Turn a WooCommerce refund into a Business Central credit memo

**Objective:** Create an unposted Business Central sales credit memo for WooCommerce refund {refund-id}, applied to the posted invoice for its order, then note the credit memo number on the WooCommerce order. Use Business Central company {company} (if blank, leave `company` off).

**Step 1: Read the refund in WooCommerce**

Call `woocommerce-get-refund` with `refund-id` set to {refund-id}. If nothing comes back, report that and stop. Note order-id, order-number, amount (treat it as positive), reason and created-date. Call `woocommerce-get-refund-line` with the same `refund-id` for each line-item-sku, line-item-quantity and line-item-total. If there are no lines, it is an amount-only refund.

**Step 2: Check it has not already been credited**

Call `woocommerce-get-refund` with `order-number` set to the order-number to see all refunds on the order. Call `business-central-get-posted-sales-credit-memo` and `business-central-get-sales-transaction` (credit memo documents only), each with `external-document-number` set to the order-number. If the existing Business Central credit memos already cover this refund (as many credit memos as refunds, or a credit memo total matching this refund's amount), report them and stop.

**Step 3: Find the invoice being credited**

Call `business-central-get-posted-sales-invoice` with `external-document-number` set to the order-number. If nothing comes back, report that the order has not been invoiced in Business Central, so there is nothing to credit yet, and stop. If more than one comes back, list them and ask the user which to credit. Keep invoice-number, sell-to-customer-number and bill-to-customer-number.

**Step 4: Build the lines**

Call `business-central-get-posted-sales-invoice-line` with `invoice-number` set to the invoice. For each refund line, find the invoice line whose number equals the line-item-sku. Credit the refunded quantity at the invoice line's unit-price. If a refund line's SKU is not on the invoice, stop and list it.

For an amount-only refund, ask the user which G/L account to credit, and use one G/L account line for the refund amount.

**Step 5: Confirm**

Show the planned credit memo: customer, invoice it applies to, external document number, and a table of line type, number, description, quantity, unit price and amount, with the total next to the WooCommerce refund amount. Wait for the user to confirm.

**Step 6: Create**

Call `business-central-create-sales-credit-memo` once, with `customer-number`, `bill-to-customer-number`, `invoice-number` set to the invoice, and `external-document-number` set to the order-number. Then call `business-central-create-sales-credit-memo-line` once per line, with `document-number` set to the new credit memo's number, the line type, `number-on-line`, `quantity` and `unit-price`.

**Step 7: Record and confirm**

Call `woocommerce-add-order-note` with the refund's `order-id`, `customer-note` false (private), and a note giving the refund id and the new credit memo number. Then call `business-central-get-sales-transaction-line` with `document-number` set to the credit memo number and compare its total with the refund amount.

**Report:** the credit memo number, invoice credited, lines, Business Central total against the WooCommerce refund amount, and a reminder that the credit memo is unposted and needs review and posting in Business Central.

**Rules & Guidelines:**

* Tools whose names start with woocommerce- are on the woocommerce server; tools whose names start with business-central- are on the business-central server.
* The only writes allowed are `business-central-create-sales-credit-memo` (once), `business-central-create-sales-credit-memo-line` (once per line) and `woocommerce-add-order-note` (once, private), all after confirmation.
* Do not call `woocommerce-add-refund` (the refund already exists), `woocommerce-update-order`, or `business-central-update-sales-credit-memo`. Do not post the credit memo.

**Validation:**

* If a line create fails partway, stop and report the credit memo number and which lines were created. Do not create the credit memo header again.
* If the Business Central total differs from the refund amount by more than 0.01, report the difference (tax or shipping is the usual cause) rather than adjusting lines.