<?php

namespace PixelYourSite;

if ( ! defined( 'ABSPATH' ) ) {
    exit; // Exit if accessed directly.
}

/**
 * Facebook REST API handler
 */
class Facebook_REST_API {

    /**
     * Register REST API routes
     */
    public function register_routes() {
        add_action( 'rest_api_init', array( $this, 'register_rest_routes' ) );
    }

    /**
     * Register REST API routes
     */
    public function register_rest_routes() {
        register_rest_route( 'pys-facebook/v1', '/event', array(
            'methods'             => 'POST',
            'callback'            => array( $this, 'handle_facebook_event' ),
            'permission_callback' => array( $this, 'check_permission' ),
            'args'                => $this->get_event_args(),
        ) );
    }

    /**
     * Handle Facebook event
     */
    public function handle_facebook_event( $request ) {
        $event = $request->get_param( 'event' );
        $data = $request->get_param( 'data' );
        $ids = $request->get_param( 'ids' );
        $eventID = $request->get_param( 'eventID' );
        $woo_order = $request->get_param( 'woo_order' );
        $edd_order = $request->get_param( 'edd_order' );
        $referrer_url = $request->get_param( 'referrer_url' );
        $event_source_url = $request->get_param( 'event_source_url' );

        // Variant B fallback: when the browser did not send an explicit page
        // URL, use this REST request's Referer header. For a fetch/sendBeacon
        // fired from the visitor's page, Referer IS that page URL — which is
        // what Meta expects for event_source_url (never the REST endpoint).
        if ( empty( $event_source_url ) ) {
            $referer = $request->get_header( 'referer' );
            if ( ! empty( $referer ) ) {
                $event_source_url = esc_url_raw( $referer );
            }
        }

        $singleEvent = $this->data_to_single_event( $event, $data, $eventID, $ids, $woo_order, $edd_order, $referrer_url, $event_source_url );

        // Send event using existing Facebook server logic
        FacebookServer()->sendEventsNow( array( $singleEvent ) );

        return new \WP_REST_Response( array( 'success' => true ), 200 );
    }

    /**
     * Check access permissions
     *
     * This is a public tracking endpoint: it must be reachable by anonymous
     * visitors and from aggressively cached HTML, so wp_verify_nonce() and
     * capability checks are intentionally NOT used here (REST nonces are
     * session-bound and roll every 12h, which breaks cached pages).
     *
     * Defense in Depth applied at this layer:
     *   1) Same-origin enforcement via Origin / Referer headers blocks the
     *      most common cross-site abuse vector.
     *   2) Payload data is sanitized in sanitize_data() / get_event_args().
     *   3) The `pys_rest_event_permission` filter lets site owners harden
     *      this further (rate limits, bot rules) or relax it on environments
     *      where Origin/Referer is stripped by proxies.
     *
     * @param \WP_REST_Request $request The request object.
     * @return bool
     */
    public function check_permission( $request ) {
        $origin    = $request->get_header( 'origin' );
        $referer   = $request->get_header( 'referer' );
        $site      = wp_parse_url( home_url() );
        $site_host = isset( $site['host'] ) ? strtolower( $site['host'] ) : '';

        $is_same_origin = false;

        if ( ! empty( $origin ) ) {
            $origin_parts = wp_parse_url( $origin );
            $is_same_origin = ! empty( $site_host )
                && isset( $origin_parts['host'] )
                && strtolower( $origin_parts['host'] ) === $site_host;
        } elseif ( ! empty( $referer ) ) {
            $referer_parts = wp_parse_url( $referer );
            $is_same_origin = ! empty( $site_host )
                && isset( $referer_parts['host'] )
                && strtolower( $referer_parts['host'] ) === $site_host;
        }

        // Per-IP rate limiting: max requests per minute per namespace.
        // The limit is configured via the 'pys_check_permission_rate_limit'
        // option (Global Settings > Ajax options). Default is 60 (1 req/sec).
        if ( $is_same_origin ) {
            $ip    = PYS()->get_user_ip();
            $key   = 'pys_rl_' . md5( $ip . '_pys-facebook/v1' );
            $count = (int) get_transient( $key );

            // Maximum allowed requests per minute, per IP, per pixel namespace.
            $limit = max( 1, (int) PYS()->getOption( 'pys_check_permission_rate_limit' ) );

            if ( $count >= $limit ) {
                return new \WP_Error( 'rate_limited', 'Too many requests', [ 'status' => 429 ] );
            }
            set_transient( $key, $count + 1, 60 );
        }

        /**
         * Filters whether a REST tracking request is allowed.
         *
         * Default: true if the request is same-origin (matching Origin or
         * Referer host), false otherwise. Return true to fully open the
         * endpoint, or implement custom rate limiting / bot filtering.
         *
         * @param bool             $allowed Whether the request is allowed.
         * @param \WP_REST_Request $request The current request object.
         */
        return (bool) apply_filters(
            'pys_rest_event_permission',
            $is_same_origin,
            $request
        );
    }

