package governance

import (
	"context"
	"encoding/binary"
	"encoding/hex"
	"sort"
	"strings"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client"
	frostfscontract "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client/frostfs"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"go.uber.org/zap"
)

const (
	alphabetUpdateIDPrefix = "AlphabetUpdate"
)

func (gp *Processor) processAlphabetSync(ctx context.Context, txHash util.Uint256) bool {
	if !gp.alphabetState.IsAlphabet(ctx) {
		gp.log.Info(ctx, logs.GovernanceNonAlphabetModeIgnoreAlphabetSync)
		return true
	}

	mainnetAlphabet, err := gp.mainnetClient.NeoFSAlphabetList()
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantFetchAlphabetListFromMainNet,
			zap.Error(err))
		return false
	}

	sidechainAlphabet, err := gp.morphClient.Committee()
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantFetchAlphabetListFromSideChain,
			zap.Error(err))
		return false
	}

	newAlphabet, err := newAlphabetList(sidechainAlphabet, mainnetAlphabet)
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantMergeAlphabetListsFromMainNetAndSideChain,
			zap.Error(err))
		return false
	}

	if newAlphabet == nil {
		gp.log.Info(ctx, logs.GovernanceNoGovernanceUpdateAlphabetListHasNotBeenChanged)
		return true
	}

	gp.log.Info(ctx, logs.GovernanceAlphabetListHasBeenChangedStartingUpdate,
		zap.String("side_chain_alphabet", prettyKeys(sidechainAlphabet)),
		zap.String("new_alphabet", prettyKeys(newAlphabet)),
	)

	votePrm := VoteValidatorPrm{
		Validators: newAlphabet,
		Hash:       &txHash,
	}

	// 1. Vote to sidechain committee via alphabet contracts.
	err = gp.voter.VoteForSidechainValidator(ctx, votePrm)
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantVoteForSideChainCommittee,
			zap.Error(err))
	}

	// 2. Update NeoFSAlphabet role in the sidechain.
	gp.updateNeoFSAlphabetRoleInSidechain(ctx, sidechainAlphabet, newAlphabet, txHash)

	// 3. Update notary role in the sidechain.
	gp.updateNotaryRoleInSidechain(ctx, newAlphabet, txHash)

	// 4. Update FrostFS contract in the mainnet.
	gp.updateFrostFSContractInMainnet(ctx, newAlphabet)

	gp.log.Info(ctx, logs.GovernanceFinishedAlphabetListUpdate)

	return true
}

func prettyKeys(keys keys.PublicKeys) string {
	const delimiter = ","

	sb := strings.Builder{}
	for _, key := range keys {
		sb.WriteString(hex.EncodeToString(key.Bytes()))
		sb.WriteString(delimiter)
	}

	return strings.TrimRight(sb.String(), delimiter)
}

func (gp *Processor) updateNeoFSAlphabetRoleInSidechain(ctx context.Context, sidechainAlphabet, newAlphabet keys.PublicKeys, txHash util.Uint256) {
	innerRing, err := gp.irFetcher.InnerRingKeys()
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantFetchInnerRingListFromSideChain,
			zap.Error(err))
		return
	}

	newInnerRing, err := updateInnerRing(innerRing, sidechainAlphabet, newAlphabet)
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantCreateNewInnerRingListWithNewAlphabetKeys,
			zap.Error(err))
		return
	}

	sort.Sort(newInnerRing)

	gp.log.Info(ctx, logs.GovernanceUpdateOfTheInnerRingList,
		zap.String("before", prettyKeys(innerRing)),
		zap.String("after", prettyKeys(newInnerRing)),
	)

	updPrm := client.UpdateAlphabetListPrm{}
	updPrm.SetList(newInnerRing)
	updPrm.SetHash(txHash)

	if err = gp.morphClient.UpdateNeoFSAlphabetList(ctx, updPrm); err != nil {
		gp.log.Error(ctx, logs.GovernanceCantUpdateInnerRingListWithNewAlphabetKeys,
			zap.Error(err))
	}
}

func (gp *Processor) updateNotaryRoleInSidechain(ctx context.Context, newAlphabet keys.PublicKeys, txHash util.Uint256) {
	updPrm := client.UpdateNotaryListPrm{}

	updPrm.SetList(newAlphabet)
	updPrm.SetHash(txHash)

	err := gp.morphClient.UpdateNotaryList(ctx, updPrm)
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantUpdateListOfNotaryNodesInSideChain,
			zap.Error(err))
	}
}

func (gp *Processor) updateFrostFSContractInMainnet(ctx context.Context, newAlphabet keys.PublicKeys) {
	epoch := gp.epochState.EpochCounter()

	buf := make([]byte, 8)
	binary.LittleEndian.PutUint64(buf, epoch)

	id := append([]byte(alphabetUpdateIDPrefix), buf...)

	prm := frostfscontract.AlphabetUpdatePrm{}

	prm.SetID(id)
	prm.SetPubs(newAlphabet)

	err := gp.frostfsClient.AlphabetUpdate(ctx, prm)
	if err != nil {
		gp.log.Error(ctx, logs.GovernanceCantUpdateListOfAlphabetNodesInFrostfsContract,
			zap.Error(err))
	}
}