package node

import (
	"bytes"
	"fmt"
	"os"
	"time"

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

	"github.com/dedis/kyber"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/harmony-one/harmony/api/proto"
	proto_identity "github.com/harmony-one/harmony/api/proto/identity"
	proto_node "github.com/harmony-one/harmony/api/proto/node"
	"github.com/harmony-one/harmony/core/types"
	hmy_crypto "github.com/harmony-one/harmony/crypto"
	"github.com/harmony-one/harmony/crypto/pki"
	"github.com/harmony-one/harmony/p2p"
	"github.com/harmony-one/harmony/p2p/host"
)

const (
	// MaxNumberOfTransactionsPerBlock is the max number of transaction per a block.
	MaxNumberOfTransactionsPerBlock = 8000
)

// MaybeBroadcastAsValidator returns if the node is a validator node.
func (node *Node) MaybeBroadcastAsValidator(content []byte) {
	// TODO: this is tree-based broadcasting. this needs to be replaced by p2p gossiping.
	if node.SelfPeer.ValidatorID > 0 && node.SelfPeer.ValidatorID <= host.MaxBroadCast {
		go host.BroadcastMessageFromValidator(node.host, node.SelfPeer, node.Consensus.GetValidatorPeers(), content)
	}
}

// StreamHandler handles a new incoming network message.
func (node *Node) StreamHandler(s p2p.Stream) {
	defer s.Close()

	// Read p2p message payload
	content, err := p2p.ReadMessageContent(s)

	if err != nil {
		node.log.Error("Read p2p data failed", "err", err, "node", node)
		return
	}
	node.MaybeBroadcastAsValidator(content)

	consensusObj := node.Consensus

	msgCategory, err := proto.GetMessageCategory(content)
	if err != nil {
		node.log.Error("Read node type failed", "err", err, "node", node)
		return
	}

	msgType, err := proto.GetMessageType(content)
	if err != nil {
		node.log.Error("Read action type failed", "err", err, "node", node)
		return
	}

	msgPayload, err := proto.GetMessagePayload(content)
	if err != nil {
		node.log.Error("Read message payload failed", "err", err, "node", node)
		return
	}

	switch msgCategory {
	case proto.Identity:
		actionType := proto_identity.IDMessageType(msgType)
		switch actionType {
		case proto_identity.Identity:
			messageType := proto_identity.MessageType(msgPayload[0])
			switch messageType {
			case proto_identity.Register:
				fmt.Println("received a identity message")
				node.log.Info("NET: received message: IDENTITY/REGISTER")
			default:
				node.log.Error("Announce message should be sent to IdentityChain")
			}
		}
	case proto.Consensus:
		msgPayload, _ := proto.GetConsensusMessagePayload(content)
		if consensusObj.IsLeader {
			node.log.Info("NET: Leader received message:", "messageCategory", msgCategory, "messageType", msgType)
			consensusObj.ProcessMessageLeader(msgPayload)
		} else {
			node.log.Info("NET: Validator received message:", "messageCategory", msgCategory, "messageType", msgType)
			consensusObj.ProcessMessageValidator(msgPayload)
			// TODO(minhdoan): add logic to check if the current blockchain is not sync with other consensus
			// we should switch to other state rather than DoingConsensus.
		}
	case proto.Node:
		actionType := proto_node.MessageType(msgType)
		switch actionType {
		case proto_node.Transaction:
			node.log.Info("NET: received message: Node/Transaction")
			node.transactionMessageHandler(msgPayload)
		case proto_node.Block:
			node.log.Info("NET: received message: Node/Block")
			blockMsgType := proto_node.BlockMessageType(msgPayload[0])
			switch blockMsgType {
			case proto_node.Sync:
				var blocks []*types.Block
				err := rlp.DecodeBytes(msgPayload[1:], &blocks) // skip the Sync messge type
				if err != nil {
					node.log.Info("NET: received message: Node/Block", "error", err)
				} else {
					if node.Client != nil && node.Client.UpdateBlocks != nil && blocks != nil {
						node.Client.UpdateBlocks(blocks)
					}
				}
			}
		case proto_node.Control:
			node.log.Info("NET: received message: Node/Control")
			controlType := msgPayload[0]
			if proto_node.ControlMessageType(controlType) == proto_node.STOP {
				node.log.Debug("Stopping Node", "node", node, "numBlocks", node.blockchain.CurrentBlock().NumberU64(), "numTxsProcessed", node.countNumTransactionsInBlockchain())

				var avgBlockSizeInBytes common.StorageSize
				txCount := 0
				blockCount := 0
				avgTxSize := 0

