Fix city-local time display for nearby stations

2026-04-19 15:37:13 +08:00
parent 7e2209e928
commit d6cc3b1b90
5 changed files with 337 additions and 15 deletions
@@ -0,0 +1,173 @@
+from __future__ import annotations
+
+from datetime import datetime, timedelta, timezone
+from typing import Any, Optional
+
+from src.data_collection.city_registry import CITY_REGISTRY
+
+try:
+    from zoneinfo import ZoneInfo
+except Exception:  # pragma: no cover - Python always has zoneinfo in supported runtimes.
+    ZoneInfo = None  # type: ignore[assignment]
+
+
+CITY_TIME_ZONES = {
+    "amsterdam": "Europe/Amsterdam",
+    "ankara": "Europe/Istanbul",
+    "atlanta": "America/New_York",
+    "aurora": "America/Denver",
+    "austin": "America/Chicago",
+    "beijing": "Asia/Shanghai",
+    "buenos aires": "America/Argentina/Buenos_Aires",
+    "busan": "Asia/Seoul",
+    "cape town": "Africa/Johannesburg",
+    "chengdu": "Asia/Shanghai",
+    "chicago": "America/Chicago",
+    "chongqing": "Asia/Shanghai",
+    "dallas": "America/Chicago",
+    "guangzhou": "Asia/Shanghai",
+    "helsinki": "Europe/Helsinki",
+    "hong kong": "Asia/Hong_Kong",
+    "houston": "America/Chicago",
+    "istanbul": "Europe/Istanbul",
+    "jakarta": "Asia/Jakarta",
+    "jeddah": "Asia/Riyadh",
+    "karachi": "Asia/Karachi",
+    "kuala lumpur": "Asia/Kuala_Lumpur",
+    "lagos": "Africa/Lagos",
+    "lau fau shan": "Asia/Hong_Kong",
+    "london": "Europe/London",
+    "los angeles": "America/Los_Angeles",
+    "lucknow": "Asia/Kolkata",
+    "madrid": "Europe/Madrid",
+    "manila": "Asia/Manila",
+    "masroor air base": "Asia/Karachi",
+    "mexico city": "America/Mexico_City",
+    "miami": "America/New_York",
+    "milan": "Europe/Rome",
+    "moscow": "Europe/Moscow",
+    "munich": "Europe/Berlin",
+    "new york": "America/New_York",
+    "panama city": "America/Panama",
+    "paris": "Europe/Paris",
+    "san francisco": "America/Los_Angeles",
+    "sao paulo": "America/Sao_Paulo",
+    "seattle": "America/Los_Angeles",
+    "seoul": "Asia/Seoul",
+    "shanghai": "Asia/Shanghai",
+    "shenzhen": "Asia/Shanghai",
+    "singapore": "Asia/Singapore",
+    "taipei": "Asia/Taipei",
+    "tel aviv": "Asia/Jerusalem",
+    "tokyo": "Asia/Tokyo",
+    "toronto": "America/Toronto",
+    "warsaw": "Europe/Warsaw",
+    "wellington": "Pacific/Auckland",
+    "wuhan": "Asia/Shanghai",
+}
+
+
+def normalize_city_key(city: Any) -> str:
+    return str(city or "").strip().lower()
+
+
+def get_city_timezone_name(city: Any) -> Optional[str]:
+    return CITY_TIME_ZONES.get(normalize_city_key(city))
+
+
+def _last_weekday(year: int, month: int, weekday: int) -> datetime:
+    if month == 12:
+        candidate = datetime(year + 1, 1, 1, tzinfo=timezone.utc) - timedelta(days=1)
+    else:
+        candidate = datetime(year, month + 1, 1, tzinfo=timezone.utc) - timedelta(days=1)
+    while candidate.weekday() != weekday:
+        candidate -= timedelta(days=1)
+    return candidate
+
+
+def _nth_weekday(year: int, month: int, weekday: int, n: int) -> datetime:
+    candidate = datetime(year, month, 1, tzinfo=timezone.utc)
+    while candidate.weekday() != weekday:
+        candidate += timedelta(days=1)
+    return candidate + timedelta(days=7 * (n - 1))
+
+
+def _fallback_zone_offset_seconds(tz_name: str, at: datetime, standard_offset: int) -> int:
+    moment = at.astimezone(timezone.utc)
+    year = moment.year
+
+    if tz_name in {
