a7b0adcbce
add_offset was calculating DST differences wrong. It assumed to lose an hour, DST would be {-1,0,0}, in fact, DST went from {1,0,0} to {0,0,0}. add_offset now uses their differences (hence requires both as arguments)
normalize/2 was added to be able to set an arbitrary flag on a plain (i.e. native erlang datetime tuple) date. This is complicated by the fact that atoms "minimum", "max", etc. are still valid and need to fall through the normalization unaltered (for now).
119 lines
2.9 KiB
Erlang
119 lines
2.9 KiB
Erlang
-module(ezic_zone).
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-include("include/ezic.hrl").
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-include_lib("eunit/include/eunit.hrl").
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-export([
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parse/1
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, current/1
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, current_as_of_utc/2
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, split_by_name/2
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, offset_sec/1
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, project_end/2
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, project_end_utc/2
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, next/3
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]).
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parse([Name,GmtOffS,Rule,FormatS | UntilTokens]) ->
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% ?debugVal(GmtOffS),
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GmtOff= ezic_parse:time_val(GmtOffS),
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Until = ezic_parse:until(UntilTokens),
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Format= ezic_parse:tz_abbr(FormatS),
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{ok, #zone{
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name=Name, gmtoff=GmtOff, rule=Rule,
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format=Format, until=Until
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}}.
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current(TzName) ->
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current_as_of_utc(erlang:universaltime(), TzName).
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current_as_of_utc(UTCDatetime, TzName) ->
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Zones= ezic_db:zones(TzName),
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get_zone_utc(UTCDatetime, Zones).
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%% returns the active zone for a given utc time
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%% note: requires that flattening be done
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%% this will likely get reworked significantly
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get_zone_utc(_, []) ->
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erlang:error(no_current);
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get_zone_utc(_UTCDatetime, _Zones) ->
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not_done.
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% returns {[SimilarZone], [DifferentZone]}
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% where Similar Zones are those with the same name as Zone
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% and DifferentZones are all the rest
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split_by_name(#zone{name=N}, Zones) ->
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lists:partition(
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fun(#zone{name=NI}) ->
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N =:= NI
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end
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, Zones).
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% @bug doesn't normalize times. Times are self-relative (to standard time), and Now may come from any timezone unless we're careful about that.
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%% older_zone(#zone{until=Until}, UTCDatetime) ->
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%% ezic_date:compare(Until, UTCDatetime).
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offset_sec(Zone) ->
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calendar:time_to_seconds((Zone#zone.gmtoff)#tztime.time).
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% returns ALL datetimes projected for zone end (given current DST Offset)
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project_end(#zone{until=Until, gmtoff=Offset}, DSTOffset) ->
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NUntil= ezic_date:normalize(Until),
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ezic_date:all_times(NUntil, Offset, DSTOffset).
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% returns just the UTC datetime projected for zone end
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project_end_utc(Zone=#zone{}, DSTOffset) ->
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% ?debugVal(Zone),
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{_,_,UTCDatetime}= project_end(Zone, DSTOffset),
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UTCDatetime.
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%% returns [Zone | Rest] where Zone is the next zone after UTCFrom,
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%% subject to the DST offset.
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%% Note that dst differences *can* change which zone comes next,
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%% though it's very unlikely (and does not exist in the current tz database files).
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%% this method covers that event, anyhow. see unit tests for examples.
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next(ZoneList, UTCFrom, DSTOff) ->
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?debugMsg("next:"),
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?debugVal(ZoneList),
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?debugVal(UTCFrom),
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DatedList= lists:map(
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fun(Z=#zone{until=Until, gmtoff=Offset})->
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NUntil= ezic_date:normalize(Until),
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{_,_,UTCDt}= ezic_date:all_times(NUntil, Offset, DSTOff),
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{UTCDt, Z}
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end
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, ZoneList),
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FilteredList= lists:filter(fun({IDt,_})-> ezic_date:compare(UTCFrom, IDt) end, DatedList),
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%x ?debugVal(FilteredList),
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SortedList= lists:sort(fun({X,_},{Y,_})->ezic_date:compare(X,Y)end, FilteredList),
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[Z || {_,Z}<- SortedList].
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