quick-multilingual.php

<?php
/**
 * Plugin Name: Quick Multilingual
 * Description: Quick Multilingual allows you to create multilingual brochure sites on WordPress with automatic language attributes and hreflang tags.
 * Author: <a href="https://so-wp.com">Pieter Bos</a>
 * Version: 1.5.6
 * Requires at least: 5.0
 * Tested up to: 6.9
 * Requires PHP: 7.0
 * License: GPL-2.0+
 * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
 * Text Domain: quick-multilingual
 * GitHub Plugin URI: https://github.com/senlin/quick-multilingual
 * GitHub Branch: master
 *
 * @package WordPress
 * @author Pieter Bos
 * @since 1.0.0
 */

// Don't load the plugin file directly
defined( 'ABSPATH' ) || exit;

/**
 * Enqueue admin scripts and styles.
 */
function so_qmp_enqueue_admin_scripts($hook) {
	// Only enqueue on this plugin's page
	if ('settings_page_quick-multilingual' !== $hook) {
		return;
	}

	wp_enqueue_script('so_qmp_admin_script', plugins_url('js/admin.js', __FILE__), array('jquery'), '1.0', true);
	wp_enqueue_style('so_qmp_admin_style', plugins_url('css/admin.css', __FILE__));

	// Localize the script with new data
	$translation_array = array(
		'select_option' => esc_html__( '— Select —', 'quick-multilingual' )
	);
	wp_localize_script( 'so_qmp_admin_script', 'so_qmp_vars', $translation_array );
}
add_action( 'admin_enqueue_scripts', 'so_qmp_enqueue_admin_scripts' );

/**
 * Register and define settings.
 */
function so_qmp_register_settings() {
	register_setting( 'so_qmp_settings_group', 'so_qmp_primary_lang', 'sanitize_text_field' );
	register_setting( 'so_qmp_settings_group', 'so_qmp_secondary_lang', 'sanitize_text_field' );
	register_setting( 'so_qmp_settings_group', 'so_qmp_primary_hreflang', 'sanitize_text_field' );
	register_setting( 'so_qmp_settings_group', 'so_qmp_secondary_hreflang', 'sanitize_text_field' );
	register_setting( 'so_qmp_settings_group', 'so_qmp_language_folder_page', 'absint' );
	register_setting( 'so_qmp_settings_group', 'so_qmp_number_of_pages', 'absint' );

	// Register page mappings settings
	for ( $i = 1; $i <= 4; $i++ ) {
		register_setting( 'so_qmp_page_translations_group', 'so_qmp_page_mapping_' . $i, 'so_qmp_sanitize_page_mapping' );
	}
}
add_action( 'admin_init', 'so_qmp_register_settings' );

/**
 * Sanitize page mapping.
 *
 * @param array $input The input array to sanitize.
 * @return array The sanitized input array.
 */
function so_qmp_sanitize_page_mapping( $input ) {
	$sanitized_input = array();
	if ( isset( $input['primary'] ) ) {
		$sanitized_input['primary'] = absint( $input['primary'] );
	}
	if ( isset( $input['secondary'] ) ) {
		$sanitized_input['secondary'] = absint( $input['secondary'] );
	}
	return $sanitized_input;
}

/**
 * Add settings page to WordPress admin.
 */
function so_qmp_create_options_page() {
	add_options_page(
		esc_html__( 'Quick Multilingual Settings', 'quick-multilingual' ),
		esc_html__( 'Quick Multilingual', 'quick-multilingual' ),
		'manage_options',
		'quick-multilingual',
		'so_qmp_options_page_html'
	);
}
add_action( 'admin_menu', 'so_qmp_create_options_page' );

/**
 * Render the options page
 */
function so_qmp_options_page_html() {
	if ( ! current_user_can( 'manage_options' ) ) {
		return;
	}

	settings_errors( 'so_qmp_messages' );
	?>
	<div class="wrap">
		<h1><?php echo esc_html( get_admin_page_title() ); ?></h1>
		<p><?php esc_html_e( 'Quick Multilingual is a WordPress plugin designed to enhance multilingual websites by adjusting the HTML lang attribute and adding hreflang tags.', 'quick-multilingual' ); ?></p>
		<p><?php esc_html_e( 'This plugin allows you to set the HTML language attribute for up to two languages, custom hreflang codes for those languages, redirect the "language folder" (the secondary language placeholder page) to its respective homepage, map up to 4 primary language pages to their secondary page translations and properly handle language attributes for better SEO and user experience.', 'quick-multilingual' ); ?></p>

