%% Copyright (c) 2011-2012, Loïc Hoguin <[email protected]>
%%
%% 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.
-module(bullet_handler).
-behaviour(cowboy_http_handler).
-behaviour(cowboy_websocket_handler).
-export([init/3]).
-export([handle/2]).
-export([info/3]).
-export([terminate/3]).
-export([websocket_init/3]).
-export([websocket_handle/3]).
-export([websocket_info/3]).
-export([websocket_terminate/3]).
-record(state, {
handler :: module(),
handler_state :: term(),
% poll or eventsource for GET requests
get_mode :: 'undefined' | 'poll' | 'eventsource',
timeout = infinity :: timeout()
}).
%% HTTP.
init(Transport, Req, Opts) ->
case cowboy_req:header(<<"upgrade">>, Req) of
{undefined, Req2} ->
{Method, Req3} = cowboy_req:method(Req2),
init(Transport, Req3, Opts, Method);
{Bin, Req2} when is_binary(Bin) ->
case cowboy_bstr:to_lower(Bin) of
<<"websocket">> ->
{upgrade, protocol, cowboy_websocket};
_Any ->
{ok, Req3} = cowboy_req:reply(501, [], [], Req2),
{shutdown, Req3, undefined}
end
end.
init(Transport, Req, Opts, <<"GET">>) ->
{handler, Handler} = lists:keyfind(handler, 1, Opts),
Timeout = get_value(timeout, Opts, 60000),
State = #state{handler=Handler},
{GetMode, Req2} = get_mode(Req),
Active = case GetMode of
poll -> once;
eventsource -> true
end,
case Handler:init(Transport, Req2, Opts, Active) of
{ok, Req3, HandlerState} ->
{ok, Req4} = start_get_mode(GetMode, Req3),
Req5 = cowboy_req:compact(Req4),
{loop, Req5, State#state{handler_state=HandlerState,
get_mode=GetMode}, Timeout, hibernate};
{shutdown, Req3, HandlerState} ->
{shutdown, Req3, State#state{handler_state=HandlerState}}
end;
init(Transport, Req, Opts, <<"POST">>) ->
{handler, Handler} = lists:keyfind(handler, 1, Opts),
State = #state{handler=Handler},
case Handler:init(Transport, Req, Opts, false) of
{ok, Req2, HandlerState} ->
{ok, Req2, State#state{handler_state=HandlerState}};
{shutdown, Req2, HandlerState} ->
{shutdown, Req2, State#state{handler_state=HandlerState}}
end;
init(_Transport, Req, _Opts, _Method) ->
{ok, Req2} = cowboy_req:reply(405, [], [], Req),
{shutdown, Req2, undefined}.
handle(Req, State) ->
{Method, Req2} = cowboy_req:method(Req),
handle(Req2, State, Method).
handle(Req, State=#state{handler=Handler, handler_state=HandlerState},
<<"POST">>) ->
case cowboy_req:body(Req) of
{ok, Data, Req2} ->
case Handler:stream(Data, Req2, HandlerState) of
{ok, Req3, HandlerState2} ->
{ok, Req3, State#state{handler_state=HandlerState2}};
{reply, Reply, Req3, HandlerState2} ->
{ok, Req4} = cowboy_req:reply(200, [], Reply, Req3),
{ok, Req4, State#state{handler_state=HandlerState2}}
end;
{error, _} ->
%% An error occurred, stop there.
{ok, Req, State}
end.
info(Message, Req,
State=#state{get_mode=GetMode, handler=Handler,
handler_state=HandlerState}) ->
case Handler:info(Message, Req, HandlerState) of
{ok, Req2, HandlerState2} ->
{loop, Req2, State#state{handler_state=HandlerState2}, hibernate};
{shutdown, Req2, HandlerState2} ->
State2 = State#state{handler_state=HandlerState2},
{ok, Req3} = shutdown_get_mode(GetMode, Req2),
{ok, Req3, State2};
{reply, Data, Req2, HandlerState2} ->
State2 = State#state{handler_state=HandlerState2},
case reply_get_mode(GetMode, Data, Req2) of
{ok, Req3} ->
{ok, Req3, State2};
{loop, Req3} ->
{loop, Req3, State2, hibernate}
end
end.
terminate(_Reason, _Req, undefined) ->
ok;
terminate(_Reason, Req, #state{handler=Handler, handler_state=HandlerState}) ->
Handler:terminate(Req, HandlerState).
