// Copyright 2018 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 statistics

import (
	"fmt"
	"strconv"

	"github.com/pingcap/kvproto/pkg/metapb"
	"github.com/tikv/pd/pkg/core"
	"github.com/tikv/pd/pkg/core/constant"
	"github.com/tikv/pd/pkg/core/storelimit"
	"github.com/tikv/pd/pkg/schedule/config"
	"github.com/tikv/pd/pkg/statistics/utils"
)

const (
	unknown   = "unknown"
	labelType = "label"
)

type storeStatistics struct {
	opt             config.ConfProvider
	Up              int
	Disconnect      int
	Unhealthy       int
	Down            int
	Offline         int
	Tombstone       int
	LowSpace        int
	Slow            int
	StorageSize     uint64
	StorageCapacity uint64
	RegionCount     int
	LeaderCount     int
	LearnerCount    int
	WitnessCount    int
	LabelCounter    map[string][]uint64
	Preparing       int
	Serving         int
	Removing        int
	Removed         int
}

func newStoreStatistics(opt config.ConfProvider) *storeStatistics {
	return &storeStatistics{
		opt:          opt,
		LabelCounter: make(map[string][]uint64),
	}
}

func (s *storeStatistics) observe(store *core.StoreInfo) {
	for _, k := range s.opt.GetLocationLabels() {
		v := store.GetLabelValue(k)
		if v == "" {
			v = unknown
		}
		key := fmt.Sprintf("%s:%s", k, v)
		// exclude tombstone
		if !store.IsRemoved() {
			s.LabelCounter[key] = append(s.LabelCounter[key], store.GetID())
		}
	}
	storeAddress := store.GetAddress()
	id := strconv.FormatUint(store.GetID(), 10)
	// Store state.
	isDown := false
	switch store.GetNodeState() {
	case metapb.NodeState_Preparing, metapb.NodeState_Serving:
		if store.DownTime() >= s.opt.GetMaxStoreDownTime() {
			isDown = true
			s.Down++
		} else if store.IsUnhealthy() {
			s.Unhealthy++
		} else if store.IsDisconnected() {
			s.Disconnect++
		} else if store.IsSlow() {
			s.Slow++
		} else {
			s.Up++
		}
		if store.IsPreparing() {
			s.Preparing++
		} else {
			s.Serving++
		}
	case metapb.NodeState_Removing:
		s.Offline++
		s.Removing++
	case metapb.NodeState_Removed:
		s.Tombstone++
		s.Removed++
		return
	}

	if !isDown && store.IsLowSpace(s.opt.GetLowSpaceRatio()) {
		s.LowSpace++
	}

	// Store stats.
	s.StorageSize += store.StorageSize()
	s.StorageCapacity += store.GetCapacity()
	s.RegionCount += store.GetRegionCount()
	s.LeaderCount += store.GetLeaderCount()
	s.WitnessCount += store.GetWitnessCount()
	s.LearnerCount += store.GetLearnerCount()
	limit, ok := store.GetStoreLimit().(*storelimit.SlidingWindows)
	if ok {
		cap := limit.GetCap()
		storeStatusGauge.WithLabelValues(storeAddress, id, "windows_size").Set(float64(cap))
		for i, use := range limit.GetUsed() {
			priority := constant.PriorityLevel(i).String()
			storeStatusGauge.WithLabelValues(storeAddress, id, "windows_used_level_"+priority).Set(float64(use))
		}
	}

	// TODO: pre-allocate gauge metrics
	storeStatusGauge.WithLabelValues(storeAddress, id, "region_score").Set(store.RegionScore(s.opt.GetRegionScoreFormulaVersion(), s.opt.GetHighSpaceRatio(), s.opt.GetLowSpaceRatio(), 0))
	storeStatusGauge.WithLabelValues(storeAddress, id, "leader_score").Set(store.LeaderScore(s.opt.GetLeaderSchedulePolicy(), 0))
	storeStatusGauge.WithLabelValues(storeAddress, id, "region_size").Set(float64(store.GetRegionSize()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "region_count").Set(float64(store.GetRegionCount()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "leader_size").Set(float64(store.GetLeaderSize()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "leader_count").Set(float64(store.GetLeaderCount()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "witness_count").Set(float64(store.GetWitnessCount()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "learner_count").Set(float64(store.GetLearnerCount()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_available").Set(float64(store.GetAvailable()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_used").Set(float64(store.GetUsedSize()))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_capacity").Set(float64(store.GetCapacity()))
	slowTrend := store.GetSlowTrend()
	if slowTrend != nil {
		storeStatusGauge.WithLabelValues(storeAddress, id, "store_slow_trend_cause_value").Set(slowTrend.CauseValue)
		storeStatusGauge.WithLabelValues(storeAddress, id, "store_slow_trend_cause_rate").Set(slowTrend.CauseRate)
		storeStatusGauge.WithLabelValues(storeAddress, id, "store_slow_trend_result_value").Set(slowTrend.ResultValue)
		storeStatusGauge.WithLabelValues(storeAddress, id, "store_slow_trend_result_rate").Set(slowTrend.ResultRate)
	}
}

