// Copyright 2016 TiKV Project Authors.
//
// 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 schedule

import (
	"context"
	"strconv"
	"sync"
	"time"

	"github.com/pingcap/errors"
	"github.com/pingcap/failpoint"
	"github.com/pingcap/log"
	"github.com/tikv/pd/pkg/core"
	"github.com/tikv/pd/pkg/errs"
	"github.com/tikv/pd/pkg/schedule/checker"
	sc "github.com/tikv/pd/pkg/schedule/config"
	sche "github.com/tikv/pd/pkg/schedule/core"
	"github.com/tikv/pd/pkg/schedule/diagnostic"
	"github.com/tikv/pd/pkg/schedule/hbstream"
	"github.com/tikv/pd/pkg/schedule/operator"
	"github.com/tikv/pd/pkg/schedule/scatter"
	"github.com/tikv/pd/pkg/schedule/schedulers"
	"github.com/tikv/pd/pkg/schedule/splitter"
	"github.com/tikv/pd/pkg/schedule/types"
	"github.com/tikv/pd/pkg/statistics"
	"github.com/tikv/pd/pkg/statistics/utils"
	"github.com/tikv/pd/pkg/utils/logutil"
	"github.com/tikv/pd/pkg/utils/syncutil"
	"go.uber.org/zap"
)

const (
	runSchedulerCheckInterval = 3 * time.Second
	collectTimeout            = 5 * time.Minute
	maxLoadConfigRetries      = 10
	// pushOperatorTickInterval is the interval try to push the operator.
	pushOperatorTickInterval = 500 * time.Millisecond

	// PluginLoad means action for load plugin
	PluginLoad = "PluginLoad"
	// PluginUnload means action for unload plugin
	PluginUnload = "PluginUnload"
)

// Coordinator is used to manage all schedulers and checkers to decide if the region needs to be scheduled.
type Coordinator struct {
	syncutil.RWMutex

	wg     sync.WaitGroup
	ctx    context.Context
	cancel context.CancelFunc

	schedulersInitialized bool

	cluster           sche.ClusterInformer
	prepareChecker    *prepareChecker
	checkers          *checker.Controller
	regionScatterer   *scatter.RegionScatterer
	regionSplitter    *splitter.RegionSplitter
	schedulers        *schedulers.Controller
	opController      *operator.Controller
	hbStreams         *hbstream.HeartbeatStreams
	pluginInterface   *PluginInterface
	diagnosticManager *diagnostic.Manager
}

// NewCoordinator creates a new Coordinator.
func NewCoordinator(parentCtx context.Context, cluster sche.ClusterInformer, hbStreams *hbstream.HeartbeatStreams) *Coordinator {
	ctx, cancel := context.WithCancel(parentCtx)
	opController := operator.NewController(ctx, cluster.GetBasicCluster(), cluster.GetSharedConfig(), hbStreams)
	schedulers := schedulers.NewController(ctx, cluster, cluster.GetStorage(), opController)
	checkers := checker.NewController(ctx, cluster, cluster.GetCheckerConfig(), cluster.GetRuleManager(), cluster.GetRegionLabeler(), opController)
	return &Coordinator{
		ctx:                   ctx,
		cancel:                cancel,
		schedulersInitialized: false,
		cluster:               cluster,
		prepareChecker:        newPrepareChecker(),
		checkers:              checkers,
		regionScatterer:       scatter.NewRegionScatterer(ctx, cluster, opController, checkers.AddPendingProcessedRegions),
		regionSplitter:        splitter.NewRegionSplitter(cluster, splitter.NewSplitRegionsHandler(cluster, opController), checkers.AddPendingProcessedRegions),
		schedulers:            schedulers,
		opController:          opController,
		hbStreams:             hbStreams,
		pluginInterface:       NewPluginInterface(),
		diagnosticManager:     diagnostic.NewManager(schedulers, cluster.GetSchedulerConfig()),
	}
}

// markSchedulersInitialized marks the scheduler initialization is finished.
func (c *Coordinator) markSchedulersInitialized() {
	c.Lock()
	defer c.Unlock()
	c.schedulersInitialized = true
}

// AreSchedulersInitialized returns whether the schedulers have been initialized.
func (c *Coordinator) AreSchedulersInitialized() bool {
	c.RLock()
	defer c.RUnlock()
	return c.schedulersInitialized
}

