package node

import (
	"math/big"
	"sort"
	"time"

	"github.com/ethereum/go-ethereum/common"

	"github.com/harmony-one/harmony/core"
	"github.com/harmony-one/harmony/core/types"
	nodeconfig "github.com/harmony-one/harmony/internal/configs/node"
	"github.com/harmony-one/harmony/internal/ctxerror"
	"github.com/harmony-one/harmony/internal/utils"
)

// Constants of lower bound limit of a new block.
const (
	PeriodicBlock = 200 * time.Millisecond
)

// WaitForConsensusReadyv2 listen for the readiness signal from consensus and generate new block for consensus.
// only leader will receive the ready signal
// TODO: clean pending transactions for validators; or validators not prepare pending transactions
func (node *Node) WaitForConsensusReadyv2(readySignal chan struct{}, stopChan chan struct{}, stoppedChan chan struct{}) {
	go func() {
		// Setup stoppedChan
		defer close(stoppedChan)

		utils.Logger().Debug().
			Msg("Waiting for Consensus ready")
		time.Sleep(30 * time.Second) // Wait for other nodes to be ready (test-only)

		var newBlock *types.Block

		// Set up the very first deadline.
		deadline := time.Now().Add(node.BlockPeriod)
		for {
			// keep waiting for Consensus ready
			select {
			case <-stopChan:
				utils.Logger().Debug().
					Msg("Consensus new block proposal: STOPPED!")
				return
			case <-readySignal:
				for {
					time.Sleep(PeriodicBlock)
					if time.Now().Before(deadline) {
						continue
					}

					coinbase := node.Consensus.SelfAddress
					// Normal tx block consensus
					selectedTxs := types.Transactions{} // Empty transaction list
					if node.NodeConfig.GetNetworkType() != nodeconfig.Mainnet {
						selectedTxs = node.getTransactionsForNewBlock(MaxNumberOfTransactionsPerBlock, coinbase)
						if err := node.Worker.UpdateCurrent(coinbase); err != nil {
							utils.Logger().Error().
								Err(err).
								Msg("Failed updating worker's state")
						}
					}
					utils.Logger().Info().
						Uint64("blockNum", node.Blockchain().CurrentBlock().NumberU64()+1).
						Int("selectedTxs", len(selectedTxs)).
						Msg("PROPOSING NEW BLOCK ------------------------------------------------")

					if err := node.Worker.CommitTransactions(selectedTxs, coinbase); err != nil {
						ctxerror.Log15(utils.GetLogger().Error,
							ctxerror.New("cannot commit transactions").
								WithCause(err))
					}
					sig, mask, err := node.Consensus.LastCommitSig()
					if err != nil {
						ctxerror.Log15(utils.GetLogger().Error,
							ctxerror.New("Cannot got commit signatures from last block").
								WithCause(err))
						continue
					}

					// Propose cross shard receipts
					receiptsList := node.proposeReceiptsProof()
					if len(receiptsList) != 0 {
						if err := node.Worker.CommitReceipts(receiptsList, coinbase); err != nil {
							ctxerror.Log15(utils.GetLogger().Error,
								ctxerror.New("cannot commit receipts").
									WithCause(err))
						}
					}

					viewID := node.Consensus.GetViewID()
					// add aggregated commit signatures from last block, except for the first two blocks

					if node.NodeConfig.ShardID == 0 {
						crossLinksToPropose, err := node.ProposeCrossLinkDataForBeaconchain()
						if err == nil {
							data, err := rlp.EncodeToBytes(crossLinksToPropose)
							if err == nil {
								newBlock, err = node.Worker.CommitWithCrossLinks(sig, mask, viewID, coinbase, data)
								utils.Logger().Debug().
									Uint64("blockNum", newBlock.NumberU64()).
									Int("numCrossLinks", len(crossLinksToPropose)).
									Msg("Successfully added cross links into new block")
							}
						} else {
							newBlock, err = node.Worker.Commit(sig, mask, viewID, coinbase)
						}
					} else {
						newBlock, err = node.Worker.Commit(sig, mask, viewID, coinbase)
					}

					if err != nil {
						ctxerror.Log15(utils.GetLogger().Error,
							ctxerror.New("cannot commit new block").
								WithCause(err))
						continue
					} else if err := node.proposeShardStateWithoutBeaconSync(newBlock); err != nil {
						ctxerror.Log15(utils.GetLogger().Error,
							ctxerror.New("cannot add shard state").
								WithCause(err))
					} else {
						utils.Logger().Debug().
							Uint64("blockNum", newBlock.NumberU64()).
							Int("numTxs", newBlock.Transactions().Len()).
							Msg("Successfully proposed new block")