// ObserveHotStat records the hot region metrics for the store.
func ObserveHotStat(store *core.StoreInfo, stats *StoresStats) {
	// Store flows.
	storeAddress := store.GetAddress()
	id := strconv.FormatUint(store.GetID(), 10)
	storeFlowStats := stats.GetRollingStoreStats(store.GetID())
	if storeFlowStats == nil {
		return
	}

	storeStatusGauge.WithLabelValues(storeAddress, id, "store_write_rate_bytes").Set(storeFlowStats.GetLoad(utils.StoreWriteBytes))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_read_rate_bytes").Set(storeFlowStats.GetLoad(utils.StoreReadBytes))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_write_rate_keys").Set(storeFlowStats.GetLoad(utils.StoreWriteKeys))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_read_rate_keys").Set(storeFlowStats.GetLoad(utils.StoreReadKeys))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_write_query_rate").Set(storeFlowStats.GetLoad(utils.StoreWriteQuery))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_read_query_rate").Set(storeFlowStats.GetLoad(utils.StoreReadQuery))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_cpu_usage").Set(storeFlowStats.GetLoad(utils.StoreCPUUsage))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_disk_read_rate").Set(storeFlowStats.GetLoad(utils.StoreDiskReadRate))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_disk_write_rate").Set(storeFlowStats.GetLoad(utils.StoreDiskWriteRate))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_regions_write_rate_bytes").Set(storeFlowStats.GetLoad(utils.StoreRegionsWriteBytes))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_regions_write_rate_keys").Set(storeFlowStats.GetLoad(utils.StoreRegionsWriteKeys))

	storeStatusGauge.WithLabelValues(storeAddress, id, "store_write_rate_bytes_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreWriteBytes))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_read_rate_bytes_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreReadBytes))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_write_rate_keys_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreWriteKeys))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_read_rate_keys_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreReadKeys))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_write_query_rate_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreWriteQuery))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_read_query_rate_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreReadQuery))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_regions_write_rate_bytes_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreRegionsWriteBytes))
	storeStatusGauge.WithLabelValues(storeAddress, id, "store_regions_write_rate_keys_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreRegionsWriteKeys))
}

func (s *storeStatistics) collect() {
	placementStatusGauge.Reset()

	metrics := make(map[string]float64)
	metrics["store_up_count"] = float64(s.Up)
	metrics["store_disconnected_count"] = float64(s.Disconnect)
	metrics["store_down_count"] = float64(s.Down)
	metrics["store_unhealth_count"] = float64(s.Unhealthy)
	metrics["store_offline_count"] = float64(s.Offline)
	metrics["store_tombstone_count"] = float64(s.Tombstone)
	metrics["store_low_space_count"] = float64(s.LowSpace)
	metrics["store_slow_count"] = float64(s.Slow)
	metrics["store_preparing_count"] = float64(s.Preparing)
	metrics["store_serving_count"] = float64(s.Serving)
	metrics["store_removing_count"] = float64(s.Removing)
	metrics["store_removed_count"] = float64(s.Removed)
	metrics["region_count"] = float64(s.RegionCount)
	metrics["leader_count"] = float64(s.LeaderCount)
	metrics["witness_count"] = float64(s.WitnessCount)
	metrics["learner_count"] = float64(s.LearnerCount)
	metrics["storage_size"] = float64(s.StorageSize)
	metrics["storage_capacity"] = float64(s.StorageCapacity)

	for typ, value := range metrics {
		clusterStatusGauge.WithLabelValues(typ).Set(value)
	}

