%% Copyright (c) 2012, 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.

%% @private
-module(ranch_server).
-behaviour(gen_server).

%% API.
-export([start_link/0]).
-export([set_new_listener_opts/3]).
-export([cleanup_listener_opts/1]).
-export([set_connections_sup/2]).
-export([get_connections_sup/1]).
-export([set_port/2]).
-export([get_port/1]).
-export([set_max_connections/2]).
-export([get_max_connections/1]).
-export([set_protocol_options/2]).
-export([get_protocol_options/1]).
-export([count_connections/1]).

%% gen_server.
-export([init/1]).
-export([handle_call/3]).
-export([handle_cast/2]).
-export([handle_info/2]).
-export([terminate/2]).
-export([code_change/3]).

-define(TAB, ?MODULE).

-type monitors() :: [{{reference(), pid()}, any()}].
-record(state, {
	monitors = [] :: monitors()
}).

%% API.

%% @doc Start the ranch_server gen_server.
-spec start_link() -> {ok, pid()}.
start_link() ->
	gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

%% @private
-spec set_new_listener_opts(any(), ranch:max_conns(), any()) -> ok.
set_new_listener_opts(Ref, MaxConns, Opts) ->
	gen_server:call(?MODULE, {set_new_listener_opts, Ref, MaxConns, Opts}).

%% @doc Cleanup listener options after it has been stopped.
-spec cleanup_listener_opts(any()) -> ok.
cleanup_listener_opts(Ref) ->
	_ = ets:delete(?TAB, {port, Ref}),
	_ = ets:delete(?TAB, {max_conns, Ref}),
	_ = ets:delete(?TAB, {opts, Ref}),
	ok.

%% @doc Set a connection supervisor associated with specific listener.
-spec set_connections_sup(any(), pid()) -> ok.
set_connections_sup(Ref, Pid) ->
	gen_server:call(?MODULE, {set_connections_sup, Ref, Pid}).

%% @doc Return the connection supervisor used by specific listener.
-spec get_connections_sup(any()) -> pid().
get_connections_sup(Ref) ->
	ets:lookup_element(?TAB, {conns_sup, Ref}, 2).

%% @private
-spec set_port(any(), inet:port_number()) -> ok.
set_port(Ref, Port) ->
	gen_server:call(?MODULE, {set_port, Ref, Port}).

%% @doc Return the listener's port.
-spec get_port(any()) -> inet:port_number().
get_port(Ref) ->
	ets:lookup_element(?TAB, {port, Ref}, 2).

%% @doc Set the max number of connections allowed concurrently.
-spec set_max_connections(any(), ranch:max_conns()) -> ok.
set_max_connections(Ref, MaxConnections) ->
	gen_server:call(?MODULE, {set_max_conns, Ref, MaxConnections}).

%% @doc Return the max number of connections allowed concurrently.
-spec get_max_connections(any()) -> ranch:max_conns().
get_max_connections(Ref) ->
	ets:lookup_element(?TAB, {max_conns, Ref}, 2).

%% @doc Upgrade the protocol options.
-spec set_protocol_options(any(), any()) -> ok.
set_protocol_options(Ref, ProtoOpts) ->
	gen_server:call(?MODULE, {set_opts, Ref, ProtoOpts}).

%% @doc Return the current protocol options.
-spec get_protocol_options(any()) -> any().
get_protocol_options(Ref) ->
	ets:lookup_element(?TAB, {opts, Ref}, 2).

%% @doc Count the number of connections in the connection pool.
-spec count_connections(any()) -> non_neg_integer().
count_connections(Ref) ->
	ranch_conns_sup:active_connections(get_connections_sup(Ref)).

%% gen_server.

%% @private
init([]) ->
	Monitors = [{{erlang:monitor(process, Pid), Pid}, Ref} ||
		[Ref, Pid] <- ets:match(?TAB, {{conns_sup, '$1'}, '$2'})],
	{ok, #state{monitors=Monitors}}.

%% @private
handle_call({set_new_listener_opts, Ref, MaxConns, Opts}, _, State) ->
	ets:insert(?TAB, {{max_conns, Ref}, MaxConns}),
	ets:insert(?TAB, {{opts, Ref}, Opts}),
	{reply, ok, State};
handle_call({set_connections_sup, Ref, Pid}, _,
		State=#state{monitors=Monitors}) ->
	true = ets:insert_new(?TAB, {{conns_sup, Ref}, Pid}),
	MonitorRef = erlang:monitor(process, Pid),
	{reply, ok, State#state{
		monitors=[{{MonitorRef, Pid}, Ref}|Monitors]}};
handle_call({set_port, Ref, Port}, _, State) ->
	true = ets:insert(?TAB, {{port, Ref}, Port}),
	{reply, ok, State};
handle_call({set_max_conns, Ref, MaxConns}, _, State) ->
	ets:insert(?TAB, {{max_conns, Ref}, MaxConns}),
	ConnsSup = get_connections_sup(Ref),
	ConnsSup ! {set_max_conns, MaxConns},
	{reply, ok, State};
handle_call({set_opts, Ref, Opts}, _, State) ->
	ets:insert(?TAB, {{opts, Ref}, Opts}),
	ConnsSup = get_connections_sup(Ref),
	ConnsSup ! {set_opts, Opts},
	{reply, ok, State};
handle_call(_Request, _From, State) ->
	{reply, ignore, State}.

%% @private
handle_cast(_Request, State) ->
	{noreply, State}.

%% @private
handle_info({'DOWN', MonitorRef, process, Pid, _},
		State=#state{monitors=Monitors}) ->
	{_, Ref} = lists:keyfind({MonitorRef, Pid}, 1, Monitors),
	true = ets:delete(?TAB, {conns_sup, Ref}),
	Monitors2 = lists:keydelete({MonitorRef, Pid}, 1, Monitors),
	{noreply, State#state{monitors=Monitors2}};
handle_info(_Info, State) ->
	{noreply, State}.

%% @private
terminate(_Reason, _State) ->
	ok.

%% @private
code_change(_OldVsn, State, _Extra) ->
	{ok, State}.