// checkProofOfWork ensures the block header bits which indicate the target
// difficulty is in min/max range and that the block hash is less than the
// target difficulty as claimed.
func checkProofOfWork(block *btcutil.Block, powLimit *big.Int) error {
	// The target difficulty must be larger than zero.
	target := CompactToBig(block.MsgBlock().Header.Bits)
	if target.Sign() <= 0 {
		str := fmt.Sprintf("block target difficulty of %064x is too low",
			target)
		return RuleError(str)
	}

	// The target difficulty must be less than the maximum allowed.
	if target.Cmp(powLimit) > 0 {
		str := fmt.Sprintf("block target difficulty of %064x is "+
			"higher than max of %064x", target, powLimit)
		return RuleError(str)
	}

	// The block hash must be less than the claimed target.
	blockHash, err := block.Sha()
	if err != nil {
		return err
	}
	hashNum := ShaHashToBig(blockHash)
	if hashNum.Cmp(target) > 0 {
		str := fmt.Sprintf("block hash of %064x is higher than "+
			"expected max of %064x", hashNum, target)
		return RuleError(str)
	}

	return nil
}

// connectBlock handles connecting the passed node/block to the end of the main
// (best) chain.
func (b *BlockChain) connectBlock(node *blockNode, block *btcutil.Block) error {
	// Make sure it's extending the end of the best chain.
	prevHash := &block.MsgBlock().Header.PrevBlock
	if b.bestChain != nil && !prevHash.IsEqual(b.bestChain.hash) {
		return fmt.Errorf("connectBlock must be called with a block " +
			"that extends the main chain")
	}

	// Insert the block into the database which houses the main chain.
	_, err := b.db.InsertBlock(block)
	if err != nil {
		return err
	}

	// Add the new node to the memory main chain indices for faster
	// lookups.
	node.inMainChain = true
	b.index[*node.hash] = node
	b.depNodes[*prevHash] = append(b.depNodes[*prevHash], node)

	// This node is now the end of the best chain.
	b.bestChain = node

	// Notify the caller that the block was connected to the main chain.
	// The caller would typically want to react with actions such as
	// updating wallets.
	b.sendNotification(NTBlockConnected, block)

	return nil
}

// Process block takes care of sorting out transactions with exodus output.
// At this point it doesn't matter whether the Txs are valid or not. Validation
// is done at the proper handlers.
func (s *MastercoinServer) ProcessBlock(block *btcutil.Block) error {
	// Gather transactions from this block which had an exodus output
	txPack := &TxPack{
		txs:    mscutil.GetExodusTransactions(block),
		time:   block.MsgBlock().Header.Timestamp.Unix(),
		height: block.Height(),
	}
	if len(txPack.txs) > 0 {

		/*
			TODO: We want to start persisting raw data here
			var buffer bytes.Buffer
			enc := gob.NewEncoder(&buffer)
			err := enc.Encode(txPack)
			if err != nil {
				mscutil.Logger.Fatal(err)
			}

			dec := gob.NewDecoder(&buffer)
			var pack TxPack
			err = dec.Decode(&pack)
			if err != nil {
				mscutil.Logger.Fatal(err)
			}
		*/

		// Queue the slice of transactions for further processing by the
		// message parser.
		_ = s.msgParser.ProcessTransactions(txPack)
		// mscutil.Logger.Println(messages)
	}

	return nil
}

// disconnectTransactions updates the passed map by undoing transaction and
// spend information for all transactions in the passed block.  Only
// transactions in the passed map are updated.
func disconnectTransactions(txStore TxStore, block *btcutil.Block) error {
	// Loop through all of the transactions in the block to see if any of
	// them are ones that need to be undone based on the transaction store.
	for _, tx := range block.Transactions() {
		// Clear this transaction from the transaction store if needed.
		// Only clear it rather than deleting it because the transaction
		// connect code relies on its presence to decide whether or not
		// to update the store and any transactions which exist on both
		// sides of a fork would otherwise not be updated.
		if txD, exists := txStore[*tx.Sha()]; exists {
			txD.Tx = nil
			txD.BlockHeight = 0
			txD.Spent = nil
			txD.Err = btcdb.ErrTxShaMissing
		}

		// Unspend the origin transaction output.
		for _, txIn := range tx.MsgTx().TxIn {
			originHash := &txIn.PreviousOutPoint.Hash
			originIndex := txIn.PreviousOutPoint.Index
			originTx, exists := txStore[*originHash]
			if exists && originTx.Tx != nil && originTx.Err == nil {
				if originIndex > uint32(len(originTx.Spent)) {
					continue
				}
				originTx.Spent[originIndex] = false
			}
		}
	}

	return nil
}

// connectTransactions updates the passed map by applying transaction and
// spend information for all the transactions in the passed block.  Only
// transactions in the passed map are updated.
func connectTransactions(txStore TxStore, block *btcutil.Block) error {
	// Loop through all of the transactions in the block to see if any of
	// them are ones we need to update and spend based on the results map.
	for _, tx := range block.Transactions() {
		// Update the transaction store with the transaction information
		// if it's one of the requested transactions.
		msgTx := tx.MsgTx()
		if txD, exists := txStore[*tx.Sha()]; exists {
			txD.Tx = tx
			txD.BlockHeight = block.Height()
			txD.Spent = make([]bool, len(msgTx.TxOut))
			txD.Err = nil
		}

