Landing/wp-content/themes/upstudy/inc/class-wishlist.php

<?php
if ( ! defined( 'ABSPATH' ) ) exit; // If this file is called directly, abort.

class Upstudy_Wishlist {
    protected static $instance = null;

    /**
     * Constructor to hook AJAX actions.
     */
    public function __construct() {
        add_action( 'wp_ajax_upstudy_wishlist_item', [ $this, 'wishlist_ajax_connect' ] );
        add_action( 'wp_ajax_nopriv_upstudy_wishlist_item', [ $this, 'wishlist_ajax_connect' ] );
        add_action( 'wp_ajax_upstudy_wishlist_item_remove', [ $this, 'wishlist_ajax_remove' ] );
        add_action( 'wp_ajax_nopriv_upstudy_wishlist_item_remove', [ $this, 'wishlist_ajax_remove' ] );
    }

    /**
     * Get the singleton instance of the class.
     *
     * @return Upstudy_Wishlist The instance of the Upstudy_Wishlist class.
     */
    public static function instance() {
        if ( null === self::$instance ) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    /**
     * Handle adding an item to the wishlist via AJAX.
     */
    public function wishlist_ajax_connect() {
        check_ajax_referer( 'upstudy-wishlist-ajax-connect', 'security' );

        $status = array();

        // Sanitize and validate post_id
        $post_id = isset( $_POST['post_id'] ) ? intval( $_POST['post_id'] ) : 0;

        if ( $post_id > 0 ) {
            self::cache_in_wishlist( $post_id );
            $status['progress'] = 'done';
            $status['text']     = __( 'Item Added to Wishlist', 'upstudy' );
        } else {
            $status['progress'] = 'undone';
            $status['text']     = __( 'Invalid item ID.', 'upstudy' );
        }

        wp_send_json( $status );
    }

    /**
     * Handle removing an item from the wishlist via AJAX.
     */
    public function wishlist_ajax_remove() {
        check_ajax_referer( 'upstudy-wishlist-ajax-connect', 'security' );

        $status = array();

        // Sanitize the post_id
        $post_id = isset( $_POST['post_id'] ) ? intval( $_POST['post_id'] ) : 0;

        if ( $post_id > 0 ) {
            $new_wishlist = array();

            if ( isset( $_COOKIE['tpc_course_wishlist'] ) ) {
                $items = explode( ',', sanitize_text_field( $_COOKIE['tpc_course_wishlist'] ) );

                // Filter out the item to remove
                foreach ( $items as $item ) {
                    if ( intval( $item ) !== $post_id ) {
                        $new_wishlist[] = intval( $item );
                    }
                }
            }

            $wishlist_string = implode( ',', $new_wishlist );

            // Set the updated cookie
            setcookie( 'tpc_course_wishlist', $wishlist_string, time() + ( 60 * 60 * 24 * 15 ), '/' );
            $_COOKIE['tpc_course_wishlist'] = $wishlist_string;

            $status['progress'] = 'done';
            $status['text']     = __( 'Item removed from wishlist', 'upstudy' );
        } else {
            $status['progress'] = 'error';
            $status['text']     = __( 'Invalid item ID.', 'upstudy' );
        }

        wp_send_json( $status );
    }

    /**
     * Cache an item in the wishlist.
     *
     * @param int $id The ID of the item to cache in the wishlist.
     */
    public static function cache_in_wishlist( $id ) {
        $items = array();

        if ( isset( $_COOKIE['tpc_course_wishlist'] ) ) {
            $items = explode( ',', $_COOKIE['tpc_course_wishlist'] );
            if ( ! self::verify_wishlisted_items( $id, $items ) ) {
                $items[] = $id;
            }
        } else {
            $items = array( $id );
        }

        setcookie( 'tpc_course_wishlist', implode( ',', $items ), time() + 60 * 60 * 24 * 15, '/' );
        $_COOKIE['tpc_course_wishlist'] = implode( ',', $items );
    }

    /**
     * Verify if an item is in the wishlist.
     *
     * @param int $id The ID of the item to verify.
     * @return bool True if the item is in the wishlist, false otherwise.
     */
    public static function verify_wishlisted_items( $id ) {
        if ( empty( $id ) ) {
            return false;
        }

        if ( isset( $_COOKIE['tpc_course_wishlist'] ) && ! empty( $_COOKIE['tpc_course_wishlist'] ) ) {
            $added_items = explode( ',', $_COOKIE['tpc_course_wishlist'] );
            if ( in_array( $id, $added_items ) ) {
                return true;
            }
        }

        return false;
    }

    /**
     * Display the wishlist button.
     *
     * @param WP_Post $post The post object.
     * @param string $type The type of button display ('icon' or 'text').
     */
    public static function content( $post, $type = 'icon' ) {
        $id = $post->ID;
        $class = '';
        $icon_class = 'dt-icon-heart';
        $text = __( 'Add Item to wishlist', 'upstudy' );

        $added = self::verify_wishlisted_items( $id );
        if ( $added ) {
            $text = __( 'Item Added to Wishlist', 'upstudy' );
            $icon_class = 'dt-icon-heart';
            $class = 'tpc-wishlisted';
        } else {
            $class = 'tpc-wishlist-non-added';
        }

        if ( 'text' === $type ) {
            echo '<a href="#tpc-wishlist-item-link" class="tpc-wishlist-button with-icon-text ' . esc_attr( $class ) . '" data-id="' . esc_attr( $id ) . '">';
                echo '<i class="' . esc_attr( $icon_class ) . '"></i>';
                echo '<span class="wishlist-text">' . esc_html( $text ) . '</span>';
            echo '</a>';
        } else {
            echo '<a href="#tpc-wishlist-item-link" class="tpc-wishlist-button with-icon ' . esc_attr( $class ) . '" data-id="' . esc_attr( $id ) . '">';
                echo '<i class="upstudy-wishlist-wrapper ' . esc_attr( $icon_class ) . '"></i>';
            echo '</a>';
        }
    }

    /**
     * Fetch all items in the wishlist.
     *
     * @return array The list of wishlist item IDs.
     */
    public static function fetch_wishlist() {
        if ( isset( $_COOKIE['tpc_course_wishlist'] ) && ! empty( $_COOKIE['tpc_course_wishlist'] ) ) {
            return explode( ',', $_COOKIE['tpc_course_wishlist'] );
        }
        return array();
    }
}

Upstudy_Wishlist::instance();