%% @author Bob Ippolito <bob@mochimedia.com>
%% @copyright 2007 Mochi Media, Inc.

%% @doc HTTP server.

-module(mochiweb_http).
-author('bob@mochimedia.com').
-export([start/1, start_link/1, stop/0, stop/1]).
-export([loop/3]).
-export([after_response/2, reentry/1]).
-export([parse_range_request/1, range_skip_length/2]).

-define(REQUEST_RECV_TIMEOUT, 300000).   %% timeout waiting for request line
-define(HEADERS_RECV_TIMEOUT, 30000).    %% timeout waiting for headers

-define(MAX_HEADERS, 1000).
-define(DEFAULTS, [{name, ?MODULE},
                   {port, 8888}]).

-ifdef(gen_tcp_r15b_workaround).
r15b_workaround() -> true.
-else.
r15b_workaround() -> false.
-endif.

parse_options(Options) ->
    {loop, HttpLoop} = proplists:lookup(loop, Options),
    Loop = {?MODULE, loop, [HttpLoop]},
    Options1 = [{loop, Loop} | proplists:delete(loop, Options)],
    mochilists:set_defaults(?DEFAULTS, Options1).

stop() ->
    mochiweb_socket_server:stop(?MODULE).

stop(Name) ->
    mochiweb_socket_server:stop(Name).

%% @spec start(Options) -> ServerRet
%%     Options = [option()]
%%     Option = {name, atom()} | {ip, string() | tuple()} | {backlog, integer()}
%%              | {nodelay, boolean()} | {acceptor_pool_size, integer()}
%%              | {ssl, boolean()} | {profile_fun, undefined | (Props) -> ok}
%%              | {link, false} | {recbuf, non_negative_integer()}
%% @doc Start a mochiweb server.
%%      profile_fun is used to profile accept timing.
%%      After each accept, if defined, profile_fun is called with a proplist of a subset of the mochiweb_socket_server state and timing information.
%%      The proplist is as follows: [{name, Name}, {port, Port}, {active_sockets, ActiveSockets}, {timing, Timing}].
%% @end
start(Options) ->
    mochiweb_socket_server:start(parse_options(Options)).

start_link(Options) ->
    mochiweb_socket_server:start_link(parse_options(Options)).

loop(Socket, Opts, Body) ->
    ok = mochiweb_socket:setopts(Socket, [{packet, http}]),
    request(Socket, Opts, Body).

request(Socket, Opts, Body) ->
    ok = mochiweb_socket:setopts(Socket, [{active, once}]),
    receive
        {Protocol, _, {http_request, Method, Path, Version}} when Protocol == http orelse Protocol == ssl ->
            ok = mochiweb_socket:setopts(Socket, [{packet, httph}]),
            headers(Socket, Opts, {Method, Path, Version}, [], Body, 0);
        {Protocol, _, {http_error, "\r\n"}} when Protocol == http orelse Protocol == ssl ->
            request(Socket, Opts, Body);
        {Protocol, _, {http_error, "\n"}} when Protocol == http orelse Protocol == ssl ->
            request(Socket, Opts, Body);
        {tcp_closed, _} ->
            mochiweb_socket:close(Socket),
            exit(normal);
        {ssl_closed, _} ->
            mochiweb_socket:close(Socket),
            exit(normal);
        Other ->
            handle_invalid_msg_request(Other, Socket, Opts)
    after ?REQUEST_RECV_TIMEOUT ->
        mochiweb_socket:close(Socket),
        exit(normal)
    end.

reentry(Body) ->
    fun (Req) ->
            ?MODULE:after_response(Body, Req)
    end.

