%%%-------------------------------------------------------------------
%% @doc Logout from the OpenID Provider
%% @end
%% @since 3.0.0
%%%-------------------------------------------------------------------
-module(oidcc_logout).

-feature(maybe_expr, enable).

-include("oidcc_client_context.hrl").
-include("oidcc_provider_configuration.hrl").
-include("oidcc_token.hrl").

-export([initiate_url/3]).

-export_type([error/0]).
-export_type([initiate_url_opts/0]).

-type error() :: end_session_endpoint_not_supported.

-type initiate_url_opts() :: #{
    logout_hint => binary(),
    post_logout_redirect_uri => uri_string:uri_string(),
    state => binary(),
    ui_locales => binary(),
    extra_query_params => oidcc_http_util:query_params()
}.
%% Configure Relaying Party initiated Logout URI
%%
%% See [https://openid.net/specs/openid-connect-rpinitiated-1_0.html#RPLogout]
%%
%% <h2>Parameters</h2>
%%
%% <ul>
%%   <li>`logout_hint' - logout_hint to pass to the provider</li>
%%   <li>`post_logout_redirect_uri' - Post Logout Redirect URI to pass to the
%%     provider</li>
%%   <li>`state' - state to pass to the provider</li>
%%   <li>`ui_locales' - UI locales to pass to the provider</li>
%%   <li>`extra_query_params' - extra query params to add to the uri</li>
%% </ul>

%% @doc
%% Initiate URI for Relaying Party initated Logout
%%
%% See [https://openid.net/specs/openid-connect-rpinitiated-1_0.html#RPLogout]
%%
%% For a high level interface using {@link oidcc_provider_configuration_worker}
%% see {@link oidcc:initiate_logout_url/4}.
%%
%% <h2>Examples</h2>
%%
%% ```
%% {ok, ClientContext} = oidcc_client_context:from_configuration_worker(
%%   provider_name,
%%   <<"client_id">>,
%%   unauthenticated
%% ),
%%
%% %% Get `Token` from `oidcc_token`
%%
%% {ok, RedirectUri} =
%%   oidcc_logout:initiate_url(
%%     Token,
%%     ClientContext,
%%     #{post_logout_redirect_uri: <<"https://my.server/return"}
%% ),
%%
%% %% RedirectUri = https://my.provider/logout?id_token_hint=IDToken&client_id=ClientId&post_logout_redirect_uri=https%3A%2F%2Fmy.server%2Freturn
%% '''
%% @end
%% @since 3.0.0
-spec initiate_url(Token, ClientContext, Opts) ->
    {ok, uri_string:uri_string()} | {error, error()}
when
    Token :: IdToken | oidcc_token:t() | undefined,
    IdToken :: binary(),
    ClientContext :: oidcc_client_context:t(),
    Opts :: initiate_url_opts().
initiate_url(#oidcc_token{id = #oidcc_token_id{token = IdToken}}, ClientContext, Opts) ->
    initiate_url(IdToken, ClientContext, Opts);
initiate_url(IdToken, ClientContext, Opts) ->
    #oidcc_client_context{
        provider_configuration = Configuration,
        client_id = ClientId
    } = ClientContext,
    #oidcc_provider_configuration{end_session_endpoint = EndSessionEndpoint} =
        Configuration,

    QueryParams0 = [
        {"id_token_hint", IdToken},
        {"logout_hint", maps:get(logout_hint, Opts, undefined)},
        {"client_id", ClientId},
        {"post_logout_redirect_uri", maps:get(post_logout_redirect_uri, Opts, undefined)},
        {"state", maps:get(state, Opts, undefined)},
        {"ui_locales", maps:get(ui_locales, Opts, undefined)}
        | maps:get(extra_query_params, Opts, [])
    ],
    QueryParams1 = lists:filter(
        fun
            ({_Name, undefined}) -> false;
            ({_Name, _Value}) -> true
        end,
        QueryParams0
    ),

    case EndSessionEndpoint of
        undefined ->
            {error, end_session_endpoint_not_supported};
        Uri0 ->
            UriMap0 = uri_string:parse(Uri0),
            QueryString0 = maps:get(query, UriMap0, <<"">>),
            QueryParams = uri_string:dissect_query(QueryString0) ++ QueryParams1,
            QueryString = uri_string:compose_query(QueryParams),
            UriMap = maps:put(query, QueryString, UriMap0),
            Uri = uri_string:recompose(UriMap),
            {ok, Uri}
    end.