// Copyright 2024 PingCAP, Inc.
//
// 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.

package integrationtests

import (
	"context"
	"flag"
	"fmt"
	"testing"
	"time"

	"github.com/pingcap/tidb/pkg/disttask/framework/handle"
	"github.com/pingcap/tidb/pkg/disttask/framework/proto"
	"github.com/pingcap/tidb/pkg/disttask/framework/scheduler"
	mockDispatch "github.com/pingcap/tidb/pkg/disttask/framework/scheduler/mock"
	"github.com/pingcap/tidb/pkg/disttask/framework/storage"
	"github.com/pingcap/tidb/pkg/disttask/framework/taskexecutor"
	"github.com/pingcap/tidb/pkg/disttask/framework/testutil"
	"github.com/pingcap/tidb/pkg/domain"
	"github.com/pingcap/tidb/pkg/session"
	"github.com/pingcap/tidb/pkg/store/driver"
	"github.com/pingcap/tidb/pkg/testkit"
	"github.com/pingcap/tidb/pkg/testkit/testfailpoint"
	"github.com/stretchr/testify/require"
	"go.opencensus.io/stats/view"
	"go.uber.org/mock/gomock"
)

var (
	maxConcurrentTask       = flag.Int("max-concurrent-task", proto.MaxConcurrentTask, "max concurrent task")
	waitDuration            = flag.Duration("task-wait-duration", 2*time.Minute, "task wait duration")
	schedulerInterval       = flag.Duration("scheduler-interval", scheduler.CheckTaskFinishedInterval, "scheduler interval")
	taskExecutorMgrInterval = flag.Duration("task-executor-mgr-interval", taskexecutor.TaskCheckInterval, "task executor mgr interval")
	taskMetaSize            = flag.Int("task-meta-size", 1<<10, "task meta size")
	noTask                  = flag.Bool("no-task", false, "no task")
)

// test overhead when starting multiple schedulers
//
// make failpoint-enable
// GOOS=linux GOARCH=amd64 go test -tags intest -c -o bench.test ./pkg/disttask/framework/integrationtests
// make failpoint-disable
//
// bench.test -test.v -run ^$ -test.bench=BenchmarkSchedulerOverhead --with-tikv "upstream-pd:2379?disableGC=true"
func BenchmarkSchedulerOverhead(b *testing.B) {
	ctx, cancel := context.WithCancel(context.Background())
	statusWG := testkit.MockTiDBStatusPort(ctx, b, "10080")
	defer func() {
		cancel()
		statusWG.Wait()
	}()
	schIntervalBak := scheduler.CheckTaskFinishedInterval
	exeMgrIntervalBak := taskexecutor.TaskCheckInterval
	bak := proto.MaxConcurrentTask
	b.Cleanup(func() {
		proto.MaxConcurrentTask = bak
		scheduler.CheckTaskFinishedInterval = schIntervalBak
		taskexecutor.TaskCheckInterval = exeMgrIntervalBak
	})
	proto.MaxConcurrentTask = *maxConcurrentTask
	scheduler.CheckTaskFinishedInterval = *schedulerInterval
	taskexecutor.TaskCheckInterval = *taskExecutorMgrInterval

	b.Logf("max concurrent task: %d", proto.MaxConcurrentTask)
	b.Logf("taks wait duration: %s", *waitDuration)
	b.Logf("task meta size: %d", *taskMetaSize)
	b.Logf("scheduler interval: %s", scheduler.CheckTaskFinishedInterval)
	b.Logf("task executor mgr interval: %s", taskexecutor.TaskCheckInterval)

	prepareForBenchTest(b)
	c := testutil.NewTestDXFContext(b, 1, 2*proto.MaxConcurrentTask, false)

	registerTaskTypeForBench(c)