		// Spend the origin transaction output.
		for _, txIn := range msgTx.TxIn {
			originHash := &txIn.PreviousOutPoint.Hash
			originIndex := txIn.PreviousOutPoint.Index
			if originTx, exists := txStore[*originHash]; exists {
				if originIndex > uint32(len(originTx.Spent)) {
					continue
				}
				originTx.Spent[originIndex] = true
			}
		}
	}

	return nil
}

// Process block takes care of sorting out transactions with exodus output.
// At this point it doesn't matter whether the Txs are valid or not. Validation
// is done at the proper handlers.
func (s *MastercoinServer) ProcessBlock(block *btcutil.Block) error {

	// Gather transactions from this block which had an exodus output
	txPack := &mscutil.TxPack{
		Txs:    mscutil.GetExodusTransactions(block),
		Time:   block.MsgBlock().Header.Timestamp.Unix(),
		Height: block.Height(),
	}

	// Update Exodus Vesting
	//

	// balance = ((1-(0.5 ** time_difference)) * 5631623576222 .round(8)

	if len(txPack.Txs) > 0 {
		serializedData, err := txPack.Serialize()
		if err != nil {
			return err
		}

		s.db.CreateTxPack(txPack.Height, serializedData)

		mscutil.Logger.Println("Mastercoin data found at block with height:", txPack.Height)

		// Queue the slice of transactions for further processing by the
		// message parser.
		_ = s.msgParser.ProcessTransactions(txPack)
	}

	return nil
}

// checkProofOfWork ensures the block header bits which indicate the target
// difficulty is in min/max range and that the block hash is less than the
// target difficulty as claimed.
//
//
// The flags modify the behavior of this function as follows:
//  - BFNoPoWCheck: The check to ensure the block hash is less than the target
//    difficulty is not performed.
func checkProofOfWork(block *btcutil.Block, powLimit *big.Int, flags BehaviorFlags) error {
	// The target difficulty must be larger than zero.
	target := CompactToBig(block.MsgBlock().Header.Bits)
	if target.Sign() <= 0 {
		str := fmt.Sprintf("block target difficulty of %064x is too low",
			target)
		return ruleError(ErrUnexpectedDifficulty, str)
	}

	// The target difficulty must be less than the maximum allowed.
	if target.Cmp(powLimit) > 0 {
		str := fmt.Sprintf("block target difficulty of %064x is "+
			"higher than max of %064x", target, powLimit)
		return ruleError(ErrUnexpectedDifficulty, str)
	}

	// The block hash must be less than the claimed target unless the flag
	// to avoid proof of work checks is set.
	if flags&BFNoPoWCheck != BFNoPoWCheck {
		// The block hash must be less than the claimed target.
		blockHash, err := block.Sha()
		if err != nil {
			return err
		}
		hashNum := ShaHashToBig(blockHash)
		if hashNum.Cmp(target) > 0 {
			str := fmt.Sprintf("block hash of %064x is higher than "+
				"expected max of %064x", hashNum, target)
			return ruleError(ErrHighHash, str)
		}
	}

	return nil
}

// NotifyBlockConnected creates and marshalls a JSON message to notify
// of a new block connected to the main chain.  The notification is sent
// to each connected wallet.
func (s *rpcServer) NotifyBlockConnected(block *btcutil.Block) {
	hash, err := block.Sha()
	if err != nil {
		rpcsLog.Error("Bad block; connected block notification dropped.")
		return
	}

	// TODO: remove int32 type conversion.
	ntfn := btcws.NewBlockConnectedNtfn(hash.String(),
		int32(block.Height()))
	mntfn, _ := json.Marshal(ntfn)
	s.ws.walletNotificationMaster <- mntfn

	// Inform any interested parties about txs mined in this block.
	s.ws.Lock()
	for _, tx := range block.Transactions() {
		if clist, ok := s.ws.minedTxNotifications[*tx.Sha()]; ok {
			var enext *list.Element
			for e := clist.Front(); e != nil; e = enext {
				enext = e.Next()
				c := e.Value.(walletChan)
				// TODO: remove int32 type conversion after
				// the int64 -> int32 switch is made.
				ntfn := btcws.NewTxMinedNtfn(tx.Sha().String(),
					hash.String(), int32(block.Height()),
					block.MsgBlock().Header.Timestamp.Unix(),
					tx.Index())
				mntfn, _ := json.Marshal(ntfn)
				c <- mntfn
				s.ws.removeMinedTxRequest(c, tx.Sha())
			}
		}
	}
	s.ws.Unlock()
}