// IsPendingRegion returns if the region is in the pending list.
func (c *Coordinator) IsPendingRegion(region uint64) bool {
	return c.checkers.IsPendingRegion(region)
}

// PatrolRegions is used to scan regions.
// The function is exposed for test purpose.
func (c *Coordinator) PatrolRegions() {
	defer logutil.LogPanic()
	defer c.wg.Done()
	log.Info("coordinator starts patrol regions")
	c.checkers.PatrolRegions()
	log.Info("patrol regions has been stopped")
}

// checkSuspectRanges would pop one suspect key range group
// The regions of new version key range and old version key range would be placed into
// the suspect regions map
func (c *Coordinator) checkSuspectRanges() {
	defer logutil.LogPanic()
	defer c.wg.Done()
	log.Info("coordinator begins to check suspect key ranges")
	c.checkers.CheckSuspectRanges()
	log.Info("check suspect key ranges has been stopped")
}

// GetPatrolRegionsDuration returns the duration of the last patrol region round.
func (c *Coordinator) GetPatrolRegionsDuration() time.Duration {
	if c == nil {
		return 0
	}
	return c.checkers.GetPatrolRegionsDuration()
}

// drivePushOperator is used to push the unfinished operator to the executor.
func (c *Coordinator) drivePushOperator() {
	defer logutil.LogPanic()

	defer c.wg.Done()
	log.Info("coordinator begins to actively drive push operator")
	ticker := time.NewTicker(pushOperatorTickInterval)
	defer ticker.Stop()
	for {
		select {
		case <-c.ctx.Done():
			log.Info("drive push operator has been stopped")
			return
		case <-ticker.C:
			c.opController.PushOperators(c.RecordOpStepWithTTL)
		}
	}
}

// driveSlowNodeScheduler is used to enable slow node scheduler when using `raft-kv2`.
func (c *Coordinator) driveSlowNodeScheduler() {
	defer logutil.LogPanic()
	defer c.wg.Done()

	ticker := time.NewTicker(time.Minute)
	defer ticker.Stop()
	for {
		select {
		case <-c.ctx.Done():
			log.Info("drive slow node scheduler is stopped")
			return
		case <-ticker.C:
			{
				// If enabled, exit.
				if exists, _ := c.schedulers.IsSchedulerExisted(types.EvictSlowTrendScheduler.String()); exists {
					return
				}
				// If the cluster was set up with `raft-kv2` engine, this cluster should
				// enable `evict-slow-trend` scheduler as default.
				if c.GetCluster().GetStoreConfig().IsRaftKV2() {
					typ := types.EvictSlowTrendScheduler
					args := []string{}

					s, err := schedulers.CreateScheduler(typ, c.opController, c.cluster.GetStorage(), schedulers.ConfigSliceDecoder(typ, args), c.schedulers.RemoveScheduler)
					if err != nil {
						log.Warn("initializing evict-slow-trend scheduler failed", errs.ZapError(err))
					} else if err = c.schedulers.AddScheduler(s, args...); err != nil {
						log.Error("can not add scheduler", zap.String("scheduler-name", s.GetName()), zap.Strings("scheduler-args", args), errs.ZapError(err))
					}
				}
			}
		}
	}
}

// RunUntilStop runs the coordinator until receiving the stop signal.
func (c *Coordinator) RunUntilStop(collectWaitTime ...time.Duration) {
	c.Run(collectWaitTime...)
	<-c.ctx.Done()
	log.Info("coordinator is stopping")
	c.GetSchedulersController().Wait()
	c.wg.Wait()
	log.Info("coordinator has been stopped")
}

// Run starts coordinator.
func (c *Coordinator) Run(collectWaitTime ...time.Duration) {
	ticker := time.NewTicker(runSchedulerCheckInterval)
	failpoint.Inject("changeCoordinatorTicker", func() {
		ticker.Reset(100 * time.Millisecond)
	})
	defer ticker.Stop()
	log.Info("coordinator starts to collect cluster information")
	for {
		if c.ShouldRun(collectWaitTime...) {
			log.Info("coordinator has finished cluster information preparation")
			break
		}
		select {
		case <-ticker.C:
		case <-c.ctx.Done():
			log.Info("coordinator stops running")
			return
		}
	}
	log.Info("coordinator starts to run schedulers")
	c.InitSchedulers(true)

	c.wg.Add(4)
	// Starts to patrol regions.
	go c.PatrolRegions()
	// Checks suspect key ranges
	go c.checkSuspectRanges()
	go c.drivePushOperator()
	// Checks whether to create evict-slow-trend scheduler.
	go c.driveSlowNodeScheduler()
}

