Added: support for add to cart tracking through direct links

src/Integrations/WooCommerce.php

@@ -69,8 +69,10 @@ private function init( $init ) {
 		 */
 		add_action( 'woocommerce_before_add_to_cart_quantity', [ $this, 'add_cart_form_hidden_input' ] );
 		add_action( 'woocommerce_after_add_to_cart_form', [ $this, 'track_add_to_cart_on_product_page' ] );
-		add_filter( 'woocommerce_store_api_validate_add_to_cart', [ $this, 'track_add_to_cart' ], 10, 2 );
-		add_filter( 'woocommerce_ajax_added_to_cart', [ $this, 'track_ajax_add_to_cart' ] );
+		add_action( 'woocommerce_store_api_validate_add_to_cart', [ $this, 'track_add_to_cart' ], 10, 2 );
+		add_action( 'woocommerce_ajax_added_to_cart', [ $this, 'track_ajax_add_to_cart' ] );
+		/** @see \WC_Form_Handler::add_to_cart_action() runs on priority 20. */
+		add_action( 'wp_loaded', [ $this, 'track_direct_add_to_cart' ], 21 );
 		add_action( 'woocommerce_remove_cart_item', [ $this, 'track_remove_cart_item' ], 10, 2 );
 		add_action( 'wp_head', [ $this, 'track_entered_checkout' ] );
 		add_action( 'woocommerce_thankyou', [ $this, 'track_purchase' ] );
@@ -173,22 +175,22 @@ public function track_add_to_cart_on_product_page() {
 	}
 
 	/**
-	 * Track (non-Interactivity API, i.e. AJAX) add to cart events.
-	 *
-	 * @param string|int $product_id ID of the product added to the cart.
+	 * Track add to cart actions by direct link, e.g. ?product_type=download&add-to-cart=1&quantity=1
 	 *
 	 * @return void
 	 *
-	 * @codeCoverageIgnore Because we can't test XHR requests here.
+	 * @codeCoverageIgnore Because we can't test XHR here.
 	 */
-	public function track_ajax_add_to_cart( $product_id ) {
-		$product          = wc_get_product( $product_id );
-		$add_to_cart_data = [
-			'id'       => $product_id,
-			'quantity' => $_POST[ 'quantity' ] ?? 1,
-		];
+	public function track_direct_add_to_cart() {
+		if ( ! isset( $_REQUEST[ 'add-to-cart' ] ) || ! is_numeric( wp_unslash( $_REQUEST[ 'add-to-cart' ] ) ) ) {
+			return;
+		}
 
-		$this->track_add_to_cart( $product, $add_to_cart_data );
+		$product_id = absint( wp_unslash( $_REQUEST[ 'add-to-cart' ] ) );
+		$product    = wc_get_product( $product_id );
+		$quantity   = isset( $_REQUEST[ 'quantity' ] ) ? absint( wp_unslash( $_REQUEST[ 'quantity' ] ) ) : 1;
+
+		$this->track_add_to_cart( $product, [ 'id' => $product_id, 'quantity' => $quantity ] );
 	}
 
 	/**
@@ -241,6 +243,25 @@ private function clean_data( $product ) {
 		return $product;
 	}
 
+	/**
+	 * Track (non-Interactivity API, i.e. AJAX) add to cart events.
+	 *
+	 * @param string|int $product_id ID of the product added to the cart.
+	 *
+	 * @return void
+	 *
+	 * @codeCoverageIgnore Because we can't test XHR requests here.
+	 */
+	public function track_ajax_add_to_cart( $product_id ) {
+		$product          = wc_get_product( $product_id );
+		$add_to_cart_data = [
+			'id'       => $product_id,
+			'quantity' => $_POST[ 'quantity' ] ?? 1,
+		];
+
+		$this->track_add_to_cart( $product, $add_to_cart_data );
+	}
+
 	/**
 	 * Track Remove from cart events.
 	 *

src/Proxy.php

@@ -112,6 +112,11 @@ public function do_request( $name = 'pageview', $domain = '', $url = '', $props
 			'u' => $url ?: wp_get_referer(),
 		];
 
+		// URL is required, so if no $url was set and no referer was found, attempt to create it from the REQUEST_URI server variable.
+		if ( empty( $body[ 'u' ] ) ) {
+			$body[ 'u' ] = $this->generate_event_url(); // @codeCoverageIgnore
+		}
+
 		// Revenue events use a different approach.
 		if ( isset( $props[ 'revenue' ] ) ) {
 			$body[ 'revenue' ] = reset( $props ); // @codeCoverageIgnore
@@ -124,6 +129,23 @@ public function do_request( $name = 'pageview', $domain = '', $url = '', $props
 		return $this->send_event( $request );
 	}
 
+	/**
+	 * Attempts to generate the Event URL from available resources.
+	 *
+	 * @return string
+	 */
+	public function generate_event_url() {
+		$url            = '';
+		$parts          = parse_url( $_SERVER[ 'REQUEST_URI' ] );
+		$home_url_parts = parse_url( get_home_url() );
+
+		if ( isset( $home_url_parts[ 'scheme' ] ) && isset( $home_url_parts[ 'host' ] ) && isset( $parts[ 'path' ] ) ) {
+			$url = $home_url_parts[ 'scheme' ] . '://' . $home_url_parts [ 'host' ] . $parts[ 'path' ];
+		}
+
+		return $url;
+	}
+
 	/**
 	 * Formats and sends $request to the Plausible API.
 	 *

tests/unit/ClientFactoryTest.php → tests/integration/ClientFactoryTest.php

@@ -3,7 +3,7 @@
  * @package Plausible Analytics Unit Tests - ClientFactory
  */
 
-namespace Plausible\Analytics\Tests\Unit;
+namespace Plausible\Analytics\Tests\Integration;
 
 use Plausible\Analytics\Tests\TestCase;
 use Plausible\Analytics\WP\Client;

tests/integration/ProxyTest.php

@@ -0,0 +1,29 @@
+<?php
+/**
+ * @package Plausible Analytics Unit Tests - ClientFactory
+ */
+
+namespace Plausible\Analytics\Tests\Integration;
+
+use Plausible\Analytics\Tests\TestCase;
+use Plausible\Analytics\WP\Proxy;
+
+class ProxyTest extends TestCase {
+	/**
+	 * @see Proxy::generate_event_url()
+	 * @return void
+	 */
+	public function testGenerateEventUrl() {
+		$proxy = new Proxy( false );
+
+		$url = $proxy->generate_event_url();
+
+		$this->assertEquals( 'http://example.org', $url );
+
+		$_SERVER[ 'REQUEST_URI' ] = '/test';
+
+		$url = $proxy->generate_event_url();
+
+		$this->assertEquals( 'http://example.org/test', $url );
+	}
+}