%%%-------------------------------------------------------------------
%%% @private
%%% @doc
%%% Denrei's protocol handler.
%%% @end
%%%-------------------------------------------------------------------
-module(denrei_protocol).

-behaviour(ranch_protocol).

%% Includes
-include("denrei.hrl").

%% ranch_protocol callbacks
-export([start_link/4, init/4]).

start_link(Ref, Socket, Transport, Opts) ->
    Pid = spawn_link(?MODULE, init, [Ref, Socket, Transport, Opts]),
    {ok, Pid}.

init(Ref, Socket, Transport, Opts) ->
    ok = ranch:accept_ack(Ref),
    ok = Transport:setopts(Socket, [binary, {packet, 4}]),
    loop(Transport, Socket, proplists:get_value(tree, Opts)).

%%%===================================================================
%%% Internal functions
%%%===================================================================
loop(Transport, Socket, TreePid) ->
    case Transport:recv(Socket, 0, 60000) of
        {ok, Packet} ->
            lager:debug([{transport, Transport}, {socket, Socket}], "~p received: ~p", [{Transport, Socket}, Packet]),
            ok = handle_packet(Transport, Socket, TreePid, Packet),
            loop(Transport, Socket, TreePid);
        {error, closed} ->
            lager:debug([{transport, Transport}, {socket, Socket}], "~p closed", [{Transport, Socket}]),
            handle_close(Transport, Socket, TreePid);
        {error, timeout} ->
            lager:debug([{transport, Transport}, {socket, Socket}], "~p timed out", [{Transport, Socket}]),
            ok = denrei_utils:send(Transport, Socket, <<?DENREI_PROTOCOL_PING>>, [denrei_utils:integer_to_binary(denrei_utils:timestamp(), 36)]),
            loop(Transport, Socket, TreePid);
        {error, Reason} ->
            lager:warning([{transport, Transport}, {socket, Socket}], "~p error: ~p", [{Transport, Socket}, Reason]),
            ok = Transport:close(Socket)
    end.

handle_close(Transport, Socket, TreePid) ->
    Subscriber = {Transport, Socket},
    denrei_tree_server:delete(TreePid, Subscriber, all).

handle_packet(_Transport, _Socket, TreePid, Packet = <<?DENREI_PROTOCOL_PUBLISH, Fields/binary>>) ->
    {Subject, _} = denrei_utils:get_next_field(Fields),
    {ok, Subscribers} = denrei_tree_server:match(TreePid, denrei_utils:tokenize_subject(Subject)),
    [denrei_utils:send(T, S, Packet) || {T, S} <- Subscribers],
    ok;

handle_packet(Transport, Socket, TreePid, <<?DENREI_PROTOCOL_SUBSCRIBE, Fields/binary>>) ->
    Subscriber = {Transport, Socket},
    {Subject, <<>>} = denrei_utils:get_next_field(Fields),
    lager:info([{transport, Transport}, {socket, Socket}], "~p subscribe to ~p", [Subscriber, Subject]),
    denrei_tree_server:insert(TreePid, Subscriber, denrei_utils:tokenize_subject(Subject));

handle_packet(Transport, Socket, TreePid, <<?DENREI_PROTOCOL_UNSUBSCRIBE>>) ->
    Subscriber = {Transport, Socket},
    lager:info([{transport, Transport}, {socket, Socket}], "~p unsubscribe from all", [Subscriber]),
    denrei_tree_server:delete(TreePid, Subscriber, all);

handle_packet(Transport, Socket, TreePid, <<?DENREI_PROTOCOL_UNSUBSCRIBE, Fields/binary>>) ->
    Subscriber = {Transport, Socket},
    {Subject, <<>>} = denrei_utils:get_next_field(Fields),
    lager:info([{transport, Transport}, {socket, Socket}], "~p unsubscribe from ~p", [Subject]),
    denrei_tree_server:delete(TreePid, Subscriber, denrei_utils:tokenize_subject(Subject));

