How to create custom discount for the cart in woocommerce

Question

I'm creating a Plugin in WooCommerce and have a small issue with adding custom discounts to the CART / CHECKOUT page.

How can I apply custom discount to the cart without creating coupons? Say I want to give some discount of 5 dollars on the cart page. How can I do that?

Below is my code from the plugin file where I have used a coupon to apply discount, but I want to add another custom discount without the use of coupon.

Action Hook in the plugin file :

add_action('woocommerce_calculate_totals',array(&$this,'cart_order_total_action'));

and its function in the plugin file is :

public function cart_order_total_action(){
    if ( is_user_logged_in() ){
        global $woocommerce;
        global $current_user;
        global $wpdb;
        $u_id = $current_user->ID;
        $table_name = $wpdb->prefix."woocommerce_customer_reward_ms";
        $thetable2  = $wpdb->prefix . "woocommerce_customer_reward_cart_ms";
        $table_name3 = $wpdb->prefix."woocommerce_customer_reward_points_log_ms";
        $data       = $wpdb->get_row("SELECT * from $table_name where id=$u_id");
        $data2      = $wpdb->get_row("SELECT * from $thetable2");
        /* Order Id goes here */
        $orders=array();//order ids
        $args = array(
            'numberposts'     => -1,
            'meta_key'        => '_customer_user',
            'meta_value'      => $current_user->ID,
            'post_type'       => 'shop_order',
            'post_status'     => 'publish',
            'tax_query'=>array(
                    array(
                        'taxonomy'  =>'shop_order_status',
                        'field'     => 'slug',
                        'terms'     =>'on-hold'
                        )
            )  
        );
        $posts=get_posts($args);
        $orders=wp_list_pluck( $posts, 'ID' );
        $order = $orders[0];
        /* Order Id ends here */
        if($data){
            $user_points = $data->points;
            $points_set  = $data2->woo_pts_set;
            $coupon_code = 'wooreward_discount';
            if($user_points>=$points_set){
                // this following Code is optional and can be removed......as there is no need of if statement here
                if ( $woocommerce->cart->has_discount( $coupon_code ) ) {
                    /*$woocommerce->add_error( __('Coupon Code Already Applied.!!','woocommerce'));*/
                    return false;
                }else{
                    $woocommerce->cart->add_discount(sanitize_text_field($coupon_code));
                    $woocommerce->add_message( __('Taxco925 Reward Discount Applied.!!','woocommerce'));
                }
            }else{
                $woocommerce->add_error( __('Not Enough Taxco925 Points.!!','woocommerce'));
            }
        }else{
            $woocommerce->add_error( __('You have have not earned any Taxco925 Points yet.!!','woocommerce'));
        }
    }
}

As you can see this line $woocommerce->cart->add_discount(sanitize_text_field($coupon_code)); adds my discount to the cart. But it uses coupon in the background to do so . Is there any way I can add a custom discount without the use of coupon.

Answer 1

add_action('woocommerce_checkout_order_processed','custom_disount',10,1);
function custom_disount($order_id){
    $order = wc_get_order($order_id);
    $order_items = $order->get_items();
    foreach ($order_items as $order_item_key => $order_item) {
        $product = new WC_Product((int) $order_item['product_id']);
        $quantity = (int) $order_item['qty'];
        $discount=($product->regular_price*30)/100;  //30% disount.
        wc_update_order_item_meta($order_item_key,'_line_total',($product->regular_price*$quantity)-($discount*$quantity));
    }
}