unshort_srv.erl

%%%-------------------------------------------------------------------
%%% File:      unshort_srv.erl
%%% @author    Sergio Veiga <> []
%%% @copyright 2010 Sergio Veiga
%%% @doc  A simple Server to retrieve the original url from a short one
%%%
%%% @end  
%%%
%%% @since 2010-02-21 by Sergio Veiga
%%%-------------------------------------------------------------------
-module(unshort_srv).
-author('Sergio Veiga').
-behaviour(gen_server).

%% API
-export([start_link/0,unshort/1]).

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

-record(state, {}).

%%====================================================================
%% API
%%====================================================================

%%--------------------------------------------------------------------
%% @spec start_link() -> {ok,Pid} | ignore | {error,Error}
%% @doc Starts the server
%% @end 
%%--------------------------------------------------------------------
start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).


%%--------------------------------------------------------------------
%% @spec unshort() -> {ok,Url} | {error,Error}
%% @doc Returns the "long" url
%% @end 
%%--------------------------------------------------------------------
unshort(Url)->
    gen_server:call(?MODULE,{unshort,Url}).

%%====================================================================
%% gen_server callbacks
%%====================================================================

init([]) ->
    inets:start(),
    {ok, #state{}}.


handle_call({unshort,Url}, _From, State) ->
    Reply = case http:request(head,{Url,[]},[{autoredirect, false}],[]) of
        {ok, {{_Version, 200, _ReasonPhrase}, _Headers, _Body}}-> 
            {ok,Url};
        {ok, {{_Version, Code, _ReasonPhrase}, Headers, _Body}}->     
            case proplists:get_value("location",Headers) of
                undefined ->
                    {error,"HTTP CODE ERROR : "++Code};
                ShortUrl->
                    {ok,ShortUrl}
            end;
        {error,Error}->
            {error,Error}
        
    end,
    {reply, Reply, State}.

handle_cast(_Msg, State) ->
    {noreply, State}.
    
handle_info(_Info, State) ->
    {noreply, State}.
    
terminate(_Reason, _State) ->
    ok.

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