Fix "Discounts not displayed properly in Orders panel" bug #2773

[efalayi]

Resolves #2773
"Add Discount" is displayed but the actual discount amount is not

Add Discount is a tag link which when clicked displays a form or list of discount codes
Total displayed does not reflect discount (if included)

Fix

• Register component that displays discount lists/form

registerComponent("DiscountList", discountListComponent);

• Replace Add Discount tag with discount amount

 {formatPriceString(invoice.discounts)}

• Update getTotalByShop function to include discount amount

const discount = parseFloat(this.getDiscounts());
const discountTotal = Math.max(0, shopSubtotal - discount);
const shopTotal = discountTotal + shopTaxes + shipping;

Test

Login as an admin and set up shipping and payment methods
Add a discount code
Check out and use that code
Go to orders panel
Observe that discount amount is displayed

[brent-hoover]

Let's just backout the change to getTotalsByShop and this looks good to go. Discounts are showing up properly in a single-shop.

[brent-hoover]

I know I said we should be reflecting discount everywhere but this is actually the exception. We haven't finalized how we are handling discounts in a multi-shop scenario and I think this is going to give us odd results, so let's back out this change for now.

[efalayi]

@zenweasel when I add a discount, it's not reflected in Total displayed on Orders page.

[joykare]

@efalayi ready for a review?

[brent-hoover]

@efalayi Can you add a little more context to your comment. In a multi-shop scenario or? Where on the orders page using what payment provider? When I tested it in a single shop I was seeing the discount show up

[efalayi]

@zenweasel here are screenshots of an order I just made

Observe total displayed. They do not match.
This is a single shop scenario.

[brent-hoover]

Added this issue #3005 for Stripe, will deal with separately.