Add EME SIG and do some refactoring

data/alert.py

@@ -1,7 +1,7 @@
 import hashlib
 import json
 import logging
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from datetime import datetime, timedelta
 
 import pytz
@@ -64,7 +64,7 @@ class Alert:
     # Special Interest Group (SIG), e.g. outdoor activity programme such as POTA
     sig: str | None = None
     # SIG references. We allow multiple here for e.g. n-fer activations, unlike ADIF SIG_INFO
-    sig_refs: list | None = None
+    sig_refs: list = field(default_factory=list)
 
     # Timing info
 
@@ -128,13 +128,13 @@ class Alert:
             # Fetch SIG data. In case a particular API doesn't provide a full set of name, lat, lon & grid for a reference
             # in its initial call, we use this code to populate the rest of the data. This includes working out grid refs
             # from WAB and WAI, which count as a SIG even though there's no real lookup, just maths
-            if self.sig_refs and len(self.sig_refs) > 0:
+            if self.sig_refs:
                 for sig_ref in self.sig_refs:
                     populate_missing_sig_ref_info(sig_ref)
 
             # If the spot itself doesn't have a SIG yet, but we have at least one SIG reference, take that reference's SIG
             # and apply it to the whole spot.
-            if self.sig_refs and len(self.sig_refs) > 0 and self.sig_refs[0] and not self.sig:
+            if self.sig_refs and self.sig_refs[0] and not self.sig:
                 self.sig = self.sig_refs[0].sig
 
             # Create an ID based on the source and source ID if possible, as these guaranee uniqueness. If there is no
@@ -160,7 +160,7 @@ class Alert:
                 self.icon = "fa-trophy"
             elif self.alert_type == AlertType.CONTEST:
                 self.icon = "fa-satellite"
-            elif self.sig_refs and len(self.sig_refs) > 0 and self.sig_refs[0].icon:
+            elif self.sig_refs and self.sig_refs[0].icon:
                 self.icon = self.sig_refs[0].icon
 
         except Exception: