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"""Compatibility layer for Office 365 and Exchange Server iCalendar files.
This module provides a context manager that can allow invalid calendar files
to be parsed.
"""
import contextlib
from collections.abc import Generator
import logging
import re
from . import timezone_compat
_LOGGER = logging.getLogger(__name__)
# Capture group that extracts the PRODID from the ics content.
_PRODID_RE = r"PRODID:(?P<prodid>.*[^\\r\\n]+)"
_EXCHANGE_PRODID = "Microsoft Exchange Server"
def _get_prodid(ics: str) -> str | None:
"""Extract the PRODID from the iCalendar content."""
match = re.search(_PRODID_RE, ics)
if match:
_LOGGER.debug("Extracted PRODID: %s", match)
return match.group("prodid")
return None
@contextlib.contextmanager
def enable_compat_mode(ics: str) -> Generator[str]:
"""Enable compatibility mode to fix known broken calendar content."""
# Check if the PRODID is from Microsoft Exchange Server
prodid = _get_prodid(ics)
if prodid and _EXCHANGE_PRODID in prodid:
_LOGGER.debug("Enabling compatibility mode for Microsoft Exchange Server")
# Enable compatibility mode for Microsoft Exchange Server
with (
timezone_compat.enable_allow_invalid_timezones(),
timezone_compat.enable_extended_timezones(),
):
yield ics
else:
_LOGGER.debug("No compatibility mode needed")
# No compatibility mode needed
yield ics
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