From 7819ac5d16c932c020371f43126b338e6abd64d0 Mon Sep 17 00:00:00 2001
From: Jeremy Felt <jeremyfelt@git.wordpress.org>
Date: Sun, 14 Jun 2015 21:44:45 +0000
Subject: [PATCH] Introduce get_main_network_id()

Expand on the logic previously available as part of `is_main_network()` and provide a way to obtain the ID of the main network. Most useful in multi-network configurations.

Props @johnjamesjacoby for the initial patch.
Fixes #30294.


git-svn-id: https://develop.svn.wordpress.org/trunk@32775 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/functions.php             | 57 +++++++++++++++------
 tests/phpunit/tests/multisite/network.php | 61 ++++++++++++++++++++++-
 2 files changed, 101 insertions(+), 17 deletions(-)

diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index b09ed844af..99cf913d9a 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -3873,38 +3873,63 @@ function is_main_site( $site_id = null ) {
  *
  * @since 3.7.0
  *
- * @global wpdb $wpdb
- *
  * @param int $network_id Optional. Network ID to test. Defaults to current network.
  * @return bool True if $network_id is the main network, or if not running Multisite.
  */
 function is_main_network( $network_id = null ) {
-	global $wpdb;
-
-	if ( ! is_multisite() )
+	if ( ! is_multisite() ) {
 		return true;
+	}
 
 	$current_network_id = (int) get_current_site()->id;
 
-	if ( ! $network_id )
+	if ( null === $network_id ) {
 		$network_id = $current_network_id;
+	}
+
 	$network_id = (int) $network_id;
 
-	if ( defined( 'PRIMARY_NETWORK_ID' ) )
-		return $network_id === (int) PRIMARY_NETWORK_ID;
+	return ( $network_id === get_main_network_id() );
+}
 
-	if ( 1 === $current_network_id )
-		return $network_id === $current_network_id;
+/**
+ * Get the main network ID.
+ *
+ * @since 4.3.0
+ *
+ * @global wpdb $wpdb
+ *
+ * @return int The ID of the main network.
+ */
+function get_main_network_id() {
+	global $wpdb;
 
-	$primary_network_id = (int) wp_cache_get( 'primary_network_id', 'site-options' );
+	if ( ! is_multisite() ) {
+		return 1;
+	}
 
-	if ( $primary_network_id )
-		return $network_id === $primary_network_id;
+	if ( defined( 'PRIMARY_NETWORK_ID' ) ) {
+		$main_network_id = PRIMARY_NETWORK_ID;
+	} elseif ( 1 === (int) get_current_site()->id ) {
+		// If the current network has an ID of 1, assume it is the main network.
+		$main_network_id = 1;
+	} else {
+		$main_network_id = wp_cache_get( 'primary_network_id', 'site-options' );
 
-	$primary_network_id = (int) $wpdb->get_var( "SELECT id FROM $wpdb->site ORDER BY id LIMIT 1" );
-	wp_cache_add( 'primary_network_id', $primary_network_id, 'site-options' );
+		if ( false === $main_network_id ) {
+			$main_network_id = (int) $wpdb->get_var( "SELECT id FROM {$wpdb->site} ORDER BY id LIMIT 1" );
+			wp_cache_add( 'primary_network_id', $main_network_id, 'site-options' );
+		}
+	}
 
-	return $network_id === $primary_network_id;
+	/**
+	 * Filter the main network ID.
+	 *
+	 * @since 4.3.0
+	 *
+	 * @param int $main_network_id The ID of the main network.
+	 */
+	return (int) apply_filters( 'get_main_network_id', $main_network_id );
 }
 
 /**
diff --git a/tests/phpunit/tests/multisite/network.php b/tests/phpunit/tests/multisite/network.php
index 7d34edcc1c..70a4a0dbeb 100644
--- a/tests/phpunit/tests/multisite/network.php
+++ b/tests/phpunit/tests/multisite/network.php
@@ -21,11 +21,70 @@ class Tests_Multisite_Network extends WP_UnitTestCase {
 	}
 
 	function tearDown() {
-		global $wpdb;
+		global $wpdb, $current_site;
 		$wpdb->suppress_errors( $this->suppress );
+		$current_site->id = 1;
 		parent::tearDown();
 	}
 
+	/**
+	 * By default, only one network exists and has a network ID of 1.
+	 */
+	function test_get_main_network_id_default() {
+		$this->assertEquals( 1, get_main_network_id() );
+	}
+
+	/**
+	 * If a second network is created, network ID 1 should still be returned
+	 * as the main network ID.
+	 */
+	function test_get_main_network_id_two_networks() {
+		$this->factory->network->create();
+
+		$this->assertEquals( 1, get_main_network_id() );
+	}
+
+	/**
+	 * When the `$current_site` global is populated with another network, the
+	 * main network should still return as 1.
+	 */
+	function test_get_main_network_id_after_network_switch() {
+		global $current_site;
+
+		$id = $this->factory->network->create();
+
+		$current_site->id = (int) $id;
+
+		$this->assertEquals( 1, get_main_network_id() );
+	}
+
+	/**
+	 * When the first network is removed, the next should return as the main
+	 * network ID.
+	 *
+	 * @todo In the future, we'll have a smarter way of deleting a network. For now,
+	 * fake the process with UPDATE queries.
+	 */
+	function test_get_main_network_id_after_network_delete() {
+		global $wpdb, $current_site;
+		$id = $this->factory->network->create();
+
+		$current_site->id = (int) $id;
+		$wpdb->query( "UPDATE {$wpdb->site} SET id=100 WHERE id=1" );
+		$this->assertEquals( $id, get_main_network_id() );
+		$wpdb->query( "UPDATE {$wpdb->site} SET id=1 WHERE id=100" );
+	}
+
+	function test_get_main_network_id_filtered() {
+		add_filter( 'get_main_network_id', array( $this, '_get_main_network_id' ) );
+		$this->assertEquals( 3, get_main_network_id() );
+		remove_filter( 'get_main_network_id', array( $this, '_get_main_network_id' ) );
+	}
+
+	function _get_main_network_id() {
+		return 3;
+	}
+
 	/**
 	 * @ticket 22917
 	 */