% Copyright (c) 2025 Onomondo ApS & sysmocom - s.f.m.c. GmbH. All rights reserved.
%
% SPDX-License-Identifier: AGPL-3.0-only
%
% Author: Harald Welte <hwelte@sysmocom.de> / sysmocom - s.f.m.c. GmbH

-module(esipa_middleware).
-behaviour(cowboy_middleware).

-export([execute/2]).

% "X-Admin-Protocol" header field SHALL be set to v2.1.0 in both HTTP request and HTTP response.
% Content-Type: "application/x-gsmsa-rsp-asn1" or "application/json;charset=UTF-8"

execute(Req0 = #{method := <<"POST">>}, State) ->
    case cowboy_req:header(<<"x-admin-protocol">>, Req0) of
        <<"gsma/rsp/v2.1.0">> ->
            {ok, Req0, State};
        Protocol ->
            logger:error(
                "Rejecting incompatible ESipa request: ~s,~nProtocol=~p, Peer=~p, Pid=~p~n",
                [maps:get(path, Req0), Protocol, maps:get(peer, Req0), maps:get(pid, Req0)]
            ),
            Req = cowboy_req:reply(400, #{}, <<"Unsupported x-admin-protocol">>, Req0),
            {stop, Req}
    end;
execute(Req0, Env) ->
    {ok, Req0, Env}.