headers(Socket, Opts, Request, Headers, _Body, ?MAX_HEADERS) ->
    %% Too many headers sent, bad request.
    ok = mochiweb_socket:setopts(Socket, [{packet, raw}]),
    handle_invalid_request(Socket, Opts, Request, Headers);
headers(Socket, Opts, Request, Headers, Body, HeaderCount) ->
    ok = mochiweb_socket:setopts(Socket, [{active, once}]),
    receive
        {Protocol, _, http_eoh} when Protocol == http orelse Protocol == ssl ->
            Req = new_request(Socket, Opts, Request, Headers),
            call_body(Body, Req),
            ?MODULE:after_response(Body, Req);
        {Protocol, _, {http_header, _, Name, _, Value}} when Protocol == http orelse Protocol == ssl ->
            headers(Socket, Opts, Request, [{Name, Value} | Headers], Body,
                    1 + HeaderCount);
        {tcp_closed, _} ->
            mochiweb_socket:close(Socket),
            exit(normal);
        Other ->
            handle_invalid_msg_request(Other, Socket, Opts, Request, Headers)
    after ?HEADERS_RECV_TIMEOUT ->
        mochiweb_socket:close(Socket),
        exit(normal)
    end.

call_body({M, F, A}, Req) ->
    erlang:apply(M, F, [Req | A]);
call_body({M, F}, Req) ->
    M:F(Req);
call_body(Body, Req) ->
    Body(Req).

-spec handle_invalid_msg_request(term(), term(), term()) -> no_return().
handle_invalid_msg_request(Msg, Socket, Opts) ->
    handle_invalid_msg_request(Msg, Socket, Opts, {'GET', {abs_path, "/"}, {0,9}}, []).

-spec handle_invalid_msg_request(term(), term(), term(), term(), term()) -> no_return().
handle_invalid_msg_request(Msg, Socket, Opts, Request, RevHeaders) ->
    case {Msg, r15b_workaround()} of
        {{tcp_error,_,emsgsize}, true} ->
            %% R15B02 returns this then closes the socket, so close and exit
            mochiweb_socket:close(Socket),
            exit(normal);
        _ ->
            handle_invalid_request(Socket, Opts, Request, RevHeaders)
    end.

-spec handle_invalid_request(term(), term(), term(), term()) -> no_return().
handle_invalid_request(Socket, Opts, Request, RevHeaders) ->
    Req = new_request(Socket, Opts, Request, RevHeaders),
    Req:respond({400, [], []}),
    mochiweb_socket:close(Socket),
    exit(normal).

new_request(Socket, Opts, Request, RevHeaders) ->
    ok = mochiweb_socket:setopts(Socket, [{packet, raw}]),
    mochiweb:new_request({Socket, Opts, Request, lists:reverse(RevHeaders)}).

after_response(Body, Req) ->
    Socket = Req:get(socket),
    case Req:should_close() of
        true ->
            mochiweb_socket:close(Socket),
            exit(normal);
        false ->
            Req:cleanup(),
            erlang:garbage_collect(),
            ?MODULE:loop(Socket, mochiweb_request:get(opts, Req), Body)
    end.

parse_range_request(RawRange) when is_list(RawRange) ->
    try
        "bytes=" ++ RangeString = RawRange,
        RangeTokens = [string:strip(R) || R <- string:tokens(RangeString, ",")],
        Ranges = [R || R <- RangeTokens, string:len(R) > 0],
        lists:map(fun ("-" ++ V)  ->
                          {none, list_to_integer(V)};
                      (R) ->
                          case string:tokens(R, "-") of
                              [S1, S2] ->
                                  {list_to_integer(S1), list_to_integer(S2)};
                              [S] ->
                                  {list_to_integer(S), none}
                          end
                  end,
                  Ranges)
    catch
        _:_ ->
            fail
    end.

range_skip_length(Spec, Size) ->
    case Spec of
        {none, R} when R =< Size, R >= 0 ->
            {Size - R, R};
        {none, _OutOfRange} ->
            {0, Size};
        {R, none} when R >= 0, R < Size ->
            {R, Size - R};
        {_OutOfRange, none} ->
            invalid_range;
        {Start, End} when Start >= 0, Start < Size, Start =< End ->
            {Start, erlang:min(End + 1, Size) - Start};
        {_InvalidStart, _InvalidEnd} ->
            invalid_range
    end.

