// 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 querycoord

import (
	"context"
	"sort"

	"go.uber.org/zap"

	"github.com/milvus-io/milvus/api/milvuspb"
	"github.com/milvus-io/milvus/internal/log"
	"github.com/milvus-io/milvus/internal/proto/querypb"
	"github.com/milvus-io/milvus/internal/util/funcutil"
	"github.com/milvus-io/milvus/internal/util/typeutil"
)

func getCompareMapFromSlice(sliceData []int64) map[int64]struct{} {
	compareMap := make(map[int64]struct{})
	for _, data := range sliceData {
		compareMap[data] = struct{}{}
	}

	return compareMap
}

func estimateSegmentSize(segmentLoadInfo *querypb.SegmentLoadInfo) int64 {
	segmentSize := int64(0)

	vecFieldID2IndexInfo := make(map[int64]*querypb.FieldIndexInfo)
	for _, fieldIndexInfo := range segmentLoadInfo.IndexInfos {
		if fieldIndexInfo.EnableIndex {
			fieldID := fieldIndexInfo.FieldID
			vecFieldID2IndexInfo[fieldID] = fieldIndexInfo
		}
	}

	for _, fieldBinlog := range segmentLoadInfo.BinlogPaths {
		fieldID := fieldBinlog.FieldID
		if FieldIndexInfo, ok := vecFieldID2IndexInfo[fieldID]; ok {
			segmentSize += FieldIndexInfo.IndexSize
		} else {
			segmentSize += funcutil.GetFieldSizeFromFieldBinlog(fieldBinlog)
		}
	}

	// get size of state data
	for _, fieldBinlog := range segmentLoadInfo.Statslogs {
		segmentSize += funcutil.GetFieldSizeFromFieldBinlog(fieldBinlog)
	}

	// get size of delete data
	for _, fieldBinlog := range segmentLoadInfo.Deltalogs {
		segmentSize += funcutil.GetFieldSizeFromFieldBinlog(fieldBinlog)
	}

	return segmentSize
}

// syncReplicaSegments syncs the segments distribution of replica to shard leaders
// only syncs the segments in shards if not nil
func syncReplicaSegments(ctx context.Context, meta Meta, cluster Cluster, replicaID UniqueID, shards ...string) error {
	replica, err := meta.getReplicaByID(replicaID)
	if err != nil {
		return err
	}

	collectionSegments := make(map[UniqueID]*querypb.SegmentInfo)
	for _, segment := range meta.showSegmentInfos(replica.CollectionID, nil) {
		collectionSegments[segment.SegmentID] = segment
	}

	shardSegments := make(map[string][]*querypb.SegmentInfo) // DMC -> []SegmentInfo
	for _, segment := range collectionSegments {
		// Group segments by shard
		segments, ok := shardSegments[segment.DmChannel]
		if !ok {
			segments = make([]*querypb.SegmentInfo, 0)
		}

		segments = append(segments, segment)
		shardSegments[segment.DmChannel] = segments
	}

	for _, shard := range replica.ShardReplicas {
		if len(shards) > 0 && !isInShards(shard.DmChannelName, shards) {
			log.Debug("skip this shard",
				zap.Int64("replicaID", replicaID),
				zap.String("shard", shard.DmChannelName))
			continue
		}

		segments := shardSegments[shard.DmChannelName]
		req := querypb.SyncReplicaSegmentsRequest{
			VchannelName:    shard.DmChannelName,
			ReplicaSegments: make([]*querypb.ReplicaSegmentsInfo, 0, len(segments)),
		}

		sort.Slice(segments, func(i, j int) bool {
			inode := getNodeInReplica(replica, segments[i].NodeIds)
			jnode := getNodeInReplica(replica, segments[j].NodeIds)

			return inode < jnode ||
				inode == jnode && segments[i].PartitionID < segments[j].PartitionID
		})

		for i, j := 0, 0; i < len(segments); i = j {
			node := getNodeInReplica(replica, segments[i].NodeIds)
			if node < 0 {
				log.Warn("syncReplicaSegments: no segment node in replica",
					zap.Int64("replicaID", replicaID),
					zap.Any("segment", segments[i]))
			}

			partition := segments[i].PartitionID

			j++
			for j < len(segments) &&
				getNodeInReplica(replica, segments[j].NodeIds) == node &&
				segments[j].PartitionID == partition {
				j++
			}

			segmentIds := make([]UniqueID, 0, len(segments[i:j]))
			for _, segment := range segments[i:j] {
				segmentIds = append(segmentIds, segment.SegmentID)
			}

			req.ReplicaSegments = append(req.ReplicaSegments, &querypb.ReplicaSegmentsInfo{
				NodeId:      node,
				PartitionId: partition,
				SegmentIds:  segmentIds,
			})
		}

		log.Debug("sync replica segments",
			zap.Int64("replicaID", replicaID),
			zap.Int64("leaderID", shard.LeaderID),
			zap.Any("req", req))
		err := cluster.SyncReplicaSegments(ctx, shard.LeaderID, &req)
		if err != nil {
			return err
		}
	}

	return nil
}

func isInShards(shard string, shards []string) bool {
	for _, item := range shards {
		if shard == item {
			return true
		}
	}

	return false
}

// getNodeInReplica gets the node which is in the replica
func getNodeInReplica(replica *milvuspb.ReplicaInfo, nodes []UniqueID) UniqueID {
	for _, node := range nodes {
		if nodeIncluded(node, replica.NodeIds) {
			return node
		}
	}

	return -1
}

func removeFromSlice(origin []UniqueID, del ...UniqueID) []UniqueID {
	set := make(typeutil.UniqueSet, len(origin))
	set.Insert(origin...)
	set.Remove(del...)

	return set.Collect()
}

func uniqueSlice(origin []UniqueID) []UniqueID {
	set := make(typeutil.UniqueSet, len(origin))
	set.Insert(origin...)
	return set.Collect()
}

// diffSlice returns a slice containing items in src but not in diff
func diffSlice(src []UniqueID, diff ...UniqueID) []UniqueID {
	set := make(typeutil.UniqueSet, len(src))
	set.Insert(src...)
	set.Remove(diff...)

	return set.Collect()
}

func getReplicaAvailableMemory(cluster Cluster, replica *milvuspb.ReplicaInfo) uint64 {
	availableMemory := uint64(0)
	nodes := getNodeInfos(cluster, replica.NodeIds)
	for _, node := range nodes {
		availableMemory += node.totalMem - node.memUsage
	}

	return availableMemory
}

// func getShardLeaderByNodeID(meta Meta, replicaID UniqueID, dmChannel string) (UniqueID, error) {
// 	replica, err := meta.getReplicaByID(replicaID)
// 	if err != nil {
// 		return 0, err
// 	}

// 	for _, shard := range replica.ShardReplicas {
// 		if shard.DmChannelName == dmChannel {
// 			return shard.LeaderID, nil
// 		}
// 	}

// 	return 0, fmt.Errorf("shard leader not found in replica %v and dm channel %s", replicaID, dmChannel)
// }