<?php
/**
 * @package Polylang
 */

/**
 * Decorator to add multilingual capability to sitemaps providers
 *
 * @since 2.8
 */
class PLL_Multilingual_Sitemaps_Provider extends WP_Sitemaps_Provider {
	/**
	 * Separator between name and language slug.
	 */
	public const SEPARATOR = '---pll-sep---';

	/**
	 * Pattern to match a name with language.
	 *  `.*` in `(?<SUBTYPE>.*)` because users don't have sub-types. See `get_sitemap_data()`.
	 */
	private const PATTERN = '#^(?<SUBTYPE>.*)' . self::SEPARATOR . '(?<LANG>.+)$#';

	/**
	 * The decorated sitemaps provider.
	 *
	 * @since 2.8
	 *
	 * @var WP_Sitemaps_Provider
	 */
	protected $provider;

	/**
	 * The PLL_Links_Model instance.
	 *
	 * @since 2.8
	 *
	 * @var PLL_Links_Model
	 */
	protected $links_model;

	/**
	 * The PLL_Model instance.
	 *
	 * @since 2.8
	 *
	 * @var PLL_Model
	 */
	protected $model;

	/**
	 * Language used to filter queries for the sitemap index.
	 *
	 * @since 2.8
	 *
	 * @var string
	 */
	private static $filter_lang = '';

	/**
	 * Constructor.
	 *
	 * @since 2.8
	 *
	 * @param WP_Sitemaps_Provider $provider    An instance of a WP_Sitemaps_Provider child class.
	 * @param PLL_Links_Model      $links_model The PLL_Links_Model instance.
	 */
	public function __construct( $provider, &$links_model ) {
		$this->name        = $provider->name;
		$this->object_type = $provider->object_type;

		$this->provider    = $provider;
		$this->links_model = &$links_model;
		$this->model       = &$links_model->model;
	}

	/**
	 * Gets a URL list for a sitemap.
	 *
	 * @since 2.8
	 *
	 * @param int    $page_num       Page of results.
	 * @param string $object_subtype Optional. Object subtype name. Default empty.
	 * @return array Array of URLs for a sitemap.
	 */
	public function get_url_list( $page_num, $object_subtype = '' ) {
		return $this->provider->get_url_list( $page_num, $object_subtype );
	}

	/**
	 * Gets the max number of pages available for the object type.
	 *
	 * @since 2.8
	 *
	 * @param string $object_subtype Optional. Object subtype. Default empty.
	 * @return int Total number of pages.
	 */
	public function get_max_num_pages( $object_subtype = '' ) {
		return $this->provider->get_max_num_pages( $object_subtype );
	}

	/**
	 * Filters the query arguments to add the language.
	 *
	 * @since 2.8
	 *
	 * @param array $args Sitemap provider WP_Query or WP_Term_Query arguments.
	 * @return array
	 */
	public static function query_args( $args ) {
		if ( ! empty( self::$filter_lang ) ) {
			$args['lang'] = self::$filter_lang;
		}
		return $args;
	}

	/**
	 * Returns data for a given sitemap sub-type.
	 * Suffixes the given sub-type with a language slug, so `get_sitemap_url()` can receive it.
	 *
	 * @since 2.8
	 *
	 * @param string $object_subtype_name Object sub-type name if any.
	 * @param string $lang                Optional language slug.
	 * @return array
	 */
	protected function get_sitemap_data( $object_subtype_name, $lang = '' ) {
		$object_subtype_name = (string) $object_subtype_name;

		if ( empty( $lang ) ) {
			return array(
				'name'  => $object_subtype_name,
				'pages' => $this->get_max_num_pages( $object_subtype_name ),
			);
		}

		// Allow `page---pll-sep---fr` (page is a "posts sub-type") and `---pll-sep---fr` (the "users" type doesn't have sub-types).
		self::$filter_lang = $lang;

		$return = array(
			'name'  => sprintf( "{$object_subtype_name}%s{$lang}", self::SEPARATOR ),
			'pages' => $this->get_max_num_pages( $object_subtype_name ),
		);

		self::$filter_lang = '';
		return $return;
	}

	/**
	 * Returns data about each sitemap type.
	 *
	 * @since 2.8
	 *
	 * @return array[] Array of sitemap types including object subtype name and number of pages.
	 */
	public function get_sitemap_type_data() {
		$sitemap_data = array();

		add_filter( 'wp_sitemaps_posts_query_args', array( self::class, 'query_args' ) );
		add_filter( 'wp_sitemaps_taxonomies_query_args', array( self::class, 'query_args' ) );

		$object_subtypes = $this->get_object_subtypes();
		$language_slugs  = $this->model->languages->get_list( array( 'fields' => 'slug' ) );

		if ( empty( $object_subtypes ) ) {
			// No sub-types. Ex: users.
			foreach ( $language_slugs as $language_slug ) {
				$sitemap_data[] = $this->get_sitemap_data( '', $language_slug );
			}
		}

		switch ( $this->provider->name ) {
			case 'posts':
				$func = array( $this->model, 'is_translated_post_type' );
				break;
			case 'taxonomies':
				$func = array( $this->model, 'is_translated_taxonomy' );
				break;
			default:
				return $sitemap_data;
		}

		foreach ( array_keys( $object_subtypes ) as $object_subtype_name ) {
			if ( ! call_user_func( $func, $object_subtype_name ) ) {
				// Not a translated sub-type.
				$sitemap_data[] = $this->get_sitemap_data( $object_subtype_name );
				continue;
			}

			foreach ( $language_slugs as $language_slug ) {
				$sitemap_data[] = $this->get_sitemap_data( $object_subtype_name, $language_slug );
			}
		}

		return $sitemap_data;
	}

	/**
	 * Returns the URL of a sitemap entry.
	 *
	 * @since 2.8
	 *
	 * @param string $name The name of the sitemap.
	 * @param int    $page The page of the sitemap.
	 * @return string The composed URL for a sitemap entry.
	 */
	public function get_sitemap_url( $name, $page ) {
		// Check if a language was added in `$name`.
		if ( preg_match( self::PATTERN, $name, $matches ) ) {
			$lang = $this->model->get_language( $matches['LANG'] );

			if ( ! empty( $lang ) ) {
				$url = $this->provider->get_sitemap_url( $matches['SUBTYPE'], $page );
				return $this->links_model->add_language_to_link( $url, $lang );
			}
			// Should not happen but we don't want our separator to stay in the final URL.
			$name = $matches['SUBTYPE'];
		}

		// If no language is present in `$name`, we may attempt to get the current sitemap URL (e.g. in `redirect_canonical()` ).
		if ( get_query_var( 'lang' ) ) {
			$lang = $this->model->get_language( get_query_var( 'lang' ) );
			$url  = $this->provider->get_sitemap_url( $name, $page );
			return $this->links_model->add_language_to_link( $url, $lang );
		}

		return $this->provider->get_sitemap_url( $name, $page );
	}

	/**
	 * Returns the list of supported object subtypes exposed by the provider.
	 *
	 * @since 2.8
	 *
	 * @return array List of object subtypes objects keyed by their name.
	 */
	public function get_object_subtypes() {
		return $this->provider->get_object_subtypes();
	}
}