%% @author Marc Worrell <marc@worrell.nl>
%% @copyright 2016-2022 Marc Worrell
%%
%% @doc Middleware for cowmachine, extra Context based initializations.
%% This starts the https request processing after the site and dispatch rule
%% have been selected by the z_sites_dispatcher middleware.

%% Copyright 2016-2022 Marc Worrell
%%
%% 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.

-module(z_cowmachine_middleware).
-author("Marc Worrell <marc@worrell.nl").

-behaviour(cowboy_middleware).

-export([
    execute/2
]).

-include_lib("../../include/zotonic.hrl").

%% @doc Call cowmachine to handle the request with the given controller. Prepare the
%%      metadata for logger and set the relevant Context arguments.
-spec execute(Req, Env) -> {ok, Req, Env} | {stop, Req}
    when Req::cowboy_req:req(), Env::cowboy_middleware:env().
execute(Req, #{ cowmachine_controller := Controller, cowmachine_controller_options := ControllerOpts } = Env) ->
    Req1 = maybe_overrule_req_headers(Req),
    Context = maps:get(cowmachine_context, Env),
    exometer:update([zotonic, z_context:site(Context), http, requests], 1),
    Context1 = z_context:set(ControllerOpts, Context),
    Context2 = z_context:set_controller_module(Controller, Context1),
    Context3 = z_context:init_cowdata(Req1, Env, Context2),
    Context4 = z_context:set_csp_nonce(Context3),
    Context5 = z_context:set_security_headers(Context4),
    Options = #{
        on_request => fun(Ctx) ->
            erlang:erase(is_dbtrace),
            Ctx1 = case z_context:get_cookie(<<"cotonic-sid">>, Ctx) of
                undefined -> Ctx;
                Sid -> z_context:set_session_id(Sid, Ctx)
            end,
            z_context:logger_md(Ctx1),
            z_notifier:foldl(#middleware{ on = request }, Ctx1, Ctx1)
        end,
        on_welformed => fun(Ctx) ->
            Ctx1 = z_context:ensure_qs(Ctx),
            Ctx2 = case z_context:get_q(<<"zotonic_http_accept">>, Ctx1) of
                undefined -> Ctx1;
                HttpAccept -> set_accept_context(HttpAccept, Ctx1)
            end,
            z_notifier:foldl(#middleware{ on = welformed }, Ctx2, Ctx2)
        end,
        on_handled => fun(Ctx) ->
            z_context:set_req_metrics(#{
                    user_id => z_acl:user(Ctx),
                    session_id => case z_context:session_id(Ctx) of {ok, SessionId} -> SessionId; _ -> undefined end,
                    language => z_context:language(Ctx),
                    timezone => z_context:tz(Ctx)
                }, Ctx),
            z_notifier:foldl(#middleware{ on = handled }, Ctx, Ctx)
        end
    },
    cowmachine:request(Context5, Options).

maybe_overrule_req_headers(#{ bindings := Bindings } = Req) ->
    case maps:get(zotonic_http_accept, Bindings, undefined) of
        undefined -> Req;
        Mime -> set_accept(map_mime(Mime), Req)
    end.

set_accept_context(HttpAccept, Context) ->
    Req = z_context:get_reqdata(Context),
    Req1 = set_accept(map_mime(HttpAccept), Req),
    z_context:set_reqdata(Req1, Context).

set_accept(Value, #{ headers := Headers } = Req) ->
    Hs1 = Headers#{ <<"accept">> => Value },
    Req#{ headers => Hs1 }.


map_mime(<<"bert">>) -> <<"application/x-bert">>;
map_mime(<<"ubf">>)  -> <<"text/x-ubf">>;
map_mime(Mime) ->
    case binary:match(Mime, <<"/">>) of
        nomatch -> hd(mimetypes:ext_to_mimes(Mime));
        _ -> Mime
    end.