handle_packet(Transport, Socket, TreePid, <<?DENREI_PROTOCOL_SUBSCRIBERS, Fields0/binary>>) ->
    {Subject, Fields1} = denrei_utils:get_next_field(Fields0),
    {CorrelationID, _} = denrei_utils:get_next_field(Fields1),
    case denrei_tree_server:match(TreePid, denrei_utils:tokenize_subject(Subject)) of
        {ok, []} ->
            denrei_utils:send(Transport, Socket, <<?DENREI_PROTOCOL_RESPONSE>>, [CorrelationID, <<0:?DENREI_COUNT_BITS>>]);
        {ok, Subscribers} ->
            Count = length(Subscribers),
            denrei_utils:send(Transport, Socket, <<?DENREI_PROTOCOL_RESPONSE>>, [CorrelationID, <<Count:?DENREI_COUNT_BITS>>])
    end;

handle_packet(Transport, Socket, TreePid, <<?DENREI_PROTOCOL_REQUEST, Fields0/binary>>) ->
    {Subject, Fields1} = denrei_utils:get_next_field(Fields0),
    case denrei_tree_server:match(TreePid, denrei_utils:tokenize_subject(Subject)) of
        {ok, []} ->
            {CorrelationID, _} = denrei_utils:get_next_field(Fields1),
            denrei_utils:send(Transport, Socket, <<?DENREI_PROTOCOL_NOSUBSCRIBER>>, [CorrelationID]);
        {ok, Subscribers} ->
            Index = random:uniform(length(Subscribers)),
            {T, S} = lists:nth(Index, Subscribers),
            EncodedCallerID = term_to_binary({Transport, Socket}),
            denrei_utils:send(T, S, <<?DENREI_PROTOCOL_REQUEST>>, [EncodedCallerID], Fields0)
    end;

handle_packet(_Transport, _Socket, _TreePid, <<?DENREI_PROTOCOL_RESPONSE, Fields0/binary>>) ->
    {EncodedCallerID, Fields1} = denrei_utils:get_next_field(Fields0),
    {T, S} = binary_to_term(EncodedCallerID),
    denrei_utils:send(T, S, [<<?DENREI_PROTOCOL_RESPONSE>>, Fields1]);

handle_packet(_Transport, _Socket, _TreePid, <<?DENREI_PROTOCOL_NOCALLBACK, Fields0/binary>>) ->
    {EncodedCallerID, Fields1} = denrei_utils:get_next_field(Fields0),
    {T, S} = binary_to_term(EncodedCallerID),
    denrei_utils:send(T, S, [<<?DENREI_PROTOCOL_NOCALLBACK>>, Fields1]);

handle_packet(_Transport, _Socket, _TreePid, <<?DENREI_PROTOCOL_TIMEOUT, Fields0/binary>>) ->
    {EncodedCallerID, Fields1} = denrei_utils:get_next_field(Fields0),
    {T, S} = binary_to_term(EncodedCallerID),
    denrei_utils:send(T, S, [<<?DENREI_PROTOCOL_TIMEOUT>>, Fields1]);

handle_packet(Transport, Socket, _TreePid, <<?DENREI_PROTOCOL_PING, Fields0/binary>>) ->
    {T1, Fields1} = denrei_utils:get_next_field(Fields0),
    {T2, <<>>} = denrei_utils:get_next_field(Fields1),
    ServerSendTime = denrei_utils:binary_to_integer(T1, 36),
    ClientSendTime = denrei_utils:binary_to_integer(T2, 36),
    ServerReceiveTime = denrei_utils:timestamp(),
    lager:debug([{transport, Transport}, {socket, Socket}], "~p ping, total: ~p, server->client: ~p, client->server: ~p", [{Transport, Socket}, (ServerReceiveTime - ServerSendTime), (ClientSendTime - ServerSendTime), (ServerReceiveTime - ClientSendTime)]),
    ok;

handle_packet(Transport, Socket, _TreePid, Packet) ->
    lager:warning([{transport, Transport}, {socket, Socket}], "~p unknown packet: ~p", [{Transport, Socket}, Packet]).