110 lines
2.8 KiB
Erlang
110 lines
2.8 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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SortedList= lists:sort(fun({X,_},{Y,_})->ezic_date:compare(X,Y)end, FilteredList),
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[Z || {_,Z}<- SortedList].
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