RAHHH

backend/lib/python3.12/site-packages/twisted/python/_tzhelper.py

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+# -*- test-case-name: twisted.python.test.test_tzhelper -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Time zone utilities.
+"""
+
+from datetime import (
+    datetime as DateTime,
+    timedelta as TimeDelta,
+    timezone,
+    tzinfo as TZInfo,
+)
+from typing import Optional
+
+__all__ = [
+    "FixedOffsetTimeZone",
+    "UTC",
+]
+
+
+class FixedOffsetTimeZone(TZInfo):
+    """
+    Represents a fixed timezone offset (without daylight saving time).
+
+    @ivar name: A L{str} giving the name of this timezone; the name just
+        includes how much time this offset represents.
+
+    @ivar offset: A L{TimeDelta} giving the amount of time this timezone is
+        offset.
+    """
+
+    def __init__(self, offset: TimeDelta, name: Optional[str] = None) -> None:
+        """
+        Construct a L{FixedOffsetTimeZone} with a fixed offset.
+
+        @param offset: a delta representing the offset from UTC.
+        @param name: A name to be given for this timezone.
+        """
+        self.offset = offset
+        self.name = name
+
+    @classmethod
+    def fromSignHoursMinutes(
+        cls, sign: str, hours: int, minutes: int
+    ) -> "FixedOffsetTimeZone":
+        """
+        Construct a L{FixedOffsetTimeZone} from an offset described by sign
+        ('+' or '-'), hours, and minutes.
+
+        @note: For protocol compatibility with AMP, this method never uses 'Z'
+
+        @param sign: A string describing the positive or negative-ness of the
+            offset.
+        @param hours: The number of hours in the offset.
+        @param minutes: The number of minutes in the offset
+
+        @return: A time zone with the given offset, and a name describing the
+            offset.
+        """
+        name = "%s%02i:%02i" % (sign, hours, minutes)
+        if sign == "-":
+            hours = -hours
+            minutes = -minutes
+        elif sign != "+":
+            raise ValueError(f"Invalid sign for timezone {sign!r}")
+        return cls(TimeDelta(hours=hours, minutes=minutes), name)
+
+    @classmethod
+    def fromLocalTimeStamp(cls, timeStamp: float) -> "FixedOffsetTimeZone":
+        """
+        Create a time zone with a fixed offset corresponding to a time stamp in
+        the system's locally configured time zone.
+        """
+        offset = DateTime.fromtimestamp(timeStamp) - DateTime.fromtimestamp(
+            timeStamp, timezone.utc
+        ).replace(tzinfo=None)
+        return cls(offset)
+
+    def utcoffset(self, dt: Optional[DateTime]) -> TimeDelta:
+        """
+        Return the given timezone's offset from UTC.
+        """
+        return self.offset
+
+    def dst(self, dt: Optional[DateTime]) -> TimeDelta:
+        """
+        Return a zero L{TimeDelta} for the daylight saving time
+        offset, since there is never one.
+        """
+        return TimeDelta(0)
+
+    def tzname(self, dt: Optional[DateTime]) -> str:
+        """
+        Return a string describing this timezone.
+        """
+        if self.name is not None:
+            return self.name
+        # XXX this is wrong; the tests are
+        dt = DateTime.fromtimestamp(0, self)
+        return dt.strftime("UTC%z")
+
+
+UTC = FixedOffsetTimeZone.fromSignHoursMinutes("+", 0, 0)