refactor types, add more to herd_datetime

Makefile

@@ -5,7 +5,7 @@ eunit:
 	rebar3 eunit
 
 console:
-	erl -pa _build/default/lib/*/ebin -s epgsql_pool test_run
+	erl -pa _build/default/lib/*/ebin
 
 d:
 	rebar3 dialyzer

include/herd.hrl

@@ -1,16 +0,0 @@
--type(timestamp() :: integer()).
--type(timestamp_micro() :: float()).
-
-%% jiffy json format
--type(json_key() :: atom() | binary()).
--type(json_value() :: atom() | integer() | float() | binary() | json_obj() | [json_value()]).
--type(json_obj() :: {[{json_key(), json_value()}]}).
-
-%% db types (PostgreSQL with epgsql driver)
--type(db_name() :: binary()).
--type(db_type() :: atom()).
--type(db_value() :: term()).
--type(db_row() :: tuple()).
--type(db_column() :: {column, db_name(), db_type(), term(), term(), term()}).
--type(db_select() :: {ok, [db_column()], [db_row()]}).
--type(db_datetime() :: {calendar:date(), {0..23, 0..59, float()}}). % PostgreSQL datetime format: 2014-12-20 17:38:56.475565+03

src/herd_datetime.erl

@@ -1,23 +1,37 @@
 -module(herd_datetime).
 
--export([now/0, now_micro/0,
-         datetime_from_db/1,
-         timestamp_to_datetime/1, datetime_to_timestamp/1,
-         datetime_to_ISO/1]).
+-export([
+    now/0, now_micro/0,
+    datetime_from_db/1,
+    timestamp_to_datetime/1,
+    timestamp_to_db_datetime/1,
+    datetime_to_timestamp/1,
+    datetime_to_ISO/1,
+    add_interval/2,
+    subtract_interval/2
+]).
 
--include("herd.hrl").
+-type(timestamp() :: integer()). % seconds, 1476882197
+-type(timestamp_micro() :: float()). % int part in seconds, 1476882197.233323
+
+%% PostgreSQL datetime format: 2014-12-20 17:38:56.475565
+-type(db_datetime() :: {calendar:date(), {0..23, 0..59, float()}}).
+
+-type(time_interval() :: {integer(), month | week | day | hour | minute | second}).
+
+-define(DAY, 24 * 3600).
 
 
 %%% module API
 
 -spec now() -> timestamp().
 now() ->
-    erlang:system_time() div 1000000000.
+    erlang:system_time(seconds).
 
 
 -spec now_micro() -> timestamp_micro().
 now_micro() ->
-    erlang:system_time() / 1000000000.
+    erlang:system_time(micro_seconds) / 1000000.
 
 
 -spec datetime_from_db(db_datetime()) -> calendar:datetime().
@@ -25,11 +39,19 @@ datetime_from_db({Date, {Hour, Minute, Second}}) ->
     {Date, {Hour, Minute, trunc(Second)}}.
 
 
--spec timestamp_to_datetime(timestamp() | timestamp_micro()) -> calendar:datetime().
+-spec timestamp_to_datetime(timestamp()) -> calendar:datetime().
 timestamp_to_datetime(Timestamp) ->
     calendar:now_to_universal_time({Timestamp div 1000000, Timestamp rem 1000000, 0}).
 
 
+-spec timestamp_to_db_datetime(timestamp_micro()) -> db_datetime().
+timestamp_to_db_datetime(Timestamp) ->
+    T = trunc(Timestamp),
+    MicroSecs = Timestamp - T,
+    {D, {H, M, S}} = calendar:now_to_universal_time({T div 1000000, T rem 1000000, 0}),
+    {D, {H, M, S + MicroSecs}}.
+
+
 -spec datetime_to_timestamp(calendar:datetime()) -> timestamp().
 datetime_to_timestamp(DateTime) ->
     % 62167219200 == calendar:datetime_to_gregorian_seconds({{1970, 1, 1}, {0, 0, 0}})
@@ -41,3 +63,29 @@ datetime_to_ISO({{Year, Month, Day}, {Hour, Minute, Second}}) ->
     lists:flatten(
         io_lib:format("~4..0b-~2..0b-~2..0bT~2..0b:~2..0b:~2..0b",
                       [Year, Month, Day, Hour, Minute, trunc(Second)])).
+
+
+-spec add_interval(calendar:datetime(), time_interval()) -> calendar:datetime().
+add_interval(Datetime, {M, month}) ->
+    add_interval(Datetime, {M * 30 * ?DAY, second});
+
+add_interval(Datetime, {W, week}) ->
+    add_interval(Datetime, {W * 7 * ?DAY, second});
+
+add_interval(Datetime, {D, day}) ->
+    add_interval(Datetime, {D * ?DAY, second});
+
+add_interval(Datetime, {H, hour}) ->
+    add_interval(Datetime, {H * 3600, second});
+
+add_interval(Datetime, {M, minute}) ->
+    add_interval(Datetime, {M * 60, second});
+
+add_interval(Datetime, {S, second}) ->
+    T = datetime_to_timestamp(Datetime),
+    timestamp_to_datetime(T + S).
+
+
+-spec subtract_interval(calendar:datetime(), time_interval()) -> calendar:datetime().
+subtract_interval(Datetime, {M, Type}) ->
+    add_interval(Datetime, {-M, Type}).

src/herd_db.erl

@@ -2,7 +2,16 @@
 
 -export([epgsql_res_to_json/1]).
 
--include("herd.hrl").
+-type(json_key() :: atom() | binary()).
+-type(json_value() :: atom() | integer() | float() | binary() | json_obj() | [json_value()]).
+-type(json_obj() :: {[{json_key(), json_value()}]}).
+
+-type(db_name() :: binary()).
+-type(db_type() :: atom()).
+-type(db_value() :: term()).
+-type(db_row() :: tuple()).
+-type(db_column() :: {column, db_name(), db_type(), term(), term(), term()}).
+-type(db_select() :: {ok, [db_column()], [db_row()]}).
 
 
 %%% module API