% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
%   http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.

-module(couch_log_test_util).
-compile(export_all).


-include("couch_log.hrl").


start() ->
    remove_error_loggers(),
    application:set_env(config, ini_files, config_files()),
    application:start(config),
    ignore_common_loggers(),
    application:start(couch_log).


stop(_) ->
    application:stop(config),
    application:stop(couch_log).


with_level(Name, Fun) ->
    with_config_listener(fun() ->
        try
            LevelStr = couch_log_util:level_to_string(Name),
            config:set("log", "level", LevelStr, false),
            wait_for_config(),
            Fun()
        after
            config:delete("log", "level", false)
        end
    end).


with_config_listener(Fun) ->
    Listener = self(),
    try
        add_listener(Listener),
        Fun()
    after
        rem_listener(Listener)
    end.


wait_for_config() ->
    receive
        couch_log_config_change_finished -> ok
    after 1000 ->
        erlang:error(config_change_timeout)
    end.


with_meck(Mods, Fun) ->
    lists:foreach(fun(M) ->
        case M of
            {Name, Opts} -> meck:new(Name, Opts);
            Name -> meck:new(Name)
        end
    end, Mods),
    try
        Fun()
    after
        lists:foreach(fun(M) ->
            case M of
                {Name, _} -> meck:unload(Name);
                Name -> meck:unload(Name)
            end
        end, Mods)
    end.


ignore_common_loggers() ->
    IgnoreSet = [
        application_controller,
        config,
        config_event
    ],
    lists:foreach(fun(Proc) ->
        disable_logs_from(Proc)
    end, IgnoreSet).


disable_logs_from(Pid) when is_pid(Pid) ->
    Ignored = case application:get_env(couch_log, ignored_pids) of
        {ok, L} when is_list(L) ->
            lists:usort([Pid | L]);
        _E ->
            [Pid]
    end,
    IgnoredAlive = [P || P <- Ignored, is_process_alive(P)],
    application:set_env(couch_log, ignored_pids, IgnoredAlive);

disable_logs_from(Name) when is_atom(Name) ->
    case whereis(Name) of
        P when is_pid(P) ->
            disable_logs_from(P);
        undefined ->
            erlang:error({unknown_pid_name, Name})
    end.


last_log_key() ->
    ets:last(?COUCH_LOG_TEST_TABLE).


last_log() ->
    [{_, Entry}] = ets:lookup(?COUCH_LOG_TEST_TABLE, last_log_key()),
    Entry.


remove_error_loggers() ->
    lists:foreach(fun(Handler) ->
        error_logger:delete_report_handler(Handler)
    end, gen_event:which_handlers(error_logger)).


config_files() ->
    Path = filename:dirname(code:which(?MODULE)),
    Name = filename:join(Path, "couch_log_test.ini"),
    ok = file:write_file(Name, "[log]\nwriter = ets\n"),
    [Name].


add_listener(Listener) ->
    Listeners = case application:get_env(couch_log, config_listeners) of
        {ok, L} when is_list(L) ->
            lists:usort([Listener | L]);
        _ ->
            [Listener]
    end,
    application:set_env(couch_log, config_listeners, Listeners).


rem_listener(Listener) ->
    Listeners = case application:get_env(couch_lig, config_listeners) of
        {ok, L} when is_list(L) ->
            L -- [Listener];
        _ ->
            []
    end,
    application:set_env(couch_log, config_listeners, Listeners).