-module(mod_acme).

-behaviour(gen_server).

%% API
-export([ start/0
        , stop/1
        %% I tried to follow the naming convention found in the acme spec
        , directory/2
        , new_nonce/2
        %% Account
        , new_account/2
        , update_account/2
        , account_info/2   %% TODO: Maybe change to get_account
        , account_key_change/2
        , deactivate_account/2
        %% Orders/Certificates
        , new_order/2
        , new_authz/2
        , get_certificate/2
        , get_authz/2
        , complete_challenge/2
        , deactivate_authz/2
        , revoke_cert/2]).

-export([init/1, handle_call/3, handle_cast/2,
         handle_info/2, terminate/2, code_change/3]).

-export([scenario/0]).

-include("ejabberd.hrl").
-include("logger.hrl").

-include("xmpp.hrl").

% -define(CA_URL, "https://acme-v01.api.letsencrypt.org").
-define(CA_URL, "https://acme-staging.api.letsencrypt.org").

-define(DEFAULT_DIRECTORY, ?CA_URL ++ "/directory").

-define(DEFAULT_NEW_NONCE, ?CA_URL ++ "/acme/new_nonce").

-record(state, {
        ca_url  = ?CA_URL :: list(),
        dir_url = ?DEFAULT_DIRECTORY :: list(),
        dirs = maps:new() 
        }).

%% This will be initially just be filled with stub functions

start() ->
    gen_server:start(?MODULE, [], []).

stop(Pid) ->
    gen_server:stop(Pid).

%% Stub functions
directory(Pid, Options) ->
    gen_server:call(Pid, ?FUNCTION_NAME).

new_nonce(Pid, Options) ->
    gen_server:call(Pid, ?FUNCTION_NAME).

new_account(Pid, Options) ->
    gen_server:call(Pid, ?FUNCTION_NAME).

update_account(Pid, Options) ->
    ok.

account_info(Pid, Options) ->
    ok.

account_key_change(Pid, Options) ->
    ok.

deactivate_account(Pid, Options) ->
    ok.

new_order(Pid, Options) ->
    ok.

new_authz(Pid, Options) ->
    ok.

get_certificate(Pid, Options) ->
    ok.

get_authz(Pid, Options) ->
    ok.

complete_challenge(Pid, Options) ->
    ok.

deactivate_authz(Pid, Options) ->
    ok.

revoke_cert(Pid, Options) ->
    ok.



%% GEN SERVER

init([]) ->
    %% TODO: Not the correct way of doing it
    ok = application:start(inets),
    ok = application:start(crypto),
    ok = application:start(asn1),
    ok = application:start(public_key),
    ok = application:start(ssl),

    ok = application:start(base64url),
    ok = application:start(jose),

    {ok, #state{}}.

handle_call(directory, _From, S = #state{dir_url=Url, dirs=Dirs}) ->
    %% Make the get request
    {ok, {_Status, _Head, Body}} = httpc:request(get, {Url, []}, [], []),

    %% Decode the json string
    Result = jiffy:decode(Body),
    {Directories} = Result,
    StrDirectories = [{bitstring_to_list(X), bitstring_to_list(Y)} || 
                        {X,Y} <- Directories],

    %% Update the directories in state
    %% TODO: Get the merge of the old and the new dictionary
    NewDirs = maps:from_list(StrDirectories),
    % io:format("New directories: ~p~n", [NewDirs]),
    
    {reply, {ok, Result}, S#state{dirs = NewDirs}};
handle_call(new_nonce, _From, S = #state{dirs=Dirs}) ->
    %% Get url from all directories
    #{"new_nonce" := Url} = Dirs,
    {ok, {Status, Head, []}} = 
        httpc:request(head, {Url, []}, [], []),
    {reply, {ok, {Status, Head}}, S};
handle_call(new_account, _From, S = #state{ca_url = Ca, dirs=Dirs}) ->
    %% Get url from all directories
    #{"new-reg" := Url} = Dirs,

    %% Make the request body
    ReqBody = jiffy:encode({[]}),

    %% Jose
    % SignedBody = sign_a_json_object_using_jose(ReqBody),

    {ok, {Status, Head, Body}} = 
        httpc:request(post, {Url, [], "application/jose+json", ReqBody}, [], []),
    {reply, {ok, {Status, Head, Body}}, S};    
handle_call(stop, _From, State) ->
    {stop, normal, ok, State}.

handle_cast(Msg, State) ->
    ?WARNING_MSG("unexpected cast: ~p", [Msg]),
    {noreply, State}.

handle_info(_Info, State) -> 
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

code_change(_OldVsn, State, _Extra) -> 
    {ok, State}.

%% Util functions

final_url(Urls) ->
    Joined = lists:join("/", Urls),
    lists:flatten(Joined).



%% Test

sign_a_json_object_using_jose(Json) ->
    % Generate a key for now
    Key = jose_jwk:generate_key({okp, 'Ed448'}),
    io:format("Key: ~p~n", [Key]),

    % Jws object containing the algorithm
    JwsObj = jose_jws:from(#{<<"alg">> => <<"Ed448">>}),
    io:format("Jws: ~p~n", [JwsObj]),

    %% Signed Message
    Signed = jose_jws:sign(Key, Json, JwsObj),
    io:format("Signed: ~p~n", [Signed]),    

    %% Compact Message
    Compact = jose_jws:compact(Signed),
    io:format("Compact: ~p~n", [Compact]),    

    %% Verify
    io:format("Verify: ~p~n", [jose_jws:verify(Key, Signed)]),
    Signed.

scenario() ->
    {ok, Pid} = start(),
    io:format("Server started: ~p~n", [Pid]),

    {ok, Result} = directory(Pid, []),
    io:format("Directory result: ~p~n", [Result]),

    {ok, Result1} = new_account(Pid, []),
    io:format("New account result: ~p~n", [Result1]),
    ok.