// Licensed to the LF AI & Data foundation under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// 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.

package meta

import (
	"sync"
	"time"

	"github.com/milvus-io/milvus/internal/log"
	"github.com/milvus-io/milvus/internal/proto/datapb"
	"github.com/milvus-io/milvus/internal/util/funcutil"
	"github.com/milvus-io/milvus/internal/util/tsoutil"
	"go.uber.org/zap"
)

type TargetManager struct {
	rwmutex sync.RWMutex

	segments   map[int64]*datapb.SegmentInfo
	dmChannels map[string]*DmChannel
}

func NewTargetManager() *TargetManager {
	return &TargetManager{
		segments:   make(map[int64]*datapb.SegmentInfo),
		dmChannels: make(map[string]*DmChannel),
	}
}

// RemoveCollection removes all channels and segments in the given collection
func (mgr *TargetManager) RemoveCollection(collectionID int64) {
	mgr.rwmutex.Lock()
	defer mgr.rwmutex.Unlock()

	log.Info("remove collection from targets")
	for _, segment := range mgr.segments {
		if segment.CollectionID == collectionID {
			mgr.removeSegment(segment.GetID())
		}
	}
	for _, dmChannel := range mgr.dmChannels {
		if dmChannel.CollectionID == collectionID {
			mgr.removeDmChannel(dmChannel.GetChannelName())
		}
	}
}

// RemovePartition removes all segment in the given partition,
// NOTE: this doesn't remove any channel even the given one is the only partition
func (mgr *TargetManager) RemovePartition(partitionID int64) {
	mgr.rwmutex.Lock()
	defer mgr.rwmutex.Unlock()

	log.Info("remove partition from targets",
		zap.Int64("partitionID", partitionID))
	for _, segment := range mgr.segments {
		if segment.GetPartitionID() == partitionID {
			mgr.removeSegment(segment.GetID())
		}
	}
}

func (mgr *TargetManager) RemoveSegment(segmentID int64) {
	mgr.rwmutex.Lock()
	defer mgr.rwmutex.Unlock()

	delete(mgr.segments, segmentID)
}

func (mgr *TargetManager) removeSegment(segmentID int64) {
	delete(mgr.segments, segmentID)
	log.Info("segment removed from targets", zap.Int64("segment", segmentID))
}

// AddSegment adds segment into target set,
// requires CollectionID, PartitionID, InsertChannel, SegmentID are set
func (mgr *TargetManager) AddSegment(segments ...*datapb.SegmentInfo) {
	mgr.rwmutex.Lock()
	defer mgr.rwmutex.Unlock()

	mgr.addSegment(segments...)
}

func (mgr *TargetManager) addSegment(segments ...*datapb.SegmentInfo) {
	for _, segment := range segments {
		log.Info("add segment into targets",
			zap.Int64("segmentID", segment.GetID()),
			zap.Int64("collectionID", segment.GetCollectionID()),
		)
		mgr.segments[segment.GetID()] = segment
	}
}

func (mgr *TargetManager) ContainSegment(id int64) bool {
	mgr.rwmutex.RLock()
	defer mgr.rwmutex.RUnlock()

	return mgr.containSegment(id)
}

func (mgr *TargetManager) containSegment(id int64) bool {
	_, ok := mgr.segments[id]
	return ok
}

func (mgr *TargetManager) GetSegmentsByCollection(collection int64, partitions ...int64) []*datapb.SegmentInfo {
	mgr.rwmutex.RLock()
	defer mgr.rwmutex.RUnlock()

	segments := make([]*datapb.SegmentInfo, 0)
	for _, segment := range mgr.segments {
		if segment.CollectionID == collection &&
			(len(partitions) == 0 || funcutil.SliceContain(partitions, segment.PartitionID)) {
			segments = append(segments, segment)
		}
	}

	return segments
}

func (mgr *TargetManager) HandoffSegment(dest *datapb.SegmentInfo, sources ...int64) {
	mgr.rwmutex.Lock()
	defer mgr.rwmutex.Unlock()

	// add dest to target
	dest.CompactionFrom = sources
	mgr.addSegment(dest)
}

// AddDmChannel adds a channel into target set,
// requires CollectionID, ChannelName are set
func (mgr *TargetManager) AddDmChannel(channels ...*DmChannel) {
	mgr.rwmutex.Lock()
	defer mgr.rwmutex.Unlock()

	for _, channel := range channels {
		ts := channel.GetSeekPosition().GetTimestamp()
		log.Info("add channel into targets",
			zap.String("channel", channel.GetChannelName()),
			zap.Uint64("checkpoint", ts),
			zap.Duration("sinceCheckpoint", time.Since(tsoutil.PhysicalTime(ts))),
		)
		mgr.dmChannels[channel.ChannelName] = channel
	}
}

func (mgr *TargetManager) GetDmChannel(channel string) *DmChannel {
	mgr.rwmutex.RLock()
	defer mgr.rwmutex.RUnlock()
	for _, ch := range mgr.dmChannels {
		if ch.ChannelName == channel {
			return ch
		}
	}
	return nil
}

func (mgr *TargetManager) ContainDmChannel(channel string) bool {
	mgr.rwmutex.RLock()
	defer mgr.rwmutex.RUnlock()

	_, ok := mgr.dmChannels[channel]
	return ok
}

func (mgr *TargetManager) removeDmChannel(channel string) {
	delete(mgr.dmChannels, channel)
	log.Info("remove channel from targets", zap.String("channel", channel))
}

func (mgr *TargetManager) GetDmChannelsByCollection(collectionID int64) []*DmChannel {
	mgr.rwmutex.RLock()
	defer mgr.rwmutex.RUnlock()

	channels := make([]*DmChannel, 0)
	for _, channel := range mgr.dmChannels {
		if channel.GetCollectionID() == collectionID {
			channels = append(channels, channel)
		}
	}
	return channels
}

func (mgr *TargetManager) GetSegment(id int64) *datapb.SegmentInfo {
	mgr.rwmutex.RLock()
	defer mgr.rwmutex.RUnlock()

	for _, s := range mgr.segments {
		if s.GetID() == id {
			return s
		}
	}
	return nil
}