const SvgNode = require("../svg-node");

function simple_radial_gradient(id, color0, color1) {
	let s0 = new SvgNode("stop", { offset: "0%", "stop-color": color0 });
	let s1 = new SvgNode("stop", { offset: "100%", "stop-color": color1 });
	return new SvgNode("radialGradient", { id }).append(s0, s1);
}

function radial_gradient(id, cx, cy, r) {
	return new SvgNode("radialGradient", { id, cx, cy, r });
}

function stop(offset, color) {
	return new SvgNode("stop", { offset, "stop-color": color });
}

/**
 * Extracts from styles items which must be in defs section.
 * @param {*} style
 */
function extract_style_defs(style) {
	const skeys = Object.keys(style).filter((x) => x.startsWith("$"));

	return skeys.map((skey) => extract_class_def(style[skey], skey.substring(1)))
}

/**
 * Extracts from styles items which must be in defs section.
 * @param {*} style
 */
function extract_class_def(cls, id) {
	if (cls.type == "radial-gradient") {
		const ckeys = Object.keys(cls);
		const stops = ckeys
			.filter((x) => x.endsWith("%"))
			.map((x) => new SvgNode("stop", { offset: x, "stop-color": cls[x] }));

		return new SvgNode("radialGradient", { id }, stops);
	}
	
	throw `Unknown system style ${cls.type}`
}

module.exports = {
	simple_radial_gradient,
	radial_gradient,
	extract_style_defs,
};

module.exports.default = module.exports;