// 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 proxy

import (
	"context"
	"sync"

	"go.uber.org/zap"
	"golang.org/x/sync/errgroup"

	"github.com/milvus-io/milvus-proto/go-api/commonpb"
	"github.com/milvus-io/milvus-proto/go-api/milvuspb"
	"github.com/milvus-io/milvus-proto/go-api/msgpb"
	"github.com/milvus-io/milvus-proto/go-api/schemapb"
	"github.com/milvus-io/milvus/internal/allocator"
	"github.com/milvus-io/milvus/pkg/log"
	"github.com/milvus-io/milvus/pkg/mq/msgstream"
	"github.com/milvus-io/milvus/pkg/util/commonpbutil"
	"github.com/milvus-io/milvus/pkg/util/retry"
	"github.com/milvus-io/milvus/pkg/util/typeutil"
)

func genInsertMsgsByPartition(ctx context.Context,
	segmentID UniqueID,
	partitionID UniqueID,
	partitionName string,
	rowOffsets []int,
	channelName string,
	insertMsg *msgstream.InsertMsg) ([]msgstream.TsMsg, error) {
	threshold := Params.PulsarCfg.MaxMessageSize.GetAsInt()

	// create empty insert message
	createInsertMsg := func(segmentID UniqueID, channelName string) *msgstream.InsertMsg {
		insertReq := msgpb.InsertRequest{
			Base: commonpbutil.NewMsgBase(
				commonpbutil.WithMsgType(commonpb.MsgType_Insert),
				commonpbutil.WithTimeStamp(insertMsg.BeginTimestamp), // entity's timestamp was set to equal it.BeginTimestamp in preExecute()
				commonpbutil.WithSourceID(insertMsg.Base.SourceID),
			),
			CollectionID:   insertMsg.CollectionID,
			PartitionID:    partitionID,
			CollectionName: insertMsg.CollectionName,
			PartitionName:  partitionName,
			SegmentID:      segmentID,
			ShardName:      channelName,
			Version:        msgpb.InsertDataVersion_ColumnBased,
		}
		insertReq.FieldsData = make([]*schemapb.FieldData, len(insertMsg.GetFieldsData()))

		msg := &msgstream.InsertMsg{
			BaseMsg: msgstream.BaseMsg{
				Ctx: ctx,
			},
			InsertRequest: insertReq,
		}

		return msg
	}

	repackedMsgs := make([]msgstream.TsMsg, 0)
	requestSize := 0
	msg := createInsertMsg(segmentID, channelName)
	for _, offset := range rowOffsets {
		curRowMessageSize, err := typeutil.EstimateEntitySize(insertMsg.GetFieldsData(), offset)
		if err != nil {
			return nil, err
		}

		// if insertMsg's size is greater than the threshold, split into multiple insertMsgs
		if requestSize+curRowMessageSize >= threshold {
			repackedMsgs = append(repackedMsgs, msg)
			msg = createInsertMsg(segmentID, channelName)
			requestSize = 0
		}

		typeutil.AppendFieldData(msg.FieldsData, insertMsg.GetFieldsData(), int64(offset))
		msg.HashValues = append(msg.HashValues, insertMsg.HashValues[offset])
		msg.Timestamps = append(msg.Timestamps, insertMsg.Timestamps[offset])
		msg.RowIDs = append(msg.RowIDs, insertMsg.RowIDs[offset])
		msg.NumRows++
		requestSize += curRowMessageSize
	}
	repackedMsgs = append(repackedMsgs, msg)

	return repackedMsgs, nil
}

func repackInsertDataByPartition(ctx context.Context,
	partitionName string,
	rowOffsets []int,
	channelName string,
	insertMsg *msgstream.InsertMsg,
	segIDAssigner *segIDAssigner) ([]msgstream.TsMsg, error) {
	res := make([]msgstream.TsMsg, 0)

	maxTs := Timestamp(0)
	for _, offset := range rowOffsets {
		ts := insertMsg.Timestamps[offset]
		if maxTs < ts {
			maxTs = ts
		}
	}

	partitionID, err := globalMetaCache.GetPartitionID(ctx, insertMsg.CollectionName, partitionName)
	if err != nil {
		return nil, err
	}
	assignedSegmentInfos, err := segIDAssigner.GetSegmentID(insertMsg.CollectionID, partitionID, channelName, uint32(len(rowOffsets)), maxTs)
	if err != nil {
		log.Error("allocate segmentID for insert data failed",
			zap.String("collection name", insertMsg.CollectionName),
			zap.String("channel name", channelName),
			zap.Int("allocate count", len(rowOffsets)),
			zap.Error(err))
		return nil, err
	}

	startPos := 0
	for segmentID, count := range assignedSegmentInfos {
		subRowOffsets := rowOffsets[startPos : startPos+int(count)]
		msgs, err := genInsertMsgsByPartition(ctx, segmentID, partitionID, partitionName, subRowOffsets, channelName, insertMsg)
		if err != nil {
			log.Warn("repack insert data to insert msgs failed",
				zap.String("collection name", insertMsg.CollectionName),
				zap.Int64("partitionID", partitionID),
				zap.Error(err))
			return nil, err
		}
		res = append(res, msgs...)
		startPos += int(count)
	}

