// [1] I USED FIRST THIS CODE ONLY JAVASCRIPT. THE ALERTBOX WILL APPEAR BUT STILL WILL REDIRECT THE PAGE

document.addEventListener('DOMContentLoaded', function() {
    // Select the form using its class
    const form = document.querySelector('.FormClass'); // This is the form class itself
    if (form) {
        form.addEventListener('submit', function(e) {
            // Select the coupon field using its name attribute
            const couponField = form.querySelector('input[name="FORMFIELDNAME"]'); // This is the field name element
            const validCouponCode = 'MYCOUPONCODE'; // This is my coupon code
            
            // Check if the coupon code entered is not valid
            if (couponField && couponField.value !== validCouponCode) {
                // Prevent form submission
                e.preventDefault();
                alert('Invalid coupon code.');
                return false; // Ensure the form is not submitted
            }
        });
    }
});


// [2] SINCE THE ABOVE CODE DIDN'T WORK, I TRIED TO USE A PHP CODE TOO AND JAVASCRIPT. THIS IS THE JAVASCRIPT CODE

document.addEventListener('DOMContentLoaded', function() {
    // Select the form using its class
    const form = document.querySelector('.FormClass');
    if (form) {
        form.addEventListener('submit', function(e) {
            e.preventDefault(); // Prevent the form from submitting immediately

            const couponField = form.querySelector('input[name="FORMFIELDNAME');
            const couponCode = couponField ? couponField.value : '';
            
            // AJAX request to validate the coupon code
            fetch(ajax_object.ajax_url, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/x-www-form-urlencoded'
                },
                body: new URLSearchParams({
                    'action': 'validate_coupon_code',
                    'form_fields[ifbfGalaCouponField]': couponCode
                })
            })
            .then(response => response.json())
            .then(data => {
                if (data.success) {
                    form.submit(); // Submit the form if the coupon code is valid
                } else {
                    alert(data.data.message); // Show error message
                }
            });
        });
    }
});

// [2] THIS IS THE PHP CODE

// Validate coupon code via AJAX
function validate_coupon_code() {
    // Check if the request is coming from our form
    if (isset($_POST['form_fields']['FORMFIELDNAME'])) {
        $entered_code = sanitize_text_field($_POST['form_fields']['FORMFIELDNAME']);
        $valid_code = 'MYCOUPONCODE'; // Your valid coupon code

        // Check if the entered code matches the valid code
        if ($entered_code !== $valid_code) {
            // Send an error response
            wp_send_json_error(array('message' => 'Invalid coupon code.'));
        } else {
            // Send a success response
            wp_send_json_success();
        }
    } else {
        // Send an error response if the code is not set
        wp_send_json_error(array('message' => 'Coupon code is required.'));
    }

    // Properly terminate the request
    wp_die();
}

// Hook the function to handle AJAX requests
add_action('wp_ajax_validate_coupon_code', 'validate_coupon_code');
add_action('wp_ajax_nopriv_validate_coupon_code', 'validate_coupon_code');

function enqueue_custom_scripts() {
    wp_enqueue_script('custom-validate-coupon', get_template_directory_uri() . '/js/custom-validate-coupon.js', array('jquery'), null, true);
    wp_localize_script('custom-validate-coupon', 'ajax_object', array('ajax_url' => admin_url('admin-ajax.php')));
}
add_action('wp_enqueue_scripts', 'enqueue_custom_scripts');