    /**
     * Get event arguments for REST API
     */
    private function get_event_args() {
        return array(
            'event'      => array(
                'required'          => true,
                'type'              => 'string',
                'sanitize_callback' => 'sanitize_text_field',
            ),
            'data'       => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '{}',
                'sanitize_callback' => array( $this, 'sanitize_data' ),
            ),
            'ids'        => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '[]',
                'sanitize_callback' => array( $this, 'sanitize_ids' ),
            ),
            'eventID'    => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '',
                'sanitize_callback' => 'sanitize_text_field',
            ),
            'woo_order'  => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '0',
                'sanitize_callback' => array( $this, 'sanitize_order_id' ),
            ),
            'edd_order'  => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '0',
                'sanitize_callback' => array( $this, 'sanitize_order_id' ),
            ),
            'event_slug' => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '',
                'sanitize_callback' => 'sanitize_text_field',
            ),
            'order_key'  => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '',
                'sanitize_callback' => 'sanitize_text_field',
            ),
            'referrer_url' => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '',
                'sanitize_callback' => 'esc_url_raw',
            ),
            'event_source_url' => array(
                'required'          => false,
                'type'              => 'string',
                'default'           => '',
                'sanitize_callback' => 'esc_url_raw',
            ),
        );
    }



    /**
     * Sanitize event data
     *
     * Recursively sanitizes every scalar value inside the decoded payload
     * with `sanitize_text_field()` to prevent injection via nested keys/values.
     *
     * @param mixed $data Data to sanitize.
     * @return array
     */
    public function sanitize_data( $data ) {
        if ( is_string( $data ) ) {
            $decoded = json_decode( $data, true );
            if ( is_array( $decoded ) ) {
                return map_deep( $decoded, 'sanitize_text_field' );
            }
        }
        if ( is_array( $data ) ) {
            return map_deep( $data, 'sanitize_text_field' );
        }
        return [];
    }

    /**
     * Sanitize ids parameter
     */
    public function sanitize_ids( $ids ) {
        if ( is_string( $ids ) ) {
            $decoded = json_decode( $ids, true );
            return is_array( $decoded ) ? $decoded : array();
        }
        return is_array( $ids ) ? $ids : array();
    }

    /**
     * Sanitize order ID
     */
    public function sanitize_order_id( $order_id ) {
        if ( empty( $order_id ) || $order_id === '0' || $order_id === 'null' || $order_id === 'undefined' ) {
            return 0;
        }
        return (int) $order_id;
    }

    /**
     * Convert data to SingleEvent object
     */
    private function data_to_single_event( $event_name, $params, $event_id, $ids, $woo_order, $edd_order, $referrer_url = '', $event_source_url = '' ) {
        $singleEvent = new SingleEvent( "", "" );

        $payload = array(
            'name'      => $event_name,
            'eventID'   => $event_id,
            'woo_order' => $woo_order,
            'edd_order' => $edd_order,
            'pixelIds'  => $ids
        );

        if ( ! empty( $referrer_url ) && wp_http_validate_url( $referrer_url ) ) {
            $payload['referrer_url'] = $referrer_url;
        }

        if ( ! empty( $event_source_url ) && wp_http_validate_url( $event_source_url ) ) {
            $payload['event_source_url'] = $event_source_url;
        }

        $singleEvent->addParams( $params );
        $singleEvent->addPayload( $payload );

        return $singleEvent;
    }

    /**
     * Enqueue scripts for frontend
     */
    public function enqueue_scripts() {
        if ( ! Facebook()->isServerApiEnabled() ) {
            return;
        }

        wp_localize_script( 'jquery', 'pysFacebookRest', array(
            'restApiUrl' => rest_url( 'pys-facebook/v1/event' ),
            'debug'      => PYS()->getOption( 'debug_enabled' )
        ) );
    }

    /**
     * Enqueue admin scripts
     */
    public function enqueue_admin_scripts() {
        if ( ! Facebook()->isServerApiEnabled() ) {
            return;
        }

        wp_localize_script( 'jquery', 'pysFacebookRest', array(
            'restApiUrl' => rest_url( 'pys-facebook/v1/event' ),
            'debug'      => PYS()->getOption( 'debug_enabled' )
        ) );
    }

    /**
     * Initialize hooks
     */
    public function init() {
        $this->register_routes();
        add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_scripts' ) );
        add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_admin_scripts' ) );
    }
}

/**
 * Accessor function for Facebook REST API
 */
function Facebook_REST_API() {
    static $instance = null;
    if ( $instance === null ) {
        $instance = new Facebook_REST_API();
        $instance->init();
    }
    return $instance;
}
