Provide lookup for normalized timezone names

This provides a helper to look up the correct timezone name independent
of the casing of the given timezone name.

frigate/api/media.py

@@ -64,6 +64,7 @@ from frigate.util.recording_coverage import (
     plan_clip,
     resolve_coverage,
 )
+from frigate.util.time import get_normalized_tz_name
 
 logger = logging.getLogger(__name__)
 
@@ -837,7 +838,9 @@ async def vod_hour(
     parts = year_month.split("-")
     start_date = (
         datetime(int(parts[0]), int(parts[1]), day, hour, tzinfo=UTC)
-        - datetime.now(ZoneInfo(tz_name.replace(",", "/"))).utcoffset()
+        - datetime.now(
+            ZoneInfo(get_normalized_tz_name(tz_name.replace(",", "/")))
+        ).utcoffset()
     )
     end_date = start_date + timedelta(hours=1) - timedelta(milliseconds=1)
     start_ts = start_date.timestamp()

frigate/api/preview.py

@@ -22,6 +22,7 @@ from frigate.api.defs.response.preview_response import (
 from frigate.api.defs.tags import Tags
 from frigate.const import BASE_DIR, CACHE_DIR, PREVIEW_FRAME_TYPE
 from frigate.models import Previews
+from frigate.util.time import get_normalized_tz_name
 
 logger = logging.getLogger(__name__)
 
@@ -126,7 +127,9 @@ def preview_hour(
     parts = year_month.split("-")
     start_date = (
         datetime(int(parts[0]), int(parts[1]), int(day), int(hour), tzinfo=UTC)
-        - datetime.now(ZoneInfo(tz_name.replace(",", "/"))).utcoffset()
+        - datetime.now(
+            ZoneInfo(get_normalized_tz_name(tz_name.replace(",", "/")))
+        ).utcoffset()
     )
     end_date = start_date + timedelta(hours=1) - timedelta(milliseconds=1)
     start_ts = start_date.timestamp()

frigate/record/export.py

@@ -49,7 +49,7 @@ from frigate.util.recording_coverage import (
     stream_media_summary,
 )
 from frigate.util.services import get_video_properties
-from frigate.util.time import is_current_hour
+from frigate.util.time import get_normalized_tz_name, is_current_hour
 
 logger = logging.getLogger(__name__)
 
@@ -874,7 +874,7 @@ class RecordingExporter(threading.Thread):
         tz_name = self.config.ui.timezone
         if tz_name:
             try:
-                tz = ZoneInfo(tz_name)
+                tz = ZoneInfo(get_normalized_tz_name(tz_name))
             except (ValueError, ZoneInfoNotFoundError):
                 tz = None
             if tz is not None:
@@ -1038,7 +1038,7 @@ class RecordingExporter(threading.Thread):
         tz: datetime.tzinfo | None = None
         if tz_name:
             try:
-                tz = ZoneInfo(tz_name)
+                tz = ZoneInfo(get_normalized_tz_name(tz_name))
             except (ValueError, ZoneInfoNotFoundError):
                 tz = None
         if tz is None:

frigate/util/time.py

@@ -3,16 +3,32 @@
 import datetime
 import logging
 import math
-from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
+from typing import Final
+from zoneinfo import ZoneInfo, ZoneInfoNotFoundError, available_timezones
 
 from tzlocal import get_localzone
 
 logger = logging.getLogger(__name__)
 
+TIMEZONE_CASEFOLD_INDEX: Final = {
+    timezone.casefold(): timezone for timezone in available_timezones()
+}
+
+
+def get_normalized_tz_name(tz_name: str) -> str:
+    """Return the canonical name for a case-insensitive IANA timezone."""
+    tz = TIMEZONE_CASEFOLD_INDEX.get(tz_name.casefold())
+    if tz:
+        return tz
+
+    raise ValueError(f"Unknown timezone: {tz_name}")
+
 
 def get_tz_modifiers(tz_name: str) -> tuple[str, str, float]:
     seconds_offset = (
-        datetime.datetime.now(ZoneInfo(tz_name)).utcoffset().total_seconds()
+        datetime.datetime.now(ZoneInfo(get_normalized_tz_name(tz_name)))
+        .utcoffset()
+        .total_seconds()
     )
     hours_offset = int(seconds_offset / 60 / 60)
     minutes_offset = int(seconds_offset / 60 - hours_offset * 60)
@@ -83,7 +99,7 @@ def get_dst_transitions(
         continuous periods with the same UTC offset
     """
     try:
-        tz = ZoneInfo(tz_name)
+        tz = ZoneInfo(get_normalized_tz_name(tz_name))
     except (ValueError, ZoneInfoNotFoundError):
         # If timezone is invalid, return single period with no offset
         return [(start_time, end_time, 0)]