initial commit
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Dmitry Melnikov
commit
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139
src/localtime.erl
Executable file
139
src/localtime.erl
Executable file
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%% Copyright (C) 07/01/2010 Dmitry S. Melnikov (dmitryme@gmail.com)
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%%
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%% This program is free software; you can redistribute it and/or
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%% modify it under the terms of the GNU General Public License
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%% as published by the Free Software Foundation; either version 2
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%% of the License, or (at your option) any later version.
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%%
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%% This program is distributed in the hope that it will be useful,
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%% but WITHOUT ANY WARRANTY; without even the implied warranty of
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%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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%% GNU General Public License for more details.
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%%
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%% You should have received a copy of the GNU General Public License
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%% along with this program; if not, write to the Free Software
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%% Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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-module(localtime).
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-author("Dmitry Melnikov <dmitryme@gmail.com>").
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-include("include/tz_database.hrl").
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-export(
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[
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utc_to_local/2
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,local_to_utc/2
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,local_to_local/3
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,tz_name/2
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]).
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% utc_to_local(UtcDateTime, Timezone) -> LocalDateTime | {error, ErrDescr}
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% UtcDateTime = DateTime()
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% Timezone = String()
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% LocalDateTime = DateTime()
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% ErrDescr = unknown_tz
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utc_to_local(UtcDateTime, Timezone) ->
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case lists:keyfind(Timezone, 1, ?tz_database) of
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false ->
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{error, unknown_tz};
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{_Tz, _, _, Shift, _DstShift, undef, _DstStartTime, undef, _DstEndTime} ->
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adjust_datetime(UtcDateTime, Shift);
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TzRule = {_, _, _, Shift, DstShift, _, _, _, _} ->
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LocalDateTime = adjust_datetime(UtcDateTime, Shift),
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case localtime_dst:check(LocalDateTime, TzRule) of
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Res when (Res == is_in_dst) or (Res == time_not_exists) ->
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adjust_datetime(LocalDateTime, DstShift);
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is_not_in_dst ->
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LocalDateTime;
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ambiguous_time ->
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RecheckIt = adjust_datetime(LocalDateTime, DstShift),
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case localtime_dst:check(RecheckIt, TzRule) of
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ambiguous_time ->
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RecheckIt;
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_ ->
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LocalDateTime
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end
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end
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end.
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% local_to_utc(LocalDateTime, Timezone) -> UtcDateTime | tim_not_exists | {error, ErrDescr}
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% LocalDateTime = DateTime()
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% Timezone = String()
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% UtcDateTime = DateTime()
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% ErrDescr = unknown_tz
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local_to_utc(LocalDateTime, Timezone) ->
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case lists:keyfind(Timezone, 1, ?tz_database) of
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false ->
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{error, unknown_tz};
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{_Tz, _, _, Shift, _DstShift, undef, _DstStartTime, undef, _DstEndTime} ->
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adjust_datetime(LocalDateTime, invert_shift(Shift));
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TzRule = {_, _, _, Shift, DstShift, _, _, _, _} ->
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UtcDateTime = adjust_datetime(LocalDateTime, invert_shift(Shift)),
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case localtime_dst:check(LocalDateTime, TzRule) of
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is_in_dst ->
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adjust_datetime(UtcDateTime, invert_shift(DstShift));
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Res when (Res == is_not_in_dst) or (Res == ambiguous_time) ->
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UtcDateTime;
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time_not_exists ->
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time_not_exists
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end
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end.
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% local_to_local(LocalDateTime, TimezoneFrom, TimezoneTo) -> LocalDateTime | tim_not_exists | {error, ErrDescr}
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% LocalDateTime = DateTime()
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% TimezoneFrom = String()
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% TimezoneTo = String()
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% ErrDescr = unknown_tz
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local_to_local(LocalDateTime, TimezoneFrom, TimezoneTo) ->
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case local_to_utc(LocalDateTime, TimezoneFrom) of
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Date = {{_,_,_},{_,_,_}} ->
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utc_to_local(Date, TimezoneTo);
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Res ->
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Res
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end.
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% tz_name(DateTime(), Timezone) -> {Abbr, Name} | {{StdAbbr, StdName}, {DstAbbr, DstName}} | unable_to_detect
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% Timezone = String()
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% Abbr = String()
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% Name = String()
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% StdAbbr = String()
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% StdName = String()
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% DstAbbr = String()
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% DstName = String()
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tz_name(_UtcDateTime, "UTC") ->
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{"UTC", "UTC"};
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tz_name(LocalDateTime, Timezone) ->
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case lists:keyfind(Timezone, 1, ?tz_database) of
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false ->
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{error, unknown_tz};
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{_Tz, StdName, undef, _Shift, _DstShift, undef, _DstStartTime, undef, _DstEndTime} ->
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StdName;
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TzRule = {_, StdName, DstName, _Shift, _DstShift, _, _, _, _} ->
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case localtime_dst:check(LocalDateTime, TzRule) of
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is_in_dst ->
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DstName;
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is_not_in_dst ->
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StdName;
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ambiguous_time ->
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{StdName, DstName};
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time_not_exists ->
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unable_to_detect
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end
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end.
