class LLMS_Post_Relationships {

	/**
	 * Configure relationships
	 *
	 * @var array
	 */
	private $relationships = array(
		'course'          => array(
			array(
				'action'    => 'delete',
				'meta_key'  => '_llms_product_id',
				'post_type' => 'llms_access_plan',
			),
		),

		'llms_membership' => array(
			array(
				'action'    => 'delete',
				'meta_key'  => '_llms_product_id',
				'post_type' => 'llms_access_plan',
			),
		),

		'lesson'          => array(
			array(
				'action'               => 'unset',
				'meta_key'             => '_llms_prerequisite', // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
				'meta_keys_additional' => array( '_llms_has_prerequisite' ),
				'post_type'            => 'lesson',
			),
			array(
				'action'    => 'unset',
				'meta_key'  => '_llms_lesson_id', // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
				'post_type' => 'llms_quiz',
			),
		),

		'llms_order'      => array(
			array(
				'action'    => 'delete',
				'meta_key'  => '_llms_order_id', // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
				'post_type' => 'llms_transaction',
			),
		),

		'llms_quiz'       => array(
			array(
				'action'    => 'delete', // Delete = force delete; trash = move to trash.
				'meta_key'  => '_llms_parent_id', // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
				'post_type' => 'llms_question',
			),
			array(
				'action'               => 'unset',
				'meta_key'             => '_llms_quiz', // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key
				'meta_keys_additional' => array( '_llms_quiz_enabled' ),
				'post_type'            => 'lesson',
			),
			array(
				'action'     => 'delete',
				'table_name' => 'lifterlms_quiz_attempts',
				'table_key'  => 'quiz_id',
			),
		),

	);

	/**
	 * Constructor.
	 *
	 * @since 3.16.12
	 * @since 5.4.0 Prevent course/membership with active subscriptions deletion.
	 * @since 6.0.0 Added hook to cleanup user post meta data when awarded certs and achievements are deleted.
	 *
	 * @return void
	 */
	public function __construct() {

		add_action( 'delete_post', array( $this, 'maybe_update_relationships' ) );
		add_action( 'pre_delete_post', array( __CLASS__, 'maybe_prevent_product_deletion' ), 10, 2 );

		add_action( 'before_delete_post', array( __CLASS__, 'maybe_clean_earned_engagments_related_user_post_meta' ) );

	}

	/**
	 * Maybe delete LifterLMS user post meta related to earned engagements.
	 *
	 * @since 6.0.0
	 *
	 * @param int $post_id Post ID.
	 * @return void
	 */
	public static function maybe_clean_earned_engagments_related_user_post_meta( $post_id ) {

		$post_types = array(
			'llms_my_certificate',
			'llms_my_achievement',
		);
		$post_type  = get_post_type( $post_id );

		if ( ! in_array( $post_type, $post_types, true ) ) {
			return;
		}

		$earned_engagement = 'llms_my_certificate' === $post_type ? new LLMS_User_Certificate( $post_id ) : new LLMS_User_Achievement( $post_id );

		do_action_deprecated(
			'llms_before_delete_' . str_replace( 'llms_my_', '', $post_type ),
			array(
				$earned_engagement,
			),
			'6.0.0',
			'',
			__( 'Use WordPress core  `before_delete_post` action hook', 'lifterlms' )
		);

		global $wpdb;
		$wpdb->delete(
			"{$wpdb->prefix}lifterlms_user_postmeta",
			array(
				'user_id'    => $earned_engagement->get_user_id(),
				'meta_key'   => '_' . str_replace( 'llms_my_', '', $post_type ) . '_earned',
				'meta_value' => $post_id,
			),
			array( '%d', '%s', '%d' )
		); // no-cache ok.

		add_action(
			'after_delete_post',
			function( $post_id ) use ( $earned_engagement, $post_type ) {

				if ( $earned_engagement->get( 'id' ) === $post_id ) {
					do_action_deprecated(
						'llms_delete_' . str_replace( 'llms_my_', '', $post_type ),
						array(
							$earned_engagement,
						),
						'6.0.0',
						'',
						__( 'Use WordPress core `deleted_post` action hook.', 'lifterlms' )
					);
				}

