Import product sale pricing from CORE

this almost certainly needs improvements for POS sake

rattail_corepos/importing/corepos/db.py

@@ -541,11 +541,55 @@ class ProductImporter(FromCOREPOS, corepos_importing.model.ProductImporter):
         'regular_price_price',
         'regular_price_multiple',
         'regular_price_type',
+        'sale_price_price',
+        'sale_price_starts',
+        'sale_price_ends',
+        'sale_price_current',
         'food_stampable',
         # 'tax1',
         'tax_code',
     ]
 
+    def setup(self):
+        super().setup()
+
+        if self.fields_active(self.sale_price_fields):
+            self.core_batch_items = {}
+
+            # TODO: it seems possible for CORE to have more than one
+            # batch item for a given product.  sort order will
+            # determine which would "win" but not clear what sort
+            # order should be used, e.g. CORE does not seem to use one
+            today = self.app.today()
+            batches = self.host_session.query(corepos.Batch)\
+                                       .filter(corepos.Batch.start_date <= today)\
+                                       .filter(corepos.Batch.end_date >= today)\
+                                       .filter(corepos.Batch.discount_type > 0)\
+                                       .options(orm.joinedload(corepos.Batch.items))\
+                                       .all()
+
+            def cache(batch, i):
+                for item in batch.items:
+                    self.core_batch_items.setdefault(item.upc, []).append(item)
+
+            self.progress_loop(cache, batches,
+                               message="Caching CORE-POS batch items")
+
+    def get_core_batch_item(self, upc):
+        if hasattr(self, 'core_batch_items'):
+            items = self.core_batch_items.get(upc)
+            if not items:
+                return
+
+            sale_price = items[0].sale_price
+            if any([item.sale_price != sale_price
+                    for item in items[1:]]):
+                log.warning("ambiguous batch items for upc: %s", upc)
+
+            return items[0]
+
+        raise NotImplementedError("TODO: fetch batch items in real-time")
+
     def normalize_host_object(self, product):
 
         try:
@@ -577,6 +621,12 @@ class ProductImporter(FromCOREPOS, corepos_importing.model.ProductImporter):
             'regular_price_price': price,
             'regular_price_multiple': 1 if price is not None else None,
             'regular_price_type': self.enum.PRICE_TYPE_REGULAR if price is not None else None,
+
+            # nb. these may get set below
+            'sale_price_price': None,
+            'sale_price_starts': None,
+            'sale_price_ends': None,
+            'sale_price_current': False,
         }
 
         if 'tax_code' in self.fields:
@@ -591,6 +641,18 @@ class ProductImporter(FromCOREPOS, corepos_importing.model.ProductImporter):
                 'uom_abbreviation': size_info['uom_abbrev'],
             })
 
+        # sale price
+        # nb. CORE discount_type indicates if item is on sale "now"
+        if self.fields_active(self.sale_price_fields) and product.discount_type:
+            item = self.get_core_batch_item(product.upc)
+            if item:
+                data.update({
+                    'sale_price_price': item.sale_price,
+                    'sale_price_starts': self.app.make_utc(self.app.localtime(item.batch.start_date)),
+                    'sale_price_ends': self.app.make_utc(self.app.localtime(item.batch.end_date)),
+                    'sale_price_current': True,
+                })
+
         return data