package querynode

import (
	"context"
	"errors"
	"fmt"
	"log"
	"sort"
	"strconv"
	"strings"
	"time"

	minioKV "github.com/zilliztech/milvus-distributed/internal/kv/minio"
	"github.com/zilliztech/milvus-distributed/internal/msgstream"
	"github.com/zilliztech/milvus-distributed/internal/proto/commonpb"
	internalPb "github.com/zilliztech/milvus-distributed/internal/proto/internalpb"
)

type loadIndexService struct {
	ctx    context.Context
	cancel context.CancelFunc
	client *minioKV.MinIOKV

	replica collectionReplica

	fieldIndexes   map[string][]*internalPb.IndexStats
	fieldStatsChan chan []*internalPb.FieldStats

	loadIndexMsgStream msgstream.MsgStream

	queryNodeID UniqueID
}

func newLoadIndexService(ctx context.Context, replica collectionReplica) *loadIndexService {
	ctx1, cancel := context.WithCancel(ctx)

	option := &minioKV.Option{
		Address:           Params.MinioEndPoint,
		AccessKeyID:       Params.MinioAccessKeyID,
		SecretAccessKeyID: Params.MinioSecretAccessKey,
		UseSSL:            Params.MinioUseSSLStr,
		CreateBucket:      true,
		BucketName:        Params.MinioBucketName,
	}

	// TODO: load bucketName from config
	MinioKV, err := minioKV.NewMinIOKV(ctx1, option)
	if err != nil {
		panic(err)
	}

	// init msgStream
	receiveBufSize := Params.LoadIndexReceiveBufSize
	pulsarBufSize := Params.LoadIndexPulsarBufSize

	msgStreamURL := Params.PulsarAddress

	consumeChannels := Params.LoadIndexChannelNames
	consumeSubName := Params.MsgChannelSubName

	loadIndexStream := msgstream.NewPulsarMsgStream(ctx, receiveBufSize)
	loadIndexStream.SetPulsarClient(msgStreamURL)
	unmarshalDispatcher := msgstream.NewUnmarshalDispatcher()
	loadIndexStream.CreatePulsarConsumers(consumeChannels, consumeSubName, unmarshalDispatcher, pulsarBufSize)

	var stream msgstream.MsgStream = loadIndexStream

	return &loadIndexService{
		ctx:    ctx1,
		cancel: cancel,
		client: MinioKV,

		replica:        replica,
		fieldIndexes:   make(map[string][]*internalPb.IndexStats),
		fieldStatsChan: make(chan []*internalPb.FieldStats, 1),

		loadIndexMsgStream: stream,

		queryNodeID: Params.QueryNodeID,
	}
}

func (lis *loadIndexService) start() {
	lis.loadIndexMsgStream.Start()

	for {
		select {
		case <-lis.ctx.Done():
			return
		default:
			messages := lis.loadIndexMsgStream.Consume()
			if messages == nil || len(messages.Msgs) <= 0 {
				log.Println("null msg pack")
				continue
			}
			for _, msg := range messages.Msgs {
				indexMsg, ok := msg.(*msgstream.LoadIndexMsg)
				if !ok {
					log.Println("type assertion failed for LoadIndexMsg")
					continue
				}
				// 1. use msg's index paths to get index bytes
				var indexBuffer [][]byte
				var err error
				fn := func() error {
					indexBuffer, err = lis.loadIndex(indexMsg.IndexPaths)
					if err != nil {
						return err
					}
					return nil
				}
				err = msgstream.Retry(5, time.Millisecond*200, fn)
				if err != nil {
					log.Println(err)
					continue
				}
				// 2. use index bytes and index path to update segment
				err = lis.updateSegmentIndex(indexBuffer, indexMsg)
				if err != nil {
					log.Println(err)
					continue
				}
				//3. update segment index stats
				err = lis.updateSegmentIndexStats(indexMsg)
				if err != nil {
					log.Println(err)
					continue
				}
			}