	// Current scheduling configurations of the cluster
	configs := make(map[string]float64)
	configs["leader-schedule-limit"] = float64(s.opt.GetLeaderScheduleLimit())
	configs["region-schedule-limit"] = float64(s.opt.GetRegionScheduleLimit())
	configs["merge-schedule-limit"] = float64(s.opt.GetMergeScheduleLimit())
	configs["replica-schedule-limit"] = float64(s.opt.GetReplicaScheduleLimit())
	configs["max-replicas"] = float64(s.opt.GetMaxReplicas())
	configs["high-space-ratio"] = s.opt.GetHighSpaceRatio()
	configs["low-space-ratio"] = s.opt.GetLowSpaceRatio()
	configs["tolerant-size-ratio"] = s.opt.GetTolerantSizeRatio()
	configs["hot-region-schedule-limit"] = float64(s.opt.GetHotRegionScheduleLimit())
	configs["hot-region-cache-hits-threshold"] = float64(s.opt.GetHotRegionCacheHitsThreshold())
	configs["max-pending-peer-count"] = float64(s.opt.GetMaxPendingPeerCount())
	configs["max-snapshot-count"] = float64(s.opt.GetMaxSnapshotCount())
	configs["max-merge-region-size"] = float64(s.opt.GetMaxMergeRegionSize())
	configs["max-merge-region-keys"] = float64(s.opt.GetMaxMergeRegionKeys())
	configs["region-max-size"] = float64(s.opt.GetRegionMaxSize())
	configs["region-split-size"] = float64(s.opt.GetRegionSplitSize())
	configs["region-split-keys"] = float64(s.opt.GetRegionSplitKeys())
	configs["region-max-keys"] = float64(s.opt.GetRegionMaxKeys())

	var enableMakeUpReplica, enableRemoveDownReplica, enableRemoveExtraReplica, enableReplaceOfflineReplica float64
	if s.opt.IsMakeUpReplicaEnabled() {
		enableMakeUpReplica = 1
	}
	if s.opt.IsRemoveDownReplicaEnabled() {
		enableRemoveDownReplica = 1
	}
	if s.opt.IsRemoveExtraReplicaEnabled() {
		enableRemoveExtraReplica = 1
	}
	if s.opt.IsReplaceOfflineReplicaEnabled() {
		enableReplaceOfflineReplica = 1
	}

	configs["enable-makeup-replica"] = enableMakeUpReplica
	configs["enable-remove-down-replica"] = enableRemoveDownReplica
	configs["enable-remove-extra-replica"] = enableRemoveExtraReplica
	configs["enable-replace-offline-replica"] = enableReplaceOfflineReplica

	for typ, value := range configs {
		configStatusGauge.WithLabelValues(typ).Set(value)
	}

	for name, stores := range s.LabelCounter {
		for _, storeID := range stores {
			placementStatusGauge.WithLabelValues(labelType, name, strconv.FormatUint(storeID, 10)).Set(1)
		}
	}

	for storeID, limit := range s.opt.GetStoresLimit() {
		id := strconv.FormatUint(storeID, 10)
		StoreLimitGauge.WithLabelValues(id, "add-peer").Set(limit.AddPeer)
		StoreLimitGauge.WithLabelValues(id, "remove-peer").Set(limit.RemovePeer)
	}
}

// ResetStoreStatistics resets the metrics of store.
func ResetStoreStatistics(storeAddress string, id string) {
	metrics := []string{
		"region_score",
		"leader_score",
		"region_size",
		"region_count",
		"leader_size",
		"leader_count",
		"witness_count",
		"learner_count",
		"store_available",
		"store_used",
		"store_capacity",
		"store_write_rate_bytes",
		"store_read_rate_bytes",
		"store_write_rate_keys",
		"store_read_rate_keys",
		"store_write_query_rate",
		"store_read_query_rate",
		"store_regions_write_rate_bytes",
		"store_regions_write_rate_keys",
		"store_slow_trend_cause_value",
		"store_slow_trend_cause_rate",
		"store_slow_trend_result_value",
		"store_slow_trend_result_rate",
	}
	for _, m := range metrics {
		storeStatusGauge.DeleteLabelValues(storeAddress, id, m)
	}
}

type storeStatisticsMap struct {
	opt   config.ConfProvider
	stats *storeStatistics
}

// NewStoreStatisticsMap creates a new storeStatisticsMap.
func NewStoreStatisticsMap(opt config.ConfProvider) *storeStatisticsMap {
	return &storeStatisticsMap{
		opt:   opt,
		stats: newStoreStatistics(opt),
	}
}

// Observe observes the store.
func (m *storeStatisticsMap) Observe(store *core.StoreInfo) {
	m.stats.observe(store)
}

// Collect collects the metrics.
func (m *storeStatisticsMap) Collect() {
	m.stats.collect()
}

// Reset resets the metrics.
func Reset() {
	storeStatusGauge.Reset()
	clusterStatusGauge.Reset()
	placementStatusGauge.Reset()
	ResetRegionStatsMetrics()
	ResetLabelStatsMetrics()
	ResetHotCacheStatusMetrics()
}