-module(woody_transport_opts_SUITE).

-include_lib("common_test/include/ct.hrl").
-include_lib("stdlib/include/assert.hrl").

-include("woody_test_thrift.hrl").

%% woody_server_thrift_handler callbacks
-behaviour(woody_server_thrift_handler).

-export([handle_function/4]).

-export([all/0]).
-export([init_per_suite/1]).
-export([end_per_suite/1]).
-export([init_per_testcase/2]).

-export([respects_max_connections/1]).
-export([shuts_down_gracefully/1]).

-type case_name() :: atom().
-type config() :: [{atom(), any()}].

-spec all() -> [case_name()].
-spec init_per_suite(config()) -> config().
-spec end_per_suite(config()) -> any().
-spec init_per_testcase(case_name(), config()) -> config().

-spec respects_max_connections(config()) -> any().
-spec shuts_down_gracefully(config()) -> any().

-spec handle_function(woody:func(), woody:args(), woody_context:ctx(), woody:options()) -> {ok, woody:result()}.

%%

all() ->
    [
        respects_max_connections,
        shuts_down_gracefully
    ].

init_per_suite(C) ->
    % dbg:tracer(), dbg:p(all, c),
    % dbg:tpl({ranch_server, '_', '_'}, x),
    {ok, Apps} = application:ensure_all_started(woody),
    [{suite_apps, Apps} | C].

end_per_suite(C) ->
    [application:stop(App) || App <- ?config(suite_apps, C)].

%%

init_per_testcase(Name, C) ->
    Port = get_random_port(),
    [
        {client, #{
            url => iolist_to_binary(["http://localhost:", integer_to_list(Port), "/"]),
            event_handler => {woody_ct_event_h, {client, Name}}
        }},
        {server, #{
            ip => {127, 0, 0, 1},
            port => Port,
            event_handler => [{woody_ct_event_h, {server, Name}}],
            shutdown_timeout => 5000
        }},
        {testcase, Name}
        | C
    ].

%%

respects_max_connections(C) ->
    % (10; 20]
    MaxConns = 10 + rand:uniform(10),
    Table = ets:new(?MODULE, [public, {read_concurrency, true}, {write_concurrency, true}]),
    true = ets:insert_new(Table, [{slot, 0}]),
    Service = {woody_test_thrift, 'Weapons'},
    Client = ?config(client, C),
    Handler = {"/", {Service, {?MODULE, {?config(testcase, C), Table}}}},
    % NOTE
    % > https://github.com/ninenines/ranch/blob/1.3.2/src/ranch_conns_sup.erl#L184
    % If we do not set `max_keepalive = 1` here then any request received by the server
    % except for `MaxConns` first will wait in queue until the keepalive times out in one of these
    % `MaxConns` connections, which results in that it exits cleanly. Unfortunately, the default keepalive
    % timeout is 5000 ms which is the same as the default woody request timeout.
    % I wonder how this behavior affects production traffic as most of woody servers there configured with
    % keepalive timeout of 60 s.
    TransportOpts = #{max_connections => MaxConns, num_acceptors => 1},
    ProtocolOpts = #{max_keepalive => 1},
    ReadBodyOpts = #{},
    {ok, ServerPid} = start_woody_server(Handler, TransportOpts, ProtocolOpts, ReadBodyOpts, C),
    Results = genlib_pmap:map(
        fun(_) ->
            woody_client:call({Service, 'get_weapon', {<<"BFG">>, <<>>}}, Client)
        end,
        lists:seq(1, MaxConns * 10)
    ),
    Slots = lists:map(
        fun({ok, #'Weapon'{slot_pos = Slot}}) -> Slot end,
        Results
    ),
    ?assert(lists:max(Slots) =< MaxConns),
    ok = stop_woody_server(ServerPid).

-define(receive_or_timeout(Msg, Timeout),
    receive
        Msg -> ok
    after Timeout -> timeout
    end
).

shuts_down_gracefully(C) ->
    Client = ?config(client, C),
    Handler = {"/", {{woody_test_thrift, 'Powerups'}, {?MODULE, {}}}},
    TransportOpts = #{max_connections => 10},
    ProtocolOpts = #{max_keepalive => 2, request_timeout => 1000},
    {ok, ServerPid} = start_woody_server(Handler, TransportOpts, ProtocolOpts, #{}, C),
    ServerMonitor = erlang:monitor(process, ServerPid),
    true = unlink(ServerPid),
    ParentPid = self(),
    %% send a shutdown signal to the server in 1000ms
    %% then try making a new connection with it, expect econnrefused
    TestPid = spawn_link(fun() -> process_econnrefused_test(Client, ParentPid) end),
    _ = spawn_link(fun() -> process_delayed_kill(ServerPid, TestPid, 1000) end),
    %% fire some requests and expect them to finish successfuly
    %% even when server is shutting down in the meantime
    _ = genlib_pmap:map(
        fun(_) ->
            ?assertEqual(
                {ok, #'Powerup'{name = <<"Warbanner">>}},
                get_powerup(Client, <<"Warbanner">>, <<>>)
            )
        end,
        lists:seq(1, 10)
    ),
    %% wait for the async test and server shutdown to finish
    ok = ?receive_or_timeout(econnrefused_test_success, 0),
    ok = ?receive_or_timeout({'DOWN', ServerMonitor, _, _, _}, 5000).

process_econnrefused_test(Client, ParentPid) ->
    receive
        listener_suspended ->
            ?assertError(
                {woody_error, {internal, resource_unavailable, <<"econnrefused">>}},
                get_powerup(Client, <<"Warbanner">>, <<>>)
            ),
            erlang:send(ParentPid, econnrefused_test_success)
    end.

process_delayed_kill(ServerPid, TestPid, Timeout) ->
    timer:sleep(Timeout),
    erlang:send_after(500, TestPid, listener_suspended),
    ok = proc_lib:stop(ServerPid, shutdown, infinity).

%%

start_woody_server(Handler, TransportOpts, ProtocolOpts, ReadBodyOpts, C) ->
    ServerOpts0 = ?config(server, C),
    SupervisorOpts = woody_server:child_spec(
        {?MODULE, ?config(testcase, C)},
        ServerOpts0#{
            handlers => [Handler],
            read_body_opts => ReadBodyOpts,
            transport_opts => TransportOpts,
            protocol_opts => ProtocolOpts
        }
    ),
    genlib_adhoc_supervisor:start_link(#{}, [SupervisorOpts]).

stop_woody_server(Pid) ->
    true = unlink(Pid),
    true = exit(Pid, shutdown),
    ok.

handle_function(get_weapon, {Name, _}, _Context, {respects_max_connections, Table}) ->
    Slot = ets:update_counter(Table, slot, 1),
    ok = timer:sleep(rand:uniform(10)),
    _ = ets:update_counter(Table, slot, -1),
    {ok, #'Weapon'{name = Name, slot_pos = Slot}};
handle_function(get_powerup, {Name, _}, _Context, _) ->
    ok = timer:sleep(2000),
    {ok, #'Powerup'{name = Name}}.

get_powerup(Client, Name, Arg) ->
    woody_client:call({{woody_test_thrift, 'Powerups'}, 'get_powerup', {Name, Arg}}, Client).

%%

get_random_port() ->
    32767 + rand:uniform(32000).