				for block := node.blockchain.CurrentBlock(); block != nil; block = node.blockchain.GetBlockByHash(block.Header().ParentHash) {
					avgBlockSizeInBytes += block.Size()
					txCount += len(block.Transactions())
					bytes, _ := rlp.EncodeToBytes(block.Transactions())
					avgTxSize += len(bytes)
					blockCount++
				}

				if blockCount != 0 {
					avgBlockSizeInBytes = avgBlockSizeInBytes / common.StorageSize(blockCount)
					avgTxSize = avgTxSize / txCount
				}

				node.log.Debug("Blockchain Report", "totalNumBlocks", blockCount, "avgBlockSizeInCurrentEpoch", avgBlockSizeInBytes, "totalNumTxs", txCount, "avgTxSzieInCurrentEpoch", avgTxSize)

				os.Exit(0)
			}
		case proto_node.PING:
			node.pingMessageHandler(msgPayload)
		case proto_node.PONG:
			node.pongMessageHandler(msgPayload)
		}
	default:
		node.log.Error("Unknown", "MsgCategory", msgCategory)
	}
}

func (node *Node) transactionMessageHandler(msgPayload []byte) {
	txMessageType := proto_node.TransactionMessageType(msgPayload[0])

	switch txMessageType {
	case proto_node.Send:
		txs := types.Transactions{}
		err := rlp.Decode(bytes.NewReader(msgPayload[1:]), &txs) // skip the Send messge type
		if err != nil {
			node.log.Error("Failed to deserialize transaction list", "error", err)
		}
		node.addPendingTransactions(txs)

	case proto_node.Request:
		reader := bytes.NewBuffer(msgPayload[1:])
		txIDs := make(map[[32]byte]bool)
		buf := make([]byte, 32) // 32 byte hash Id
		for {
			_, err := reader.Read(buf)
			if err != nil {
				break
			}

			var txID [32]byte
			copy(txID[:], buf)
			txIDs[txID] = true
		}

		var txToReturn []*types.Transaction
		for _, tx := range node.pendingTransactions {
			if txIDs[tx.Hash()] {
				txToReturn = append(txToReturn, tx)
			}
		}
	}
}

// WaitForConsensusReady listen for the readiness signal from consensus and generate new block for consensus.
func (node *Node) WaitForConsensusReady(readySignal chan struct{}) {
	node.log.Debug("Waiting for Consensus ready", "node", node)
	time.Sleep(15 * time.Second) // Wait for other nodes to be ready (test-only)

	firstTime := true
	var newBlock *types.Block
	timeoutCount := 0
	for {
		// keep waiting for Consensus ready
		select {
		case <-readySignal:
			time.Sleep(100 * time.Millisecond) // Delay a bit so validator is catched up (test-only).
		case <-time.After(200 * time.Second):
			node.Consensus.ResetState()
			timeoutCount++
			node.log.Debug("Consensus timeout, retry!", "count", timeoutCount, "node", node)
		}

		for {
			// threshold and firstTime are for the test-only built-in smart contract tx. TODO: remove in production
			threshold := 1
			if firstTime {
				threshold = 2
				firstTime = false
			}
			node.log.Debug("STARTING BLOCK", "threshold", threshold, "pendingTransactions", len(node.pendingTransactions))
			if len(node.pendingTransactions) >= threshold {
				// Normal tx block consensus
				selectedTxs := node.getTransactionsForNewBlock(MaxNumberOfTransactionsPerBlock)
				if len(selectedTxs) != 0 {
					node.Worker.CommitTransactions(selectedTxs)
					block, err := node.Worker.Commit()
					if err != nil {
						node.log.Debug("Failed commiting new block", "Error", err)
					} else {
						newBlock = block
						break
					}
				}
			}
			// If not enough transactions to run Consensus,
			// periodically check whether we have enough transactions to package into block.
			time.Sleep(1 * time.Second)
		}
		// Send the new block to Consensus so it can be confirmed.
		if newBlock != nil {
			node.BlockChannel <- newBlock
		}
	}
}

// BroadcastNewBlock is called by consensus leader to sync new blocks with other clients/nodes.
// NOTE: For now, just send to the client (basically not broadcasting)
func (node *Node) BroadcastNewBlock(newBlock *types.Block) {
	if node.ClientPeer != nil {
		node.log.Debug("Sending new block to client", "client", node.ClientPeer)
		node.SendMessage(*node.ClientPeer, proto_node.ConstructBlocksSyncMessage([]*types.Block{newBlock}))
	}
}

// VerifyNewBlock is called by consensus participants to verify the block (account model) they are running consensus on
func (node *Node) VerifyNewBlock(newBlock *types.Block) bool {
	err := node.blockchain.ValidateNewBlock(newBlock, pki.GetAddressFromPublicKey(node.SelfPeer.PubKey))
	if err != nil {
		node.log.Debug("Failed verifying new block", "Error", err, "tx", newBlock.Transactions()[0])
		return false
	}
	return true
}

