const fs = require("./fs_promises.js"),
	path = require("path"),
	wboPencilPoint = require("../client-data/tools/pencil/wbo_pencil_point.js").wboPencilPoint;

function htmlspecialchars(str) {
	if (typeof str !== "string") return "";

	return str.replace(/[<>&"']/g, function (c) {
		switch (c) {
			case '<': return '&lt;';
			case '>': return '&gt;';
			case '&': return '&amp;';
			case '"': return '&quot;';
			case "'": return '&#39;'; }});
}

function renderPath(el, pathstring) {
	return '<path ' +
		(el.id ?
			('id="' + htmlspecialchars(el.id) + '" ') : '') +
		'stroke-width="' + (el.size | 0) + '" ' +
		(el.opacity ?
			('opacity="' + parseFloat(el.opacity) + '" ') : '') +
		'stroke="' + htmlspecialchars(el.color) + '" ' +
		'd="' + pathstring + '" ' +
		'/>';
}

const Tools = {
	/**
	 * @return {string}
	 */
	"Text": function (el) {
		return '<text ' +
			'id="' + htmlspecialchars(el.id || "t") + '" ' +
			'x="' + (el.x | 0) + '" ' +
			'y="' + (el.y | 0) + '" ' +
			'font-size="' + (el.size | 0) + '" ' +
			'fill="' + htmlspecialchars(el.color || "#000") + '" ' +
			'>' + htmlspecialchars(el.txt || "") + '</text>';
	},
	/**
	 * @return {string}
	 */
	"Pencil": function (el) {
		if (!el._children) return "";
		let pts = el._children.reduce(function (pts, point) {
			return wboPencilPoint(pts, point.x, point.y);
		}, []);
		const pathstring = pts.map(function (op) {
			return op.type + ' ' + op.values.join(' ')
		}).join(' ');
		return renderPath(el, pathstring);
	},
	/**
	 * @return {string}
	 */
	"Rectangle": function (el) {
		return '<rect ' +
			(el.id ?
				('id="' + htmlspecialchars(el.id) + '" ') : '') +
			'x="' + (el.x || 0) + '" ' +
			'y="' + (el.y || 0) + '" ' +
			'width="' + (el.x2 - el.x) + '" ' +
			'height="' + (el.y2 - el.y) + '" ' +
			'stroke="' + htmlspecialchars(el.color) + '" ' +
			'stroke-width="' + (el.size | 0) + '" ' +
			'/>';
	},
	/**
	 * @return {string}
	 */
	"Ellipse": function (el) {
		const cx = Math.round((el.x2 + el.x) / 2);
		const cy = Math.round((el.y2 + el.y) / 2);
		const rx = Math.abs(el.x2 - el.x) / 2;
		const ry = Math.abs(el.y2 - el.y) / 2;
		const pathstring =
			"M" + (cx - rx) + " " + cy +
			"a" + rx + "," + ry + " 0 1,0 " + (rx * 2) + ",0" +
			"a" + rx + "," + ry + " 0 1,0 " + (rx * -2) + ",0";
		return renderPath(el, pathstring);
	},
	/**
	 * @return {string}
	 */
	"Straight line": function (el) {
		const pathstring = "M" + el.x + " " + el.y + "L" + el.x2 + " " + el.y2;
		return renderPath(el, pathstring);
	}
};


/**
 * Writes the given board as an svg to the given writeable stream
 * @param {Object[string, BoardElem]} obj 
 * @param {WritableStream} writeable 
 */
async function toSVG(obj, writeable) {
	const margin = 400;
	const elems = Object.values(obj);
	const dim = elems.reduce(function (dim, elem) {
		return [
			Math.max(elem.x + margin | 0, dim[0]),
			Math.max(elem.y + margin | 0, dim[1]),
		]
	}, [margin, margin]);
	writeable.write(
		'<svg xmlns="http://www.w3.org/2000/svg" version="1.1" ' +
		'width="' + dim[0] + '" height="' + dim[1] + '">' +
		'<defs><style type="text/css"><![CDATA[' +
		'text {font-family:"Arial"}' +
		'path {fill:none;stroke-linecap:round;stroke-linejoin:round;}' +
		'rect {fill:none}' +
		']]></style></defs>'
	);
	await Promise.all(elems.map(async function (elem) {
		await Promise.resolve(); // Do not block the event loop
		const renderFun = Tools[elem.tool];
		if (renderFun) writeable.write(renderFun(elem));
		else console.warn("Missing render function for tool", elem.tool);
	}));
	writeable.write('</svg>');
}

async function renderBoard(file, stream) {
	const data = await fs.promises.readFile(file);
	var board = JSON.parse(data);
	return toSVG(board, stream);
}

if (require.main === module) {
	const config = require("./configuration.js");
	const HISTORY_FILE = process.argv[2] || path.join(config.HISTORY_DIR, "board-anonymous.json");

	renderBoard(HISTORY_FILE, process.stdout)
		.catch(console.error.bind(console));
} else {
	module.exports = { 'renderBoard': renderBoard };
}