Starting to implement alerts #17

spotproviders/spot_provider.py

@@ -0,0 +1,57 @@
+from datetime import datetime
+
+import pytz
+
+from core.constants import SOFTWARE_NAME, SOFTWARE_VERSION
+from core.config import SERVER_OWNER_CALLSIGN, MAX_SPOT_AGE
+
+
+# Generic spot provider class. Subclasses of this query the individual APIs for data.
+class SpotProvider:
+
+    # HTTP headers used for spot providers that use HTTP
+    HTTP_HEADERS = { "User-Agent": SOFTWARE_NAME + " " + SOFTWARE_VERSION + " (operated by " + SERVER_OWNER_CALLSIGN + ")" }
+
+    # Constructor
+    def __init__(self, provider_config):
+        self.name = provider_config["name"]
+        self.enabled = provider_config["enabled"]
+        self.last_update_time = datetime.min.replace(tzinfo=pytz.UTC)
+        self.last_spot_time = datetime.min.replace(tzinfo=pytz.UTC)
+        self.status = "Not Started" if self.enabled else "Disabled"
+        self.spots = None
+
+    # Set up the provider, e.g. giving it the spot list to work from
+    def setup(self, spots):
+        self.spots = spots
+
+    # 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 a batch of 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. Spots passing the check will also have
+    # their infer_missing() method called to complete their data set. This is called by the API-querying
+    # subclasses on receiving spots.
+    def submit_batch(self, spots):
+        for spot in spots:
+            if datetime.fromtimestamp(spot.time, pytz.UTC) > self.last_spot_time:
+                # Fill in any blanks
+                spot.infer_missing()
+                # Add to the list
+                self.spots.add(spot.id, spot, expire=MAX_SPOT_AGE)
+        self.last_spot_time = datetime.fromtimestamp(max(map(lambda s: s.time, spots)), pytz.UTC)
+
+    # Submit a single spot retrieved from the provider. This will be added to the list regardless of its age. Spots
+    # passing the check will also have their infer_missing() method called to complete their data set. This is called by
+    # the data streaming subclasses, which can be relied upon not to re-provide old spots.
+    def submit(self, spot):
+        # Fill in any blanks
+        spot.infer_missing()
+        # Add to the list
+        self.spots.add(spot.id, spot, expire=MAX_SPOT_AGE)
+        self.last_spot_time = datetime.fromtimestamp(spot.time, pytz.UTC)
+
+    # Stop any threads and prepare for application shutdown
+    def stop(self):
+        raise NotImplementedError("Subclasses must implement this method")