<?php

// (c) Copyright by authors of the Tiki Wiki CMS Groupware Project
//
// All Rights Reserved. See copyright.txt for details and a complete list of authors.
// Licensed under the GNU LESSER GENERAL PUBLIC LICENSE. See license.txt for details.
// $Id$

namespace Tiki\TikiDb;

class SanitizeEncoding
{
    /**
     * string Replacement char when checking for invalid chars
     */
    const INVALID_CHAR_REPLACEMENT = ' '; // invalid chars will be replaced with space

    /**
     * Filter chars from the input (string or array) based on the expected charset in the database
     *
     * @param string|array $values
     * @param array $utf8FieldList
     * @param string $field
     * @return string|array
     */
    public static function filterMysqlUtf8($values, $utf8FieldList = [], $field = null)
    {
        // shortcut to avoid extra processing, if not needed
        if (empty($utf8FieldList)) {
            return $values;
        }

        if (is_array($values)) {
            foreach ($values as $key => $value) {
                if (isset($utf8FieldList[$key])) {
                    $values[$key] = self::filterAllowedCharsInMysqlCharsetUtf8($value);
                }
            }
            return $values;
        } else {
            if (isset($utf8FieldList[$field])) {
                $values = self::filterAllowedCharsInMysqlCharsetUtf8($values);
            }
        }

        return $values;
    }

    /**
     * Filter chars based on the encoding expected by the db
     *
     * @param string $value
     * @return string
     */
    protected static function filterAllowedCharsInMysqlCharsetUtf8($value)
    {
        // TODO: Something more fancy like replace emoji with asccii smiles when possible

        // Regular expression from https://www.w3.org/International/questions/qa-forms-utf-8.en
        $value = preg_replace(
            '%(?:
            \xF0[\x90-\xBF][\x80-\xBF]{2}      # planes 1-3
            | [\xF1-\xF3][\x80-\xBF]{3}        # planes 4-15
            | \xF4[\x80-\x8F][\x80-\xBF]{2}    # plane 16
            )%xs',
            self::INVALID_CHAR_REPLACEMENT,
            $value
        );

        return $value;
    }
}