%% Copyright (c) 2023, Loïc Hoguin <essen@ninenines.eu>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

%% QUIC transport using the emqx/quicer NIF.

-module(cowboy_quicer).

%% Connection.
-export([peername/1]).
-export([sockname/1]).
-export([peercert/1]).
-export([shutdown/2]).

%% Streams.
-export([start_unidi_stream/2]).
-export([send/3]).
-export([send/4]).
-export([shutdown_stream/4]).

%% Messages.
-export([handle/1]).

-ifndef(COWBOY_QUICER).

-spec peername(_) -> no_return().
peername(_) -> no_quicer().

-spec sockname(_) -> no_return().
sockname(_) -> no_quicer().

-spec peercert(_) -> no_return().
peercert(_) -> no_quicer().

-spec shutdown(_, _) -> no_return().
shutdown(_, _) -> no_quicer().

-spec start_unidi_stream(_, _) -> no_return().
start_unidi_stream(_, _) -> no_quicer().

-spec send(_, _, _) -> no_return().
send(_, _, _) -> no_quicer().

-spec send(_, _, _, _) -> no_return().
send(_, _, _, _) -> no_quicer().

-spec shutdown_stream(_, _, _, _) -> no_return().
shutdown_stream(_, _, _, _) -> no_quicer().

-spec handle(_) -> no_return().
handle(_) -> no_quicer().

no_quicer() ->
	error({no_quicer,
		"Cowboy must be compiled with environment variable COWBOY_QUICER=1 "
		"or with compilation flag -D COWBOY_QUICER=1 in order to enable "
		"QUIC support using the emqx/quic NIF"}).

-else.

%% @todo Make quicer export these types.
-type quicer_connection_handle() :: reference().
-export_type([quicer_connection_handle/0]).

-type quicer_app_errno() :: non_neg_integer().

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

%% Connection.

-spec peername(quicer_connection_handle())
	-> {ok, {inet:ip_address(), inet:port_number()}}
	| {error, any()}.

peername(Conn) ->
	quicer:peername(Conn).

-spec sockname(quicer_connection_handle())
	-> {ok, {inet:ip_address(), inet:port_number()}}
	| {error, any()}.

sockname(Conn) ->
	quicer:sockname(Conn).

-spec peercert(quicer_connection_handle())
	-> {ok, public_key:der_encoded()}
	| {error, any()}.

peercert(Conn) ->
  quicer_nif:peercert(Conn).

-spec shutdown(quicer_connection_handle(), quicer_app_errno())
	-> ok | {error, any()}.

shutdown(Conn, ErrorCode) ->
	quicer:shutdown_connection(Conn,
		?QUIC_CONNECTION_SHUTDOWN_FLAG_NONE,
		ErrorCode).

%% Streams.

-spec start_unidi_stream(quicer_connection_handle(), iodata())
	-> {ok, cow_http3:stream_id()}
	| {error, any()}.

start_unidi_stream(Conn, HeaderData) ->
	case quicer:start_stream(Conn, #{
			active => true,
			open_flag => ?QUIC_STREAM_OPEN_FLAG_UNIDIRECTIONAL}) of
		{ok, StreamRef} ->
			case quicer:send(StreamRef, HeaderData) of
				{ok, _} ->
					{ok, StreamID} = quicer:get_stream_id(StreamRef),
					put({quicer_stream, StreamID}, StreamRef),
					{ok, StreamID};
				Error ->
					Error
			end;
		{error, Reason1, Reason2} ->
			{error, {Reason1, Reason2}};
		Error ->
			Error
	end.

-spec send(quicer_connection_handle(), cow_http3:stream_id(), iodata())
	-> ok | {error, any()}.

send(Conn, StreamID, Data) ->
	send(Conn, StreamID, Data, nofin).

