<?php
/**
 * AirTheme — Kyr-To-Lat
 * Automatic transliteration of slugs (Cyrillic → Latin)
 * Applies ONLY on creation, does NOT affect existing content.
 */

if ( ! defined('ABSPATH') ) {
    exit;
}

/**
 * Check if Kyr-To-Lat is enabled (default ON)
 */
function airtheme_kyr_to_lat_enabled() {
    return get_theme_mod('airtheme_kyr_to_lat_enable', true);
}

/**
 * Transliteration map
 */
function airtheme_kyr_to_lat_map() {
    return [
        'а'=>'a','б'=>'b','в'=>'v','г'=>'g','д'=>'d','е'=>'e','ё'=>'yo',
        'ж'=>'zh','з'=>'z','и'=>'i','й'=>'y','к'=>'k','л'=>'l','м'=>'m',
        'н'=>'n','о'=>'o','п'=>'p','р'=>'r','с'=>'s','т'=>'t','у'=>'u',
        'ф'=>'f','х'=>'h','ц'=>'ts','ч'=>'ch','ш'=>'sh','щ'=>'sch',
        'ъ'=>'','ы'=>'y','ь'=>'','э'=>'e','ю'=>'yu','я'=>'ya',
        ' '=>'-'
    ];
}

/**
 * Transliterate slug
 */
function airtheme_kyr_to_lat_slug( $title, $raw_title = '', $context = 'display' ) {

    if ( ! airtheme_kyr_to_lat_enabled() ) {
        return $title;
    }

    // Only for save / edit context
    if ( $context !== 'save' ) {
        return $title;
    }

    // Do NOT touch existing slugs
    if ( ! empty($_POST['post_name']) ) {
        return $title;
    }

    $map = airtheme_kyr_to_lat_map();

    $title = mb_strtolower($title);
    $title = strtr($title, $map);
    $title = preg_replace('/[^a-z0-9\-]/', '', $title);
    $title = preg_replace('/-+/', '-', $title);
    $title = trim($title, '-');

    return $title;
}

add_filter('sanitize_title', 'airtheme_kyr_to_lat_slug', 9, 3);