Add decoupled GTag infrastructure.

sayanm085 · Mar 18, 2024 · cb715a9 · cb715a9
1 parent 5b30061
commit cb715a9
Showing 1 changed file with 191 additions and 0 deletions.
diff --git a/includes/Core/Tags/GTag.php b/includes/Core/Tags/GTag.php
@@ -0,0 +1,191 @@
+<?php
+/**
+ * Class Google\Site_Kit\Core\Tags\GTag
+ *
+ * @package   Google\Site_Kit
+ * @copyright 2024 Google LLC
+ * @license   https://www.apache.org/licenses/LICENSE-2.0 Apache License 2.0
+ * @link      https://sitekit.withgoogle.com
+ */
+
+namespace Google\Site_Kit\Core\Tags;
+
+use Google\Site_Kit\Core\Util\Method_Proxy_Trait;
+
+/**
+ * Class to handle gtag rendering across modules.
+ *
+ * @since n.e.x.t
+ * @access public
+ * @ignore
+ */
+class GTag {
+	use Method_Proxy_Trait;
+
+	const HANDLE = 'google_gtagjs';
+	/**
+	 * Holds an array of gtag ID's and their inline config elements.
+	 *
+	 * @var array $tags Array of tag ID's and their configs.
+	 */
+	private $tags = array();
+	/**
+	 * Holds an array of gtag commands, their parameters and command positions.
+	 *
+	 * @var array $commands Array of gtag config commands.
+	 */
+	private $commands = array();
+
+	/**
+	 * Register method called after class instantiation.
+	 *
+	 * @since n.e.x.t
+	 * @access public
+	 *
+	 * @return void
+	 */
+	public function register() {
+		add_action( 'wp_enqueue_scripts', $this->get_method_proxy( 'enqueue_gtag_script' ), 20 );
+
+		add_filter(
+			'wp_resource_hints',
+			function ( $urls, $relation_type ) {
+				if ( 'dns-prefetch' === $relation_type ) {
+					$urls[] = '//www.googletagmanager.com';
+				}
+
+				return $urls;
+			},
+			10,
+			2
+		);
+	}
+
+	/**
+	 * Method to add a gtag ID and config for output rendering.
+	 *
+	 * @since n.e.x.t
+	 * @access public
+	 *
+	 * @param string $tag_id The gtag ID.
+	 * @param array  $config Array of inline gtag config values.
+	 *
+	 * @return void
+	 */
+	public function add_tag( $tag_id, $config = array() ) {
+		$this->tags[] = array(
+			'tag_id' => $tag_id,
+			'config' => $config,
+		);
+	}
+
+	/**
+	 * Method to add a gtag command, associated parameters and output position.
+	 *
+	 * @since n.e.x.t
+	 * @access public
+	 *
+	 * @param string $command    The gtag command to add.
+	 * @param array  $parameters Array of command parameters.
+	 * @param string $position   Position of command."before|after".
+	 *
+	 * @return void
+	 */
+	public function add_command( $command, $parameters, $position = 'after' ) {
+		$this->commands[] = array(
+			'command'    => $command,       // e.g. 'config', 'event', etc.
+			'parameters' => $parameters,    // e.g. array( 'send_to', 'AW-123456789' ).
+			'position'   => $position,      // e.g. 'after', 'before'. This determines the position of the inline script relative to the gtag.js script.
+		);
+	}
+
+	/**
+	 * Method used to enqueue the gtag script along with additional tags,
+	 * configs and commands.
+	 *
+	 * @since n.e.x.t
+	 * @access protected
+	 *
+	 * @return void
+	 */
+	protected function enqueue_gtag_script() {
+		// $this->tags and $this->commands will be populated via this action's handlers.
+		do_action( 'googlesitekit_setup_gtag', $this );
+
+		if ( empty( $this->tags ) ) {
+			return;
+		}
+
+		// Load the GTag scripts using the first tag ID - it doesn't matter which is used, all registered tags will be setup with a
+		// config command regardless of which is used to load the source.
+		$gtag_src = 'https://www.googletagmanager.com/gtag/js?id=' . rawurlencode( $this->tags[0]['tag_id'] );
+
+		// phpcs:ignore WordPress.WP.EnqueuedResourceParameters.MissingVersion
+		wp_enqueue_script( self::HANDLE, $gtag_src, false, null, false );
+		wp_script_add_data( self::HANDLE, 'script_execution', 'async' );
+
+		// Note that `gtag()` may already be defined via the `Consent_Mode` output, but this is safe to call multiple times.
+		wp_add_inline_script( self::HANDLE, 'window.dataLayer = window.dataLayer || [];function gtag(){dataLayer.push(arguments);}' );
+		wp_add_inline_script( self::HANDLE, 'gtag("js", new Date());' );
+		wp_add_inline_script( self::HANDLE, 'gtag("set", "developer_id.dZTNiMT", true);' ); // Site Kit developer ID.
+
+		foreach ( $this->tags as $tag ) {
+			wp_add_inline_script( self::HANDLE, $this->get_gtag_call_for_tag( $tag ) );
+		}
+
+		foreach ( $this->commands as $command ) {
+			wp_add_inline_script( self::HANDLE, $this->get_gtag_call_for_command( $command ), $command['position'] );
+		}
+
+		$filter_google_gtagjs = function ( $tag, $handle ) {
+			if ( self::HANDLE !== $handle ) {
+				return $tag;
+			}
+
+			$snippet_comment_begin = sprintf( "\n<!-- %s -->\n", esc_html__( 'Google tag (gtag.js) snippet added by Site Kit', 'google-site-kit' ) );
+			$snippet_comment_end   = sprintf( "\n<!-- %s -->\n", esc_html__( 'End Google tag (gtag.js) snippet added by Site Kit', 'google-site-kit' ) );
+
+			return $snippet_comment_begin . $tag . $snippet_comment_end;
+		};
+
+		add_filter( 'script_loader_tag', $filter_google_gtagjs, 20, 2 );
+	}
+
+	/**
+	 * Method used to return gtag() config call for selected tag.
+	 *
+	 * @since n.e.x.t
+	 * @access protected
+	 *
+	 * @param array $tag The Gtag tag, along with its config parameters.
+	 *
+	 * @return string Gtag call for tag in question.
+	 */
+	protected function get_gtag_call_for_tag( $tag ) {
+		return empty( $tag['config'] )
+			? sprintf( 'gtag("config", "%s");', esc_js( $tag['tag_id'] ) )
+			: sprintf( 'gtag("config", "%s", %s);', esc_js( $tag['tag_id'] ), wp_json_encode( $tag['config'] ) );
+	}
+
+	/**
+	 * Method used to return gtag call for specific command.
+	 *
+	 * @since n.e.x.t
+	 * @access protected
+	 *
+	 * @param array $command The command array with applicable command and params.
+	 *
+	 * @return string Gtag function call for specific command.
+	 */
+	protected function get_gtag_call_for_command( $command ) {
+		$gtag_args = array_merge( array( $command['command'] ), $command['parameters'] );
+		$gtag_args = array_map(
+			function( $arg ) {
+				return wp_json_encode( $arg );
+			},
+			$gtag_args
+		);
+
+		return sprintf( 'gtag(%s);', implode( ',', $gtag_args ) );
+	}
+}