%%% @hidden
%%% @doc Storage backend for PostgreSQL.
%%%
%%% Copyright 2012 Inaka <hello@inaka.net>
%%%
%%% Licensed under the Apache License, Version 2.0 (the "License");
%%% you may not use this file except in compliance with the License.
%%% You may obtain a copy of the License at
%%%
%%%     http://www.apache.org/licenses/LICENSE-2.0
%%%
%%% Unless required by applicable law or agreed to in writing, software
%%% distributed under the License is distributed on an "AS IS" BASIS,
%%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%%% See the License for the specific language governing permissions and
%%% limitations under the License.
%%% @end
%%% @copyright Inaka <hello@inaka.net>
%%%
-module(sumo_backend_pgsql).
-author("Juan Facorro <juan.facorro@inakanetworks.com>").

-behaviour(gen_server).
-behaviour(sumo_backend).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Exports.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%% Public API.
-export([
         get_connection/1
        ]).

%%% Exports for sumo_backend
-export([
         start_link/2
        ]).

%%% Exports for gen_server
-export([
         init/1,
         handle_call/3,
         handle_cast/2,
         handle_info/2,
         terminate/2,
         code_change/3
        ]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Types.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-type state() :: #{}.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% External API.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-spec start_link(atom(), proplists:proplist()) -> {ok, pid()}|term().
start_link(Name, Options) ->
  gen_server:start_link({local, Name}, ?MODULE, Options, []).

-spec get_connection(atom() | pid()) -> atom().
get_connection(Name) ->
  gen_server:call(Name, get_connection).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% gen_server stuff.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-spec init([term()]) -> {ok, state()}.
init(Options) ->
  Host     = proplists:get_value(host,     Options, "localhost"),
  Username = proplists:get_value(username, Options),
  Password = proplists:get_value(password, Options),
  Opts = [{port,     proplists:get_value(port,     Options, 5432)},
          {database, proplists:get_value(database, Options)}],

  {ok, #{host => Host, user => Username, pass => Password, opts => Opts}}.

-spec handle_call(term(), term(), state()) -> {reply, term(), state()}.
handle_call(get_connection, _From, State) ->
  #{ host := Host
   , user := Username
   , pass := Password
   , opts := Opts} = State,
  {ok, Conn} = epgsql:connect(Host, Username, Password, Opts),
  {reply, Conn, State}.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%% Unused Callbacks
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

-spec handle_cast(term(), state()) -> {noreply, state()}.
handle_cast(_Msg, State) -> {noreply, State}.

-spec handle_info(term(), state()) -> {noreply, state()}.
handle_info(_Msg, State) -> {noreply, State}.

-spec terminate(term(), state()) -> ok.
terminate(_Reason, _State) -> ok.

-spec code_change(term(), state(), term()) -> {ok, state()}.
code_change(_OldVsn, State, _Extra) -> {ok, State}.