%%
%% %CopyrightBegin%
%%
%% SPDX-License-Identifier: Apache-2.0
%%
%% Copyright Ericsson AB 2015-2025. All Rights Reserved.
%%
%% 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.
%%
%% %CopyrightEnd%
%%
%%
-module(httpd_custom).
-moduledoc false.

-export([response_header/1, request_header/1, response_default_headers/0]).
-export([customize_headers/3, response_default_headers/1]).

-include("../inets_app/inets_internal.hrl").

-behaviour(httpd_custom_api).

%%--------------------------------------------------------------------
%% Behavior API -----------------------------------
%%--------------------------------------------------------------------

response_header(Header) -> 
    {true, httpify(Header)}.
request_header(Header) -> 
    {true, Header}.
response_default_headers() ->
    [].

%%--------------------------------------------------------------------
%% Internal API  -----------------------------------
%%--------------------------------------------------------------------
customize_headers(?MODULE, Function, Arg) ->
    ?MODULE:Function(Arg);
customize_headers(Module, Function, Arg) ->
    try Module:Function(Arg) of
	{true, Value} ->
	    ?MODULE:Function(Value);
	false ->
	    false
    catch
	_:_ ->
	    ?MODULE:Function(Arg)
    end.

response_default_headers(?MODULE) ->
    response_default_headers();
response_default_headers(Module) ->
    try Module:response_default_headers() of
	Defaults ->
	    [{http_util:to_lower(Key), Value} ||  {Key, Value} <- Defaults, 
						  is_list(Key), is_list(Value)]
    catch
	_:_ ->
	    ?MODULE:response_default_headers()
    end.
%%--------------------------------------------------------------------
%% Internal functions -----------------------------------
%%--------------------------------------------------------------------
httpify({Key0, Value}) ->
    %% make sure first letter is capital (defacto standard)
    Words1 = string:tokens(Key0, "-"),
    Words2 = upify(Words1, []),
    Key    = new_key(Words2),
    Key ++ ": " ++ Value ++ ?CRLF .

new_key([]) ->
    "";
new_key([W]) ->
    W;
new_key([W1,W2]) ->
    W1 ++ "-" ++ W2;
new_key([W|R]) ->
    W ++ "-" ++ new_key(R).
    
upify([], Acc) ->
    lists:reverse(Acc);
upify([Key|Rest], Acc) ->
    upify(Rest, [upify2(Key)|Acc]).

upify2([C|Rest]) when (C >= $a) andalso (C =< $z) ->
    [C-($a-$A)|Rest];
upify2(Str) ->
    Str.
