woocommerce/woocommerce

<?php
/**
 * Send Tracks events on behalf of a user.
 *
 * @package WooCommerce\Tracks
 */

use Automattic\Jetpack\Constants;
use Automattic\WooCommerce\Utilities\NumberUtil;

defined( 'ABSPATH' ) || exit;

/**
 * WC_Tracks_Client class.
 */
class WC_Tracks_Client {

    /**
     * Pixel URL.
     */
    const PIXEL = 'https://pixel.wp.com/t.gif';

    /**
     * Browser type.
     */
    const BROWSER_TYPE = 'php-agent';

    /**
     * User agent.
     */
    const USER_AGENT_SLUG = 'tracks-client';

    /**
     * Initialize tracks client class
     *
     * @return void
     */
    public static function init() {
        // Use wp hook for setting the identity cookie to avoid headers already sent warnings.
        add_action( 'admin_init', array( __CLASS__, 'maybe_set_identity_cookie' ) );
    }

    /**
     * Check if identiy cookie is set, if not set it.
     *
     * @return void
     */
    public static function maybe_set_identity_cookie() {
        // Do not set on AJAX requests.
        if ( Constants::is_true( 'DOING_AJAX' ) ) {
            return;
        }

        // Bail if cookie already set.
        if ( isset( $_COOKIE['tk_ai'] ) ) {
            return;
        }

        $user = wp_get_current_user();

        // We don't want to track user events during unit tests/CI runs.
        if ( $user instanceof WP_User && 'wptests_capabilities' === $user->cap_key ) {
            return false;
        }
        $user_id = $user->ID;
        $anon_id = get_user_meta( $user_id, '_woocommerce_tracks_anon_id', true );

        // If an id is still not found, create one and save it.
        if ( ! $anon_id ) {
            $anon_id = self::get_anon_id();
            update_user_meta( $user_id, '_woocommerce_tracks_anon_id', $anon_id );
        }

        // Don't set cookie on API requests.
        if ( ! Constants::is_true( 'REST_REQUEST' ) && ! Constants::is_true( 'XMLRPC_REQUEST' ) ) {
            wc_setcookie( 'tk_ai', $anon_id );
        }
    }

    /**
     * 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;
        }

        $pixel = $event->build_pixel_url( $event );

        if ( ! $pixel ) {
            return new WP_Error( 'invalid_pixel', 'cannot generate tracks pixel for given input', 400 );
        }

        return self::record_pixel( $pixel );
    }

    /**
     * Synchronously request the pixel.
     *
     * @param string $pixel pixel url and query string.
     * @return bool Always returns true.
     */
    public static function record_pixel( $pixel ) {
        // Add the Request Timestamp and URL terminator just before the HTTP request.
        $pixel .= '&_rt=' . self::build_timestamp() . '&_=_';

        wp_safe_remote_get(
            $pixel,
            array(
                'blocking'    => false,
                'redirection' => 2,
                'httpversion' => '1.1',
                'timeout'     => 1,
            )
        );

        return true;
    }

    /**
     * Create a timestap representing milliseconds since 1970-01-01
     *
     * @return string A string representing a timestamp.
     */
    public static function build_timestamp() {
        $ts = NumberUtil::round( microtime( true ) * 1000 );

        return number_format( $ts, 0, '', '' );
    }

    /**
     * Get a user's identity to send to Tracks. If Jetpack exists, default to its implementation.
     *
     * @param int $user_id User id.
     * @return array Identity properties.
     */
    public static function get_identity( $user_id ) {
        $jetpack_lib = '/tracks/client.php';

        if ( class_exists( 'Jetpack' ) && Constants::is_defined( 'JETPACK__VERSION' ) ) {
            if ( version_compare( Constants::get_constant( 'JETPACK__VERSION' ), '7.5', '<' ) ) {
                if ( file_exists( jetpack_require_lib_dir() . $jetpack_lib ) ) {
                    include_once jetpack_require_lib_dir() . $jetpack_lib;
                    if ( function_exists( 'jetpack_tracks_get_identity' ) ) {
                        return jetpack_tracks_get_identity( $user_id );
                    }
                }
            } else {
                $tracking = new Automattic\Jetpack\Tracking();
                return $tracking->tracks_get_identity( $user_id );
            }
        }

        // Start with a previously set cookie.
        $anon_id = isset( $_COOKIE['tk_ai'] ) ? sanitize_text_field( wp_unslash( $_COOKIE['tk_ai'] ) ) : false;

        // If there is no cookie, apply a saved id.
        if ( ! $anon_id ) {
            $anon_id = get_user_meta( $user_id, '_woocommerce_tracks_anon_id', true );
        }

        // If an id is still not found, create one and save it.
        if ( ! $anon_id ) {
            $anon_id = self::get_anon_id();

            update_user_meta( $user_id, '_woocommerce_tracks_anon_id', $anon_id );
        }

        return array(
            '_ut' => 'anon',
            '_ui' => $anon_id,
        );
    }

    /**
     * Grabs the user's anon id from cookies, or generates and sets a new one
     *
     * @return string An anon id for the user
     */
    public static function get_anon_id() {
        static $anon_id = null;

        if ( ! isset( $anon_id ) ) {

            // Did the browser send us a cookie?
            if ( isset( $_COOKIE['tk_ai'] ) ) {
                $anon_id = sanitize_text_field( wp_unslash( $_COOKIE['tk_ai'] ) );
            } else {

                $binary = '';

                // Generate a new anonId and try to save it in the browser's cookies.
                // Note that base64-encoding an 18 character string generates a 24-character anon id.
                for ( $i = 0; $i < 18; ++$i ) {
                    $binary .= chr( wp_rand( 0, 255 ) );
                }

                // phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.obfuscation_base64_encode
                $anon_id = 'woo:' . base64_encode( $binary );
            }
        }

        return $anon_id;
    }
}

WC_Tracks_Client::init();