introduce BTUUID class

As a preparation to move away from bluepy, introduce a new class BTUUID.
Bluepy provides its unique UUID class which handles UUIDs of Bluetooth
devices well. Instead of it, introduce BTUUID which extends python
standard uuid.UUID class and support Bluetooth devices.

Signed-off-by: Shin'ichiro Kawasaki <kawasaki@juno.dti.ne.jp>

pyscrlink/scratch_link.py

@@ -10,6 +10,7 @@ import ssl
 import websockets
 import socket
 import json
+import uuid
 import base64
 import logging
 import sys
@@ -44,6 +45,24 @@ logger.propagate = False
 HOSTNAME="device-manager.scratch.mit.edu"
 scan_seconds=10.0
 
+class BTUUID(uuid.UUID):
+    BLUETOOTH_BASE_UUID = "00001000800000805F9B34FB"
+
+    def __init__(self, val):
+        if isinstance(val, int):
+            if (val < 0) or (val > 0xFFFFFFFF):
+                raise ValueError(
+                    "Short form UUIDs must be in range 0..0xFFFFFFFF")
+            val = "%04X" % val
+        else:
+            val = str(val)
+
+        val = val.replace("-", "")
+        if len(val) <= 8:  # Short form
+            val = ("0" * (8 - len(val))) + val + self.BLUETOOTH_BASE_UUID
+
+        uuid.UUID.__init__(self, val)
+
 class Session():
     """Base class for BTSession and BLESession"""
     def __init__(self, websocket, loop):