Need help with group discount + restricted coupon

I'm having some trouble achieving the correct calculations with my order total modules.

We have a discount group that gets 3% off all orders.

I have set up a $10 coupon that is valid only on one product, with no minimum purchase.

If I restrict the coupon to the product, it calculates $10 minus the group discount, instead of applying the full $10.

Example:

Product A $10.00
Product B $1.00
Coupon restricted to product A

Order total shows:

Sub-Total: CDN $11.00
Group Discount - 3%: -CDN $0.33
Discount Coupon: wy487nwb: -CDN $9.67
Warehouse Pickup: CDN $0.00
13% Tax (ON): CDN $0.09
Total: CDN $0.76

Why is the coupon deducting the group discount from the coupon amount?

If I remove the restriction, the coupon applies correctly.

My order total modules sort order:
100 Sub-Total
102 Group Discount
103 Discount Coupon
200 Shipping
300 Tax
310 Gift Certificates
900 Total

Also, if the group discount is larger than $10, it won't allow you to apply the coupon at all.

I can't reorder the group discount to apply after the coupon, because then any percentage coupons are calculated on the full subtotal instead of the subtotal minus the group discount. I guess I'm kind of stuck.

In a perfect world, what should happen is that restricted dollar amount coupons should be applied to the product price minus the group discount. NOT the entire subtotal minus the group discount. I'm sure that's not something that would be an easy fix though...

What I'd like to try is to change the code so that when the coupon is for a dollar amount AND there is more than one product, the coupon will ignore the group discount. Can anyone help?

I'm assuming it would be in this function?

 /**
   * Method used to produce final figures for deductions. This information is used to produce the output<br>
   * shown on the checkout pages
   *
   */
  function process() {
    global $order, $currencies;
    $order_total = $this->get_order_total();
    $od_amount = $this->calculate_deductions($order_total['total']);
    $this->deduction = $od_amount['total'];
    if ($od_amount['total'] > 0) {
      reset($order->info['tax_groups']);
      $tax = 0;
      while (list($key, $value) = each($order->info['tax_groups'])) {
        if ($od_amount['tax_groups'][$key]) {
          $order->info['tax_groups'][$key] -= $od_amount['tax_groups'][$key];
          $tax += $od_amount['tax_groups'][$key];
        }
      }
      if ($od_amount['type'] == 'S') $order->info['shipping_cost'] = 0;
      $order->info['total'] = $order->info['total'] - $od_amount['total'];
      if (DISPLAY_PRICE_WITH_TAX != 'true') {
        $order->info['total'] -= $tax;
      }
      $order->info['tax'] = $order->info['tax'] - $tax;
      //      if ($this->calculate_tax == "Standard") $order->info['total'] -= $tax;
      if ($order->info['total'] < 0) $order->info['total'] = 0;
      $this->output[] = array('title' => $this->title . ': ' . $this->coupon_code . ' :',
                              'text' => '-' . $currencies->format($od_amount['total']),
                              'value' => $od_amount['total']);
    }
  }
  /**

What I need is:

If the coupon type is 'F' (flat amount)
AND there is more than 1 product in the cart
AND the customer is in a discount group
THEN the coupon = the full coupon amount up to 100% of the subtotal price

I think I would need to change this code... But not sure how.

} elseif ($coupon->fields['coupon_type'] == 'F') {
            $od_amount['total'] = round($coupon->fields['coupon_amount'] * ($orderTotal>0), 3);
            $od_amount['type'] = 'F';
            $ratio = $od_amount['total']/$orderTotal;
          }

What happens if you change the Modules ... Order Total ... sort orders to the defaults:

100 Sub-Total
102 Group Discount 290
103 Discount Coupon 280
200 Shipping
300 Tax
310 Gift Certificates 840
900 Total

If I do that, then a percentage coupon is taken off the full subtotal instead of the subtotal after the group discount. I need the group discount to come off first, then the additional coupon discount to come off after that.

Maybe it would be easier to edit the group pricing module to force the discount to be based off the product subtotal?

abcisme:

Maybe it would be easier to edit the group pricing module to force the discount to be based off the product subtotal?

Ugh, that doesn't make proper sense either. I would still need the percentage coupons to be calculated after the group discount.

Came up with a solution. This edit makes it so that if the coupon is a dollar amount AND is restricted to one product AND the customer is in a discount group, the coupon will deduct the value of the coupon MINUS the discount group percentage.

This allows me to offer a full dollar amount coupon that is restricted to a single product and have it adjust the price if the customer is in a discount group. For example, a coupon for $10 off a $10 product will adjust to $9.70 if the customer gets a 3% discount, otherwise it will be $10.

If you want to make sure it is the full amount, you can just restrict the coupon to a second product that is disabled. For example, if you want a coupon for $5 off a $10 product and you want group discount members to get the entire $5, you would restrict the coupon to the eligible product, then add a second restriction for a disabled product.

Percentage coupons will be deducted from the subtotal AFTER the group discount (as long as your coupon order total module is after the group discount module).

  
          } elseif ($coupon->fields['coupon_type'] == 'F') {
              
            //IF customer is in a discount group
            //AND coupon code is dollar amount (not percentage)
            //AND coupon is only valid on one item
            //THEN coupon amount is the total coupon minus group discount
            //ELSE coupon amount is 100% of coupon value

            $group_query = $db->Execute("select customers_group_pricing from " . TABLE_CUSTOMERS . " where customers_id = '" . (int)$_SESSION['customer_id'] . "'");
            $cr_query = $db->Execute("select count(product_id) as total_restrictions from " . TABLE_COUPON_RESTRICT . " where coupon_id = '" . (int)$coupon->fields['coupon_id'] . "' and coupon_restrict = 'N' and category_id = '0'");

            if ($group_query->fields['customers_group_pricing'] != '0' && (int)$cr_query->fields['total_restrictions'] == 1) {
                $group_percentage_query = $db->Execute("select group_percentage from " . TABLE_GROUP_PRICING . "
                                      where group_id = '" . (int)$group_query->fields['customers_group_pricing'] . "'");
                $coupon->fields['coupon_amount'] -= $coupon->fields['coupon_amount'] * $group_percentage_query->fields['group_percentage']/100;
            }
              
            $od_amount['total'] = round($coupon->fields['coupon_amount'] * ($orderTotal>0), 3);
            $od_amount['type'] = 'F';
            $ratio = $od_amount['total']/$orderTotal;
          }