		<h2 class="nav-tab-wrapper">
			<a href="#general-settings" class="nav-tab"><?php esc_html_e( 'General Settings', 'quick-multilingual' ); ?></a>
			<a href="#page-translations" class="nav-tab"><?php esc_html_e( 'Page Translations', 'quick-multilingual' ); ?></a>
		</h2>

		<div id="general-settings" class="so_qmp-tab-content">
			<h3><?php
				printf(
					wp_kses(
						/* translators: %s: URL to lang attributes gist */
						__( 'Find all HTML lang attributes <a href="%s" target="_blank">here</a>.', 'quick-multilingual' ),
						array( 'a' => array( 'href' => array(), 'target' => array() ) )
					),
					'https://gist.github.com/JamieMason/3748498'
				);
			?></h3>
			<form method="post" action="options.php">
				<?php
				settings_fields( 'so_qmp_settings_group' );
				do_settings_sections( 'so_qmp_settings_group' );
				?>
				<table class="form-table">
					<tr valign="top">
						<th scope="row"><?php esc_html_e( 'HTML lang attribute primary language', 'quick-multilingual' ); ?></th>
						<td><input type="text" name="so_qmp_primary_lang" value="<?php echo esc_attr( get_option('so_qmp_primary_lang') ); ?>" /></td>
					</tr>
					<tr valign="top">
						<th scope="row"><?php esc_html_e( 'HTML lang attribute secondary language', 'quick-multilingual' ); ?></th>
						<td><input type="text" name="so_qmp_secondary_lang" value="<?php echo esc_attr( get_option('so_qmp_secondary_lang') ); ?>" /></td>
					</tr>
					<tr valign="top">
						<th scope="row"><?php esc_html_e( 'Hreflang primary language', 'quick-multilingual' ); ?></th>
						<td><input type="text" name="so_qmp_primary_hreflang" value="<?php echo esc_attr( get_option('so_qmp_primary_hreflang') ); ?>" /></td>
					</tr>
					<tr valign="top">
						<th scope="row"><?php esc_html_e( 'Hreflang secondary language', 'quick-multilingual' ); ?></th>
						<td><input type="text" name="so_qmp_secondary_hreflang" value="<?php echo esc_attr( get_option('so_qmp_secondary_hreflang') ); ?>" /></td>
					</tr>
					<tr valign="top">
						<th scope="row"><?php esc_html_e( 'Language Folder Page', 'quick-multilingual' ); ?></th>
						<td>
							<?php
							wp_dropdown_pages(array(
								'name' => 'so_qmp_language_folder_page',
								'selected' => get_option('so_qmp_language_folder_page'),
								'show_option_none' => esc_html__( '— Select —', 'quick-multilingual' ),
								'option_none_value' => '0'
							));
							?>
						</td>
					</tr>
					<tr valign="top">
						<th scope="row"><?php esc_html_e( 'Number of Pages to Map', 'quick-multilingual' ); ?></th>
						<td>
							<input type="number" id="so_qmp_number_of_pages" name="so_qmp_number_of_pages" value="<?php echo esc_attr( get_option('so_qmp_number_of_pages', 1) ); ?>" min="1" max="4" />
						</td>
					</tr>
				</table>
				<?php submit_button(); ?>
			</form>
		</div>

		<div id="page-translations" class="so_qmp-tab-content" style="display:none;">
			<h3><?php esc_html_e( 'Here you can map the pages of the primary language to the secondary language.', 'quick-multilingual' ); ?></h3>
			<form method="post" action="options.php">
				<?php
				settings_fields( 'so_qmp_page_translations_group' );
				do_settings_sections( 'so_qmp_page_translations_group' );

