First commit

providers/provider.py

@@ -0,0 +1,41 @@
+from datetime import datetime
+import pytz
+from core.constants import SOFTWARE_NAME, SOFTWARE_VERSION
+
+# Generic data provider class. Subclasses of this query the individual APIs for data.
+class Provider:
+
+    # HTTP headers used for providers that use HTTP
+    HTTP_HEADERS = { "User-Agent": SOFTWARE_NAME + " " + SOFTWARE_VERSION }
+
+    # Constructor
+    def __init__(self):
+        self.last_update_time = datetime.min.replace(tzinfo=pytz.UTC)
+        self.last_spot_time = datetime.min.replace(tzinfo=pytz.UTC)
+        self.status = "Not Started"
+        self.spot_list = None
+
+    # Return the name of the provider
+    def name(self):
+        raise NotImplementedError("Subclasses must implement this method")
+
+    # Set up the provider, e.g. giving it the spot list to work from
+    def setup(self, spot_list):
+        self.spot_list = spot_list
+
+    # Start the provider. This should return immediately after spawning threads to access the remote resources
+    def start(self):
+        raise NotImplementedError("Subclasses must implement this method")
+
+    # Submit one or more new spots retrieved from the provider. Only spots that are newer than the last spot retrieved
+    # by this provider will be added to the spot list, to prevent duplications. This is called by the subclasses on
+    # receiving spots.
+    def submit(self, spots):
+        for spot in spots:
+            if spot.time > self.last_spot_time:
+                self.spot_list.append(spot)
+        self.last_spot_time = max(map(lambda s: s.time, spots))
+
+    # Stop any threads and prepare for application shutdown
+    def stop(self):
+        raise NotImplementedError("Subclasses must implement this method")