package node

import (
	"encoding/binary"
	"errors"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/harmony-one/bls/ffi/go/bls"
	proto_node "github.com/harmony-one/harmony/api/proto/node"
	"github.com/harmony-one/harmony/block"
	"github.com/harmony-one/harmony/core"
	"github.com/harmony-one/harmony/core/types"
	bls_cosi "github.com/harmony-one/harmony/crypto/bls"
	nodeconfig "github.com/harmony-one/harmony/internal/configs/node"
	"github.com/harmony-one/harmony/internal/ctxerror"
	"github.com/harmony-one/harmony/internal/utils"
	"github.com/harmony-one/harmony/p2p/host"
	"github.com/harmony-one/harmony/shard"
)

// BroadcastCXReceipts broadcasts cross shard receipts to correspoding
// destination shards
func (node *Node) BroadcastCXReceipts(newBlock *types.Block, lastCommits []byte) {

	//#### Read payload data from committed msg
	if len(lastCommits) <= 96 {
		utils.Logger().Debug().Int("lastCommitsLen", len(lastCommits)).Msg("[BroadcastCXReceipts] lastCommits Not Enough Length")
	}
	commitSig := make([]byte, 96)
	commitBitmap := make([]byte, len(lastCommits)-96)
	offset := 0
	copy(commitSig[:], lastCommits[offset:offset+96])
	offset += 96
	copy(commitBitmap[:], lastCommits[offset:])
	//#### END Read payload data from committed msg

	epoch := newBlock.Header().Epoch()
	shardingConfig := shard.Schedule.InstanceForEpoch(epoch)
	shardNum := int(shardingConfig.NumShards())
	myShardID := node.Consensus.ShardID
	utils.Logger().Info().Int("shardNum", shardNum).Uint32("myShardID", myShardID).Uint64("blockNum", newBlock.NumberU64()).Msg("[BroadcastCXReceipts]")

	for i := 0; i < shardNum; i++ {
		if i == int(myShardID) {
			continue
		}
		go node.BroadcastCXReceiptsWithShardID(newBlock, commitSig, commitBitmap, uint32(i))
	}
}

// BroadcastCXReceiptsWithShardID broadcasts cross shard receipts to given ToShardID
func (node *Node) BroadcastCXReceiptsWithShardID(block *types.Block, commitSig []byte, commitBitmap []byte, toShardID uint32) {
	myShardID := node.Consensus.ShardID
	utils.Logger().Info().Uint32("toShardID", toShardID).Uint32("myShardID", myShardID).Uint64("blockNum", block.NumberU64()).Msg("[BroadcastCXReceiptsWithShardID]")

	cxReceipts, err := node.Blockchain().ReadCXReceipts(toShardID, block.NumberU64(), block.Hash(), false)
	if err != nil || len(cxReceipts) == 0 {
		utils.Logger().Info().Err(err).Uint32("ToShardID", toShardID).Int("numCXReceipts", len(cxReceipts)).Msg("[BroadcastCXReceiptsWithShardID] No ReadCXReceipts found")
		return
	}
	merkleProof, err := node.Blockchain().CXMerkleProof(toShardID, block)
	if err != nil {
		utils.Logger().Warn().Uint32("ToShardID", toShardID).Msg("[BroadcastCXReceiptsWithShardID] Unable to get merkleProof")
		return
	}

	groupID := nodeconfig.NewGroupIDByShardID(nodeconfig.ShardID(toShardID))
	utils.Logger().Info().Uint32("ToShardID", toShardID).Str("GroupID", string(groupID)).Msg("[BroadcastCXReceiptsWithShardID] ReadCXReceipts and MerkleProof Found")
	// TODO ek – limit concurrency
	go node.host.SendMessageToGroups([]nodeconfig.GroupID{groupID}, host.ConstructP2pMessage(byte(0), proto_node.ConstructCXReceiptsProof(cxReceipts, merkleProof, block.Header(), commitSig, commitBitmap)))
}

// BroadcastMissingCXReceipts broadcasts missing cross shard receipts per request
func (node *Node) BroadcastMissingCXReceipts() {
	sendNextTime := []core.CxEntry{}
	it := node.CxPool.Pool().Iterator()
	for entry := range it.C {
		cxEntry := entry.(core.CxEntry)
		toShardID := cxEntry.ToShardID
		blk := node.Blockchain().GetBlockByHash(cxEntry.BlockHash)
		if blk == nil {
			continue
		}
		blockNum := blk.NumberU64()
		nextHeader := node.Blockchain().GetHeaderByNumber(blockNum + 1)
		if nextHeader == nil {
			sendNextTime = append(sendNextTime, cxEntry)
			continue
		}
		sig := nextHeader.LastCommitSignature()
		bitmap := nextHeader.LastCommitBitmap()
		node.BroadcastCXReceiptsWithShardID(blk, sig[:], bitmap, toShardID)
	}
	node.CxPool.Clear()
	// this should not happen or maybe happen for impatient user
	for _, entry := range sendNextTime {
		node.CxPool.Add(entry)
	}
}