	return res, nil
}

func setMsgID(ctx context.Context,
	msgs []msgstream.TsMsg,
	idAllocator *allocator.IDAllocator) error {
	var idBegin int64
	var err error

	err = retry.Do(ctx, func() error {
		idBegin, _, err = idAllocator.Alloc(uint32(len(msgs)))
		return err
	})
	if err != nil {
		log.Error("failed to allocate msg id", zap.Error(err))
		return err
	}

	for i, msg := range msgs {
		msg.SetID(idBegin + UniqueID(i))
	}

	return nil
}

func repackInsertData(ctx context.Context,
	channelNames []string,
	insertMsg *msgstream.InsertMsg,
	result *milvuspb.MutationResult,
	idAllocator *allocator.IDAllocator,
	segIDAssigner *segIDAssigner) (*msgstream.MsgPack, error) {
	msgPack := &msgstream.MsgPack{
		BeginTs: insertMsg.BeginTs(),
		EndTs:   insertMsg.EndTs(),
	}

	channel2RowOffsets := assignChannelsByPK(result.IDs, channelNames, insertMsg)
	for channel, rowOffsets := range channel2RowOffsets {
		partitionName := insertMsg.PartitionName
		msgs, err := repackInsertDataByPartition(ctx, partitionName, rowOffsets, channel, insertMsg, segIDAssigner)
		if err != nil {
			log.Warn("repack insert data to msg pack failed",
				zap.String("collection name", insertMsg.CollectionName),
				zap.String("partition name", partitionName),
				zap.Error(err))
			return nil, err
		}

		msgPack.Msgs = append(msgPack.Msgs, msgs...)
	}

	err := setMsgID(ctx, msgPack.Msgs, idAllocator)
	if err != nil {
		log.Error("failed to set msgID when repack insert data",
			zap.String("collection name", insertMsg.CollectionName),
			zap.String("partition name", insertMsg.PartitionName),
			zap.Error(err))
		return nil, err
	}

	return msgPack, nil
}

func repackInsertDataWithPartitionKey(ctx context.Context,
	channelNames []string,
	partitionKeys *schemapb.FieldData,
	insertMsg *msgstream.InsertMsg,
	result *milvuspb.MutationResult,
	idAllocator *allocator.IDAllocator,
	segIDAssigner *segIDAssigner) (*msgstream.MsgPack, error) {
	msgPack := &msgstream.MsgPack{
		BeginTs: insertMsg.BeginTs(),
		EndTs:   insertMsg.EndTs(),
	}

	channel2RowOffsets := assignChannelsByPK(result.IDs, channelNames, insertMsg)
	partitionNames, err := getDefaultPartitionNames(ctx, insertMsg.CollectionName)
	if err != nil {
		log.Warn("get default partition names failed in partition key mode",
			zap.String("collection name", insertMsg.CollectionName),
			zap.Error(err))
		return nil, err
	}
	hashValues, err := typeutil.HashKey2Partitions(partitionKeys, partitionNames)
	if err != nil {
		log.Warn("has partition keys to partitions failed",
			zap.String("collection name", insertMsg.CollectionName),
			zap.Error(err))
		return nil, err
	}

	for channel, rowOffsets := range channel2RowOffsets {
		partition2RowOffsets := make(map[string][]int)
		for _, idx := range rowOffsets {
			partitionName := partitionNames[hashValues[idx]]
			if _, ok := partition2RowOffsets[partitionName]; !ok {
				partition2RowOffsets[partitionName] = []int{}
			}
			partition2RowOffsets[partitionName] = append(partition2RowOffsets[partitionName], idx)
		}

		errGroup, _ := errgroup.WithContext(ctx)
		partition2Msgs := sync.Map{}
		for partitionName, offsets := range partition2RowOffsets {
			partitionName := partitionName
			offsets := offsets
			errGroup.Go(func() error {
				msgs, err := repackInsertDataByPartition(ctx, partitionName, offsets, channel, insertMsg, segIDAssigner)
				if err != nil {
					return err
				}

				partition2Msgs.Store(partitionName, msgs)
				return nil
			})
		}

		err = errGroup.Wait()
		if err != nil {
			log.Warn("repack insert data into insert msg pack failed",
				zap.String("collection name", insertMsg.CollectionName),
				zap.String("channel name", channel),
				zap.Error(err))
			return nil, err
		}

		partition2Msgs.Range(func(k, v interface{}) bool {
			msgs := v.([]msgstream.TsMsg)
			msgPack.Msgs = append(msgPack.Msgs, msgs...)
			return true
		})
	}

	err = setMsgID(ctx, msgPack.Msgs, idAllocator)
	if err != nil {
		log.Error("failed to set msgID when repack insert data",
			zap.String("collection name", insertMsg.CollectionName),
			zap.Error(err))
		return nil, err
	}

	return msgPack, nil
}