% 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_task_status_tests).

-include("couch_eunit.hrl").
-include_lib("couchdb/couch_db.hrl").

-define(TIMEOUT, 1000).


setup() ->
    {ok, TaskStatusPid} = couch_task_status:start_link(),
    TaskUpdaterPid = spawn(fun() -> loop() end),
    {TaskStatusPid, TaskUpdaterPid}.

teardown({TaskStatusPid, _}) ->
    erlang:monitor(process, TaskStatusPid),
    couch_task_status:stop(),
    receive
        {'DOWN', _, _, TaskStatusPid, _} ->
            ok
    after ?TIMEOUT ->
        throw(timeout_error)
    end.


couch_task_status_test_() ->
    {
        "CouchDB task status updates",
        {
            foreach,
            fun setup/0, fun teardown/1,
            [
                fun should_register_task/1,
                fun should_set_task_startup_time/1,
                fun should_have_update_time_as_startup_before_any_progress/1,
                fun should_set_task_type/1,
                fun should_not_register_multiple_tasks_for_same_pid/1,
                fun should_set_task_progress/1,
                fun should_update_task_progress/1,
                fun should_update_time_changes_on_task_progress/1,
                fun should_control_update_frequency/1,
                fun should_reset_control_update_frequency/1,
                fun should_track_multiple_tasks/1,
                fun should_finish_task/1

            ]
        }
    }.


should_register_task({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    ?_assertEqual(1, length(couch_task_status:all())).

should_set_task_startup_time({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    ?_assert(is_integer(get_task_prop(Pid, started_on))).

should_have_update_time_as_startup_before_any_progress({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    StartTime = get_task_prop(Pid, started_on),
    ?_assertEqual(StartTime, get_task_prop(Pid, updated_on)).

should_set_task_type({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    ?_assertEqual(replication, get_task_prop(Pid, type)).

should_not_register_multiple_tasks_for_same_pid({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    ?_assertEqual({add_task_error, already_registered},
                  call(Pid, add, [{type, compaction}, {progress, 0}])).

should_set_task_progress({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    ?_assertEqual(0, get_task_prop(Pid, progress)).

should_update_task_progress({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    call(Pid, update, [{progress, 25}]),
    ?_assertEqual(25, get_task_prop(Pid, progress)).

should_update_time_changes_on_task_progress({_, Pid}) ->
    ?_assert(
        begin
            ok = call(Pid, add, [{type, replication}, {progress, 0}]),
            ok = timer:sleep(1000),  % sleep awhile to customize update time
            call(Pid, update, [{progress, 25}]),
            get_task_prop(Pid, updated_on) > get_task_prop(Pid, started_on)
        end).

should_control_update_frequency({_, Pid}) ->
    ?_assertEqual(66,
        begin
            ok = call(Pid, add, [{type, replication}, {progress, 0}]),
            call(Pid, update, [{progress, 50}]),
            call(Pid, update_frequency, 500),
            call(Pid, update, [{progress, 66}]),
            call(Pid, update, [{progress, 77}]),
            get_task_prop(Pid, progress)
        end).

should_reset_control_update_frequency({_, Pid}) ->
    ?_assertEqual(87,
        begin
            ok = call(Pid, add, [{type, replication}, {progress, 0}]),
            call(Pid, update, [{progress, 50}]),
            call(Pid, update_frequency, 500),
            call(Pid, update, [{progress, 66}]),
            call(Pid, update, [{progress, 77}]),
            call(Pid, update_frequency, 0),
            call(Pid, update, [{progress, 87}]),
            get_task_prop(Pid, progress)
        end).

should_track_multiple_tasks(_) ->
    ?_assert(run_multiple_tasks()).

should_finish_task({_, Pid}) ->
    ok = call(Pid, add, [{type, replication}, {progress, 0}]),
    ?assertEqual(1, length(couch_task_status:all())),
    ok = call(Pid, done),
    ?_assertEqual(0, length(couch_task_status:all())).


run_multiple_tasks() ->
    Pid1 = spawn(fun() -> loop() end),
    Pid2 = spawn(fun() -> loop() end),
    Pid3 = spawn(fun() -> loop() end),
    call(Pid1, add, [{type, replication}, {progress, 0}]),
    call(Pid2, add, [{type, compaction}, {progress, 0}]),
    call(Pid3, add, [{type, indexer}, {progress, 0}]),

    ?assertEqual(3, length(couch_task_status:all())),
    ?assertEqual(replication, get_task_prop(Pid1, type)),
    ?assertEqual(compaction, get_task_prop(Pid2, type)),
    ?assertEqual(indexer, get_task_prop(Pid3, type)),

    call(Pid2, update, [{progress, 33}]),
    call(Pid3, update, [{progress, 42}]),
    call(Pid1, update, [{progress, 11}]),
    ?assertEqual(42, get_task_prop(Pid3, progress)),
    call(Pid1, update, [{progress, 72}]),
    ?assertEqual(72, get_task_prop(Pid1, progress)),
    ?assertEqual(33, get_task_prop(Pid2, progress)),

    call(Pid1, done),
    ?assertEqual(2, length(couch_task_status:all())),
    call(Pid3, done),
    ?assertEqual(1, length(couch_task_status:all())),
    call(Pid2, done),
    ?assertEqual(0, length(couch_task_status:all())),

    true.


loop() ->
    receive
        {add, Props, From} ->
            Resp = couch_task_status:add_task(Props),
            From ! {ok, self(), Resp},
            loop();
        {update, Props, From} ->
            Resp = couch_task_status:update(Props),
            From ! {ok, self(), Resp},
            loop();
        {update_frequency, Msecs, From} ->
            Resp = couch_task_status:set_update_frequency(Msecs),
            From ! {ok, self(), Resp},
            loop();
        {done, From} ->
            From ! {ok, self(), ok}
    end.

call(Pid, Command) ->
    Pid ! {Command, self()},
    wait(Pid).

call(Pid, Command, Arg) ->
    Pid ! {Command, Arg, self()},
    wait(Pid).

wait(Pid) ->
    receive
        {ok, Pid, Msg} ->
            Msg
    after ?TIMEOUT ->
        throw(timeout_error)
    end.

get_task_prop(Pid, Prop) ->
    From = list_to_binary(pid_to_list(Pid)),
    Element = lists:foldl(
        fun(PropList, Acc) ->
            case couch_util:get_value(pid, PropList) of
                From ->
                    [PropList | Acc];
                _ ->
                    Acc
            end
        end,
        [], couch_task_status:all()
    ),
    case couch_util:get_value(Prop, hd(Element), nil) of
        nil ->
            erlang:error({assertion_failed,
                         [{module, ?MODULE},
                          {line, ?LINE},
                          {reason, "Could not get property '"
                                   ++ couch_util:to_list(Prop)
                                   ++ "' for task "
                                   ++ pid_to_list(Pid)}]});
        Value ->
            Value
    end.