// VerifyBlockCrossLinks verifies the cross links of the block
func (node *Node) VerifyBlockCrossLinks(block *types.Block) error {
	if len(block.Header().CrossLinks()) == 0 {
		return nil
	}
	crossLinks := &types.CrossLinks{}
	err := rlp.DecodeBytes(block.Header().CrossLinks(), crossLinks)
	if err != nil {
		return ctxerror.New("[CrossLinkVerification] failed to decode cross links",
			"blockHash", block.Hash(),
			"crossLinks", len(block.Header().CrossLinks()),
		).WithCause(err)
	}

	if !crossLinks.IsSorted() {
		return ctxerror.New("[CrossLinkVerification] cross links are not sorted",
			"blockHash", block.Hash(),
			"crossLinks", len(block.Header().CrossLinks()),
		)
	}

	firstCrossLinkBlock := core.EpochFirstBlock(node.Blockchain().Config().CrossLinkEpoch)

	for i, crossLink := range *crossLinks {
		lastLink := &types.CrossLink{}
		if i == 0 {
			if crossLink.BlockNum().Cmp(firstCrossLinkBlock) > 0 {
				lastLink, err = node.Blockchain().ReadShardLastCrossLink(crossLink.ShardID())
				if err != nil {
					return ctxerror.New("[CrossLinkVerification] no last cross link found 1",
						"blockHash", block.Hash(),
						"crossLink", lastLink,
					).WithCause(err)
				}
			}
		} else {
			if (*crossLinks)[i-1].Header().ShardID() != crossLink.Header().ShardID() {
				if crossLink.BlockNum().Cmp(firstCrossLinkBlock) > 0 {
					lastLink, err = node.Blockchain().ReadShardLastCrossLink(crossLink.ShardID())
					if err != nil {
						return ctxerror.New("[CrossLinkVerification] no last cross link found 2",
							"blockHash", block.Hash(),
							"crossLink", lastLink,
						).WithCause(err)
					}
				}
			} else {
				lastLink = &(*crossLinks)[i-1]
			}
		}

		if crossLink.BlockNum().Cmp(firstCrossLinkBlock) > 0 { // TODO: verify genesis block
			err = node.VerifyCrosslinkHeader(lastLink.Header(), crossLink.Header())
			if err != nil {
				return ctxerror.New("cannot ValidateNewBlock",
					"blockHash", block.Hash(),
					"numTx", len(block.Transactions()),
				).WithCause(err)
			}
		}
	}
	return nil
}

// ProcessHeaderMessage verify and process Node/Header message into crosslink when it's valid
func (node *Node) ProcessHeaderMessage(msgPayload []byte) {
	if node.NodeConfig.ShardID == 0 {

		var headers []*block.Header
		err := rlp.DecodeBytes(msgPayload, &headers)
		if err != nil {
			utils.Logger().Error().
				Err(err).
				Msg("[ProcessingHeader] Crosslink Headers Broadcast Unable to Decode")
			return
		}

		// Try to reprocess all the pending cross links
		node.pendingClMutex.Lock()
		crossLinkHeadersToProcess := node.pendingCrossLinks
		node.pendingCrossLinks = []*block.Header{}
		node.pendingClMutex.Unlock()

		firstCrossLinkBlock := core.EpochFirstBlock(node.Blockchain().Config().CrossLinkEpoch)
		for _, header := range headers {
			if header.Number().Cmp(firstCrossLinkBlock) >= 0 {
				// Only process cross link starting from FirstCrossLinkBlock
				utils.Logger().Debug().Msgf("[ProcessHeaderMessage] Add Pending CrossLink, shardID %d, blockNum %d", header.ShardID(), header.Number())
				crossLinkHeadersToProcess = append(crossLinkHeadersToProcess, header)
			}
		}
		utils.Logger().Debug().
			Msgf("[ProcessingHeader] number of crosslink headers to propose %d, firstCrossLinkBlock %d", len(crossLinkHeadersToProcess), firstCrossLinkBlock)

