<?php

namespace WPCoder\Optimization;

// Exit if accessed directly.
defined( 'ABSPATH' ) || exit;

class CSSMinifier {

	public static function minify($input): string {
		if(trim($input) === "") {
			return $input;
		}
		$replaced = preg_replace(
			array(
				// Remove comment(s)
				'#("(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\')|\/\*(?!\!)(?>.*?\*\/)|^\s*|\s*$#s',
				// Remove unused white-space(s)
				'#("(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\'|\/\*(?>.*?\*\/))|\s*+;\s*+(})\s*+|\s*+([*$~^|]?+=|[{};,>~]|\s(?![0-9\.])|!important\b)\s*+|([[(:])\s++|\s++([])])|\s++(:)\s*+(?!(?>[^{}"\']++|"(?:[^"\\\]++|\\\.)*+"|\'(?:[^\'\\\\]++|\\\.)*+\')*+{)|^\s++|\s++\z|(\s)\s+#si',
				// Replace `0(cm|em|ex|in|mm|pc|pt|px|vh|vw|%)` with `0`
				'#(?<=[\s:])(0)(cm|em|ex|in|mm|pc|pt|px|vh|vw|%)#si',
				// Replace `:0 0 0 0` with `:0`
				'#:(0\s+0|0\s+0\s+0\s+0)(?=[;\}]|\!important)#i',
				// Replace `background-position:0` with `background-position:0 0`
				'#(background-position):0(?=[;\}])#si',
				// Replace `0.6` with `.6`, but only when preceded by `:`, `,`, `-` or a white-space
				'#(?<=[\s:,\-])0+\.(\d+)#s',
				// Minify string value
				'#(\/\*(?>.*?\*\/))|(?<!content\:)([\'"])([a-z_][a-z0-9\-_]*?)\2(?=[\s\{\}\];,])#si',
				'#(\/\*(?>.*?\*\/))|(\burl\()([\'"])([^\s]+?)\3(\))#si',
				// Minify HEX color code
				'#(?<=[\s:,\-]\#)([a-f0-6]+)\1([a-f0-6]+)\2([a-f0-6]+)\3#i',
				// Replace `(border|outline):none` with `(border|outline):0`
				'#(?<=[\{;])(border|outline):none(?=[;\}\!])#',
				// Remove empty selector(s)
				'#(\/\*(?>.*?\*\/))|(^|[\{\}])(?:[^\s\{\}]+)\{\}#s'
			),
			array(
				'$1',
				'$1$2$3$4$5$6$7',
				'$1',
				':0',
				'$1:0 0',
				'.$1',
				'$1$3',
				'$1$2$4$5',
				'$1$2$3',
				'$1:0',
				'$1$2'
			),
			$input);
		return str_replace('fill=none', '', $replaced); // fix for url("data:image/svg+xml,%3Csvg ...  fill='none'
	}

}