<?php

namespace wcf\util;

/**
 * Contains Style-related functions.
 *
 * @author  Marcel Werk
 * @copyright   2001-2019 WoltLab GmbH
 * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
 */
final class StyleUtil
{
    /**
     * Converts css code from LTR to RTL.
     */
    public static function convertCSSToRTL(string $contents): string
    {
        // parse style attributes
        // background
        // background-position
        $contents = \preg_replace('/background-position:\s*left/', 'wcf-background-position:left', $contents);
        $contents = \preg_replace('/background-position:\s*right/', 'background-position:left', $contents);
        $contents = \str_replace('wcf-background-position:left', 'background-position:right', $contents);
        $contents = \preg_replace_callback('/background-position:\s*([\d\.]+)%/', static function ($matches) {
            return 'background-position:' . (100.0 - $matches[1]) . '%';
        }, $contents);

        // background-image
        $contents = \str_replace('-ltr', '-rtl', $contents);

        // (border, margin, padding) left / right
        $contents = \str_replace('left:', 'wcf-left:', $contents);
        $contents = \str_replace('right:', 'left:', $contents);
        $contents = \str_replace('wcf-left:', 'right:', $contents);

        // border-width
        $contents = \preg_replace(
            '/border-width:\s*([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)/',
            'border-width:\\1 \\4 \\3 \\2',
            $contents
        );

        // (border-left-width, border-right-width)
        $contents = \str_replace('border-left-width:', 'wcf-border-left-width:', $contents);
        $contents = \str_replace('border-right-width:', 'border-left-width:', $contents);
        $contents = \str_replace('wcf-border-left-width:', 'border-right-width:', $contents);

        // border-style
        $contents = \preg_replace(
            '/border-style:\s*([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)/',
            'border-style:\\1 \\4 \\3 \\2',
            $contents
        );

        // (border-left-style, border-right-style)
        $contents = \str_replace('border-left-style:', 'wcf-border-left-style:', $contents);
        $contents = \str_replace('border-right-style:', 'border-left-style:', $contents);
        $contents = \str_replace('wcf-border-left-style:', 'border-right-style:', $contents);

        // (border-left-color, border-right-color)
        $contents = \str_replace('border-left-color:', 'wcf-border-left-color:', $contents);
        $contents = \str_replace('border-right-color:', 'border-left-color:', $contents);
        $contents = \str_replace('wcf-border-left-color:', 'border-right-color:', $contents);

        // box-shadow
        $contents = \preg_replace_callback(
            '~box-shadow:\s*(?P<inset>inset)?\s*(?P<negate>-)?(?P<number>\d+)~',
            static function ($matches) {
                return 'box-shadow: ' . $matches['inset'] . ' ' . ($matches['negate'] ? '' : '-') . $matches['number'];
            },
            $contents
        );

        // clear
        $contents = \preg_replace('/clear:\s*left/', 'wcf-clear:left', $contents);
        $contents = \preg_replace('/clear:\s*right/', 'clear:left', $contents);
        $contents = \str_replace('wcf-clear:left', 'clear:right', $contents);

        // float
        $contents = \preg_replace('/float:\s*left/', 'wcf-float:left', $contents);
        $contents = \preg_replace('/float:\s*right/', 'float:left', $contents);
        $contents = \str_replace('wcf-float:left', 'float:right', $contents);

        // margin
        $contents = \preg_replace(
            '/margin:\s*([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)/',
            'margin:\\1 \\4 \\3 \\2',
            $contents
        );

        // padding
        $contents = \preg_replace(
            '/padding:\s*([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)/',
            'padding:\\1 \\4 \\3 \\2',
            $contents
        );

        // text-align
        $contents = \preg_replace('/text-align:\s*left/', 'wcf-text-align:left', $contents);
        $contents = \preg_replace('/text-align:\s*right/', 'text-align:left', $contents);
        $contents = \str_replace('wcf-text-align:left', 'text-align:right', $contents);

        // text-shadow
        $contents = \preg_replace('/text-shadow:\s*(\d)/', 'text-shadow:-\\1', $contents);

        // border-radius
        $contents = \preg_replace(
            '/border-radius:\s*([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)\s+([^\s;\}]+)/',
            'border-radius:\\2 \\1 \\4 \\3',
            $contents
        );
        $contents = \str_replace('border-top-left-radius:', 'wcf-border-top-left-radius:', $contents);
        $contents = \str_replace('border-top-right-radius:', 'border-top-left-radius:', $contents);
        $contents = \str_replace('wcf-border-top-left-radius:', 'border-top-right-radius:', $contents);
        $contents = \str_replace('border-bottom-left-radius:', 'wcf-border-bottom-left-radius:', $contents);
        $contents = \str_replace('border-bottom-right-radius:', 'border-bottom-left-radius:', $contents);
        $contents = \str_replace('wcf-border-bottom-left-radius:', 'border-bottom-right-radius:', $contents);

        // transform: translateX
        return \preg_replace_callback(
            '/transform:\s*translateX\((?P<negate>-)?(?P<number>\d+)(?P<unit>[^\s\)]+)\)/',
            static function ($matches) {
                return 'transform: translateX(' . ($matches['negate'] ? '' : '-') . $matches['number'] . $matches['unit'] . ')';
            },
            $contents
        );
    }

    /**
     * Compresses css code.
     */
    public static function compressCSS(string $string): string
    {
        $string = StringUtil::unifyNewlines($string);

        // remove comments
        $string = \preg_replace('!/\*.*?\*/\r?\n?!s', '', $string);
        // remove tabs
        $string = \preg_replace('!\t+!', '', $string);
        // remove line breaks
        $string = \preg_replace('!(?<=\{|;) *\n!', '', $string);
        $string = \preg_replace('! *\n(?=})!', '', $string);
        // remove empty lines
        $string = \preg_replace('~\n{2,}~s', "\n", $string);

        return StringUtil::trim($string);
    }

    /**
     * Forbid creation of StyleUtil objects.
     */
    private function __construct()
    {
        // does nothing
    }
}