// InitSchedulers initializes schedulers.
func (c *Coordinator) InitSchedulers(needRun bool) {
	var (
		scheduleNames []string
		configs       []string
		err           error
	)
	for i := range maxLoadConfigRetries {
		scheduleNames, configs, err = c.cluster.GetStorage().LoadAllSchedulerConfigs()
		select {
		case <-c.ctx.Done():
			log.Info("init schedulers has been stopped")
			return
		default:
		}
		if err == nil {
			break
		}
		log.Error("cannot load schedulers' config", zap.Int("retry-times", i), errs.ZapError(err))
	}
	if err != nil {
		log.Fatal("cannot load schedulers' config", errs.ZapError(err))
	}
	scheduleCfg := c.cluster.GetSchedulerConfig().GetScheduleConfig().Clone()
	// The new way to create scheduler with the independent configuration.
	for i, name := range scheduleNames {
		data := configs[i]
		typ := schedulers.FindSchedulerTypeByName(name)
		var cfg sc.SchedulerConfig
		for _, c := range scheduleCfg.Schedulers {
			if c.Type == types.SchedulerTypeCompatibleMap[typ] {
				cfg = c
				break
			}
		}
		if len(cfg.Type) == 0 {
			log.Error("the scheduler type not found", zap.String("scheduler-name", name), errs.ZapError(errs.ErrSchedulerNotFound))
			continue
		}
		if cfg.Disable {
			log.Info("skip create scheduler with independent configuration", zap.String("scheduler-name", name), zap.String("scheduler-type", cfg.Type), zap.Strings("scheduler-args", cfg.Args))
			continue
		}
		s, err := schedulers.CreateScheduler(types.ConvertOldStrToType[cfg.Type], c.opController,
			c.cluster.GetStorage(), schedulers.ConfigJSONDecoder([]byte(data)), c.schedulers.RemoveScheduler)
		if err != nil {
			log.Error("can not create scheduler with independent configuration", zap.String("scheduler-name", name), zap.Strings("scheduler-args", cfg.Args), errs.ZapError(err))
			continue
		}
		if needRun {
			log.Info("create scheduler with independent configuration", zap.String("scheduler-name", s.GetName()))
			if err = c.schedulers.AddScheduler(s); err != nil {
				log.Error("can not add scheduler with independent configuration",
					zap.String("scheduler-name", s.GetName()), zap.Strings("scheduler-args", cfg.Args), errs.ZapError(err))
			}
		} else {
			log.Info("create scheduler handler with independent configuration", zap.String("scheduler-name", s.GetName()))
			if err = c.schedulers.AddSchedulerHandler(s); err != nil {
				log.Error("can not add scheduler handler with independent configuration",
					zap.String("scheduler-name", s.GetName()), zap.Strings("scheduler-args", cfg.Args), errs.ZapError(err))
			}
		}
	}

	// The old way to create the scheduler.
	k := 0
	for _, schedulerCfg := range scheduleCfg.Schedulers {
		if schedulerCfg.Disable {
			scheduleCfg.Schedulers[k] = schedulerCfg
			k++
			log.Info("skip create scheduler", zap.String("scheduler-type", schedulerCfg.Type), zap.Strings("scheduler-args", schedulerCfg.Args))
			continue
		}

		tp := types.ConvertOldStrToType[schedulerCfg.Type]
		s, err := schedulers.CreateScheduler(tp, c.opController,
			c.cluster.GetStorage(), schedulers.ConfigSliceDecoder(tp, schedulerCfg.Args), c.schedulers.RemoveScheduler)
		if err != nil {
			log.Error("can not create scheduler", zap.Stringer("type", tp), zap.String("scheduler-type", schedulerCfg.Type),
				zap.Strings("scheduler-args", schedulerCfg.Args), errs.ZapError(err))
			continue
		}

