Add support for Rattail -> CORE export/sync for Member data

also refactor CORE -> Rattail logic to use `api.set_member()` etc.

rattail_corepos/corepos/util.py

@@ -24,11 +24,48 @@
 CORE-POS misc. utilities
 """
 
+import logging
+
 import sqlalchemy as sa
 
 from corepos.db.office_op import Session as CoreSession, model as corepos
 
 from rattail.db.util import short_session
+from rattail.util import OrderedDict, progress_loop
+
+
+log = logging.getLogger(__name__)
+
+
+def get_core_members(api, progress=None):
+    """
+    Shared logic for fetching *all* customer accounts from CORE-POS API.
+    """
+    # TODO: ideally could do this, but API doesn't let us fetch "all"
+    # return api.get_members()
+
+    # first we fetch all customer records from CORE DB
+    with short_session(Session=CoreSession) as s:
+        db_customers = s.query(corepos.Customer).all()
+        s.expunge_all()
+
+    # now we must fetch each customer account individually from API
+    members = OrderedDict()
+
+    def fetch(dbcust, i):
+        if dbcust.card_number in members:
+            return          # already fetched this one
+        member = api.get_member(dbcust.card_number)
+        if member:
+            members[dbcust.card_number] = member
+        else:
+            logger = log.warning if dbcust.account_holder else log.debug
+            logger("could not fetch member from CORE API: %s",
+                   dbcust.card_number)
+
+    progress_loop(fetch, db_customers, progress,
+                  message="Fetching Member data from CORE API")
+    return list(members.values())
 
 
 def get_max_existing_vendor_id(session=None):