Timezone conversion. Initial tests.

src/qdate.erl

@@ -3,7 +3,9 @@
 -export([
 	to_string/1,
 	to_string/2,
+	to_string/3,
 	to_date/1,
+	to_date/2,
 	to_now/1,
 	to_unixtime/1,
 	unixtime/0
@@ -15,6 +17,11 @@
 %% ]).
 %%
 %% -export([
+%% 	register_format/2,
+%% 	register_format/1
+%% ]).
+%% 
+%% -export([
 %% 	set_timezone/1,
 %% 	set_timezone/2,
 %% 	get_timezone/0,
@@ -32,13 +39,17 @@
 %% This the value in gregorian seconds for jan 1st 1970, 12am
 %% It's used to convert to and from unixtime, since unixtime starts 
 %% 1970-01-01 12:00am
--define(UNIXTIME_BASE, 62176219200).
+-define(UNIXTIME_BASE, 62167219200).
+-define(DEFAULT_TZ, "GMT").
 
 to_string(Format) ->
 	to_string(Format, now()).
 
 to_string(Format, Date) ->
-	ec_date:format(Format,to_date(Date)).
+	to_string(Format, ?DEFAULT_TZ, Date).
+
+to_string(Format, ToTZ, Date) ->
+	ec_date:format(Format,to_date(Date,ToTZ)).
 
 format(Format) ->
 	to_string(Format).
@@ -52,20 +63,54 @@ parse(String) ->
 nparse(String) ->
 	to_now(String).
 
-to_date(Unixtime) when is_integer(Unixtime) ->
+%% This converts dates without regard to timezone.
+%% Unixtime just goes to UTC
+raw_to_date(Unixtime) when is_integer(Unixtime) ->
 	unixtime_to_date(Unixtime);
-to_date(DateString) when is_list(DateString) ->
+raw_to_date(DateString) when is_list(DateString) ->
 	ec_date:parse(DateString);
-to_date(Now = {_,_,_}) ->
+raw_to_date(Now = {_,_,_}) ->
 	calendar:now_to_datetime(Now);
-to_date(Date = {{_,_,_},{_,_,_}}) ->
+raw_to_date(Date = {{_,_,_},{_,_,_}}) ->
 	Date.
 
+to_date(RawDate) ->
+	to_date(RawDate, ?DEFAULT_TZ).
+
+to_date(RawDate, ToTZ)  ->
+	{RawDate2,FromTZ} = extract_timezone(RawDate),
+	Date = raw_to_date(RawDate2),
+	sigma:log({FromTZ,ToTZ}),
+	localtime:local_to_local(Date,FromTZ,ToTZ).
+
+extract_timezone(Unixtime) when is_integer(Unixtime) ->
+	{Unixtime, ?DEFAULT_TZ};
+extract_timezone(DateString) when is_list(DateString) ->
+	AllTimezones = localtime:list_timezones(),
+	RevDate = lists:reverse(DateString),
+	extract_timezone_helper(RevDate, AllTimezones);
+extract_timezone(Date={{_,_,_},{_,_,_}}) ->
+	{Date, ?DEFAULT_TZ};
+extract_timezone(Now={_,_,_}) ->
+	{Now, ?DEFAULT_TZ};
+extract_timezone({MiscDate,TZ}) ->
+	{MiscDate,TZ}.
+	
+extract_timezone_helper(RevDate, []) ->
+	{lists:reverse(RevDate), ?DEFAULT_TZ};
+extract_timezone_helper(RevDate, [TZ | TZs]) ->
+	RevTZ = lists:reverse(TZ),
+	case lists:split(length(TZ),RevDate) of
+		{RevTZ," " ++ Remainder} ->
+			{lists:reverse(Remainder), TZ};
+		_ ->
+			extract_timezone_helper(RevDate, TZs)
+	end.
 
 to_unixtime(Unixtime) when is_integer(Unixtime) ->
 	Unixtime;
 to_unixtime({MegaSecs,Secs,_}) ->
-	MegaSecs*1000000 + Secs;
+	MegaSecs*10000000 + Secs;
 to_unixtime(ToParse) ->
 	Date = to_date(ToParse),
 	calendar:datetime_to_gregorian_seconds(Date) - ?UNIXTIME_BASE.
@@ -98,3 +143,21 @@ floor(N) when N < 0 ->
 		true -> Int-1
 	end.
 	
+
+%% TESTS
+-include_lib("eunit/include/eunit.hrl").
+
+all_test_() ->
+	[
+		?_assertEqual(0,to_unixtime({0,0,0})),
+		?_assertEqual({0,0,0},to_now(0)),
+		?_assertEqual(0,to_unixtime("1970-01-01 12:00am GMT")),
+		?_assertEqual(21600,to_unixtime("1970-01-01 12:00am CST")),
+		?_assertEqual(0,to_unixtime({{1970,1,1},{0,0,0}})),
+		?_assertEqual({{1970,1,1},{0,0,0}},to_date(0)),
+		?_assertEqual("2012-12-01 1:00pm", to_string("Y-m-d g:ia","EST","2012-12-01 12:00pm CST")),
+		?_assertEqual(to_unixtime("2012-01-01 12:00pm CST"), to_unixtime("2012-01-01 10:00am PST")),
+		?_assertEqual({{2012,12,31},{18,15,15}},to_date("Dec 31, 2012 6:15:15pm")),
+		?_assertEqual({{2013,1,1},{0,15,15}},to_date("December 31, 2012 6:15:15pm CST","GMT"))
+	].
+