			}
		);
	}

	/**
	 * Determine whether a product deletion should take place.
	 *
	 * @since 5.4.0
	 *
	 * @param bool|null $delete Whether to go forward with deletion.
	 * @param WP_Post   $post   Post object.
	 * @return bool|null
	 */
	public static function maybe_prevent_product_deletion( $delete, $post ) {

		if ( ! in_array( get_post_type( $post ), array( 'course', 'llms_membership' ), true ) ) {
			return $delete;
		}

		$product = llms_get_product( $post );

		if ( empty( $product ) || ! $product->has_active_subscriptions() ) {
			return $delete;
		}

		// If performing the deletion via REST API change the error message to reflect the reason for the prevention.
		if ( llms_is_rest() ) {
			// Filter the error message.
			add_filter( 'rest_request_after_callbacks', array( __CLASS__, 'rest_filter_products_with_active_subscriptions_error_message' ), 10, 3 );
		} else { // Deleting via wp-admin.
			wp_die(
				self::delete_product_with_active_subscriptions_error_message( $product->get( 'id' ) )
			);
		}

		return false;

	}

	/**
	 * Filter the error message returned when trying to delete a product with active subscription via REST API.
	 *
	 * The original message is a standard permission denied message.
	 *
	 * @since 5.4.0
	 *
	 * @param WP_REST_Response|WP_HTTP_Response|WP_Error|mixed $response Result to send to the client.
	 *                                                                   Usually a WP_REST_Response or WP_Error.
	 * @param array                                            $handler  Route handler used for the request.
	 * @param WP_REST_Request                                  $request  Request used to generate the response.
	 * @return WP_REST_Response|WP_HTTP_Response|WP_Error|mixed
	 */
	public static function rest_filter_products_with_active_subscriptions_error_message( $response, $handler, $request ) {

		if ( is_wp_error( $response ) ) {
			foreach ( $response->errors as $code => &$data ) {
				// Error code can be produced by our rest-api or by wp core.
				if ( in_array( $code, array( 'llms_rest_cannot_delete', 'rest_cannot_delete' ), true ) ) {
					$data[0] = self::delete_product_with_active_subscriptions_error_message( $request['id'] );
					break;
				}
			}
		}

		return $response;

	}

	/**
	 * Returns the error message to display when deleting a product with active subscriptions.
	 *
	 * @since 5.4.0
	 *
	 * @param int $post_id The WP_Post ID of the product.
	 * @return string
	 */
	public static function delete_product_with_active_subscriptions_error_message( $post_id ) {

		$post_type = get_post_type( $post_id );

		if ( ! in_array( $post_type, array( 'course', 'llms_membership' ), true ) ) {
			return '';
		}

		$post_type_object = get_post_type_object( $post_type );
		$post_type_name   = $post_type_object->labels->name;
		return sprintf(
			// Translators: %s = The post type plural name.
			__( 'Sorry, you are not allowed to delete %s with active subscriptions.', 'lifterlms' ),
			$post_type_name
		);

	}

	/**
	 * Delete / Trash posts related to the deleted post.
	 *
	 * @since 3.16.12
	 * @since 3.37.8 Allow for deletion of related items outside the WP core posts table.
	 *
	 * @param WP_Post $post WP Post that's been deleted.
	 * @param array   $data Relationship data array.
	 * @return void
	 */
	private function delete_relationships( $post, $data ) {

		if ( isset( $data['post_type'] ) && isset( $data['meta_key'] ) ) {

			$this->delete_wp_posts( $post, $data );

		} elseif ( isset( $data['table_name'] ) && isset( $data['table_key'] ) ) {

			$this->delete_table_records( $post, $data );

