initial commit

includes/tracks/class-wc-tracks-footer-pixel.php

@@ -0,0 +1,113 @@
+<?php
+/**
+ * Send Tracks events on behalf of a user using pixel images in page footer.
+ *
+ * @package WooCommerce\Tracks
+ */
+
+defined( 'ABSPATH' ) || exit;
+
+/**
+ * WC_Tracks_Footer_Pixel class.
+ */
+class WC_Tracks_Footer_Pixel {
+	/**
+	 * Singleton instance.
+	 *
+	 * @var WC_Tracks_Footer_Pixel
+	 */
+	protected static $instance = null;
+
+	/**
+	 * Events to send to Tracks.
+	 *
+	 * @var array
+	 */
+	protected $events = array();
+
+	/**
+	 * Instantiate the singleton.
+	 *
+	 * @return WC_Tracks_Footer_Pixel
+	 */
+	public static function instance() {
+		if ( is_null( self::$instance ) ) {
+			self::$instance = new WC_Tracks_Footer_Pixel();
+		}
+
+		return self::$instance;
+	}
+
+	/**
+	 * Constructor - attach hooks to the singleton instance.
+	 */
+	public function __construct() {
+		add_action( 'admin_footer', array( $this, 'render_tracking_pixels' ) );
+		add_action( 'shutdown', array( $this, 'send_tracks_requests' ) );
+	}
+
+	/**
+	 * Record a Tracks event
+	 *
+	 * @param  array $event Array of event properties.
+	 * @return bool|WP_Error True on success, WP_Error on failure.
+	 */
+	public static function record_event( $event ) {
+		if ( ! $event instanceof WC_Tracks_Event ) {
+			$event = new WC_Tracks_Event( $event );
+		}
+
+		if ( is_wp_error( $event ) ) {
+			return $event;
+		}
+
+		self::instance()->add_event( $event );
+
+		return true;
+	}
+
+	/**
+	 * Add a Tracks event to the queue.
+	 *
+	 * @param WC_Tracks_Event $event Event to track.
+	 */
+	public function add_event( $event ) {
+		$this->events[] = $event;
+	}
+
+	/**
+	 * Add events as tracking pixels to page footer.
+	 */
+	public function render_tracking_pixels() {
+		if ( empty( $this->events ) ) {
+			return;
+		}
+
+		foreach ( $this->events as $event ) {
+			$pixel = $event->build_pixel_url();
+
+			if ( ! $pixel ) {
+				continue;
+			}
+
+			echo '<img style="position: fixed;" src="', esc_url( $pixel ), '" />';
+		}
+
+		$this->events = array();
+	}
+
+	/**
+	 * Fire off API calls for events that weren't converted to pixels.
+	 *
+	 * This handles wp_redirect().
+	 */
+	public function send_tracks_requests() {
+		if ( empty( $this->events ) ) {
+			return;
+		}
+
+		foreach ( $this->events as $event ) {
+			WC_Tracks_Client::record_event( $event );
+		}
+	}
+}