package core

import (
	"errors"
	"math/big"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/harmony-one/harmony/core/rawdb"
	"github.com/harmony-one/harmony/core/state"
	"github.com/harmony-one/harmony/core/types"
	"github.com/harmony-one/harmony/internal/utils"
	"github.com/harmony-one/harmony/shard"
)

// CommitOffChainData write off chain data of a block onto db writer.
func (bc *BlockChain) CommitOffChainData(
	batch rawdb.DatabaseWriter, block *types.Block, receipts []*types.Receipt,
	cxReceipts []*types.CXReceipt, payout *big.Int, state *state.DB, root common.Hash) (status WriteStatus, err error) {
	//// Write receipts of the block
	rawdb.WriteReceipts(batch, block.Hash(), block.NumberU64(), receipts)

	//// Cross-shard txns
	epoch := block.Header().Epoch()
	if bc.chainConfig.HasCrossTxFields(block.Epoch()) {
		shardingConfig := shard.Schedule.InstanceForEpoch(epoch)
		shardNum := int(shardingConfig.NumShards())
		for i := 0; i < shardNum; i++ {
			if i == int(block.ShardID()) {
				continue
			}

			shardReceipts := types.CXReceipts(cxReceipts).GetToShardReceipts(uint32(i))
			err := rawdb.WriteCXReceipts(batch, uint32(i), block.NumberU64(), block.Hash(), shardReceipts)
			if err != nil {
				utils.Logger().Error().Err(err).Interface("shardReceipts", shardReceipts).Int("toShardID", i).Msg("WriteCXReceipts cannot write into database")
				return NonStatTy, err
			}
		}
		// Mark incomingReceipts in the block as spent
		bc.WriteCXReceiptsProofSpent(batch, block.IncomingReceipts())
	}

	//// VRF + VDF
	//check non zero VRF field in header and add to local db
	//if len(block.Vrf()) > 0 {
	//	vrfBlockNumbers, _ := bc.ReadEpochVrfBlockNums(block.Header().Epoch())
	//	if (len(vrfBlockNumbers) > 0) && (vrfBlockNumbers[len(vrfBlockNumbers)-1] == block.NumberU64()) {
	//		utils.Logger().Error().
	//			Str("number", block.Number().String()).
	//			Str("epoch", block.Header().Epoch().String()).
	//			Msg("VRF block number is already in local db")
	//	} else {
	//		vrfBlockNumbers = append(vrfBlockNumbers, block.NumberU64())
	//		err = bc.WriteEpochVrfBlockNums(block.Header().Epoch(), vrfBlockNumbers)
	//		if err != nil {
	//			utils.Logger().Error().
	//				Str("number", block.Number().String()).
	//				Str("epoch", block.Header().Epoch().String()).
	//				Msg("failed to write VRF block number to local db")
	//			return NonStatTy, err
	//		}
	//	}
	//}
	//
	////check non zero Vdf in header and add to local db
	//if len(block.Vdf()) > 0 {
	//	err = bc.WriteEpochVdfBlockNum(block.Header().Epoch(), block.Number())
	//	if err != nil {
	//		utils.Logger().Error().
	//			Str("number", block.Number().String()).
	//			Str("epoch", block.Header().Epoch().String()).
	//			Msg("failed to write VDF block number to local db")
	//		return NonStatTy, err
	//	}
	//}

	//// Shard State and Validator Update
	header := block.Header()
	if len(header.ShardState()) > 0 {
		// Write shard state for the new epoch
		epoch := new(big.Int).Add(header.Epoch(), common.Big1)
		shardState, err := block.Header().GetShardState()
		if err == nil && shardState.Epoch != nil && bc.chainConfig.IsStaking(shardState.Epoch) {
			// After staking, the epoch will be decided by the epoch in the shard state.
			epoch = new(big.Int).Set(shardState.Epoch)
		}

		newShardState, err := bc.WriteShardStateBytes(batch, epoch, header.ShardState())
		if err != nil {
			header.Logger(utils.Logger()).Warn().Err(err).Msg("cannot store shard state")
			return NonStatTy, err
		}

