Issue #110 "JS tracking and AMP compatibility" (#116)

* Update class-statify-frontend.php

* Add filter for AMP analytics

* Update class-statify.php

* minor code style corrections (no semantics changed)

* do not append AMP analytics script if no JS tracking is used

* do not specity "type" attribute for AMP analytics script

There is no valid analytics vendor "statify" and we trigger a local
endpoint. To prevent AMP analtics from calling a vendor-endpoint with
404 result in this case, the type attribute is left empty.

* docs++

* adjust AMP analytics config to issue a POST request for WP-AJAX

Co-authored-by: Stefan Kalscheuer <[email protected]>
Co-authored-by: Torsten Landsiedel <[email protected]>
Co-authored-by: Patrick Robrecht <[email protected]>

CHANGELOG.md

@@ -8,7 +8,8 @@ All notable changes to this project will be documented in this file. This projec
 * Add option to show total visits
 * Refactored JavaScript tracking to use WP AJAX
 * Updated Chartist JS library for dashboard widget
-* Introduced new option to separate display from storage range 
+* Introduced new option to separate display from storage range
+* Automatically add AMP analytics trigger if official AMP PlugIn is installed
 * Dashboard widget is now scrollable to keep long-term statistics readable
 
 ## 1.6.3

inc/class-statify-frontend.php

@@ -35,7 +35,7 @@ public static function track_visit( $is_snippet = false ) {
 		$use_snippet = self::$_options['snippet'];
 
 		// Set target & referrer.
-		$target = null;
+		$target   = null;
 		$referrer = null;
 		if ( $use_snippet && $is_snippet ) {
 			if ( isset( $_REQUEST['statify_target'] ) ) {
@@ -390,4 +390,50 @@ public static function wp_footer() {
 			)
 		);
 	}
+
+	/**
+	 * Add amp-analytics.
+	 *
+	 * @see https://amp-wp.org/documentation/playbooks/analytics/
+	 *
+	 * @param array $analytics Analytics.
+	 */
+	public static function amp_post_template_analytics( $analytics ) {
+		if ( ! is_array( $analytics ) ) {
+			$analytics = array();
+		}
+
+		// Analytics script is only relevant, if "JS" tracking is enabled, to prevent double tracking.
+		if ( self::$_options['snippet'] ) {
+			$analytics['statify'] = array(
+				'type'        => '',
+				'attributes'  => array(),
+				'config_data' => array(
+					'extraUrlParams' => array(
+						'action'           => 'statify_track',
+						'_ajax_nonce'      => wp_create_nonce( 'statify_track' ),
+						'statify_referrer' => '${documentReferrer}',
+						'statify_target'   => '${canonicalPath}amp/',
+					),
+					'requests'       => array(
+						'event' => admin_url( 'admin-ajax.php' ),
+					),
+					'triggers'       => array(
+						'trackPageview' => array(
+							'on'      => 'visible',
+							'request' => 'event',
+							'vars'    => array(
+								'eventId' => 'pageview',
+							),
+						),
+					),
+					'transport'      => array(
+						'xhrpost' => true,
+					),
+				),
+			);
+		}
+
+		return $analytics;
+	}
 }

inc/class-statify-settings.php

@@ -138,7 +138,7 @@ public static function options_snippet() {
 		<input id="statify-snippet" type="checkbox" name="statify[snippet]" value="1" <?php checked( Statify::$_options['snippet'], 1 ); ?>>
 		(<?php esc_html_e( 'Default', 'statify' ); ?>: <?php esc_html_e( 'No', 'statify' ); ?>)
 		<br>
-		<p class="description"><?php esc_html_e( 'This option is strongly recommended if caching is in use.', 'statify' ); ?></p>
+		<p class="description"><?php esc_html_e( 'This option is strongly recommended if caching or AMP is in use.', 'statify' ); ?></p>
 		<?php
 	}
 

inc/class-statify.php

@@ -95,6 +95,9 @@ public static function init() {
 			add_action( 'template_redirect', array( 'Statify_Frontend', 'track_visit' ) );
 			add_filter( 'query_vars', array( 'Statify_Frontend', 'query_vars' ) );
 			add_action( 'wp_footer', array( 'Statify_Frontend', 'wp_footer' ) );
+			if ( function_exists( 'is_amp_endpoint' ) ) { // Automattic AMP plugin present.
+				add_filter( 'amp_post_template_analytics', array( 'Statify_Frontend', 'amp_post_template_analytics' ) );
+			}
 		}
 	}
 }