Convert time to use tzdata (#2425)

esphome/components/time/__init__.py

@@ -1,10 +1,8 @@
-import bisect
-import datetime
 import logging
-import math
-import string
+from importlib import resources
+from typing import Optional
+from datetime import timezone
 
-import pytz
 import tzlocal
 
 import esphome.codegen as cg
@@ -44,111 +42,47 @@ ESPTime = time_ns.struct("ESPTime")
 TimeHasTimeCondition = time_ns.class_("TimeHasTimeCondition", Condition)
 
 
-def _tz_timedelta(td):
-    offset_hour = int(td.total_seconds() / (60 * 60))
-    offset_minute = int(abs(td.total_seconds() / 60)) % 60
-    offset_second = int(abs(td.total_seconds())) % 60
-    if offset_hour == 0 and offset_minute == 0 and offset_second == 0:
-        return "0"
-    if offset_minute == 0 and offset_second == 0:
-        return f"{offset_hour}"
-    if offset_second == 0:
-        return f"{offset_hour}:{offset_minute}"
-    return f"{offset_hour}:{offset_minute}:{offset_second}"
-
-
-# https://stackoverflow.com/a/16804556/8924614
-def _week_of_month(dt):
-    first_day = dt.replace(day=1)
-    dom = dt.day
-    adjusted_dom = dom + first_day.weekday()
-    return int(math.ceil(adjusted_dom / 7.0))
-
-
-def _tz_dst_str(dt):
-    td = datetime.timedelta(hours=dt.hour, minutes=dt.minute, seconds=dt.second)
-    return f"M{dt.month}.{_week_of_month(dt)}.{dt.isoweekday() % 7}/{_tz_timedelta(td)}"
-
-
-def _safe_tzname(tz, dt):
-    tzname = tz.tzname(dt)
-    # pytz does not always return valid tznames
-    # For example: 'Europe/Saratov' returns '+04'
-    # Work around it by using a generic name for the timezone
-    if not all(c in string.ascii_letters for c in tzname):
-        return "TZ"
-    return tzname
-
-
-def _non_dst_tz(tz, dt):
-    tzname = _safe_tzname(tz, dt)
-    utcoffset = tz.utcoffset(dt)
-    _LOGGER.info(
-        "Detected timezone '%s' with UTC offset %s", tzname, _tz_timedelta(utcoffset)
-    )
-    tzbase = f"{tzname}{_tz_timedelta(-1 * utcoffset)}"
-    return tzbase
-
-
-def convert_tz(pytz_obj):
-    tz = pytz_obj
-
-    now = datetime.datetime.now()
-    first_january = datetime.datetime(year=now.year, month=1, day=1)
-
-    if not isinstance(tz, pytz.tzinfo.DstTzInfo):
-        return _non_dst_tz(tz, first_january)
-
-    # pylint: disable=protected-access
-    transition_times = tz._utc_transition_times
-    transition_info = tz._transition_info
-    idx = max(0, bisect.bisect_right(transition_times, now))
-    if idx >= len(transition_times):
-        return _non_dst_tz(tz, now)
-
-    idx1, idx2 = idx, idx + 1
-    dstoffset1 = transition_info[idx1][1]
-    if dstoffset1 == datetime.timedelta(seconds=0):
-        # Normalize to 1 being DST on
-        idx1, idx2 = idx + 1, idx + 2
-
-    if idx2 >= len(transition_times):
-        return _non_dst_tz(tz, now)
-
-    if transition_times[idx2].year > now.year + 1:
-        # Next transition is scheduled after this year
-        # Probably a scheduler timezone change.
-        return _non_dst_tz(tz, now)
-
-    utcoffset_on, _, tzname_on = transition_info[idx1]
-    utcoffset_off, _, tzname_off = transition_info[idx2]
-    dst_begins_utc = transition_times[idx1]
-    dst_begins_local = dst_begins_utc + utcoffset_off
-    dst_ends_utc = transition_times[idx2]
-    dst_ends_local = dst_ends_utc + utcoffset_on
-
-    tzbase = f"{tzname_off}{_tz_timedelta(-1 * utcoffset_off)}"
-
-    tzext = f"{tzname_on}{_tz_timedelta(-1 * utcoffset_on)},{_tz_dst_str(dst_begins_local)},{_tz_dst_str(dst_ends_local)}"
-    _LOGGER.info(
-        "Detected timezone '%s' with UTC offset %s and daylight saving time from "
-        "%s to %s",
-        tzname_off,
-        _tz_timedelta(utcoffset_off),
-        dst_begins_local.strftime("%d %B %X"),
-        dst_ends_local.strftime("%d %B %X"),
-    )
-    return tzbase + tzext
-
-
-def detect_tz():
+def _load_tzdata(iana_key: str) -> Optional[bytes]:
+    # From https://tzdata.readthedocs.io/en/latest/#examples
     try:
-        tz = tzlocal.get_localzone()
-    except pytz.exceptions.UnknownTimeZoneError:
-        _LOGGER.warning("Could not auto-detect timezone. Using UTC...")
-        return "UTC"
+        package_loc, resource = iana_key.rsplit("/", 1)
+    except ValueError:
+        return None
+    package = "tzdata.zoneinfo." + package_loc.replace("/", ".")
 
-    return convert_tz(tz)
+    try:
+        return resources.read_binary(package, resource)
+    except (FileNotFoundError, ModuleNotFoundError):
+        return None
+
+
+def _extract_tz_string(tzfile: bytes) -> str:
+    try:
+        return tzfile.split(b"\n")[-2].decode()
+    except (IndexError, UnicodeDecodeError):
+        _LOGGER.error("Could not determine TZ string. Please report this issue.")
+        _LOGGER.error("tzfile contents: %s", tzfile, exc_info=True)
+        raise
+
+
+def detect_tz() -> str:
+    localzone = tzlocal.get_localzone()
+    if localzone is timezone.utc:
+        return "UTC0"
+    if not hasattr(localzone, "key"):
+        raise cv.Invalid(
+            "Could not automatically determine timezone, please set timezone manually."
+        )
+    iana_key = localzone.key
+    _LOGGER.info("Detected timezone '%s'", iana_key)
+    tzfile = _load_tzdata(iana_key)
+    if tzfile is None:
+        raise cv.Invalid(
+            "Could not automatically determine timezone, please set timezone manually."
+        )
+    ret = _extract_tz_string(tzfile)
+    _LOGGER.debug(" -> TZ string %s", ret)
+    return ret
 
 
 def _parse_cron_int(value, special_mapping, message):
@@ -327,15 +261,15 @@ def validate_cron_keys(value):
     return cv.has_at_least_one_key(*CRON_KEYS)(value)
 
 
-def validate_tz(value):
+def validate_tz(value: str) -> str:
     value = cv.string_strict(value)
 
-    try:
-        pytz_obj = pytz.timezone(value)
-    except pytz.UnknownTimeZoneError:  # pylint: disable=broad-except
+    tzfile = _load_tzdata(value)
+    if tzfile is None:
+        # Not a IANA key, probably a TZ string
         return value
 
-    return convert_tz(pytz_obj)
+    return _extract_tz_string(tzfile)
 
 
 TIME_SCHEMA = cv.Schema(

requirements.txt

@@ -3,8 +3,8 @@ PyYAML==5.4.1
 paho-mqtt==1.5.1
 colorama==0.4.4
 tornado==6.1
-tzlocal==3.0
-pytz==2021.1
+tzlocal==3.0    # from time
+tzdata>=2021.1  # from time
 pyserial==3.5
 platformio==5.2.0
 esptool==3.1