%% This Source Code Form is subject to the terms of the Mozilla Public
%% License, v. 2.0. If a copy of the MPL was not distributed with this
%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
%%
%% Copyright (c) 2007-2026 Broadcom. All Rights Reserved. The term “Broadcom” refers to Broadcom Inc. and/or its subsidiaries. All rights reserved.
%%

-module(rabbit_mgmt_oauth_bootstrap).

-export([init/2]).
-include("rabbit_mgmt.hrl").
-include_lib("kernel/include/logger.hrl").

%%--------------------------------------------------------------------
%% js/oidc-oauth/bootstrap.js
%% It produces a javascript file with all the oauth2 configuration needed
%% in the client-side of the management ui.
%% This endpoint only accepts GET method.
%%
%% It can work in conjunction with the /login endpoint. If the users are
%% redirected to the home page of the management ui, and eventually to this endpoint,
%% via the /login endpoint is very likely that the request carries a cookie.
%% It can be the <<"access_token">> cookie or the cookies <<"strict_auth_mechanism">>
%% or <<"preferred_auth_mechanism">>.
%% These cookies are consumed by this endpoint and removed afterwards.
%%
%% Additionally, this endpoint may accept users' authentication mechanism preferences
%% via its corresponding header, in addition to the two cookies mentioned above.
%% But not via request parameters. If this endpoint would have accepted request parameters,
%% it would have to use the "Referer" header to extract the original request parameters.
%% It is possible that in some environments, these headers may be dropped before they reach this endpoint.
%% Therefore, users who can only use request parameters, they have to use the /login
%% endpoint instead.

init(Req0, State) ->
    bootstrap_oauth(rabbit_mgmt_headers:set_no_cache_headers(
        rabbit_mgmt_headers:set_common_permission_headers(Req0, ?MODULE), ?MODULE), State).

bootstrap_oauth(Req0, State) ->
    AuthSettings0 = rabbit_mgmt_wm_auth:authSettings(),
    {Req1, AuthSettings} = enrich_oauth_settings(Req0, AuthSettings0),
    Dependencies = oauth_dependencies(),
    {Req2, SetTokenAuth} = set_token_auth(AuthSettings, Req1),
    JSContent = import_dependencies(Dependencies) ++
                set_oauth_settings(AuthSettings) ++
                SetTokenAuth ++
                export_dependencies(Dependencies),

    {ok, cowboy_req:reply(200, #{<<"content-type">> => <<"text/javascript; charset=utf-8">>},
        JSContent, Req2), State}.

enrich_oauth_settings(Req0, AuthSettings) ->
    {Req1, Auth} = get_auth_mechanism(Req0),
    case Auth of 
        undefined -> {Req0, AuthSettings};
        _ ->
            ValidAuth = validate_auth_mechanism(Auth, AuthSettings),
            case ValidAuth of
                {preferred_auth_mechanism, Args} -> {Req1, [{preferred_auth_mechanism, Args} | AuthSettings]};
                {strict_auth_mechanism, Args} -> {Req1, [{strict_auth_mechanism, Args} | AuthSettings]};
                {error, _Reason} -> {Req1, AuthSettings}
            end
    end.
get_auth_mechanism(Req) ->
    case get_auth_mechanism_from_cookies(Req) of
        undefined ->
            case cowboy_req:header(<<"x-", ?MANAGEMENT_LOGIN_STRICT_AUTH_MECHANISM/binary>>, Req) of
                undefined ->
                    case cowboy_req:header(<<"x-", ?MANAGEMENT_LOGIN_PREFERRED_AUTH_MECHANISM/binary>>, Req) of
                        undefined -> {Req, undefined};
                        Val -> {Req, {preferred_auth_mechanism, Val}}
                    end;
                Val -> {Req, {strict_auth_mechanism, Val}}
            end;
        {Type, _} = Auth -> { cowboy_req:set_resp_cookie(term_to_binary(Type),
                                    <<"">>, Req, #{
                                        max_age => 0,
                                        http_only => true,
                                        path => ?OAUTH2_BOOTSTRAP_PATH,
                                        same_site => strict
                                }),
                                Auth
                            }
    end.

get_auth_mechanism_from_cookies(Req) ->
    Cookies = cowboy_req:parse_cookies(Req),
    case proplists:get_value(?MANAGEMENT_LOGIN_STRICT_AUTH_MECHANISM, Cookies) of
        undefined ->
            case proplists:get_value(?MANAGEMENT_LOGIN_PREFERRED_AUTH_MECHANISM, Cookies) of
                undefined -> undefined;
                Val -> {preferred_auth_mechanism, Val}
            end;
        Val -> {strict_auth_mechanism, Val}
    end.
validate_auth_mechanism({Type, <<"oauth2:", Id/binary>>}, AuthSettings) ->
    case maps:is_key(Id, proplists:get_value(oauth_resource_servers, AuthSettings)) of
        true -> {Type, [{type, <<"oauth2">>}, {resource_id, Id}]};
        _ -> {error, {unknown_resource_id, Id}}
    end;
validate_auth_mechanism({Type, <<"basic">>}, _AuthSettings) ->
    {Type, [{type, <<"basic">>}]};
validate_auth_mechanism({_, _}, _AuthSettings) -> {error, unknown_auth_mechanism}.

set_oauth_settings(AuthSettings) ->
    JsonAuthSettings = rabbit_json:encode(rabbit_mgmt_format:prepare_for_encoding(AuthSettings)),
    ["set_oauth_settings(", JsonAuthSettings, ");"].

set_token_auth(AuthSettings, Req0) ->
    case proplists:get_value(oauth_enabled, AuthSettings, false) of
        true ->
            case cowboy_req:parse_header(<<"authorization">>, Req0) of
                {bearer, Token} ->
                    {
                        Req0,
                        ["set_token_auth('", Token, "');"]
                    };
                _ ->
                    Cookies = cowboy_req:parse_cookies(Req0),
                    case proplists:get_value(?OAUTH2_ACCESS_TOKEN, Cookies) of
                         undefined -> {
                                Req0,
                                []
                            };
                        Token ->
                            {
                                cowboy_req:set_resp_cookie(
                                    ?OAUTH2_ACCESS_TOKEN, <<"">>, Req0, #{
                                        max_age => 0,
                                        http_only => true,
                                        path => ?OAUTH2_BOOTSTRAP_PATH,
                                        same_site => strict
                                    }),
                                ["set_token_auth('", Token, "');"]
                            }
                    end
            end;
        false -> {
                Req0,
                []
            }
    end.

import_dependencies(Dependencies) ->
    ["import {", string:join(Dependencies, ","), "} from './helper.js';"].

oauth_dependencies() ->
    ["oauth_initialize_if_required",
        "hasAnyResourceServerReady",
        "oauth_initialize", "oauth_initiate",
        "oauth_initiateLogin",
        "oauth_initiateLogout",
        "oauth_completeLogin",
        "oauth_completeLogout",
        "set_oauth_settings"].

export_dependencies(Dependencies) ->
    [ io_lib:format("window.~s = ~s;", [Dep, Dep]) || Dep <- Dependencies ].