						// Set deadline will be BlockPeriod from now at this place. Announce stage happens right after this.
						deadline = time.Now().Add(node.BlockPeriod)
						// Send the new block to Consensus so it can be confirmed.
						node.BlockChannel <- newBlock
						break
					}
				}
			}
		}
	}()
}

func (node *Node) proposeShardStateWithoutBeaconSync(block *types.Block) error {
	if !core.IsEpochLastBlock(block) {
		return nil
	}
	nextEpoch := new(big.Int).Add(block.Header().Epoch, common.Big1)
	shardState := core.GetShardState(nextEpoch)
	return block.AddShardState(shardState)
}

func (node *Node) proposeShardState(block *types.Block) error {
	switch node.Consensus.ShardID {
	case 0:
		return node.proposeBeaconShardState(block)
	default:
		node.proposeLocalShardState(block)
		return nil
	}
}

func (node *Node) proposeBeaconShardState(block *types.Block) error {
	// TODO ek - replace this with variable epoch logic.
	if !core.IsEpochLastBlock(block) {
		// We haven't reached the end of this epoch; don't propose yet.
		return nil
	}
	nextEpoch := new(big.Int).Add(block.Header().Epoch, common.Big1)
	shardState, err := core.CalculateNewShardState(
		node.Blockchain(), nextEpoch, &node.CurrentStakes)
	if err != nil {
		return err
	}
	return block.AddShardState(shardState)
}

func (node *Node) proposeLocalShardState(block *types.Block) {
	logger := block.Logger(utils.Logger())
	// TODO ek – read this from beaconchain once BC sync is fixed
	if node.nextShardState.master == nil {
		logger.Debug().Msg("yet to receive master proposal from beaconchain")
		return
	}

	nlogger := logger.With().
		Uint64("nextEpoch", node.nextShardState.master.Epoch).
		Time("proposeTime", node.nextShardState.proposeTime).
		Logger()
	logger = &nlogger
	if time.Now().Before(node.nextShardState.proposeTime) {
		logger.Debug().Msg("still waiting for shard state to propagate")
		return
	}
	masterShardState := node.nextShardState.master.ShardState
	var localShardState types.ShardState
	committee := masterShardState.FindCommitteeByID(block.ShardID())
	if committee != nil {
		logger.Info().Msg("found local shard info; proposing it")
		localShardState = append(localShardState, *committee)
	} else {
		logger.Info().Msg("beacon committee disowned us; proposing nothing")
		// Leave local proposal empty to signal the end of shard (disbanding).
	}
	err := block.AddShardState(localShardState)
	if err != nil {
		logger.Error().Err(err).Msg("Failed proposin local shard state")
	}
}

func (node *Node) proposeReceiptsProof() []*types.CXReceiptsProof {
	validReceiptsList := []*types.CXReceiptsProof{}
	pendingReceiptsList := []*types.CXReceiptsProof{}
	node.pendingCXMutex.Lock()

	sort.Slice(node.pendingCXReceipts, func(i, j int) bool {
		return node.pendingCXReceipts[i].MerkleProof.ShardID < node.pendingCXReceipts[j].MerkleProof.ShardID || (node.pendingCXReceipts[i].MerkleProof.ShardID == node.pendingCXReceipts[j].MerkleProof.ShardID && node.pendingCXReceipts[i].MerkleProof.BlockNum.Cmp(node.pendingCXReceipts[j].MerkleProof.BlockNum) < 0)
	})

	for _, cxp := range node.pendingCXReceipts {
		//		sourceShardID := cxp.MerkleProof.ShardID
		//		sourceBlockNum := cxp.MerkleProof.BlockNum
		//
		//		beaconChain := node.Blockchain() // TODO: read from real beacon chain
		//		crossLink, err := beaconChain.ReadCrossLink(sourceShardID, sourceBlockNum.Uint64(), false)
		//		if err == nil {
		//			// verify the source block hash is from a finalized block
		//			if crossLink.ChainHeader.Hash() == cxp.MerkleProof.BlockHash && crossLink.ChainHeader.OutgoingReceiptHash == cxp.MerkleProof.CXReceiptHash {
		//				receiptsList = append(receiptsList, cxp.Receipts)
		//			}
		//		}
		// TODO: remove it after beacon chain sync is ready, for pass the test only
		validReceiptsList = append(validReceiptsList, cxp)
	}
	node.pendingCXReceipts = pendingReceiptsList
	node.pendingCXMutex.Unlock()
	return validReceiptsList
}