Mandatory redemption coupon for gifted items in WooCommerce

I’m using the below function which currently accepts a single (or array of) static coupon codes. How can I change this to work with any valid (i.e. not already used the maximum times etc.) coupon code that exists in the site?

add_action( 'woocommerce_check_cart_items', 'mandatory_coupon_code' );

function mandatory_coupon_code() {
    $product_categories = array( 'gifts' ); // Category ID or slug of targeted category

    // NEED TO EDIT THIS PART TO GET THE LIST OF VALID CODES
    $coupon_code = 'testing1'; // The required coupon code

    $coupon_applied = in_array( strtolower($coupon_code), WC()->cart->get_applied_coupons() );
    // Loop through cart items
    
    foreach ( WC()->cart->get_cart() as $cart_item ){
        if( has_term( $product_categories, 'product_cat', $cart_item['product_id'] ) && ! $coupon_applied ) {
            wc_clear_notices(); // Clear all other notices
            
            // Avoid checkout displaying an error notice
            wc_add_notice( sprintf( 'The product "%s" requires a valid redemption code for checkout.', $cart_item['data']->get_name() ), 'error' );
        
            break; // stop the loop
        }
    }
}

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Edit:

Further to the comments and information from this link, I’ve tried the below code but this isn’t working:

add_action( 'woocommerce_check_cart_items', 'mandatory_coupon_code' );
function mandatory_coupon_code() {
    $product_categories = array( 'gifts' ); // Category ID or slug of targeted category
    $coupon_code = array();
    
    foreach ( $coupons as $coupon ) {
        $coupon_name = $coupon->post_title;
        array_push( $coupon_code, $coupon_name );
    }
    
    $coupon_applied = in_array( strtolower($coupon_code), WC()->cart->get_applied_coupons() );
    
    // Loop through cart items
    foreach ( WC()->cart->get_cart() as $cart_item ){
        if( has_term( $product_categories, 'product_cat', $cart_item['product_id'] ) && ! $coupon_applied ) {
            wc_clear_notices(); // Clear all other notices
            // Avoid checkout displaying an error notice
            wc_add_notice( sprintf( 'The product "%s" requires a valid redemption code for checkout.', $cart_item['data']->get_name() ), 'error' );
            break; // stop the loop
        }
    }
}

Answer

As wooCommerce already check for coupons validity when they are applied, If they are not valid it displays different warning messages depending on the reason for invalidity, removing invalid applied coupons…

So you don’t need to get all valid coupons in your code… You just need the following:

add_action( 'woocommerce_check_cart_items', 'mandatory_redemption_coupon_code_for_gifted_items' );
function mandatory_redemption_coupon_code_for_gifted_items() {
    $product_categories = array( 'gifts' ); // Term ID, slug or name of targeted category

    $applied_coupons    = WC()->cart->get_applied_coupons();
    
    // When no coupon has been applied
    if( empty($applied_coupons) ) {
        // Loop through cart items
        foreach ( WC()->cart->get_cart() as $item ){
            // Check for gifted items
            if( has_term( $product_categories, 'product_cat', $item['product_id'] ) ) {
                wc_clear_notices(); // Clear all other notices
                
                // Avoid checkout displaying an error notice
                wc_add_notice( sprintf( 'The product "%s" requires a valid redemption code for checkout.', $item['data']->get_name() ), 'error' );
                break; // stop the loop
            }
        }
    }
}

Code goes in functions.php file of the active child theme (or active theme). Tested and works.

Now if the required coupons needs to be specific, you will have make a custom SQL query to check if any applied coupon is valid for redemption.

Note: on your Edit, the coupon query is missing, so that’s why it doesn’t work.