%%%-------------------------------------------------------------------
%%% @author cheese
%%% @copyright (C) 2015, <COMPANY>
%%% @doc
%%%
%%% @end
%%% Created : 24. Nov 2015 8:22
%%%-------------------------------------------------------------------
-module(http_utilites).
-author("cheese").

%% API
-export([is_valid_client/2, get_current_user_ip/1, is_websocket_request/1, get_header_value/2]).

%% Internal
-export([get_client_ip/2, check_client_ip/2]).

get_current_user_ip(CowboyReq) ->
  {{Client, _Port}, Req1} = cowboy_req:peer(CowboyReq),
  {XRealIP, Req}  = cowboy_req:header(<<"x-real-ip">>,Req1, <<"">>),
  {get_client_ip(XRealIP, Client), Req}.


-spec(is_valid_client(any(), [binary()]) -> {ok, binary(), any()} | {error, binary(), any()}).
is_valid_client(CowboyReq, ValidIpList) ->
  {RealClient, Req} = get_current_user_ip(CowboyReq),
  case check_client_ip(RealClient, ValidIpList) of
    {ok} ->
      {ok, RealClient, Req};
    {error, Reason} ->
      {error, RealClient, Reason}
  end.



%% Internal
get_client_ip(<<>>, Client) ->
  Client;
get_client_ip(XRealIP, _Client) ->
  socket_utilites:parse_ip_from_bytes(XRealIP).


check_client_ip(_ClientIP, []) ->
  {error, access_denied};
check_client_ip(_ClientIP, [all | _OtherIP]) ->
  {ok};
check_client_ip(ClientIP, [ClientIP | _OtherIP]) ->
  {ok};
check_client_ip(ClientIP, [_IP | OtherIP]) ->
  check_client_ip(ClientIP, OtherIP).


-spec(is_websocket_request(term()) -> {true | false, term()}).
is_websocket_request(Req) ->
  {AllHeaders, Req2} = cowboy_req:headers(Req),
  Value = get_header_value(<<"UPGRADE">>, AllHeaders),
  case list_to_binary(string:to_upper(binary_to_list(Value))) of
    <<"WEBSOCKET">> ->
      {true, Req2};
    _ ->
      {false, Req2}
  end.

-spec(get_header_value(binary(), [{term(), term()}]) -> binary()).
get_header_value(_Name, []) ->
  <<>>;
get_header_value(Name, [{Key, Val} | Tail]) ->
  KeyUpper = list_to_binary(string:to_upper(binary_to_list(Key))),
  case bytes_extension:are_equal(KeyUpper, Name) of
    true ->
      Val;
    _ ->
      get_header_value(Name, Tail)
  end.