		if needRun {
			log.Info("create scheduler", zap.String("scheduler-name", s.GetName()),
				zap.Strings("scheduler-args", schedulerCfg.Args))
			if err = c.schedulers.AddScheduler(s, schedulerCfg.Args...); err != nil &&
				!errors.ErrorEqual(err, errs.ErrSchedulerExisted.FastGenByArgs()) {
				log.Error("can not add scheduler", zap.String("scheduler-name",
					s.GetName()), zap.Strings("scheduler-args", schedulerCfg.Args), errs.ZapError(err))
			} else {
				// Only records the valid scheduler config.
				scheduleCfg.Schedulers[k] = schedulerCfg
				k++
			}
		} else {
			log.Info("create scheduler handler", zap.String("scheduler-name", s.GetName()), zap.Strings("scheduler-args", schedulerCfg.Args))
			if err = c.schedulers.AddSchedulerHandler(s, schedulerCfg.Args...); err != nil && !errors.ErrorEqual(err, errs.ErrSchedulerExisted.FastGenByArgs()) {
				log.Error("can not add scheduler handler", zap.String("scheduler-name", s.GetName()), zap.Strings("scheduler-args", schedulerCfg.Args), errs.ZapError(err))
			} else {
				scheduleCfg.Schedulers[k] = schedulerCfg
				k++
			}
		}
	}

	// Removes the invalid scheduler config and persist.
	scheduleCfg.Schedulers = scheduleCfg.Schedulers[:k]
	c.cluster.GetSchedulerConfig().SetScheduleConfig(scheduleCfg)
	if err := c.cluster.GetSchedulerConfig().Persist(c.cluster.GetStorage()); err != nil {
		log.Error("cannot persist schedule config", errs.ZapError(err))
	}
	log.Info("scheduler config is updated", zap.Reflect("scheduler-config", scheduleCfg.Schedulers))

	c.markSchedulersInitialized()
}

// LoadPlugin load user plugin
func (c *Coordinator) LoadPlugin(pluginPath string, ch chan string) {
	log.Info("load plugin", zap.String("plugin-path", pluginPath))
	// get func: SchedulerType from plugin
	SchedulerType, err := c.pluginInterface.GetFunction(pluginPath, "SchedulerType")
	if err != nil {
		log.Error("GetFunction SchedulerType error", errs.ZapError(err))
		return
	}
	schedulerType := SchedulerType.(func() types.CheckerSchedulerType)
	// get func: SchedulerArgs from plugin
	SchedulerArgs, err := c.pluginInterface.GetFunction(pluginPath, "SchedulerArgs")
	if err != nil {
		log.Error("GetFunction SchedulerArgs error", errs.ZapError(err))
		return
	}
	schedulerArgs := SchedulerArgs.(func() []string)
	// create and add user scheduler
	s, err := schedulers.CreateScheduler(schedulerType(), c.opController, c.cluster.GetStorage(), schedulers.ConfigSliceDecoder(schedulerType(), schedulerArgs()), c.schedulers.RemoveScheduler)
	if err != nil {
		log.Error("can not create scheduler", zap.Stringer("scheduler-type", schedulerType()), errs.ZapError(err))
		return
	}
	log.Info("create scheduler", zap.String("scheduler-name", s.GetName()))
	// TODO: handle the plugin in API service mode.
	if err = c.schedulers.AddScheduler(s); err != nil {
		log.Error("can't add scheduler", zap.String("scheduler-name", s.GetName()), errs.ZapError(err))
		return
	}

	c.wg.Add(1)
	go c.waitPluginUnload(pluginPath, s.GetName(), ch)
}

func (c *Coordinator) waitPluginUnload(pluginPath, schedulerName string, ch chan string) {
	defer logutil.LogPanic()
	defer c.wg.Done()
	// Get signal from channel which means user unload the plugin
	for {
		select {
		case action := <-ch:
			if action == PluginUnload {
				err := c.schedulers.RemoveScheduler(schedulerName)
				if err != nil {
					log.Error("can not remove scheduler", zap.String("scheduler-name", schedulerName), errs.ZapError(err))
				} else {
					log.Info("unload plugin", zap.String("plugin", pluginPath))
					return
				}
			} else {
				log.Error("unknown action", zap.String("action", action))
			}
		case <-c.ctx.Done():
			log.Info("unload plugin has been stopped")
			return
		}
	}
}

