renamed the API methods, updated the README

README.md

@@ -1,11 +1,27 @@
 ezic
 ====
-ezic is a set of erlang utilities for the Olsen timezone database files.
-
-see the [tz database](http://www.twinsun.com/tz/tz-link.htm) page for more information.
+ezic is a set of erlang utilities for the Olsen timezone database files. See the [tz database](http://www.twinsun.com/tz/tz-link.htm) page for more information.
 
 
-Usage
+
+API
+---
+
+ * `ezic:localtime(TimeZone) -> datetime()`
+ * `ezic:utc_to_time(universal_datetime(), TimeZone) -> local_datetime()`
+ * `ezic:utc_from_time(local_datetime(), TimeZone) -> universal_datetime()`
+ * `ezic:zone_convert(from_datetime(), TimeZoneFrom, TimeZoneTo) -> to_datetime()`
+
+
+
+Admin API
+-------
+
+ * `ezic:load("/path/to/tzdata") -> ok`
+
+
+
+Setup
 -----
   
     # download the timezone data files
@@ -22,25 +38,26 @@ Usage
     2> ezic:localtime("Australia/Adelaide").
 
 
-API
----
-
- * `ezic:load(Folder)`
- * `ezic:localtime(TimeZone) -> datetime()`
- * `ezic:time(datetime(), TimeZone) -> datetime()`
- * `ezic:time2time(datetime(), TimeZoneFrom, TimeZoneTo) -> datetime()`
 
 
 Purpose
 -------
 
-The [recommended way](http://www.erlang.org/pipermail/erlang-questions/2006-December/024291.html) of handling timezones in erlang involves setting the system environment variable `TZ` to the desired timezone, then calling erlang time functions. This technique is probably sufficient for many purposes, but it has a few key issues:
+The [recommended way](http://www.erlang.org/pipermail/erlang-questions/2006-December/024291.html) of handling timezones in erlang involves setting the system environment variable `TZ` to the desired timezone, then calling erlang time functions. This technique has a few key issues:
 
  * it only works on *nix systems,
- * it depends on your system's timezone data (preventing customization), and
+ * it depends on your system's timezone data (preventing custom timezone hackery), and
  * you can create race conditions if you aren't careful
 
-A pure erlang solution avoids all of these pitfalls, hence this project.
+A self-containted erlang solution would avoid these pitfalls, but to be fair, it introduces a few others:
+
+ * you (the admin) are responsible for updating the timezone database yourself
+ * ezic has not yet been battle tested
+
+I think both of these issues will disappear over time, so I opted to write ezic.
+
+
+
 
 License
 -------

src/ezic.erl

@@ -1,7 +1,8 @@
 -module(ezic).
 -include("include/ezic.hrl").
 
--export([localtime/1, time2time/3]).
+-export([localtime/1, utc_to_local/2, utc_from_local/2, zone_convert/3]).
+
 -export([load/1, dev_start/0, test/0]).
 
 
@@ -10,36 +11,37 @@
 
 
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% API
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+
 localtime(TzName) ->
-    time(erlang:universaltime(), TzName).
+    utc_to_local(erlang:universaltime(), TzName).
 
 
-time(Datetime, TzName) ->
+utc_to_local(Datetime, TzName) ->
+    {ok, Zone, Rule}= current(Datetime, TzName),
+    SecDiff= offset(Zone, Rule),
+    date_add(Datetime, SecDiff).
 
-    Zones= ezic_db:zones(TzName),
-%    ?debug("All Zones: ~p", [Zones]),
-    CZone= ezic_zone:current(Datetime, Zones),
-%    ?debug("Current Zone: ~p", [CZone]),
     
-    RuleName= CZone#zone.rule,
-    Rules= ezic_db:rules(RuleName),
-%    ?debug("All Rules: ~p", [Rules]),
-    CRule= ezic_rule:current(Datetime, Rules),
-%    ?debug("Current Rule: ~p", [CRule]),
+utc_from_local(Datetime, TzName) ->
+    {ok, Zone, Rule}= current(Datetime, TzName),
+    SecDiff= offset(Zone, Rule),
+    date_subtract(Datetime, SecDiff).
     
-    OffsetSec= ezic_zone:offset_sec(CZone),
-    DSTSec= ezic_rule:dst_sec(CRule),
 
-    SecDiff= OffsetSec + DSTSec,
-    ?gs2dt(?dt2gs(Datetime) + SecDiff).
-    
-
-
-time2time(_DateTime, _FromTimeZone, _ToTimeZone) ->
-    void.
+zone_convert(Datetime, FromTimeZone, ToTimeZone) ->
+    UTC= utc_from_local(Datetime, FromTimeZone),
+    utc_to_local(UTC, ToTimeZone).
 
 
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% DEV API
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 
 
@@ -57,3 +59,40 @@ test() ->
 	      io:format("~s: ~p~n", [TZ, localtime(TZ)])
       end,
       ["Asia/Tokyo", "America/New_York", "America/Los_Angeles", "America/Jamaica", "Australia/Adelaide"]).
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% PRIVATE
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+current(Datetime, TzName) ->
+    Zones= ezic_db:zones(TzName),
+%    ?debug("All Zones: ~p", [Zones]),
+    CZone= ezic_zone:current(Datetime, Zones),
+%    ?debug("Current Zone: ~p", [CZone]),
+
+    RuleName= CZone#zone.rule,
+    Rules= ezic_db:rules(RuleName),
+%    ?debug("All Rules: ~p", [Rules]),
+    CRule= ezic_rule:current(Datetime, Rules),
+%    ?debug("Current Rule: ~p", [CRule]),
+    {ok, CZone, CRule}.
+    
+
+
+
+offset(Zone, Rule) ->
+    OffsetSec= ezic_zone:offset_sec(Zone),
+    DSTSec= ezic_rule:dst_sec(Rule),
+    OffsetSec + DSTSec.
+    
+
+
+date_add(Datetime, SecDiff) ->
+    ?gs2dt(?dt2gs(Datetime) + SecDiff).    
+
+date_subtract(Datetime, SecDiff) ->
+    ?gs2dt(?dt2gs(Datetime) - SecDiff).
+