-spec send(quicer_connection_handle(), cow_http3:stream_id(), iodata(), cow_http:fin())
	-> ok | {error, any()}.

send(_Conn, StreamID, Data, IsFin) ->
	StreamRef = get({quicer_stream, StreamID}),
	Size = iolist_size(Data),
	case quicer:send(StreamRef, Data, send_flag(IsFin)) of
		{ok, Size} ->
			ok;
		{error, Reason1, Reason2} ->
			{error, {Reason1, Reason2}};
		Error ->
			Error
	end.

send_flag(nofin) -> ?QUIC_SEND_FLAG_NONE;
send_flag(fin) -> ?QUIC_SEND_FLAG_FIN.

-spec shutdown_stream(quicer_connection_handle(),
	cow_http3:stream_id(), both | receiving, quicer_app_errno())
	-> ok.

shutdown_stream(_Conn, StreamID, Dir, ErrorCode) ->
	StreamRef = get({quicer_stream, StreamID}),
	_ = quicer:shutdown_stream(StreamRef, shutdown_flag(Dir), ErrorCode, infinity),
	ok.

shutdown_flag(both) -> ?QUIC_STREAM_SHUTDOWN_FLAG_ABORT;
shutdown_flag(receiving) -> ?QUIC_STREAM_SHUTDOWN_FLAG_ABORT_RECEIVE.

%% Messages.

%% @todo Probably should have the Conn given as argument too?
-spec handle({quic, _, _, _})
	-> {data, cow_http3:stream_id(), cow_http:fin(), binary()}
	| {stream_started, cow_http3:stream_id(), unidi | bidi}
	| {stream_closed, cow_http3:stream_id(), quicer_app_errno()}
	| closed
	| ok
	| unknown
	| {socket_error, any()}.

handle({quic, Data, StreamRef, #{flags := Flags}}) when is_binary(Data) ->
	{ok, StreamID} = quicer:get_stream_id(StreamRef),
	IsFin = case Flags band ?QUIC_RECEIVE_FLAG_FIN of
		?QUIC_RECEIVE_FLAG_FIN -> fin;
		_ -> nofin
	end,
	{data, StreamID, IsFin, Data};
%% QUIC_CONNECTION_EVENT_PEER_STREAM_STARTED.
handle({quic, new_stream, StreamRef, #{flags := Flags}}) ->
	case quicer:setopt(StreamRef, active, true) of
		ok ->
			{ok, StreamID} = quicer:get_stream_id(StreamRef),
			put({quicer_stream, StreamID}, StreamRef),
			StreamType = case quicer:is_unidirectional(Flags) of
				true -> unidi;
				false -> bidi
			end,
			{stream_started, StreamID, StreamType};
		{error, Reason} ->
			{socket_error, Reason}
	end;
%% QUIC_STREAM_EVENT_SHUTDOWN_COMPLETE.
handle({quic, stream_closed, StreamRef, #{error := ErrorCode}}) ->
	{ok, StreamID} = quicer:get_stream_id(StreamRef),
	{stream_closed, StreamID, ErrorCode};
%% QUIC_CONNECTION_EVENT_SHUTDOWN_COMPLETE.
handle({quic, closed, Conn, _Flags}) ->
	_ = quicer:close_connection(Conn),
	closed;
%% The following events are currently ignored either because
%% I do not know what they do or because we do not need to
%% take action.
handle({quic, streams_available, _Conn, _Props}) ->
	ok;
handle({quic, dgram_state_changed, _Conn, _Props}) ->
	ok;
%% QUIC_CONNECTION_EVENT_SHUTDOWN_INITIATED_BY_TRANSPORT
handle({quic, transport_shutdown, _Conn, _Flags}) ->
	ok;
handle({quic, peer_send_shutdown, _StreamRef, undefined}) ->
	ok;
handle({quic, send_shutdown_complete, _StreamRef, _IsGraceful}) ->
	ok;
handle({quic, shutdown, _Conn, success}) ->
	ok;
handle(_Msg) ->
	unknown.

-endif.