// Stop stops the coordinator.
func (c *Coordinator) Stop() {
	c.cancel()
}

// GetHotRegionsByType gets hot regions' statistics by RWType.
func (c *Coordinator) GetHotRegionsByType(typ utils.RWType) *statistics.StoreHotPeersInfos {
	isTraceFlow := c.cluster.GetSchedulerConfig().IsTraceRegionFlow()
	storeLoads := c.cluster.GetStoresLoads()
	stores := c.cluster.GetStores()
	hotPeerStats := c.cluster.GetHotPeerStats(typ)
	infos := statistics.GetHotStatus(stores, storeLoads, hotPeerStats, typ, isTraceFlow)
	// update params `IsLearner` and `LastUpdateTime`
	s := []statistics.StoreHotPeersStat{infos.AsLeader, infos.AsPeer}
	for i, stores := range s {
		for j, store := range stores {
			for k := range store.Stats {
				h := &s[i][j].Stats[k]
				region := c.cluster.GetRegion(h.RegionID)
				if region != nil {
					h.IsLearner = core.IsLearner(region.GetPeer(h.StoreID))
				}
				switch typ {
				case utils.Write:
					if region != nil {
						h.LastUpdateTime = time.Unix(int64(region.GetInterval().GetEndTimestamp()), 0)
					}
				case utils.Read:
					store := c.cluster.GetStore(h.StoreID)
					if store != nil {
						ts := store.GetMeta().GetLastHeartbeat()
						h.LastUpdateTime = time.Unix(ts/1e9, ts%1e9)
					}
				default:
				}
			}
		}
	}
	return infos
}

// GetHotRegions gets hot regions' statistics by RWType and storeIDs.
// If storeIDs is empty, it returns all hot regions' statistics by RWType.
func (c *Coordinator) GetHotRegions(typ utils.RWType, storeIDs ...uint64) *statistics.StoreHotPeersInfos {
	hotRegions := c.GetHotRegionsByType(typ)
	if len(storeIDs) > 0 && hotRegions != nil {
		asLeader := statistics.StoreHotPeersStat{}
		asPeer := statistics.StoreHotPeersStat{}
		for _, storeID := range storeIDs {
			asLeader[storeID] = hotRegions.AsLeader[storeID]
			asPeer[storeID] = hotRegions.AsPeer[storeID]
		}
		return &statistics.StoreHotPeersInfos{
			AsLeader: asLeader,
			AsPeer:   asPeer,
		}
	}
	return hotRegions
}

// GetWaitGroup returns the wait group. Only for test purpose.
func (c *Coordinator) GetWaitGroup() *sync.WaitGroup {
	return &c.wg
}

// CollectHotSpotMetrics collects hot spot metrics.
func (c *Coordinator) CollectHotSpotMetrics() {
	stores := c.cluster.GetStores()
	// Collects hot write region metrics.
	collectHotMetrics(c.cluster, stores, utils.Write)
	// Collects hot read region metrics.
	collectHotMetrics(c.cluster, stores, utils.Read)
}

func collectHotMetrics(cluster sche.ClusterInformer, stores []*core.StoreInfo, typ utils.RWType) {
	kind := typ.String()
	hotPeerStats := cluster.GetHotPeerStats(typ)
	status := statistics.CollectHotPeerInfos(stores, hotPeerStats) // only returns TotalBytesRate,TotalKeysRate,TotalQueryRate,Count

	for _, s := range stores {
		// TODO: pre-allocate gauge metrics
		storeAddress := s.GetAddress()
		storeID := s.GetID()
		storeLabel := strconv.FormatUint(storeID, 10)
		stat, hasHotLeader := status.AsLeader[storeID]
		if hasHotLeader {
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "total_"+kind+"_bytes_as_leader").Set(stat.TotalBytesRate)
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "total_"+kind+"_keys_as_leader").Set(stat.TotalKeysRate)
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "total_"+kind+"_query_as_leader").Set(stat.TotalQueryRate)
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "hot_"+kind+"_region_as_leader").Set(float64(stat.Count))
		} else {
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "total_"+kind+"_bytes_as_leader")
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "total_"+kind+"_keys_as_leader")
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "total_"+kind+"_query_as_leader")
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "hot_"+kind+"_region_as_leader")
		}

