models: create subscription model

bfxapi/models/Subscription.py

@@ -0,0 +1,45 @@
+import time
+import json
+
+class Subscription:
+
+  def __init__(self, ws, channel_name, symbol, timeframe=None, **kwargs):
+    self.ws = ws
+    self.channel_name = channel_name
+    self.symbol = symbol
+    self.timeframe = timeframe
+    self.is_subscribed_bool = False
+    self.key = None
+    if timeframe:
+      self.key = 'trade:{}:{}'.format(self.timeframe, self.symbol)
+    self.sub_id = int(round(time.time() * 1000))
+    self.send_payload = self._generate_payload(**kwargs)
+
+  async def subscribe(self):
+    await self.ws.send(json.dumps(self.get_send_payload()))
+
+  async def unsubscribe(self):
+    if not self.is_subscribed():
+      raise Exception("Subscription is not subscribed to websocket")
+    payload = { 'event': 'unsubscribe', 'chanId': self.chanId }
+    await self.ws.send(json.dumps(payload))
+
+  def confirm_subscription(self, chanId):
+    self.is_subscribed_bool = True
+    self.chanId = chanId
+
+  def confirm_unsubscribe(self):
+    self.is_subscribed_bool = False
+
+  def is_subscribed(self):
+    return self.is_subscribed_bool
+
+  def _generate_payload(self, **kwargs):
+    payload = { 'event': 'subscribe', 'channel': self.channel_name, 'symbol': self.symbol }
+    if self.timeframe:
+      payload['key'] = self.key
+    payload.update(**kwargs)
+    return payload
+
+  def get_send_payload(self):
+    return self.send_payload