguments.length) return xScale;
    		xScale = _v;
    		return my;
    	};

    	/**
    	 * Y Scale Getter / Setter
    	 *
    	 * @param {d3.scale} _v - D3 scale.
    	 * @returns {*}
    	 */
    	my.yScale = function(_v) {
    		if (!arguments.length) return yScale;
    		yScale = _v;
    		return my;
    	};

    	/**
    	 * Z Scale Getter / Setter
    	 *
    	 * @param {d3.scale} _v - D3 scale.
    	 * @returns {*}
    	 */
    	my.zScale = function(_v) {
    		if (!arguments.length) return zScale;
    		zScale = _v;
    		return my;
    	};

    	/**
    	 * Colors Getter / Setter
    	 *
    	 * @param {Array} _v - Array of colours used by color scale.
    	 * @returns {*}
    	 */
    	my.colors = function(_v) {
    		if (!arguments.length) return colors;
    		colors = _v;
    		return my;
    	};

    	return my;
    }