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adjust_datetime(DateTime, {Hours, Minutes}) ->
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Seconds = calendar:datetime_to_gregorian_seconds(DateTime) + Hours * 3600,
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case Hours < 0 of
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true ->
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calendar:gregorian_seconds_to_datetime(Seconds - Minutes * 60);
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false ->
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calendar:gregorian_seconds_to_datetime(Seconds + Minutes * 60)
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end.
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invert_shift({Hours, Minutes}) ->
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{-Hours, Minutes}.
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-ifdef(EUNIT).
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-include_lib("eunit/include/eunit.hrl").
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-endif.
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162
src/localtime_dst.erl
Executable file
162
src/localtime_dst.erl
Executable file
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@ -0,0 +1,162 @@
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%% Copyright (C) 07/01/2010 Dmitry S. Melnikov (dmitryme@gmail.com)
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%%
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%% This program is free software; you can redistribute it and/or
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%% modify it under the terms of the GNU General Public License
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%% as published by the Free Software Foundation; either version 2
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%% of the License, or (at your option) any later version.
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%%
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%% This program is distributed in the hope that it will be useful,
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%% but WITHOUT ANY WARRANTY; without even the implied warranty of
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%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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%% GNU General Public License for more details.
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%%
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%% You should have received a copy of the GNU General Public License
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%% along with this program; if not, write to the Free Software
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%% Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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-module(localtime_dst).
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-author("Dmitry Melnikov <dmitryme@gmail.com>").
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-export(
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[
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check/2
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]).
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-compile([export_all]).
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% check(DateTime, TimeZone) -> is_in_dst | is_not_in_dst | ambiguous_time | time_not_exists
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% DateTime = DateTime()
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% TimeZone = tuple()
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check({Date = {Year, _, _},Time}, {_, _, _, _Shift, DstShift, DstStartRule, DstStartTime, DstEndRule, DstEndTime}) ->
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DstStartDay = get_dst_day_of_year(DstStartRule, Year),
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DstEndDay = get_dst_day_of_year(DstEndRule, Year),
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CurrDay = get_day_of_year(Date),
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case is_dst_date(DstStartDay, DstEndDay, CurrDay) of
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equal_to_start ->
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is_dst_start_time(time_to_minutes(Time), time_to_minutes(DstStartTime), time_to_minutes(DstShift));
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equal_to_end ->
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is_dst_end_time(time_to_minutes(Time), time_to_minutes(DstEndTime), time_to_minutes(DstShift));
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Res ->
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Res
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end.
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is_dst_start_time(CurrTime, DstStartTime, _DstShift) when CurrTime < DstStartTime ->
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is_not_in_dst;
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is_dst_start_time(CurrTime, DstStartTime, DstShift) when CurrTime >= (DstStartTime + DstShift) ->
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is_in_dst;
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is_dst_start_time(_CurrTime, _DstStartTime, _DstShift) ->
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time_not_exists.
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is_dst_end_time(CurrTime, DstEndTime, DstShift) when CurrTime < (DstEndTime - DstShift) ->
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is_in_dst;
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is_dst_end_time(CurrTime, DstEndTime, _DstShift) when CurrTime >= DstEndTime ->
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is_not_in_dst;
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is_dst_end_time(_CurrTime, _DstStartTime, _DstShift) ->
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ambiguous_time.
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is_dst_date(DstStartDay, _DstEndDay, CurrDay) when (CurrDay == DstStartDay) -> equal_to_start;
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is_dst_date(_DstStartDay, DstEndDay, CurrDay) when (CurrDay == DstEndDay) -> equal_to_end;
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is_dst_date(DstStartDay, DstEndDay, CurrDay)
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when (DstStartDay < DstEndDay) andalso ((CurrDay > DstStartDay) and (CurrDay < DstEndDay)) ->
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is_in_dst;
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is_dst_date(DstStartDay, DstEndDay, CurrDay)
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when (DstStartDay < DstEndDay) andalso ((CurrDay < DstStartDay) or (CurrDay > DstEndDay)) ->
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is_not_in_dst;
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is_dst_date(DstStartDay, DstEndDay, CurrDay)
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when (DstStartDay > DstEndDay) andalso ((CurrDay < DstStartDay) and (CurrDay > DstEndDay)) ->
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is_not_in_dst;
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is_dst_date(DstStartDay, DstEndDay, CurrDay)
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when (DstStartDay > DstEndDay) andalso ((CurrDay > DstStartDay) or (CurrDay < DstEndDay)) ->
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is_in_dst.
