<?php

// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * @package    moodlecore
 * @subpackage backup-helper
 * @copyright  2010 onwards Eloy Lafuente (stronk7) {@link http://stronk7.com}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

/**
 * Helper class for anonymization of data
 *
 * This functions includes a collection of methods that are invoked
 * from the backup process when anonymization services have been
 * requested.
 *
 * The name of each method must be "process_parentname_name", as defined
 * byt the @anonymizer_final_element final element class, where
 * parentname is the name ob the parent tag and name the name of the tag
 * contents to be anonymized (i.e. process_user_username) with one param
 * being the value to anonymize.
 *
 * Note: current implementation of anonymization is pretty simple, just some
 * sequential values are used. If we want more elaborated generation, it
 * can be replaced later (using generators or wathever). Don't forget we must
 * ensure some fields (username, idnumber, email) are unique always.
 *
 * TODO: Improve to use more advanced anonymization
 *
 * TODO: Finish phpdocs
 */
class backup_anonymizer_helper {

    /**
     * Determine if the given user is an 'anonymous' user, based on their username, firstname, lastname
     * and email address.
     * @param stdClass $user the user record to test
     * @return bool true if this is an 'anonymous' user
     */
    public static function is_anonymous_user($user) {
        if (preg_match('/^anon\d*$/', $user->username)) {
            $match = preg_match('/^anonfirstname\d*$/', $user->firstname);
            $match = $match && preg_match('/^anonlastname\d*$/', $user->lastname);
            // Check .com for backwards compatibility.
            $emailmatch = preg_match('/^anon\d*@doesntexist\.com$/', $user->email) ||
                preg_match('/^anon\d*@doesntexist\.invalid$/', $user->email);
            if ($match && $emailmatch) {
                return true;
            }
        }
        return false;
    }

    public static function process_user_auth($value) {
        return 'manual'; // Set them to manual always
    }

    public static function process_user_username($value) {
        static $counter = 0;
        $counter++;
        return 'anon' . $counter; // Just a counter
    }

    public static function process_user_idnumber($value) {
        return ''; // Just blank it
    }

    public static function process_user_firstname($value) {
        static $counter = 0;
        $counter++;
        return 'anonfirstname' . $counter; // Just a counter
    }

    public static function process_user_lastname($value) {
        static $counter = 0;
        $counter++;
        return 'anonlastname' . $counter; // Just a counter
    }

    public static function process_user_email($value) {
        static $counter = 0;
        $counter++;
        return 'anon' . $counter . '@doesntexist.invalid'; // Just a counter.
    }

    public static function process_user_phone1($value) {
        return ''; // Clean phone1
    }

    public static function process_user_phone2($value) {
        return ''; // Clean phone2
    }

    public static function process_user_institution($value) {
        return ''; // Clean institution
    }

    public static function process_user_department($value) {
        return ''; // Clean department
    }

    public static function process_user_address($value) {
        return ''; // Clean address
    }

    public static function process_user_city($value) {
        return 'Perth'; // Set city
    }

    public static function process_user_country($value) {
        return 'AU'; // Set country
    }

    public static function process_user_lastip($value) {
        return '127.0.0.1'; // Set lastip to localhost
    }

    public static function process_user_picture($value) {
        return 0; // No picture
    }

    public static function process_user_description($value) {
        return ''; // No user description
    }

    public static function process_user_descriptionformat($value) {
        return 0; // Format moodle
    }

    public static function process_user_imagealt($value) {
        return ''; // No user imagealt
    }

    /**
     * Anonymises user's phonetic name field
     * @param string $value value of the user field
     * @return string anonymised phonetic name
     */
    public static function process_user_firstnamephonetic($value) {
        static $counter = 0;
        $counter++;
        return 'anonfirstnamephonetic' . $counter; // Just a counter.
    }

    /**
     * Anonymises user's phonetic last name field
     * @param string $value value of the user field
     * @return string anonymised last phonetic name
     */
    public static function process_user_lastnamephonetic($value) {
        static $counter = 0;
        $counter++;
        return 'anonlastnamephonetic' . $counter; // Just a counter.
    }

    /**
     * Anonymises user's middle name field
     * @param string $value value of the user field
     * @return string anonymised middle name
     */
    public static function process_user_middlename($value) {
        static $counter = 0;
        $counter++;
        return 'anonmiddlename' . $counter; // Just a counter.
    }

    /**
     * Anonymises user's alternate name field
     * @param string $value value of the user field
     * @return string anonymised alternate name
     */
    public static function process_user_alternatename($value) {
        static $counter = 0;
        $counter++;
        return 'anonalternatename' . $counter; // Just a counter.
    }
}
