mirror of https://github.com/zulip/zulip.git
60 lines
2.0 KiB
Python
60 lines
2.0 KiB
Python
import datetime
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from typing import Any, Dict, List, Union
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import pytz
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def get_all_timezones() -> List[str]:
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return sorted(pytz.all_timezones)
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def get_timezone(tz: str) -> pytz.BaseTzInfo:
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return pytz.timezone(tz)
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# This method carefully trims a list of common timezones in the pytz
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# database and handles duplicate abbreviations in favor of the most
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# common/popular offset. The output of this can be directly passed as
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# tz_data to dateutil.parser.
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def _calculate_timezones() -> Dict[str, Union[int, Any]]:
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tzdata = {}
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normal = datetime.datetime(2009, 9, 1) # Any random date is fine here.
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for str in pytz.all_timezones:
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tz = pytz.timezone(str)
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timedelta = tz.utcoffset(normal)
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if not timedelta:
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continue
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offset = timedelta.seconds
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tz_name = tz.tzname(normal)
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tzdata[tz_name] = offset
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# Handle known duplicates/exceptions.
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# IST: Asia/Kolkata and Europe/Dublin.
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if tz_name == 'IST':
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tzdata[tz_name] = 19800 # Asia/Kolkata
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# CDT: America/AlmostAll and America/Havana.
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if tz_name == 'CDT':
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tzdata[tz_name] = -68400 # America/AlmostAll
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# CST America/Belize -64800
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# CST America/Costa_Rica -64800
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# CST America/El_Salvador -64800
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# CST America/Guatemala -64800
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# CST America/Managua -64800
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# CST America/Regina -64800
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# CST America/Swift_Current -64800
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# CST America/Tegucigalpa -64800
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# CST Asia/Macau 28800
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# CST Asia/Shanghai 28800
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# CST Asia/Taipei 28800
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if tz_name == 'CST':
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tzdata[tz_name] = -64800 # America/All
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return tzdata
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timezone_data = None
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# _calculate_timezones takes about 25ms to run, so we want to cache
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# its results (while avoiding running it on process startup since we
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# only need it for Markdown rendering).
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def get_common_timezones() -> Dict[str, Union[int, Any]]:
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global timezone_data
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if timezone_data is None:
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timezone_data = _calculate_timezones()
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return timezone_data
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