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get_dst_day_of_year({WeekDay,DayOfWeek,Month}, Year) when (WeekDay == last) or (WeekDay == 5) ->
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IntMonth = month_to_int(Month),
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IntDayOfWeek = day_to_int(DayOfWeek),
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get_last_dst(IntDayOfWeek, IntMonth, Year);
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get_dst_day_of_year({WeekDay,DayOfWeek,Month}, Year) when (WeekDay > 0) and (WeekDay =< 4) ->
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IntMonth = month_to_int(Month),
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IntDayOfWeek = day_to_int(DayOfWeek),
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DstDays = get_day_of_year({Year, IntMonth, 1}),
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DstDayOfWeek = calendar:day_of_the_week({Year, IntMonth, 1}),
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case (DstDayOfWeek =:= IntDayOfWeek) and (WeekDay =:= 1) of
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true ->
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DstDays;
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false ->
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AdjustedDstDays =
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case IntDayOfWeek >= DstDayOfWeek of
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true ->
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DstDays + (IntDayOfWeek - DstDayOfWeek);
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false ->
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DstDays + (7 - DstDayOfWeek) + IntDayOfWeek
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end,
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AdjustedDstDays + (WeekDay - 1) * 7
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end;
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get_dst_day_of_year(_, _) ->
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throw({error, wrong_week_day}).
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get_last_dst(IntDayOfWeek, IntMonth, Year) ->
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MonthLastDays = calendar:date_to_gregorian_days(Year, IntMonth, 1) + calendar:last_day_of_the_month(Year, IntMonth),
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MonthLastDate = calendar:gregorian_days_to_date(MonthLastDays),
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MonthLastDayOfWeek = calendar:day_of_the_week(MonthLastDate),
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case MonthLastDayOfWeek > IntDayOfWeek of
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true ->
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MonthLastDays - (MonthLastDayOfWeek - IntDayOfWeek) - calendar:date_to_gregorian_days({Year - 1, 12, 31});
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false ->
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MonthLastDays - MonthLastDayOfWeek - (7 - IntDayOfWeek) - calendar:date_to_gregorian_days({Year - 1, 12, 31})
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end.
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get_day_of_year(Date = {Year, _Month, _Day}) ->
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calendar:date_to_gregorian_days(Date) - calendar:date_to_gregorian_days({Year - 1, 12, 31}).
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month_to_int(jan) -> 1;
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month_to_int(feb) -> 2;
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month_to_int(mar) -> 3;
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month_to_int(apr) -> 4;
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month_to_int(may) -> 5;
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month_to_int(jun) -> 6;
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month_to_int(jul) -> 7;
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month_to_int(aug) -> 8;
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month_to_int(sep) -> 9;
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month_to_int(oct) -> 10;
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month_to_int(nov) -> 11;
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month_to_int(dec) -> 12.
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day_to_int(mon) -> 1;
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day_to_int(tue) -> 2;
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day_to_int(wed) -> 3;
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day_to_int(thu) -> 4;
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day_to_int(fri) -> 5;
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day_to_int(sat) -> 6;
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day_to_int(sun) -> 7.
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time_to_minutes({Hours, Minutes}) ->
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Hours * 60 + Minutes;
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time_to_minutes({Hours, Minutes, _Seconds}) ->
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Hours * 60 + Minutes.
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-ifdef(EUNIT).
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-include_lib("eunit/include/eunit.hrl").
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get_day_of_year_test() ->
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?assertEqual(62, get_dst_day_of_year({1,wed,mar}, 2010)).
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check_test() ->
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Tz = {"Europe/Moscow",{3,0},{1,0},{last,sun,mar},{2,0},{last,sun,oct},{3,0}},
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?assertEqual(is_not_in_dst, local_time_dst:check({{2010, 1, 1}, {10, 10, 0}}, Tz)),
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?assertEqual(is_in_dst, check({{2010, 7, 8}, {10, 10, 0}}, Tz)),
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?assertEqual(is_not_in_dst, check({{2010, 3, 28}, {1, 59, 0}}, Tz)),
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?assertEqual(invalid_label, check({{2010, 3, 28}, {2, 00, 0}}, Tz)),
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?assertEqual(invalid_label, check({{2010, 3, 28}, {2, 15, 0}}, Tz)),
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?assertEqual(invalid_label, check({{2010, 3, 28}, {2, 30, 0}}, Tz)),
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?assertEqual(invalid_label, check({{2010, 3, 28}, {2, 59, 0}}, Tz)),
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?assertEqual(is_in_dst, check({{2010, 3, 28}, {3, 00, 0}}, Tz)),
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?assertEqual(is_in_dst, check({{2010, 10, 31}, {1, 59, 0}}, Tz)),
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?assertEqual(ambiguos, check({{2010, 10, 31}, {2, 00, 0}}, Tz)),
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?assertEqual(ambiguos, check({{2010, 10, 31}, {2, 10, 0}}, Tz)),
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?assertEqual(ambiguos, check({{2010, 10, 31}, {2, 30, 0}}, Tz)),
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?assertEqual(ambiguos, check({{2010, 10, 31}, {2, 59, 0}}, Tz)),
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?assertEqual(is_not_in_dst, check({{2010, 10, 31}, {3, 00, 0}}, Tz)).
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-endif.
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