Address lookup to mocked S/4HANA system

What's working:
- Address information on OP
- Reading of S/4HANA Addresses
- Translations

packages/bookshop/srv/admin-service.js

@@ -0,0 +1,67 @@
+const cds = require('@sap/cds')
+const { Books, ShippingAddresses } = cds.entities
+
+const bupaSrv = cds.connect.to('API_BUSINESS_PARTNER')
+
+/** Service implementation for CatalogService */
+module.exports = cds.service.impl(function () {
+  this.before('CREATE', 'Orders', _reduceStock)
+  // this.before('CREATE', 'Orders', _fillAddress)
+  this.before('PATCH', 'Orders', _fillAddress)
+
+  this.on('READ', 'Addresses', _readAddresses)
+})
+
+function _readAddresses (req) {
+  // TODO: Delegate to external service
+}
+
+/** Fill Address data from external service */
+async function _fillAddress (req) {
+  console.log('retrieving addresses')
+  if (req.data.shippingAddress_AddressID) {
+    const tx = bupaSrv.transaction(req)
+    const response = await tx.run(
+      SELECT.from('API_BUSINESS_PARTNER.A_BusinessPartnerAddress')
+        .columns('AddressID', 'CityName', 'StreetName', 'HouseNumber')
+        .where({ AddressID: req.data.shippingAddress_AddressID })
+    )
+    if (response && response.length > 0) {
+      console.log('filling addresses')
+      const tx2 = cds.transaction(req)
+      try {
+        await tx2.run(
+          INSERT.into('sap.capire.bookshop.ShippingAddresses').entries(response)
+        )
+      } catch (e) {
+        // already in there
+      }
+    } else {
+      req.error('Shipping address not found.')
+    }
+  }
+}
+
+/** Reduce stock of ordered books if available stock suffices */
+async function _reduceStock (req) {
+  const { Items: OrderItems } = req.data
+  if (OrderItems && OrderItems.length > 0) {
+    const all = await cds.transaction(req).run(() =>
+      OrderItems.map(order =>
+        UPDATE(Books)
+          .set('stock -=', order.amount)
+          .where('ID =', order.book_ID)
+          .and('stock >=', order.amount)
+      )
+    )
+    all.forEach((affectedRows, i) => {
+      if (affectedRows === 0)
+        req.error(
+          409,
+          `${OrderItems[i].amount} exceeds stock for book #${
+            OrderItems[i].book_ID
+          }`
+        )
+    })
+  }
+}