	if *noTask {
		time.Sleep(*waitDuration)
	} else {
		// in this test, we will start 4*proto.MaxConcurrentTask tasks, but only
		// proto.MaxConcurrentTask will be scheduled at the same time, for other
		// tasks will be in queue only to check the performance of querying them.
		for i := 0; i < 4*proto.MaxConcurrentTask; i++ {
			taskKey := fmt.Sprintf("task-%03d", i)
			taskMeta := make([]byte, *taskMetaSize)
			_, err := handle.SubmitTask(c.Ctx, taskKey, proto.TaskTypeExample, 1, "", taskMeta)
			require.NoError(c.T, err)
		}
		// task has 2 steps, each step has 1 subtask，wait in serial to reduce WaitTask check overhead.
		// only wait first proto.MaxConcurrentTask and exit
		time.Sleep(2 * *waitDuration)
		for i := 0; i < proto.MaxConcurrentTask; i++ {
			taskKey := fmt.Sprintf("task-%03d", i)
			testutil.WaitTaskDoneOrPaused(c.Ctx, c.T, taskKey)
		}
	}
}

func prepareForBenchTest(b *testing.B) {
	testfailpoint.Enable(b, "github.com/pingcap/tidb/pkg/domain/MockDisableDistTask", "return(true)")

	var d driver.TiKVDriver
	var err error
	store, err := d.Open("tikv://" + *testkit.WithTiKV)
	require.NoError(b, err)

	var dom *domain.Domain
	dom, err = session.BootstrapSession(store)
	defer func() {
		dom.Close()
		err := store.Close()
		require.NoError(b, err)
		view.Stop()
	}()
	require.NoError(b, err)

	tk := testkit.NewTestKit(b, store)
	tk.MustExec("delete from mysql.tidb_global_task")
	tk.MustExec("delete from mysql.tidb_global_task_history")
	tk.MustExec("delete from mysql.tidb_background_subtask")
	tk.MustExec("delete from mysql.tidb_background_subtask_history")
}

func registerTaskTypeForBench(c *testutil.TestDXFContext) {
	stepTransition := map[proto.Step]proto.Step{
		proto.StepInit: proto.StepOne,
		proto.StepOne:  proto.StepTwo,
		proto.StepTwo:  proto.StepDone,
	}
	schedulerExt := mockDispatch.NewMockExtension(c.MockCtrl)
	schedulerExt.EXPECT().OnTick(gomock.Any(), gomock.Any()).Return().AnyTimes()
	schedulerExt.EXPECT().GetEligibleInstances(gomock.Any(), gomock.Any()).Return(nil, nil).AnyTimes()
	schedulerExt.EXPECT().IsRetryableErr(gomock.Any()).Return(false).AnyTimes()
	schedulerExt.EXPECT().GetNextStep(gomock.Any()).DoAndReturn(
		func(task *proto.TaskBase) proto.Step {
			return stepTransition[task.Step]
		},
	).AnyTimes()
	schedulerExt.EXPECT().OnNextSubtasksBatch(gomock.Any(), gomock.Any(), gomock.Any(), gomock.Any(), gomock.Any()).DoAndReturn(
		func(_ context.Context, _ storage.TaskHandle, task *proto.Task, _ []string, nextStep proto.Step) (metas [][]byte, err error) {
			cnt := 1
			res := make([][]byte, cnt)
			for i := 0; i < cnt; i++ {
				res[i] = []byte(task.Key)
			}
			return res, nil
		},
	).AnyTimes()
	schedulerExt.EXPECT().OnDone(gomock.Any(), gomock.Any(), gomock.Any()).Return(nil).AnyTimes()

	testutil.RegisterTaskMetaWithDXFCtx(c, schedulerExt, func(ctx context.Context, subtask *proto.Subtask) error {
		select {
		case <-ctx.Done():
			taskManager, err := storage.GetTaskManager()
			if err != nil {
				return err
			}
			return taskManager.CancelTask(ctx, subtask.TaskID)
		case <-time.After(*waitDuration):
		}
		return nil
	})
}