%%
%% Tests
%%
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").

range_test() ->
    %% valid, single ranges
    ?assertEqual([{20, 30}], parse_range_request("bytes=20-30")),
    ?assertEqual([{20, none}], parse_range_request("bytes=20-")),
    ?assertEqual([{none, 20}], parse_range_request("bytes=-20")),

    %% trivial single range
    ?assertEqual([{0, none}], parse_range_request("bytes=0-")),

    %% invalid, single ranges
    ?assertEqual(fail, parse_range_request("")),
    ?assertEqual(fail, parse_range_request("garbage")),
    ?assertEqual(fail, parse_range_request("bytes=-20-30")),

    %% valid, multiple range
    ?assertEqual(
       [{20, 30}, {50, 100}, {110, 200}],
       parse_range_request("bytes=20-30,50-100,110-200")),
    ?assertEqual(
       [{20, none}, {50, 100}, {none, 200}],
       parse_range_request("bytes=20-,50-100,-200")),

    %% valid, multiple range with whitespace
    ?assertEqual(
       [{20, 30}, {50, 100}, {110, 200}],
       parse_range_request("bytes=20-30, 50-100 , 110-200")),

    %% valid, multiple range with extra commas
    ?assertEqual(
       [{20, 30}, {50, 100}, {110, 200}],
       parse_range_request("bytes=20-30,,50-100,110-200")),
    ?assertEqual(
       [{20, 30}, {50, 100}, {110, 200}],
       parse_range_request("bytes=20-30, ,50-100,,,110-200")),

    %% no ranges
    ?assertEqual([], parse_range_request("bytes=")),
    ok.

range_skip_length_test() ->
    Body = <<"012345678901234567890123456789012345678901234567890123456789">>,
    BodySize = byte_size(Body), %% 60
    BodySize = 60,

    %% these values assume BodySize =:= 60
    ?assertEqual({1,9}, range_skip_length({1,9}, BodySize)), %% 1-9
    ?assertEqual({10,10}, range_skip_length({10,19}, BodySize)), %% 10-19
    ?assertEqual({40, 20}, range_skip_length({none, 20}, BodySize)), %% -20
    ?assertEqual({30, 30}, range_skip_length({30, none}, BodySize)), %% 30-

    %% valid edge cases for range_skip_length
    ?assertEqual({BodySize, 0}, range_skip_length({none, 0}, BodySize)),
    ?assertEqual({0, BodySize}, range_skip_length({none, BodySize}, BodySize)),
    ?assertEqual({0, BodySize}, range_skip_length({0, none}, BodySize)),
    ?assertEqual({0, BodySize}, range_skip_length({0, BodySize + 1}, BodySize)),
    BodySizeLess1 = BodySize - 1,
    ?assertEqual({BodySizeLess1, 1},
                 range_skip_length({BodySize - 1, none}, BodySize)),
    ?assertEqual({BodySizeLess1, 1},
                 range_skip_length({BodySize - 1, BodySize+5}, BodySize)),
    ?assertEqual({BodySizeLess1, 1},
                 range_skip_length({BodySize - 1, BodySize}, BodySize)),

    %% out of range, return whole thing
    ?assertEqual({0, BodySize},
                 range_skip_length({none, BodySize + 1}, BodySize)),
    ?assertEqual({0, BodySize},
                 range_skip_length({none, -1}, BodySize)),
    ?assertEqual({0, BodySize},
                 range_skip_length({0, BodySize + 1}, BodySize)),

    %% invalid ranges
    ?assertEqual(invalid_range,
                 range_skip_length({-1, 30}, BodySize)),
    ?assertEqual(invalid_range,
                 range_skip_length({-1, BodySize + 1}, BodySize)),
    ?assertEqual(invalid_range,
                 range_skip_length({BodySize, 40}, BodySize)),
    ?assertEqual(invalid_range,
                 range_skip_length({-1, none}, BodySize)),
    ?assertEqual(invalid_range,
                 range_skip_length({BodySize, none}, BodySize)),
    ?assertEqual(invalid_range,
                 range_skip_length({BodySize + 1, BodySize + 5}, BodySize)),
    ok.

-endif.