			// sendQueryNodeStats
			err := lis.sendQueryNodeStats()
			if err != nil {
				log.Println(err)
				continue
			}
		}
	}
}

func (lis *loadIndexService) printIndexParams(index []*commonpb.KeyValuePair) {
	fmt.Println("=================================================")
	for i := 0; i < len(index); i++ {
		fmt.Println(index[i])
	}
}

func (lis *loadIndexService) indexParamsEqual(index1 []*commonpb.KeyValuePair, index2 []*commonpb.KeyValuePair) bool {
	if len(index1) != len(index2) {
		return false
	}

	for i := 0; i < len(index1); i++ {
		kv1 := *index1[i]
		kv2 := *index2[i]
		if kv1.Key != kv2.Key || kv1.Value != kv2.Value {
			return false
		}
	}

	return true
}

func (lis *loadIndexService) fieldsStatsIDs2Key(collectionID UniqueID, fieldID UniqueID) string {
	return strconv.FormatInt(collectionID, 10) + "/" + strconv.FormatInt(fieldID, 10)
}

func (lis *loadIndexService) fieldsStatsKey2IDs(key string) (UniqueID, UniqueID, error) {
	ids := strings.Split(key, "/")
	if len(ids) != 2 {
		return 0, 0, errors.New("illegal fieldsStatsKey")
	}
	collectionID, err := strconv.ParseInt(ids[0], 10, 64)
	if err != nil {
		return 0, 0, err
	}
	fieldID, err := strconv.ParseInt(ids[1], 10, 64)
	if err != nil {
		return 0, 0, err
	}
	return collectionID, fieldID, nil
}

func (lis *loadIndexService) updateSegmentIndexStats(indexMsg *msgstream.LoadIndexMsg) error {
	targetSegment, err := lis.replica.getSegmentByID(indexMsg.SegmentID)
	if err != nil {
		return err
	}

	fieldStatsKey := lis.fieldsStatsIDs2Key(targetSegment.collectionID, indexMsg.FieldID)
	_, ok := lis.fieldIndexes[fieldStatsKey]
	newIndexParams := indexMsg.IndexParams
	// sort index params by key
	sort.Slice(newIndexParams, func(i, j int) bool { return newIndexParams[i].Key < newIndexParams[j].Key })
	if !ok {
		lis.fieldIndexes[fieldStatsKey] = make([]*internalPb.IndexStats, 0)
		lis.fieldIndexes[fieldStatsKey] = append(lis.fieldIndexes[fieldStatsKey],
			&internalPb.IndexStats{
				IndexParams:        newIndexParams,
				NumRelatedSegments: 1,
			})
	} else {
		isNewIndex := true
		for _, index := range lis.fieldIndexes[fieldStatsKey] {
			if lis.indexParamsEqual(newIndexParams, index.IndexParams) {
				index.NumRelatedSegments++
				isNewIndex = false
			}
		}
		if isNewIndex {
			lis.fieldIndexes[fieldStatsKey] = append(lis.fieldIndexes[fieldStatsKey],
				&internalPb.IndexStats{
					IndexParams:        newIndexParams,
					NumRelatedSegments: 1,
				})
		}
	}

	return nil
}

func (lis *loadIndexService) loadIndex(indexPath []string) ([][]byte, error) {
	index := make([][]byte, 0)

	for _, path := range indexPath {
		fmt.Println("load path = ", indexPath)
		indexPiece, err := (*lis.client).Load(path)
		if err != nil {
			return nil, err
		}
		index = append(index, []byte(indexPiece))
	}

	return index, nil
}

func (lis *loadIndexService) updateSegmentIndex(bytesIndex [][]byte, loadIndexMsg *msgstream.LoadIndexMsg) error {
	segment, err := lis.replica.getSegmentByID(loadIndexMsg.SegmentID)
	if err != nil {
		return err
	}

	loadIndexInfo, err := newLoadIndexInfo()
	defer deleteLoadIndexInfo(loadIndexInfo)
	if err != nil {
		return err
	}
	err = loadIndexInfo.appendFieldInfo(loadIndexMsg.FieldName, loadIndexMsg.FieldID)
	if err != nil {
		return err
	}
	for _, indexParam := range loadIndexMsg.IndexParams {
		err = loadIndexInfo.appendIndexParam(indexParam.Key, indexParam.Value)
		if err != nil {
			return err
		}
	}
	err = loadIndexInfo.appendIndex(bytesIndex, loadIndexMsg.IndexPaths)
	if err != nil {
		return err
	}
	err = segment.updateSegmentIndex(loadIndexInfo)
	if err != nil {
		return err
	}

	return nil
}

func (lis *loadIndexService) sendQueryNodeStats() error {
	resultFieldsStats := make([]*internalPb.FieldStats, 0)
	for fieldStatsKey, indexStats := range lis.fieldIndexes {
		colID, fieldID, err := lis.fieldsStatsKey2IDs(fieldStatsKey)
		if err != nil {
			return err
		}
		fieldStats := internalPb.FieldStats{
			CollectionID: colID,
			FieldID:      fieldID,
			IndexStats:   indexStats,
		}
		resultFieldsStats = append(resultFieldsStats, &fieldStats)
	}

	lis.fieldStatsChan <- resultFieldsStats
	fmt.Println("sent field stats")
	return nil
}