%% Websocket.
websocket_init(Transport, Req, Opts) ->
{handler, Handler} = lists:keyfind(handler, 1, Opts),
Timeout = get_value(timeout, Opts, 60000),
State = #state{handler=Handler},
case Handler:init(Transport, Req, Opts, true) of
{ok, Req2, HandlerState} ->
Req3 = cowboy_req:compact(Req2),
{ok, Req3, State#state{handler_state=HandlerState},
Timeout, hibernate};
{shutdown, Req2, _HandlerState} ->
{shutdown, Req2}
end.
websocket_handle({text, Data}, Req,
State=#state{handler=Handler, handler_state=HandlerState}) ->
case Handler:stream(Data, Req, HandlerState) of
{ok, Req2, HandlerState2} ->
{ok, Req2, State#state{handler_state=HandlerState2}, hibernate};
{reply, Reply, Req2, HandlerState2} ->
{reply, {text, Reply}, Req2,
State#state{handler_state=HandlerState2}, hibernate};
{shutdown, Req2, HandlerState2} ->
{shutdown, Req2, State#state{handler_state=HandlerState2}}
end;
websocket_handle(_Frame, Req, State) ->
{ok, Req, State, hibernate}.
websocket_info(Info, Req, State=#state{
handler=Handler, handler_state=HandlerState}) ->
case Handler:info(Info, Req, HandlerState) of
{ok, Req2, HandlerState2} ->
{ok, Req2, State#state{handler_state=HandlerState2}, hibernate};
{reply, Reply, Req2, HandlerState2} ->
{reply, {text, Reply}, Req2,
State#state{handler_state=HandlerState2}, hibernate};
{shutdown, Req2, HandlerState2} ->
{shutdown, Req2, State#state{handler_state=HandlerState2}}
end.
websocket_terminate(_Reason, Req,
#state{handler=Handler, handler_state=HandlerState}) ->
Handler:terminate(Req, HandlerState).
%% Eventsource and poll utilities
get_mode(Req) ->
case cowboy_req:parse_header(<<"accept">>, Req) of
{ok, Accepts, Req2} ->
get_mode(Accepts, Req2);
_ ->
{poll, Req}
end.
get_mode([{{<<"text">>, <<"event-stream">>, _}, _, _}|_], Req) ->
{eventsource, Req};
get_mode([_|Accepts], Req) ->
get_mode(Accepts, Req);
get_mode([], Req) ->
{poll, Req};
get_mode(undefined, Req) ->
{poll, Req}.
start_get_mode(poll, Req) ->
{ok, Req};
start_get_mode(eventsource, Req) ->
Headers = [{<<"content-type">>, <<"text/event-stream">>}],
{ok, _} = cowboy_req:chunked_reply(200, Headers, Req).
shutdown_get_mode(poll, Req) ->
cowboy_req:reply(204, [], <<"">>, Req);
shutdown_get_mode(eventsource, Req) ->
{ok, Req}.
reply_get_mode(poll, Data, Req) ->
{ok, _} = cowboy_req:reply(200, [], Data, Req);
reply_get_mode(eventsource, Data, Req) ->
Bin = iolist_to_binary(Data),
Event = [[<<"data: ">>, Line, <<"\n">>] ||
Line <- binary:split(Bin, [<<"\r\n">>, <<"\r">>, <<"\n">>], [global])],
ok = cowboy_req:chunk([Event, <<"\n">>], Req),
{loop, Req}.
%% Internal.
%% @doc Faster alternative to proplists:get_value/3.
%% @private
get_value(Key, Opts, Default) ->
case lists:keyfind(Key, 1, Opts) of
{_, Value} -> Value;
_ -> Default
end.
