OAuth login example

login.erl

%% log in with the request token
%% will return the verifier
login(LoginUrl, User, Pass, RequestToken, Domain) ->
    PostData = build_post_data([
                                {"email", User},
                                {"password", Pass},
                                {"oauth_token", RequestToken}
                               ]),
    Request = {LoginUrl, [], "application/x-www-form-urlencoded", PostData},
    %% turn on cookies
    httpc:set_options([{cookies, enabled}]),
    %% make the log in request
    case httpc:request(post, Request, [{autoredirect, true}, {relaxed, true}], []) of
      {ok, {{_, 302, _}, LoginResponse, _}} ->
          {_,Location} = lists:keyfind("location", 1, LoginResponse),

          NewUrl = string:concat("https://", string:concat(Domain, Location)),
          {ok, {{_, 200, _}, _, Result}} = 
              httpc:request(post, 
                            {NewUrl, [], "application/x-www-form-urlencoded", PostData}, 
                            [{autoredirect, true}], []);
      {ok, {{_, 200, _}, _, Body}} ->
          Result = Body;
      Error ->
          Result = Error,
          erlang:error(Result)
    end,
    get_verifier(Result).

build_post_data(L) ->
    build_post_data(L, "").
build_post_data([], DataString) ->
    string:substr(DataString, 1, string:len(DataString)-1);
build_post_data([{Key, Value}|T], DataString) ->
    ThisString = string:concat(string:concat(string:concat(Key, "="), Value), "&"),
    build_post_data(T, string:concat(DataString, ThisString)).