/*
 * The MIT License (MIT)
 *
 * Author: Gildas Lormeau
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:

 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

// derived from https://github.com/postcss/postcss-selector-parser/blob/master/src/util/unesc.js

/*
 * The MIT License (MIT)
 * Copyright (c) Ben Briggs <beneb.info@gmail.com> (http://beneb.info)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

const whitespace = "[\\x20\\t\\r\\n\\f]";
const unescapeRegExp = new RegExp("\\\\([\\da-f]{1,6}" + whitespace + "?|(" + whitespace + ")|.)", "ig");

export {
	process
};

function process(str) {
	return str.replace(unescapeRegExp, (_, escaped, escapedWhitespace) => {
		const high = "0x" + escaped - 0x10000;

		// NaN means non-codepoint
		// Workaround erroneous numeric interpretation of +"0x"
		// eslint-disable-next-line no-self-compare
		return high !== high || escapedWhitespace
			? escaped
			: high < 0
				? // BMP codepoint
				String.fromCharCode(high + 0x10000)
				: // Supplemental Plane codepoint (surrogate pair)
				String.fromCharCode((high >> 10) | 0xd800, (high & 0x3ff) | 0xdc00);
	});
}