<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Finder;

/**
 * Gitignore matches against text.
 *
 * @author Ahmed Abdou <mail@ahmd.io>
 */
class Gitignore
{
    /**
     * Returns a regexp which is the equivalent of the gitignore pattern.
     *
     * @param string $gitignoreFileContent
     *
     * @return string The regexp
     */
    public static function toRegex(string $gitignoreFileContent): string
    {
        $gitignoreFileContent = preg_replace('/^[^\\\\]*#.*/', '', $gitignoreFileContent);
        $gitignoreLines = preg_split('/\r\n|\r|\n/', $gitignoreFileContent);
        $gitignoreLines = array_map('trim', $gitignoreLines);
        $gitignoreLines = array_filter($gitignoreLines);

        $ignoreLinesPositive = array_filter($gitignoreLines, function (string $line) {
            return !preg_match('/^!/', $line);
        });

        $ignoreLinesNegative = array_filter($gitignoreLines, function (string $line) {
            return preg_match('/^!/', $line);
        });

        $ignoreLinesNegative = array_map(function (string $line) {
            return preg_replace('/^!(.*)/', '${1}', $line);
        }, $ignoreLinesNegative);
        $ignoreLinesNegative = array_map([__CLASS__, 'getRegexFromGitignore'], $ignoreLinesNegative);

        $ignoreLinesPositive = array_map([__CLASS__, 'getRegexFromGitignore'], $ignoreLinesPositive);
        if (empty($ignoreLinesPositive)) {
            return '/^$/';
        }

        if (empty($ignoreLinesNegative)) {
            return sprintf('/%s/', implode('|', $ignoreLinesPositive));
        }

        return sprintf('/(?=^(?:(?!(%s)).)*$)(%s)/', implode('|', $ignoreLinesNegative), implode('|', $ignoreLinesPositive));
    }

    private static function getRegexFromGitignore(string $gitignorePattern): string
    {
        $regex = '(';
        if (0 === strpos($gitignorePattern, '/')) {
            $gitignorePattern = substr($gitignorePattern, 1);
            $regex .= '^';
        } else {
            $regex .= '(^|\/)';
        }

        if ('/' === $gitignorePattern[\strlen($gitignorePattern) - 1]) {
            $gitignorePattern = substr($gitignorePattern, 0, -1);
        }

        $iMax = \strlen($gitignorePattern);
        for ($i = 0; $i < $iMax; ++$i) {
            $doubleChars = substr($gitignorePattern, $i, 2);
            if ('**' === $doubleChars) {
                $regex .= '.+';
                ++$i;
                continue;
            }

            $c = $gitignorePattern[$i];
            switch ($c) {
                case '*':
                    $regex .= '[^\/]+';
                    break;
                case '/':
                case '.':
                case ':':
                case '(':
                case ')':
                case '{':
                case '}':
                    $regex .= '\\'.$c;
                    break;
                default:
                    $regex .= $c;
            }
        }

        $regex .= '($|\/)';
        $regex .= ')';

        return $regex;
    }
}