		headersToQuque := []*block.Header{}

		for _, header := range crossLinkHeadersToProcess {
			if len(headersToQuque) > crossLinkBatchSize {
				break
			}
			exist, err := node.Blockchain().ReadCrossLink(header.ShardID(), header.Number().Uint64(), false)
			if err == nil && exist != nil {
				utils.Logger().Debug().
					Msgf("[ProcessingHeader] Cross Link already exists, pass. Block num: %d, shardID %d", header.Number(), header.ShardID())
				continue
			}

			if header.Number().Cmp(firstCrossLinkBlock) > 0 { // Directly trust the first cross-link
				// Sanity check on the previous link with the new link
				previousLink, err := node.Blockchain().ReadCrossLink(header.ShardID(), header.Number().Uint64()-1, false)
				if err != nil {
					previousLink, err = node.Blockchain().ReadCrossLink(header.ShardID(), header.Number().Uint64()-1, true)
					if err != nil {
						headersToQuque = append(headersToQuque, header)
						utils.Logger().Error().Err(err).
							Msgf("[ProcessingHeader] ReadCrossLink cannot read previousLink with number %d, shardID %d", header.Number().Uint64()-1, header.ShardID())
						continue
					}
				}

				err = node.VerifyCrosslinkHeader(previousLink.Header(), header)
				if err != nil {
					utils.Logger().Error().
						Err(err).
						Msgf("[ProcessingHeader] Failed to verify new cross link header for shardID %d, blockNum %d", header.ShardID(), header.Number())
					continue
				}
			}

			crossLink := types.NewCrossLink(header)
			utils.Logger().Debug().
				Msgf("[ProcessingHeader] committing for shardID %d, blockNum %d", header.ShardID(), header.Number().Uint64())
			node.Blockchain().WriteCrossLinks(types.CrossLinks{crossLink}, true)
		}

		// Queue up the cross links that's in the future
		node.pendingClMutex.Lock()
		node.pendingCrossLinks = append(node.pendingCrossLinks, headersToQuque...)
		node.pendingClMutex.Unlock()
	}
}

func (node *Node) verifyIncomingReceipts(block *types.Block) error {
	m := make(map[common.Hash]struct{})
	cxps := block.IncomingReceipts()
	for _, cxp := range cxps {
		// double spent
		if node.Blockchain().IsSpent(cxp) {
			return ctxerror.New("[verifyIncomingReceipts] Double Spent!")
		}
		hash := cxp.MerkleProof.BlockHash
		// duplicated receipts
		if _, ok := m[hash]; ok {
			return ctxerror.New("[verifyIncomingReceipts] Double Spent!")
		}
		m[hash] = struct{}{}

		for _, item := range cxp.Receipts {
			if item.ToShardID != node.Blockchain().ShardID() {
				return ctxerror.New("[verifyIncomingReceipts] Invalid ToShardID", "myShardID", node.Blockchain().ShardID(), "expectShardID", item.ToShardID)
			}
		}

		if err := node.Blockchain().Validator().ValidateCXReceiptsProof(cxp); err != nil {
			return ctxerror.New("[verifyIncomingReceipts] verification failed").WithCause(err)
		}
	}

	incomingReceiptHash := types.EmptyRootHash
	if len(cxps) > 0 {
		incomingReceiptHash = types.DeriveSha(cxps)
	}
	if incomingReceiptHash != block.Header().IncomingReceiptHash() {
		return ctxerror.New("[verifyIncomingReceipts] Invalid IncomingReceiptHash in block header")
	}

	return nil
}

// VerifyCrosslinkHeader verifies the header is valid against the prevHeader.
func (node *Node) VerifyCrosslinkHeader(prevHeader, header *block.Header) error {

	// TODO: add fork choice rule
	parentHash := header.ParentHash()
	if prevHeader.Hash() != parentHash {
		return ctxerror.New("[CrossLink] Invalid cross link header - parent hash mismatch", "shardID", header.ShardID(), "blockNum", header.Number())
	}

	// Verify signature of the new cross link header
	// TODO: check whether to recalculate shard state
	shardState, err := node.Blockchain().ReadShardState(prevHeader.Epoch())
	committee := shardState.FindCommitteeByID(prevHeader.ShardID())

	if err != nil || committee == nil {
		return ctxerror.New("[CrossLink] Failed to read shard state for cross link header", "shardID", header.ShardID(), "blockNum", header.Number()).WithCause(err)
	}
	var committerKeys []*bls.PublicKey

