Random Redirect: add module to jetpack-mu-wpcom package (#38374)

* Random Redirect: add to jetpack-mu-wpcom package for simple sites

* Prevent Phan warning

* Fix wrong hook

projects/packages/jetpack-mu-wpcom/changelog/add-random-redirect-module-to-mu-wpcom

@@ -0,0 +1,4 @@
+Significance: patch
+Type: added
+
+Add Random Redirect module for simple sites

projects/packages/jetpack-mu-wpcom/src/class-jetpack-mu-wpcom.php

@@ -53,6 +53,7 @@ public static function init() {
 			add_action( 'plugins_loaded', array( __CLASS__, 'load_verbum_comments' ) );
 			add_action( 'wp_loaded', array( __CLASS__, 'load_verbum_comments_admin' ) );
 			add_action( 'admin_menu', array( __CLASS__, 'load_wpcom_simple_odyssey_stats' ) );
+			add_action( 'plugins_loaded', array( __CLASS__, 'load_wpcom_random_redirect' ) );
 		}
 
 		// These features run only on atomic sites.
@@ -357,4 +358,11 @@ public static function load_custom_css() {
 		require_once __DIR__ . '/features/custom-css/custom-css/preprocessors.php';
 		require_once __DIR__ . '/features/custom-css/custom-css.php';
 	}
+
+	/**
+	 * Load the Random Redirect feature.
+	 */
+	public static function load_wpcom_random_redirect() {
+		require_once __DIR__ . '/features/random-redirect/random-redirect.php';
+	}
 }

projects/packages/jetpack-mu-wpcom/src/features/random-redirect/random-redirect.php

@@ -0,0 +1,102 @@
+<?php
+/**
+ * Plugin Name: Random Redirect
+ * Plugin URI: https://wordpress.org/extend/plugins/random-redirect/
+ * Description: Allows you to create a link to yourblog.example.com/?random which will redirect someone to a random post on your blog, in a StumbleUpon-like fashion.
+ * Version: 1.2-wpcom
+ * Author: Matt Mullenweg
+ * Author URI: https://ma.tt/
+ * Text Domain: jetpack
+ *
+ * @package automattic/jetpack
+ */
+
+// phpcs:disable WordPress.Security.NonceVerification -- No changes to the site here, it just redirects.
+
+/**
+ * Redirects to a random post on the site.
+ */
+function jetpack_matt_random_redirect() {
+	// Verify that the Random Redirect plugin this code is from is not active
+	// See https://plugins.trac.wordpress.org/ticket/1898
+	if ( ! ( defined( 'IS_WPCOM' ) && IS_WPCOM ) ) {
+		require_once ABSPATH . 'wp-admin/includes/plugin.php';
+		if ( is_plugin_active( 'random-redirect/random-redirect.php' ) ) {
+			return;
+		}
+	}
+
+	// Acceptable URL formats: /[...]/?random=[post type], /?random, /&random, /&random=1
+	if ( ! isset( $_GET['random'] ) && ! ( isset( $_SERVER['REQUEST_URI'] ) && in_array( strtolower( $_SERVER['REQUEST_URI'] ), array( '/&random', '/&random=1' ), true ) ) ) {
+		return;
+	}
+
+	// Ignore POST requests.
+	if ( ! empty( $_POST ) ) {
+		return;
+	}
+
+	// Persistent AppEngine abuse.  ORDER BY RAND is expensive.
+	if ( isset( $_SERVER['HTTP_USER_AGENT'] ) && strstr( filter_var( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ), 'AppEngine-Google' ) ) {
+		wp_die( 'Please <a href="https://en.support.wordpress.com/contact/" rel="noopener noreferrer" target="_blank">contact support</a>' );
+	}
+
+	$where      = array(
+		"post_password = ''",
+		"post_status = 'publish'",
+	);
+	$where_args = array();
+
+	// Set default post type.
+	$post_type = get_post_type();
+
+	// Change the post type if the parameter is set.
+	if ( isset( $_GET['random_post_type'] ) && post_type_exists( sanitize_key( $_GET['random_post_type'] ) ) ) {
+		$post_type = sanitize_key( $_GET['random_post_type'] );
+	}
+
+	// Don't show a random page if 'page' isn't specified as the post type specifically.
+	if ( 'page' === $post_type && is_front_page() && ! isset( $_GET['random_post_type'] ) ) {
+		$post_type = 'post';
+	}
+
+	$where[]      = 'p.post_type = %s';
+	$where_args[] = $post_type;
+
+	// Set author name if we're on an author archive.
+	if ( is_author() ) {
+		$where[]      = 'post_author = %s';
+		$where_args[] = get_the_author_meta( 'ID' );
+	}
+
+	// Set default category type
+	if ( is_category() ) {
+		$category = get_the_category();
+		if ( isset( $category ) && ! empty( $category ) ) {
+			$random_cat_id = $category[0]->term_id;
+		}
+	}
+
+	// Set the category ID if the parameter is set.
+	if ( isset( $_GET['random_cat_id'] ) ) {
+		$random_cat_id = (int) $_GET['random_cat_id'];
+	}
+
+	global $wpdb;
+
+	$where = implode( ' AND ', $where );
+	if ( isset( $random_cat_id ) ) {
+		// phpcs:ignore WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber
+		$random_id = $wpdb->get_var( $wpdb->prepare( "SELECT DISTINCT ID FROM $wpdb->posts AS p INNER JOIN $wpdb->term_relationships AS tr ON (p.ID = tr.object_id AND tr.term_taxonomy_id = %s) INNER JOIN  $wpdb->term_taxonomy AS tt ON(tr.term_taxonomy_id = tt.term_taxonomy_id AND taxonomy = 'category') WHERE $where ORDER BY RAND() LIMIT 1", $random_cat_id, ...$where_args ) );
+	} else {
+		// phpcs:ignore WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare
+		$random_id = $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $wpdb->posts AS p WHERE $where ORDER BY RAND() LIMIT 1", ...$where_args ) );
+	}
+
+	// @phan-suppress-next-line PhanTypeMismatchArgument
+	$permalink = get_permalink( $random_id );
+	wp_safe_redirect( $permalink );
+	exit;
+}
+
+add_action( 'template_redirect', 'jetpack_matt_random_redirect' );