		}

	}

	/**
	 * Delete records from a table that are related to the deleted post.
	 *
	 * @since 3.37.8
	 *
	 * @param WP_Post $post WP Post that's been deleted.
	 * @param array   $data Relationship data array.
	 * @return void
	 */
	private function delete_table_records( $post, $data ) {

		global $wpdb;
		$wpdb->delete( // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
			$wpdb->prefix . $data['table_name'],
			array(
				$data['table_key'] => $post->ID,
			),
			'%d'
		);

	}

	/**
	 * Delete or trash WP Posts related to the deleted post.
	 *
	 * @since 3.37.8
	 *
	 * @param WP_Post $post WP Post that's been deleted.
	 * @param array   $data Relationship data array.
	 * @return void
	 */
	private function delete_wp_posts( $post, $data ) {

		$relationships = $this->get_related_posts( $post->ID, $data['post_type'], $data['meta_key'] );

		$force = ( 'delete' === $data['action'] );

		foreach ( $relationships as $id ) {
			wp_delete_post( $id, $force );
		}

	}

	/**
	 * Get a list of post types with relationships that should be checked.
	 *
	 * @since 3.16.12
	 *
	 * @return array
	 */
	private function get_post_types() {
		return array_keys( $this->get_relationships() );
	}

	/**
	 * Retrieve filtered LifterLMS post relationships array.
	 *
	 * @since 3.16.12
	 *
	 * @return array
	 */
	private function get_relationships() {
		return apply_filters( 'llms_get_post_relationships', $this->relationships );
	}

	/**
	 * Retrieve an array of post ids related to the deleted post by post type and meta key.
	 *
	 * @since 3.16.12
	 *
	 * @param int    $post_id   WP Post ID of the deleted post.
	 * @param string $post_type WP Post type of the related post(s).
	 * @param string $meta_key  meta_key to check for relations by.
	 * @return array
	 */
	private function get_related_posts( $post_id, $post_type, $meta_key ) {

		global $wpdb;
		return $wpdb->get_col(
			$wpdb->prepare(
				"SELECT p.ID
			 FROM {$wpdb->posts} AS p
			 LEFT JOIN {$wpdb->postmeta} AS pm
			        ON p.ID = pm.post_id
			       AND pm.meta_key = %s
			 WHERE p.post_type = %s
			   AND pm.meta_value = %d",
				$meta_key,
				$post_type,
				$post_id
			)
		); // db-call ok; no-cache ok.

	}

	/**
	 * Check relationships and delete / update related posts when a post is deleted.
	 *
	 * Called on `delete_post` hook (before a post is deleted).
	 *
	 * @since 3.16.12
	 * @since 3.24.0 Unknown.
	 *
	 * @param int $post_id WP Post ID of the deleted post.
	 * @return void
	 */
	public function maybe_update_relationships( $post_id ) {

		$post = get_post( $post_id );
		if ( ! in_array( $post->post_type, $this->get_post_types(), true ) ) {
			return;
		}

		foreach ( $this->get_relationships() as $post_type => $relationships ) {

			if ( $post->post_type !== $post_type ) {
				continue;
			}

			foreach ( $relationships as $data ) {

				if ( in_array( $data['action'], array( 'delete', 'trash' ), true ) ) {

					$this->delete_relationships( $post, $data );

				} elseif ( 'unset' === $data['action'] ) {

					$this->unset_relationships( $post, $data );

				}
			}
		}

	}

	/**
	 * Unsets relationship data from post_meta when a post is deleted.
	 *
	 * @since 3.16.12
	 * @since 3.24.0 Unknown.
	 *
	 * @param WP_Post $post WP Post that's been deleted.
	 * @param array   $data Relationship data array.
	 * @return void
	 */
	private function unset_relationships( $post, $data ) {

		$relationships = $this->get_related_posts( $post->ID, $data['post_type'], $data['meta_key'] );

		foreach ( $relationships as $id ) {

			delete_post_meta( $id, $data['meta_key'], $post->ID );

			if ( isset( $data['meta_keys_additional'] ) ) {
				foreach ( $data['meta_keys_additional'] as $key ) {
					delete_post_meta( $id, $key );
				}
			}
		}

	}

}