%% Copyright (c) 2011-2017, 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.
%% Handler middleware.
%%
%% Execute the handler given by the <em>handler</em> and <em>handler_opts</em>
%% environment values. The result of this execution is added to the
%% environment under the <em>result</em> value.
-module(cowboy_handler).
-behaviour(cowboy_middleware).
-export([execute/2]).
-export([terminate/4]).
-callback init(Req, any())
-> {ok | module(), Req, any()}
| {module(), Req, any(), any()}
when Req::cowboy_req:req().
-callback terminate(any(), map(), any()) -> ok.
-optional_callbacks([terminate/3]).
-spec execute(Req, Env) -> {ok, Req, Env}
when Req::cowboy_req:req(), Env::cowboy_middleware:env().
execute(Req, Env=#{handler := Handler, handler_opts := HandlerOpts}) ->
try Handler:init(Req, HandlerOpts) of
{ok, Req2, State} ->
Result = terminate(normal, Req2, State, Handler),
{ok, Req2, Env#{result => Result}};
{Mod, Req2, State} ->
Mod:upgrade(Req2, Env, Handler, State);
{Mod, Req2, State, Opts} ->
Mod:upgrade(Req2, Env, Handler, State, Opts)
catch Class:Reason:Stacktrace ->
terminate({crash, Class, Reason}, Req, HandlerOpts, Handler),
erlang:raise(Class, Reason, Stacktrace)
end.
-spec terminate(any(), Req | undefined, any(), module()) -> ok when Req::cowboy_req:req().
terminate(Reason, Req, State, Handler) ->
case erlang:function_exported(Handler, terminate, 3) of
true ->
Handler:terminate(Reason, Req, State);
false ->
ok
end.
