%% -------------------------------------------------------------------
%%
%% Copyright (c) 2011-2017 Basho Technologies, Inc.
%%
%% This file is provided to you 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(lager_test_function_transform).

-include("eRum.hrl").

-compile([{nowarn_deprecated_function, [{erlang, now, 0}]}]).

-lager_function_transforms([
   {returns_static_emit, on_emit, {lager_test_function_transform, transform_static}},
   {returns_dynamic_emit, on_emit, {lager_test_function_transform, transform_dynamic}},
   {returns_undefined_emit, on_emit, {not_real_module_fake, fake_not_real_function}},

   {returns_static_log, on_log, {lager_test_function_transform, transform_static}},
   {returns_dynamic_log, on_log, {lager_test_function_transform, transform_dynamic}}
]).

-compile({parse_transform, lager_transform}).

-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
-export([
   transform_static/0,
   transform_dynamic/0
]).
-endif.

-ifdef(TEST).

transform_static() ->
   static_result.

transform_dynamic() ->
   erlang:now().

not_running_test() ->
   ?assertEqual({error, lager_not_running}, eRum:log(info, self(), "not running")).

setup() ->
   ok = error_logger:tty(false),
   ok = rumUtil:safe_application_load(lager),
   ok = application:set_env(lager, handlers, [{lager_test_backend, info}]),
   ok = application:set_env(lager, errLoggerRedirect, false),
   ok = application:unset_env(lager, traces),
   ok = eRum:start(),
   %% There is a race condition between the application start up, lager logging its own
   %% start up condition and several tests that count messages or parse the output of
   %% tests.  When the lager start up message wins the race, it causes these tests
   %% which parse output or count message arrivals to fail.
   %%
   %% We introduce a sleep here to allow `flush' to arrive *after* the start up
   %% message has been received and processed.
   %%
   %% This race condition was first exposed during the work on
   %% 4b5260c4524688b545cc12da6baa2dfa4f2afec9 which introduced the lager
   %% manager killer PR.
   ok = timer:sleep(250),
   ok = gen_event:call(rumEvent, lager_test_backend, flush).

cleanup(_) ->
   catch ets:delete(lager_config), %% kill the ets config table with fire
   ok = application:stop(lager),
   ok = application:stop(goldrush),
   ok = error_logger:tty(true).

transform_function_test_() ->
   {foreach,
      fun setup/0,
      fun cleanup/1,
      [
         {"observe that there is nothing up my sleeve",
            fun() ->
               ?assertEqual(undefined, lager_test_backend:pop()),
               ?assertEqual(0, lager_test_backend:count())
            end
         },
         {"logging works",
            fun() ->
               eRum:warning("test message"),
               ?assertEqual(1, lager_test_backend:count()),
               {Level, _Time, Message, _Metadata} = lager_test_backend:pop(),
               ?assertMatch(Level, rumUtil:levelToNum(warning)),
               ?assertEqual("test message", Message),
               ok
            end
         },
         {"Testing calling a function returns the same content on emit",
            fun() ->
               eRum:warning("static message"),
               ?assertEqual(1, lager_test_backend:count()),
               {_Level, _Time, _Message, Metadata} = lager_test_backend:pop(),
               Function = proplists:get_value(returns_static_emit, Metadata),
               ?assertEqual(transform_static(), Function()),
               ok
            end
         },
         {"Testing calling a function which returns content which can change on emit",
            fun() ->
               eRum:warning("dynamic message"),
               ?assertEqual(1, lager_test_backend:count()),
               {_Level, _Time, _Message, Metadata} = lager_test_backend:pop(),
               Function = proplists:get_value(returns_dynamic_emit, Metadata),
               ?assert(Function() =< Function()),
               ?assert(Function() =< Function()),
               ?assert(Function() =< Function()),
               ?assert(Function() =< Function()),
               ok
            end
         },
         {"Testing a undefined function returns undefined on emit",
            fun() ->
               eRum:warning("Undefined error"),
               ?assertEqual(1, lager_test_backend:count()),
               {_Level, _Time, _Message, Metadata} = lager_test_backend:pop(),
               Function = proplists:get_value(returns_undefined_emit, Metadata),
               [{module, Module}, {name, Name} | _] = erlang:fun_info(Function),
               ?assertNot(erlang:function_exported(Module, Name, 0)),
               ok
            end
         },
         {"Testing calling a function returns the same content on log",
            fun() ->
               eRum:warning("static message"),
               ?assertEqual(1, lager_test_backend:count()),
               {_Level, _Time, _Message, Metadata} = lager_test_backend:pop(),
               ?assertEqual(transform_static(), proplists:get_value(returns_static_log, Metadata)),
               ok
            end
         },
         {"Testing calling a dynamic function on log which returns the same value",
            fun() ->
               eRum:warning("dynamic message"),
               ?assertEqual(1, lager_test_backend:count()),
               {_Level, _Time, _Message, Metadata} = lager_test_backend:pop(),
               Value = proplists:get_value(returns_dynamic_log, Metadata),
               ?assert(Value =< transform_dynamic()),
               ?assert(Value =< transform_dynamic()),
               ?assert(Value =< transform_dynamic()),
               ?assert(Value =< transform_dynamic()),
               ?assert(Value =< transform_dynamic()),
               ok
            end
         },
         {"Testing differences in results for on_log vs on emit from dynamic function",
            fun() ->
               eRum:warning("on_log vs on emit"),
               ?assertEqual(1, lager_test_backend:count()),
               {_Level, _Time, _Message, Metadata} = lager_test_backend:pop(),
               Value = proplists:get_value(returns_dynamic_log, Metadata),
               Function = proplists:get_value(returns_dynamic_emit, Metadata),
               FunctionResult = Function(),
               ?assert(Value =< FunctionResult),
               ?assert(Value =< Function()),
               ?assert(FunctionResult =< Function()),
               ok
            end
         },
         {"Testing a function provided via metadata",
            fun() ->
               Provided = fun() ->
                  provided_metadata
                          end,
               eRum:md([{provided, Provided}]),
               eRum:warning("Provided metadata"),
               ?assertEqual(1, lager_test_backend:count()),
               {_Level, _Time, _Message, Metadata} = lager_test_backend:pop(),
               Function = proplists:get_value(provided, Metadata),
               ?assertEqual(Provided(), Function()),
               ok
            end
         }
      ]
   }.

-endif.