	parseKeysSuccess := true
	for _, member := range committee.Slots {
		committerKey := new(bls.PublicKey)
		err = member.BlsPublicKey.ToLibBLSPublicKey(committerKey)
		if err != nil {
			parseKeysSuccess = false
			break
		}
		committerKeys = append(committerKeys, committerKey)
	}
	if !parseKeysSuccess {
		return ctxerror.New("[CrossLink] cannot convert BLS public key", "shardID", header.ShardID(), "blockNum", header.Number()).WithCause(err)
	}

	if header.Number().Uint64() > 1 { // First block doesn't have last sig
		mask, err := bls_cosi.NewMask(committerKeys, nil)
		if err != nil {
			return ctxerror.New("cannot create group sig mask", "shardID", header.ShardID(), "blockNum", header.Number()).WithCause(err)
		}
		if err := mask.SetMask(header.LastCommitBitmap()); err != nil {
			return ctxerror.New("cannot set group sig mask bits", "shardID", header.ShardID(), "blockNum", header.Number()).WithCause(err)
		}

		aggSig := bls.Sign{}
		sig := header.LastCommitSignature()
		err = aggSig.Deserialize(sig[:])
		if err != nil {
			return ctxerror.New("unable to deserialize multi-signature from payload").WithCause(err)
		}

		blockNumBytes := make([]byte, 8)
		binary.LittleEndian.PutUint64(blockNumBytes, header.Number().Uint64()-1)
		commitPayload := append(blockNumBytes, parentHash[:]...)
		if !aggSig.VerifyHash(mask.AggregatePublic, commitPayload) {
			return ctxerror.New("Failed to verify the signature for cross link header ", "shardID", header.ShardID(), "blockNum", header.Number())
		}
	}
	return nil
}

// ProposeCrossLinkDataForBeaconchain propose cross links for beacon chain new block
func (node *Node) ProposeCrossLinkDataForBeaconchain() (types.CrossLinks, error) {
	utils.Logger().Info().
		Uint64("blockNum", node.Blockchain().CurrentBlock().NumberU64()+1).
		Msg("Proposing cross links ...")
	curBlock := node.Blockchain().CurrentBlock()
	numShards := shard.Schedule.InstanceForEpoch(curBlock.Header().Epoch()).NumShards()

	shardCrossLinks := make([]types.CrossLinks, numShards)

	firstCrossLinkBlock := core.EpochFirstBlock(node.Blockchain().Config().CrossLinkEpoch)

	for i := 0; i < int(numShards); i++ {
		curShardID := uint32(i)
		lastLink, err := node.Blockchain().ReadShardLastCrossLink(curShardID)

		lastLinkblockNum := firstCrossLinkBlock
		blockNumoffset := 0
		if err == nil && lastLink != nil {
			blockNumoffset = 1
			lastLinkblockNum = lastLink.BlockNum()
		}

		for true {
			link, err := node.Blockchain().ReadCrossLink(curShardID, lastLinkblockNum.Uint64()+uint64(blockNumoffset), true)
			if err != nil || link == nil {
				break
			}

			if link.BlockNum().Cmp(firstCrossLinkBlock) > 0 {
				if lastLink == nil {
					utils.Logger().Error().
						Err(err).
						Msgf("[CrossLink] Haven't received the first cross link %d", link.BlockNum().Uint64())
					break
				} else {
					err := node.VerifyCrosslinkHeader(lastLink.Header(), link.Header())
					if err != nil {
						utils.Logger().Error().
							Err(err).
							Msgf("[CrossLink] Failed verifying temp cross link %d", link.BlockNum().Uint64())
						break
					}
				}
			}
			shardCrossLinks[i] = append(shardCrossLinks[i], *link)
			lastLink = link
			blockNumoffset++
		}
	}

	crossLinksToPropose := types.CrossLinks{}
	for _, crossLinks := range shardCrossLinks {
		crossLinksToPropose = append(crossLinksToPropose, crossLinks...)
	}
	if len(crossLinksToPropose) != 0 {
		crossLinksToPropose.Sort()

		return crossLinksToPropose, nil
	}
	return types.CrossLinks{}, errors.New("No cross link to propose")
}

// ProcessReceiptMessage store the receipts and merkle proof in local data store
func (node *Node) ProcessReceiptMessage(msgPayload []byte) {
	cxp := types.CXReceiptsProof{}
	if err := rlp.DecodeBytes(msgPayload, &cxp); err != nil {
		utils.Logger().Error().Err(err).Msg("[ProcessReceiptMessage] Unable to Decode message Payload")
		return
	}
	utils.Logger().Debug().Interface("cxp", cxp).Msg("[ProcessReceiptMessage] Add CXReceiptsProof to pending Receipts")
	// TODO: integrate with txpool
	node.AddPendingReceipts(&cxp)
}