// PostConsensusProcessing is called by consensus participants, after consensus is done, to:
// 1. add the new block to blockchain
// 2. [leader] send new block to the client
func (node *Node) PostConsensusProcessing(newBlock *types.Block) {
	if node.Consensus.IsLeader {
		node.BroadcastNewBlock(newBlock)
	}

	node.AddNewBlock(newBlock)
}

// AddNewBlock is usedd to add new block into the blockchain.
func (node *Node) AddNewBlock(newBlock *types.Block) {
	blockNum, err := node.blockchain.InsertChain([]*types.Block{newBlock})
	if err != nil {
		node.log.Debug("Error adding new block to blockchain", "blockNum", blockNum, "Error", err)
	}
}

func (node *Node) pingMessageHandler(msgPayload []byte) int {
	ping, err := proto_node.GetPingMessage(msgPayload)
	if err != nil {
		node.log.Error("Can't get Ping Message")
		return -1
	}
	//	node.log.Info("Ping", "Msg", ping)

	peer := new(p2p.Peer)
	peer.IP = ping.Node.IP
	peer.Port = ping.Node.Port
	peer.ValidatorID = ping.Node.ValidatorID

	peer.PubKey = hmy_crypto.Ed25519Curve.Point()
	err = peer.PubKey.UnmarshalBinary(ping.Node.PubKey[:])
	if err != nil {
		node.log.Error("UnmarshalBinary Failed", "error", err)
		return -1
	}

	if ping.Node.Role == proto_node.ClientRole {
		node.log.Info("Add Client Peer to Node", "Node", node.Consensus.GetNodeID(), "Client", peer)
		node.ClientPeer = peer
		return 0
	}

	// Add to Node's peer list anyway
	node.AddPeers([]*p2p.Peer{peer})

	peers := node.Consensus.GetValidatorPeers()
	pong := proto_node.NewPongMessage(peers, node.Consensus.PublicKeys)
	buffer := pong.ConstructPongMessage()

	// Send a Pong message directly to the sender
	// This is necessary because the sender will need to get a ValidatorID
	// Just broadcast won't work, some validators won't receive the latest
	// PublicKeys as we rely on a valid ValidatorID to do broadcast.
	// This is very buggy, but we will move to libp2p, hope the problem will
	// be resolved then.
	// However, I disable it for now as we are sending redundant PONG messages
	// to all validators.  This may not be needed. But it maybe add back.
	//   p2p.SendMessage(*peer, buffer)

	// Broadcast the message to all validators, as publicKeys is updated
	// FIXME: HAR-89 use a separate nodefind/neighbor message
	host.BroadcastMessageFromLeader(node.GetHost(), peers, buffer, node.Consensus.OfflinePeers)

	return len(peers)
}

func (node *Node) pongMessageHandler(msgPayload []byte) int {
	pong, err := proto_node.GetPongMessage(msgPayload)
	if err != nil {
		node.log.Error("Can't get Pong Message")
		return -1
	}

	//	node.log.Debug("pongMessageHandler", "pong", pong, "nodeID", node.Consensus.GetNodeID())

	peers := make([]*p2p.Peer, 0)

	for _, p := range pong.Peers {
		peer := new(p2p.Peer)
		peer.IP = p.IP
		peer.Port = p.Port
		peer.ValidatorID = p.ValidatorID

		peer.PubKey = hmy_crypto.Ed25519Curve.Point()
		err = peer.PubKey.UnmarshalBinary(p.PubKey[:])
		if err != nil {
			node.log.Error("UnmarshalBinary Failed", "error", err)
			continue
		}
		peers = append(peers, peer)
	}

	if len(peers) > 0 {
		node.AddPeers(peers)
	}

	// Reset Validator PublicKeys every time we receive PONG message from Leader
	// The PublicKeys has to be idential across the shard on every node
	// TODO (lc): we need to handle RemovePeer situation
	publicKeys := make([]kyber.Point, 0)

	// Create the the PubKey from the []byte sent from leader
	for _, k := range pong.PubKeys {
		key := hmy_crypto.Ed25519Curve.Point()
		err = key.UnmarshalBinary(k[:])
		if err != nil {
			node.log.Error("UnmarshalBinary Failed PubKeys", "error", err)
			continue
		}
		publicKeys = append(publicKeys, key)
	}

	if node.State == NodeWaitToJoin {
		node.State = NodeJoinedShard
		// Notify JoinShard to stop sending Ping messages
		if node.StopPing != nil {
			node.StopPing <- struct{}{}
		}
	}

	return node.Consensus.UpdatePublicKeys(publicKeys)
}