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

/**
 * Decorator to add multilingual capability to sitemaps providers
 *
 * @since 2.8
 */
class PLL_Multilingual_Sitemaps_Provider extends WP_Sitemaps_Provider {
	/**
	 * 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;
	}

	/**
	 * Gets data for a given sitemap type.
	 *
	 * @since 2.8
	 *
	 * @param string $object_subtype_name Object subtype name if any.
	 * @param string $lang                Optional language name.
	 * @return array
	 */
	protected function get_sitemap_data( $object_subtype_name, $lang = '' ) {
		$object_subtype_name = (string) $object_subtype_name;

		if ( ! empty( $lang ) ) {
			self::$filter_lang = $lang;
		}

		$return = array(
			'name'  => implode( '-', array_filter( array( $object_subtype_name, $lang ) ) ),
			'pages' => $this->get_max_num_pages( $object_subtype_name ),
		);

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

	/**
	 * Gets 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();

		if ( empty( $object_subtypes ) ) {
			foreach ( $this->model->get_languages_list( array( 'fields' => 'slug' ) ) as $language ) {
				$sitemap_data[] = $this->get_sitemap_data( '', $language );
			}
		}

		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 ) ) {
				foreach ( $this->model->get_languages_list( array( 'fields' => 'slug' ) ) as $language ) {
					$sitemap_data[] = $this->get_sitemap_data( $object_subtype_name, $language );
				}
			} else {
				$sitemap_data[] = $this->get_sitemap_data( $object_subtype_name );
			}
		}

		return $sitemap_data;
	}

	/**
	 * Gets 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.
		$pattern = '#(' . implode( '|', $this->model->get_languages_list( array( 'fields' => 'slug' ) ) ) . ')$#';
		if ( preg_match( $pattern, $name, $matches ) ) {
			$lang = $this->model->get_language( $matches[1] );

			if ( ! empty( $lang ) ) {
				$name = preg_replace( '#(-?' . $lang->slug . ')$#', '', $name );
				$url = $this->provider->get_sitemap_url( $name, $page );
				return $this->links_model->add_language_to_link( $url, $lang );
			}
		}

		// 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();
	}
}