				$number_of_pages = intval( get_option( 'so_qmp_number_of_pages', 1 ) );
				?>
				<table class="form-table" id="page-translations-table">
					<thead>
						<tr>
							<th><?php esc_html_e('Page', 'quick-multilingual'); ?></th>
							<th><?php esc_html_e('Primary Language Page', 'quick-multilingual'); ?></th>
							<th><?php esc_html_e('Secondary Language Page', 'quick-multilingual'); ?></th>
						</tr>
					</thead>
					<tbody>
						<?php
						for ($i = 1; $i <= $number_of_pages; $i++) {
							$page_mapping = get_option('so_qmp_page_mapping_' . $i, array());
							$primary_page = isset($page_mapping['primary']) ? $page_mapping['primary'] : 0;
							$secondary_page = isset($page_mapping['secondary']) ? $page_mapping['secondary'] : 0;
							?>
							<tr valign="top" class="page-mapping-row">
								<td><?php echo esc_html(sprintf(__('Page %d', 'quick-multilingual'), $i)); ?></td>
								<td>
									<?php
									$language_folder_page_id = get_option('so_qmp_language_folder_page');
									$exclude_pages = array($language_folder_page_id);
									$children_pages = get_pages(array('child_of' => $language_folder_page_id));
									foreach ($children_pages as $child_page) {
										$exclude_pages[] = $child_page->ID;
									}

									wp_dropdown_pages(array(
										'name' => 'so_qmp_page_mapping_' . $i . '[primary]',
										'selected' => $primary_page,
										'exclude' => implode(',', $exclude_pages),
										'show_option_none' => esc_html__('— Select —', 'quick-multilingual'),
										'option_none_value' => '0'
									));
									?>
								</td>
								<td>
									<?php
									wp_dropdown_pages(array(
										'name' => 'so_qmp_page_mapping_' . $i . '[secondary]',
										'selected' => $secondary_page,
										'child_of' => $language_folder_page_id,
										'show_option_none' => esc_html__('— Select —', 'quick-multilingual'),
										'option_none_value' => '0'
									));
									?>
								</td>
							</tr>
							<?php
						}
						?>
					</tbody>
				</table>
				<?php submit_button(); ?>
			</form>
		</div>
	</div>
	<?php
}

/**
 * Get the corresponding page ID from the mapping
 *
 * @param int $page_id The page ID to find the mapping for.
 * @param string $language The language to search in ('primary' or 'secondary').
 * @return int|null The mapped page ID or null if not found.
 */
function so_qmp_get_mapped_page_id( $page_id, $language = 'primary' ) {
	for ( $i = 1; $i <= 4; $i++ ) {
		$page_mapping = get_option( 'so_qmp_page_mapping_' . $i );
		if ( $page_mapping && isset($page_mapping[$language]) && $page_mapping[$language] == $page_id ) {
			return $page_mapping[$language === 'primary' ? 'secondary' : 'primary'];
		}
	}
	return null;
}

/**
 * Outputs hreflang tags in the <head> section of the website.
 */
function so_qmp_add_hreflang_tags() {
	$primary_hreflang = get_option('so_qmp_primary_hreflang');
	$secondary_hreflang = get_option('so_qmp_secondary_hreflang');

	$current_page_id = get_queried_object_id();
	$current_page_url = get_permalink($current_page_id);

	$is_mapped = false;
	$mapped_primary_id = null;
	$mapped_secondary_id = null;

	for ($i = 1; $i <= 4; $i++) {
		$page_mapping = get_option('so_qmp_page_mapping_' . $i);
		if ($page_mapping) {
			if (isset($page_mapping['primary']) && $page_mapping['primary'] == $current_page_id) {
				$mapped_primary_id = $current_page_id;
				$mapped_secondary_id = isset($page_mapping['secondary']) ? $page_mapping['secondary'] : null;
				$is_mapped = true;
				break;
			} elseif (isset($page_mapping['secondary']) && $page_mapping['secondary'] == $current_page_id) {
				$mapped_secondary_id = $current_page_id;
				$mapped_primary_id = isset($page_mapping['primary']) ? $page_mapping['primary'] : null;
				$is_mapped = true;
				break;
			}
		}
	}

	if ($is_mapped) {
		$primary_url = $mapped_primary_id ? get_permalink($mapped_primary_id) : '';
		$secondary_url = $mapped_secondary_id ? get_permalink($mapped_secondary_id) : '';

		if ($mapped_primary_id && $primary_url) {
			echo '<link rel="alternate" hreflang="' . esc_attr($primary_hreflang) . '" href="' . esc_url($primary_url) . '" />' . PHP_EOL;
		}
		if ($mapped_secondary_id && $secondary_url) {
			echo '<link rel="alternate" hreflang="' . esc_attr($secondary_hreflang) . '" href="' . esc_url($secondary_url) . '" />' . PHP_EOL;
		}