		stat, hasHotPeer := status.AsPeer[storeID]
		if hasHotPeer {
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "total_"+kind+"_bytes_as_peer").Set(stat.TotalBytesRate)
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "total_"+kind+"_keys_as_peer").Set(stat.TotalKeysRate)
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "total_"+kind+"_query_as_peer").Set(stat.TotalQueryRate)
			hotSpotStatusGauge.WithLabelValues(storeAddress, storeLabel, "hot_"+kind+"_region_as_peer").Set(float64(stat.Count))
		} else {
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "total_"+kind+"_bytes_as_peer")
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "total_"+kind+"_keys_as_peer")
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "total_"+kind+"_query_as_peer")
			hotSpotStatusGauge.DeleteLabelValues(storeAddress, storeLabel, "hot_"+kind+"_region_as_peer")
		}

		if !hasHotLeader && !hasHotPeer {
			utils.ForeachRegionStats(func(rwTy utils.RWType, dim int, _ utils.RegionStatKind) {
				schedulers.HotPendingSum.DeleteLabelValues(storeLabel, rwTy.String(), utils.DimToString(dim))
			})
		}
	}
}

// ResetHotSpotMetrics resets hot spot metrics.
func ResetHotSpotMetrics() {
	hotSpotStatusGauge.Reset()
	schedulers.HotPendingSum.Reset()
}

// ShouldRun returns true if the coordinator should run.
func (c *Coordinator) ShouldRun(collectWaitTime ...time.Duration) bool {
	return c.prepareChecker.check(c.cluster.GetBasicCluster(), collectWaitTime...)
}

// GetSchedulersController returns the schedulers controller.
func (c *Coordinator) GetSchedulersController() *schedulers.Controller {
	return c.schedulers
}

// PauseOrResumeChecker pauses or resumes a checker by name.
func (c *Coordinator) PauseOrResumeChecker(name string, t int64) error {
	c.Lock()
	defer c.Unlock()
	if c.cluster == nil {
		return errs.ErrNotBootstrapped.FastGenByArgs()
	}
	p, err := c.checkers.GetPauseController(name)
	if err != nil {
		return err
	}
	p.PauseOrResume(t)
	return nil
}

// IsCheckerPaused returns whether a checker is paused.
func (c *Coordinator) IsCheckerPaused(name string) (bool, error) {
	c.RLock()
	defer c.RUnlock()
	if c.cluster == nil {
		return false, errs.ErrNotBootstrapped.FastGenByArgs()
	}
	p, err := c.checkers.GetPauseController(name)
	if err != nil {
		return false, err
	}
	return p.IsPaused(), nil
}

// GetRegionScatterer returns the region scatterer.
func (c *Coordinator) GetRegionScatterer() *scatter.RegionScatterer {
	return c.regionScatterer
}

// GetRegionSplitter returns the region splitter.
func (c *Coordinator) GetRegionSplitter() *splitter.RegionSplitter {
	return c.regionSplitter
}

// GetOperatorController returns the operator controller.
func (c *Coordinator) GetOperatorController() *operator.Controller {
	return c.opController
}

// GetCheckerController returns the checker controller.
func (c *Coordinator) GetCheckerController() *checker.Controller {
	return c.checkers
}

// GetMergeChecker returns the merge checker.
func (c *Coordinator) GetMergeChecker() *checker.MergeChecker {
	return c.checkers.GetMergeChecker()
}

// GetRuleChecker returns the rule checker.
func (c *Coordinator) GetRuleChecker() *checker.RuleChecker {
	return c.checkers.GetRuleChecker()
}

// GetPrepareChecker returns the prepare checker.
func (c *Coordinator) GetPrepareChecker() *prepareChecker {
	return c.prepareChecker
}

// GetHeartbeatStreams returns the heartbeat streams. Only for test purpose.
func (c *Coordinator) GetHeartbeatStreams() *hbstream.HeartbeatStreams {
	return c.hbStreams
}

// GetCluster returns the cluster. Only for test purpose.
func (c *Coordinator) GetCluster() sche.ClusterInformer {
	return c.cluster
}

// GetDiagnosticResult returns the diagnostic result.
func (c *Coordinator) GetDiagnosticResult(name string) (*schedulers.DiagnosticResult, error) {
	return c.diagnosticManager.GetDiagnosticResult(name)
}

// RecordOpStepWithTTL records OpStep with TTL
func (c *Coordinator) RecordOpStepWithTTL(regionID uint64) {
	c.GetRuleChecker().RecordRegionPromoteToNonWitness(regionID)
}