+        "Europe/Amsterdam",
+        "Europe/Berlin",
+        "Europe/Helsinki",
+        "Europe/London",
+        "Europe/Madrid",
+        "Europe/Paris",
+        "Europe/Rome",
+        "Europe/Warsaw",
+    }:
+        start = _last_weekday(year, 3, 6).replace(hour=1, minute=0, second=0, microsecond=0)
+        end = _last_weekday(year, 10, 6).replace(hour=1, minute=0, second=0, microsecond=0)
+        return standard_offset + 3600 if start <= moment < end else standard_offset
+
+    north_america_standard = {
+        "America/New_York": -18000,
+        "America/Toronto": -18000,
+        "America/Chicago": -21600,
+        "America/Denver": -25200,
+        "America/Los_Angeles": -28800,
+    }
+    if tz_name in north_america_standard:
+        standard = north_america_standard[tz_name]
+        start_hour_utc = 2 - (standard // 3600)
+        end_hour_utc = 1 - (standard // 3600)
+        start = _nth_weekday(year, 3, 6, 2).replace(hour=start_hour_utc, minute=0, second=0, microsecond=0)
+        end = _nth_weekday(year, 11, 6, 1).replace(hour=end_hour_utc, minute=0, second=0, microsecond=0)
+        return standard + 3600 if start <= moment < end else standard
+
+    if tz_name == "Pacific/Auckland":
+        standard = 43200
+        start_local = _last_weekday(year, 9, 6).replace(hour=2, minute=0, second=0, microsecond=0)
+        start = (start_local - timedelta(seconds=standard)).replace(tzinfo=timezone.utc)
+        end_local = _nth_weekday(year, 4, 6, 1).replace(hour=3, minute=0, second=0, microsecond=0)
+        end = (end_local - timedelta(seconds=standard + 3600)).replace(tzinfo=timezone.utc)
+        return standard + 3600 if moment >= start or moment < end else standard
+
+    if tz_name == "Asia/Jerusalem":
+        start = (_last_weekday(year, 3, 6) - timedelta(days=2)).replace(hour=0, minute=0, second=0, microsecond=0)
+        end = _last_weekday(year, 10, 6).replace(hour=0, minute=0, second=0, microsecond=0)
+        return 10800 if start <= moment < end else 7200
+
+    return standard_offset
+
+
+def get_city_utc_offset_seconds(city: Any, at: Optional[datetime] = None) -> int:
+    key = normalize_city_key(city)
+    meta = CITY_REGISTRY.get(key, {}) or {}
+    fallback = int(meta.get("tz_offset") or 0)
+    tz_name = CITY_TIME_ZONES.get(key)
+    if not tz_name or ZoneInfo is None:
+        return _fallback_zone_offset_seconds(tz_name or "", at or datetime.now(timezone.utc), fallback)
+    try:
+        moment = at or datetime.now(timezone.utc)
+        if moment.tzinfo is None:
+            moment = moment.replace(tzinfo=timezone.utc)
+        offset = moment.astimezone(ZoneInfo(tz_name)).utcoffset()
+        if offset is None:
+            return _fallback_zone_offset_seconds(tz_name, moment, fallback)
+        return int(offset.total_seconds())
+    except Exception:
+        return _fallback_zone_offset_seconds(tz_name, at or datetime.now(timezone.utc), fallback)
+
+
+def city_local_datetime(city: Any, at: Optional[datetime] = None) -> datetime:
+    moment = at or datetime.now(timezone.utc)
+    if moment.tzinfo is None:
+        moment = moment.replace(tzinfo=timezone.utc)
+    tz_name = get_city_timezone_name(city)
+    if tz_name and ZoneInfo is not None:
+        try:
+            return moment.astimezone(ZoneInfo(tz_name))
+        except Exception:
+            pass
+    return moment.astimezone(timezone(timedelta(seconds=get_city_utc_offset_seconds(city, moment))))