		$x_default_url = $primary_url ? $primary_url : ($secondary_url ? $secondary_url : $current_page_url);
		echo '<link rel="alternate" hreflang="x-default" href="' . esc_url($x_default_url) . '" />' . PHP_EOL;
	} else {
		$current_lang_prefix = so_qmp_get_current_language_prefix();
		$is_secondary_lang_page = ($current_lang_prefix === '/' . $secondary_hreflang . '/');

		if ($is_secondary_lang_page) {
			echo '<link rel="alternate" hreflang="' . esc_attr($secondary_hreflang) . '" href="' . esc_url($current_page_url) . '" />' . PHP_EOL;
		} else {
			echo '<link rel="alternate" hreflang="' . esc_attr($primary_hreflang) . '" href="' . esc_url($current_page_url) . '" />' . PHP_EOL;
		}

		echo '<link rel="alternate" hreflang="x-default" href="' . esc_url($current_page_url) . '" />' . PHP_EOL;
	}
}
add_action( 'wp_head', 'so_qmp_add_hreflang_tags', 1 );

/**
 * Set the HTML lang attribute based on the current language.
 */
function so_qmp_set_html_lang($output) {
	$primary_lang = get_option('so_qmp_primary_lang');
	$secondary_lang = get_option('so_qmp_secondary_lang');

	$current_lang_prefix = so_qmp_get_current_language_prefix();
	$html_lang = ($current_lang_prefix === '/' . get_option('so_qmp_secondary_hreflang') . '/') ? $secondary_lang : $primary_lang;

	// Debug information (commented out for production)
	/*
	error_log('Quick Multilingual Debug - Primary Lang: ' . $primary_lang);
	error_log('Quick Multilingual Debug - Secondary Lang: ' . $secondary_lang);
	error_log('Quick Multilingual Debug - Current Lang Prefix: ' . $current_lang_prefix);
	error_log('Quick Multilingual Debug - Chosen Lang: ' . $html_lang);
	*/

	// Replace the entire lang attribute
	$new_output = preg_replace('/lang="[^"]*"/', 'lang="' . esc_attr($html_lang) . '"', $output);

	// If no lang attribute found, add it
	if ($new_output === $output) {
		$new_output = str_replace('<html', '<html lang="' . esc_attr($html_lang) . '"', $output);
	}

	return $new_output;
}
// Use a high priority to ensure this runs after WordPress core
add_filter('language_attributes', 'so_qmp_set_html_lang', 100);

/**
 * Get the current language prefix based on the URL.
 *
 * @return string The current language prefix.
 */
function so_qmp_get_current_language_prefix() {
	$secondary_hreflang = get_option('so_qmp_secondary_hreflang');
	$secondary_lang_prefix = '/' . $secondary_hreflang . '/';

	$current_url = isset($_SERVER['REQUEST_URI']) ? esc_url_raw(wp_unslash($_SERVER['REQUEST_URI'])) : '';
	return (strpos($current_url, $secondary_lang_prefix) === 0) ? $secondary_lang_prefix : '';
}

/**
 * Redirect the language folder page to the first mapped secondary language page.
 */
function so_qmp_redirect_language_folder_to_secondary_homepage() {
	$language_folder_page_id = get_option('so_qmp_language_folder_page');

	if ($language_folder_page_id && is_page($language_folder_page_id)) {
		$page_mapping = get_option('so_qmp_page_mapping_1');

		if ($page_mapping && isset($page_mapping['secondary']) && !empty($page_mapping['secondary'])) {
			$first_mapped_secondary_page_id = $page_mapping['secondary'];

			$redirect_url = get_permalink($first_mapped_secondary_page_id);

			if ($redirect_url) {
				wp_safe_redirect(esc_url($redirect_url), 301);
				exit;
			}
		}
	}
}
add_action( 'template_redirect', 'so_qmp_redirect_language_folder_to_secondary_homepage' );

/**
 * Add settings link to plugin page.
 *
 * @param array $links Array of plugin action links.
 * @return array Modified array of plugin action links.
 */
function so_qmp_add_settings_link($links) {
	$settings_link = '<a href="' . esc_url(admin_url('options-general.php?page=quick-multilingual')) . '">' . esc_html__('Settings', 'quick-multilingual') . '</a>';
	array_push($links, $settings_link);
	return $links;
}
add_filter('plugin_action_links_' . plugin_basename(__FILE__), 'so_qmp_add_settings_link');