mdb: support vend success/failure/completion, checksum cleanup

bitvend/mdb.py

@@ -39,12 +39,19 @@ class BitvendCashlessMDBDevice(CashlessMDBDevice):
 
                 db.session.commit()
 
-            self.current_tx_id = None
-
-            cashless_purchase_counter.inc()
-
         return True
 
+    def vend_failure(self):
+        with self.app.app_context():
+            self.logger.info("Reverting transaction {}...".format(self.current_tx_id))
+            Transaction.query.filter(Transaction.id == self.current_tx_id).delete()
+            db.session.commit()
+
+    def vend_complete(self):
+        self.logger.info("Vend complete!")
+        self.current_tx_id = None
+        cashless_purchase_counter.inc()
+
     last_purchase = 0
 
     def process_request(self, req):

mdb/device.py

@@ -9,6 +9,7 @@ except ImportError:
 
 try:
     import cygpio
+    from cygpio import CythonRaspiBackend
 except ImportError:
     cygpio = None
 
@@ -33,17 +34,18 @@ class MDBRequest(object):
         self.data = bytearray()
 
     def validate_checksum(self):
-        if not self.data:
-            return False
-
         try:
             if self.ack:
                 if len(self.data) == 1 and self.processed:
                     return True  # Only ACK
 
-                return self.data[-2] == compute_checksum(self.command, self.data[:-2])
+                return len(self.data) >= 2 and self.data[-2] == compute_checksum(
+                    self.command, self.data[:-2]
+                )
             else:
-                return self.data[-1] == compute_checksum(self.command, self.data[:-1])
+                return len(self.data) >= 1 and self.data[-1] == compute_checksum(
+                    self.command, self.data[:-1]
+                )
         except KeyboardInterrupt:
             raise
         except:
@@ -184,23 +186,6 @@ class CashlessMDBDevice(MDBDevice):
     lockup_counter = 0
 
     def process_request(self, req):
-        # FIXME this shouldn't be required...
-        # if req.command == 0x30 and req.validate_checksum():
-        #    self.lockup_counter += 1
-
-        #    if self.lockup_counter % 50 == 0:
-        #        self.logger.info('YOLO')
-        #        return []
-        #    return
-        # if req.command == 0x31 and req.validate_checksum():
-        #    return []
-        # if req.command == 0x37 and req.validate_checksum():
-        #    return []
-        # if req.command == 0x36 and req.validate_checksum():
-        #    return []
-        # if req.command == 0x34 and req.validate_checksum():
-        #    return []
-
         if (req.command & self.base_address) != self.base_address:
             # Target mismatch
             return
@@ -254,15 +239,18 @@ class CashlessMDBDevice(MDBDevice):
 
             elif req.data[0] == 0x02:  # vend succ
                 self.logger.info("VEND: success %r", req)
+                self.vend_success()
                 return []
 
             elif req.data[0] == 0x03:
                 self.logger.info("VEND: failure")
+                self.vend_failure()
                 return []
 
             elif req.data[0] == 0x04:
                 self.logger.info("VEND: session complete %r", req)
                 self.state = "OK"
+                self.vend_complete()
                 return [0x07]
 
             elif req.data[0] == 0x05:
@@ -311,8 +299,9 @@ class CashlessMDBDevice(MDBDevice):
             return []
 
     def begin_session(self, amount):
-        self.logger.info("Beginning session for %d", amount)
         # Begins new session with balance provided
+
+        self.logger.info("Beginning session for %d", amount)
         if amount > 10000:
             amount = 10000
 
@@ -323,9 +312,22 @@ class CashlessMDBDevice(MDBDevice):
         self.poll_queue.put([0x04])
 
     def vend_request(self, product, value):
-        # Called when user selects a product
+        # Called when user selects a product - funds shall be locked here
         return True
 
+    def vend_success(self):
+        # Called when product has been released to user - funds shall be
+        # deducted here
+        pass
+
+    def vend_failure(self):
+        # Called when product release has failed - funds shall be reverted here
+        pass
+
+    def vend_complete(self):
+        # Called after vend request/success/failure
+        pass
+
     @property
     def online(self):
         return time.time() - self.last_poll < 5