dev_agent
0e726ac64f
Co-authored-by: dev_agent <dev_agent@cubecraftlabs.com> Co-committed-by: dev_agent <dev_agent@cubecraftlabs.com>
63 lines
2.2 KiB
Python
63 lines
2.2 KiB
Python
"""The API's effective application timezone (task 7e173881).
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The admin-stored ``timezone`` setting is the single source of local-time
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truth; stored empty, the API reads its clock in the API host's local
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time. :func:`effective_timezone` names the zone the API actually uses —
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the stored zone, or else the host's own IANA zone — so the panel cards
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and the admin app format local time in exactly the API's zone instead of
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guessing with Home Assistant's or the browser's. ``""`` only when the
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host's zone genuinely cannot be named.
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"""
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from __future__ import annotations
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import os
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from collections.abc import Mapping
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from pathlib import Path
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from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
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def _valid_zone(name: str) -> str:
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"""Return ``name`` if it is a loadable IANA zone key, else ``""``."""
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name = name.strip().removeprefix(":")
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if not name:
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return ""
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try:
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ZoneInfo(name)
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except (ZoneInfoNotFoundError, ValueError):
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return ""
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return name
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def host_timezone(
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environ: Mapping[str, str] = os.environ,
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timezone_file: Path = Path("/etc/timezone"),
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localtime: Path = Path("/etc/localtime"),
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) -> str:
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"""Name the API host's local zone as an IANA key, or ``""``.
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In the order the C library honours them: the ``TZ`` environment
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variable, then the ``/etc/localtime`` zoneinfo link (with Debian's
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``/etc/timezone`` naming it when the link is a copy). A host with
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none of them configured runs UTC. A setting that names no IANA
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zone (a POSIX rule string, a copied file) is ``""``.
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"""
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configured = environ.get("TZ")
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if configured is not None:
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# An empty TZ is UTC to the C library.
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return _valid_zone(configured) if configured.strip() else "UTC"
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if localtime.is_symlink():
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target = str(localtime.resolve())
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marker = "/zoneinfo/"
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if marker in target:
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return _valid_zone(target.split(marker, 1)[1])
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if timezone_file.is_file():
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return _valid_zone(timezone_file.read_text(encoding="utf-8"))
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if not localtime.exists():
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return "UTC"
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return ""
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def effective_timezone(stored: str) -> str:
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"""The zone the API reads its clock in: ``stored``, else the host's."""
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return stored or host_timezone()
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