<?php 

/** cron hooking function 
 * deletes users that were prepared last week
 * prepares users for deletion next week
 * deletes deletion info that is older than DELETION_DELETION_DELAY (months)
*/
function sntg_aud_cron_job(){
    delete_prepared_users();
    prepare_users_for_deletion();
    delete_deletion_entries();
}

/** delete users that were prepared the last time the job ran */
function delete_prepared_users(){
    $users = get_users( array( 'fields' => array( 'ID' ) ) );
    foreach($users as $user){
        $usermeta = get_user_meta ( $user->ID, 'sntg_user_to_be_deleted');
        if (sizeof($usermeta) == 1){
            write_log("user " . $user->ID . " has to be deleted: " .$usermeta[0]);
            delete_user($user->ID);
        }
        else {
            echo var_dump($usermeta);
        }
    }
}

/** add db entries for non-admin users (wp_user_level < 10) 
 * that have not been logged in for longer than USER_DELETION_DELAY (->constants.php)
 * 
 */
function prepare_users_for_deletion(){
    //write_log("prepare users for deletion");
    $users = get_users( array( 'fields' => array( 'ID' ) ) );
    foreach($users as $user){
        $wp_user_level = get_user_meta ( $user->ID, 'wp_user_level', true); 
        $user_object = get_user_by('id', $user->ID);
        //only delete non admins
        if (($wp_user_level < 10)  && ($user_object->user_login != DELETED_USER_NAME )){
            $last_login = get_user_meta ($user->ID, 'sntg_last_login', true);
            //if no entry exists, create one with date now
            if ($last_login == ''){
                update_user_meta($user->ID, 'sntg_last_login', time(), true);
            }
            //otherwise check if it was more then USER_DELETION_DELAY (one year) ago
            elseif ( ( (time() - $last_login) / SEC_TO_MONTH) > USER_DELETION_DELAY){
                    update_user_meta($user->ID, 'sntg_user_to_be_deleted', time(), true);
                    write_log("deletion mail sent: " . send_deletion_warning_mail($user->ID));
                    write_log($user_object->user_login . " prepared for deletion");
            }
        }
    }
}

/** creates an db entry with info about deletion, reassigns users content to default user (DELETED_USER_NAME -> constants.php) and deletes the user */
function delete_user($old_user_ID){
    $reassign_user = get_user_by('login', DELETED_USER_NAME);
    $reassign_user_id = $reassign_user->ID;
    write_log ("deleting user with id: " . $old_user_ID);
    create_deletion_entry($old_user_ID);
    require_once(ABSPATH.'wp-admin/includes/user.php');
    wp_delete_user($old_user_ID, $reassign_user_id);
}

/** creates a post with info about deleted user */
function create_deletion_entry($user_id){
    $user = get_user_by('id', $user_id);
    $info =     "user id: " . $user_id . "; " .
                "email: " . $user->user_email . '; ' . 
                "username: " . $user->user_login .";";
    wp_insert_post(array(
            'post_type' => 'sntg_ud_info',
            'post_content' => $info,
            'post_status' => 'publish'
    ));
}

/** sends an email (templates/info_mail.php) to user with subject SUBJECT (->constants.php) */
function send_deletion_warning_mail($user_id){
    $user = get_user_by('id', $user_id);
    add_filter( 'wp_mail_content_type', function( $content_type ) {
        return 'text/html';
    });
    $subject = get_bloginfo ('name') . ': ' . SUBJECT;  //set subject in constants.php

    ob_start();
    include (ABSPATH . 'wp-content/plugins/sntg-automatic-user-deletion/templates/info_mail.php');
    $message = ob_get_clean();

    wp_mail($user->user_email, $subject, $message);
}

/** after DELETION_DELETION_DELAY, most of the info about deleted users (eg email address) 
 * has to be deleted as well (DSGVO), but the info that a user was deleted has to be stored*/
function delete_deletion_entries(){
    $delay_years = intdiv( DELETION_DELETION_DELAY, 12 );
    $delay_months = DELETION_DELETION_DELAY % 12;
    $entries_to_delete = get_posts(array(
        'post_type'     => 'sntg_ud_info',
        'numberposts'   => '-1',
        'date_query' => array(
            array(
                'before' => array(
                    'year'  => date('Y') - $delay_years,
                    'month' => date('n') - $delay_months,
                ),
                'inclusive' => true,
            )
        ),
    ));
    foreach ($entries_to_delete as $entry){
        $info = "deleted deletion info. post_id: " . $entry->ID . "; " . explode(";", $entry->post_content)[0];
        write_log($info);
        wp_insert_post(array(
            'post_type' => 'sntg_ud_deletion',
            'post_content' => $info,
            'post_status' => 'publish'
        ));
        wp_delete_post ($entry->ID);
    }
}