		// Find all the elected validator addresses and store them in db
		allElectedValidators := []common.Address{}
		processed := make(map[common.Address]struct{})
		for i := range newShardState.Shards {
			shard := newShardState.Shards[i]
			for j := range shard.Slots {
				slot := shard.Slots[j]
				if slot.EffectiveStake != nil { // For external validator
					_, ok := processed[slot.EcdsaAddress]
					if !ok {
						processed[slot.EcdsaAddress] = struct{}{}
						allElectedValidators = append(allElectedValidators, shard.Slots[j].EcdsaAddress)
					}
				}
			}
		}

		// Update elected validators
		if err := bc.WriteElectedValidatorList(batch, allElectedValidators); err != nil {
			return NonStatTy, err
		}

		// Update snapshots for all validators
		if err := bc.UpdateValidatorSnapshots(batch, epoch); err != nil {
			return NonStatTy, err
		}
	}

	// Do bookkeeping for new staking txns
	for _, tx := range block.StakingTransactions() {
		err = bc.UpdateStakingMetaData(batch, tx, root)
		// keep offchain database consistency with onchain we need revert
		// but it should not happend unless local database corrupted
		if err != nil {
			utils.Logger().Debug().Msgf("oops, UpdateStakingMetaData failed, err: %+v", err)
			return NonStatTy, err
		}
	}

	// Update voting power of validators for all shards
	if block.ShardID() == shard.BeaconChainShardID &&
		len(block.Header().ShardState()) > 0 {
		shardState := new(shard.State)

		if shardState, err = shard.DecodeWrapper(block.Header().ShardState()); err == nil {
			if err = bc.UpdateValidatorVotingPower(batch, shardState); err != nil {
				utils.Logger().Err(err).Msg("[UpdateValidatorVotingPower] Failed to update voting power")
			}
		} else {
			utils.Logger().Err(err).Msg("[UpdateValidatorVotingPower] Failed to decode shard state")
		}
	}

	//// Writing beacon chain cross links
	if header.ShardID() == shard.BeaconChainShardID &&
		bc.chainConfig.IsCrossLink(block.Epoch()) &&
		len(header.CrossLinks()) > 0 {
		crossLinks := &types.CrossLinks{}
		err = rlp.DecodeBytes(header.CrossLinks(), crossLinks)
		if err != nil {
			header.Logger(utils.Logger()).Warn().Err(err).Msg("[insertChain/crosslinks] cannot parse cross links")
			return NonStatTy, err
		}
		if !crossLinks.IsSorted() {
			header.Logger(utils.Logger()).Warn().Err(err).Msg("[insertChain/crosslinks] cross links are not sorted")
			return NonStatTy, errors.New("proposed cross links are not sorted")
		}
		for _, crossLink := range *crossLinks {
			// Process crosslink
			if err := bc.WriteCrossLinks(batch, types.CrossLinks{crossLink}); err == nil {
				utils.Logger().Info().Uint64("blockNum", crossLink.BlockNum()).Uint32("shardID", crossLink.ShardID()).Msg("[insertChain/crosslinks] Cross Link Added to Beaconchain")
			}
			bc.LastContinuousCrossLink(batch, crossLink)
		}

		//clean/update local database cache after crosslink inserted into blockchain
		num, err := bc.DeleteCommittedFromPendingCrossLinks(*crossLinks)
		utils.Logger().Debug().Msgf("DeleteCommittedFromPendingCrossLinks, crosslinks in header %d,  pending crosslinks: %d, error: %+v", len(*crossLinks), num, err)
	}

	if bc.CurrentHeader().ShardID() == shard.BeaconChainShardID {
		if bc.chainConfig.IsStaking(block.Epoch()) {
			if err := bc.UpdateBlockRewardAccumulator(
				batch, payout, block.Number().Uint64(),
			); err != nil {
				return NonStatTy, err
			}
			if err := bc.DeletePendingSlashingCandidates(); err != nil {
				return NonStatTy, err
			}
		} else {
			// block reward never accumulate before staking
			bc.WriteBlockRewardAccumulator(batch, big.NewInt(0), block.Number().Uint64())
		}
	}

	return CanonStatTy, nil
}