<?php

/**

 * Sitemaps: WP_Sitemaps_Index class.

 *

 * Generates the sitemap index.

 *

 * @package WordPress

 * @subpackage Sitemaps

 * @since 5.5.0

 */

/**

 * Class WP_Sitemaps_Index.

 * Builds the sitemap index page that lists the links to all of the sitemaps.

 *

 * @since 5.5.0

 */

class WP_Sitemaps_Index {

	/**

	 * The main registry of supported sitemaps.

	 *

	 * @since 5.5.0

	 * @var WP_Sitemaps_Registry

	 */

	protected $registry;

	/**

	 * Maximum number of sitemaps to include in an index.

	 *

	 * @sincee 5.5.0

	 *

	 * @var int Maximum number of sitemaps.

	 */

	private $max_sitemaps = 50000;

	/**

	 * WP_Sitemaps_Index constructor.

	 *

	 * @since 5.5.0

	 *

	 * @param WP_Sitemaps_Registry $registry Sitemap provider registry.

	 */

	public function __construct( WP_Sitemaps_Registry $registry ) {

		$this->registry = $registry;

	}

	/**

	 * Gets a sitemap list for the index.

	 *

	 * @since 5.5.0

	 *

	 * @return array[] Array of all sitemaps.

	 */

	public function get_sitemap_list() {

		$sitemaps = array();

		$providers = $this->registry->get_providers();

		/* @var WP_Sitemaps_Provider $provider */

		foreach ( $providers as $name => $provider ) {

			$sitemap_entries = $provider->get_sitemap_entries();

			// Prevent issues with array_push and empty arrays on PHP < 7.3.

			if ( ! $sitemap_entries ) {

				continue;

			}

			// Using array_push is more efficient than array_merge in a loop.

			array_push( $sitemaps, ...$sitemap_entries );

			if ( count( $sitemaps ) >= $this->max_sitemaps ) {

				break;

			}

		}

		return array_slice( $sitemaps, 0, $this->max_sitemaps, true );

	}

	/**

	 * Builds the URL for the sitemap index.

	 *

	 * @since 5.5.0

	 *

	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.

	 *

	 * @return string The sitemap index URL.

	 */

	public function get_index_url() {

		global $wp_rewrite;

		if ( ! $wp_rewrite->using_permalinks() ) {

			return home_url( '/?sitemap=index' );

		}

		return home_url( '/wp-sitemap.xml' );

	}

}