Re-implement xOTA using Websocket client

spotproviders/websocket_spot_provider.py

@@ -0,0 +1,74 @@
+import logging
+from datetime import datetime
+from threading import Thread
+from time import sleep
+
+import pytz
+from websocket import create_connection
+
+from core.constants import HTTP_HEADERS
+from spotproviders.spot_provider import SpotProvider
+
+
+# Spot provider using websockets.
+class WebsocketSpotProvider(SpotProvider):
+
+    def __init__(self, provider_config, url):
+        super().__init__(provider_config)
+        self.url = url
+        self.ws = None
+        self.thread = None
+        self.stopped = False
+        self.last_event_id = None
+
+    def start(self):
+        logging.info("Set up websocket connection to " + self.name + " spot API.")
+        self.stopped = False
+        self.thread = Thread(target=self.run)
+        self.thread.daemon = True
+        self.thread.start()
+
+    def stop(self):
+        self.stopped = True
+        if self.ws:
+            self.ws.close()
+        if self.thread:
+            self.thread.join()
+
+    def _on_open(self):
+        self.status = "Waiting for Data"
+
+    def _on_error(self):
+        self.status = "Connecting"
+
+    def run(self):
+        while not self.stopped:
+            try:
+                logging.debug("Connecting to " + self.name + " spot API...")
+                self.status = "Connecting"
+                self.ws = create_connection(self.url, header=HTTP_HEADERS)
+                data = self.ws.recv()
+                if data:
+                    try:
+                        new_spot = self.ws_message_to_spot(data)
+                        if new_spot:
+                            self.submit(new_spot)
+
+                        self.status = "OK"
+                        self.last_update_time = datetime.now(pytz.UTC)
+                        logging.debug("Received data from " + self.name + " spot API.")
+
+                    except Exception as e:
+                        logging.exception("Exception processing message from Websocket Spot Provider (" + self.name + ")")
+
+            except Exception as e:
+                self.status = "Error"
+                logging.exception("Exception in Websocket Spot Provider (" + self.name + ")", e)
+            else:
+                self.status = "Disconnected"
+            sleep(5)  # Wait before trying to reconnect
+
+    # Convert a WS message received from the API into a spot. The exact message data (in bytes) is provided here so the
+    # subclass implementations can handle the message as string, JSON, XML, whatever the API actually provides.
+    def ws_message_to_spot(self, bytes):
+        raise NotImplementedError("Subclasses must implement this method")