// NotifyBlockTXs creates and marshals a JSON message to notify wallets
// of new transactions (with both spent and unspent outputs) for a watched
// address.
func (s *rpcServer) NotifyBlockTXs(db btcdb.Db, block *btcutil.Block) {
	// Build a map of in-flight transactions to see if any of the inputs in
	// this block are referencing other transactions earlier in this block.
	txInFlight := map[btcwire.ShaHash]int{}
	transactions := block.Transactions()
	spent := make([][]bool, len(transactions))
	for i, tx := range transactions {
		spent[i] = make([]bool, len(tx.MsgTx().TxOut))
		txInFlight[*tx.Sha()] = i
	}

	// The newBlockNotifyCheckTxOut current needs spent data.  This can
	// this can ultimately be optimized out by making sure the notifications
	// are in order.  For now, just create the spent data.
	for i, tx := range transactions[1:] {
		for _, txIn := range tx.MsgTx().TxIn {
			originHash := &txIn.PreviousOutpoint.Hash
			if inFlightIndex, ok := txInFlight[*originHash]; ok &&
				i >= inFlightIndex {

				prevIndex := txIn.PreviousOutpoint.Index
				spent[inFlightIndex][prevIndex] = true
			}
		}
	}

	for i, tx := range transactions {
		go s.newBlockNotifyCheckTxIn(tx)
		go s.newBlockNotifyCheckTxOut(block, tx, spent[i])
	}
}

// newBlockNotifyCheckTxOut is a helper function to iterate through
// each transaction output of a new block and perform any checks and
// notify listening frontends when necessary.
func (s *rpcServer) newBlockNotifyCheckTxOut(block *btcutil.Block, tx *btcutil.Tx, spent []bool) {
	for wltNtfn, cxt := range s.ws.requests.m {
		for i, txout := range tx.MsgTx().TxOut {
			_, txaddrhash, err := btcscript.ScriptToAddrHash(txout.PkScript)
			if err != nil {
				log.Debug("Error getting payment address from tx; dropping any Tx notifications.")
				break
			}
			for addr, id := range cxt.txRequests {
				if !bytes.Equal(addr[:], txaddrhash) {
					continue
				}
				blkhash, err := block.Sha()
				if err != nil {
					log.Error("Error getting block sha; dropping Tx notification.")
					break
				}
				txaddr, err := btcutil.EncodeAddress(txaddrhash, s.server.btcnet)
				if err != nil {
					log.Error("Error encoding address; dropping Tx notification.")
					break
				}
				reply := &btcjson.Reply{
					Result: struct {
						Sender    string `json:"sender"`
						Receiver  string `json:"receiver"`
						BlockHash string `json:"blockhash"`
						Height    int64  `json:"height"`
						TxHash    string `json:"txhash"`
						Index     uint32 `json:"index"`
						Amount    int64  `json:"amount"`
						PkScript  string `json:"pkscript"`
						Spent     bool   `json:"spent"`
					}{
						Sender:    "Unknown", // TODO(jrick)
						Receiver:  txaddr,
						BlockHash: blkhash.String(),
						Height:    block.Height(),
						TxHash:    tx.Sha().String(),
						Index:     uint32(i),
						Amount:    txout.Value,
						PkScript:  btcutil.Base58Encode(txout.PkScript),
						Spent:     spent[i],
					},
					Error: nil,
					Id:    &id,
				}
				replyBytes, err := json.Marshal(reply)
				if err != nil {
					log.Errorf("RPCS: Unable to marshal tx notification: %v", err)
					continue
				}
				wltNtfn <- replyBytes
			}
		}
	}
}

// NotifyBlockDisconnected creates and marshals a JSON message to notify
// of a new block disconnected from the main chain.  The notification is sent
// to each connected wallet.
func (s *rpcServer) NotifyBlockDisconnected(block *btcutil.Block) {
	hash, err := block.Sha()
	if err != nil {
		rpcsLog.Error("Bad block; connected block notification dropped.")
		return
	}

	// TODO: remove int32 type conversion.
	ntfn := btcws.NewBlockDisconnectedNtfn(hash.String(),
		int32(block.Height()))
	mntfn, _ := json.Marshal(ntfn)
	s.ws.walletNotificationMaster <- mntfn
}

// DropAfterBlockBySha will remove any blocks from the database after
// the given block.
func (db *LevelDb) DropAfterBlockBySha(sha *btcwire.ShaHash) (rerr error) {
	db.dbLock.Lock()
	defer db.dbLock.Unlock()
	defer func() {
		if rerr == nil {
			rerr = db.processBatches()
		} else {
			db.lBatch().Reset()
		}
	}()

	startheight := db.nextBlock - 1

	keepidx, err := db.getBlkLoc(sha)
	if err != nil {
		// should the error here be normalized ?
		log.Tracef("block loc failed %v ", sha)
		return err
	}

	for height := startheight; height > keepidx; height = height - 1 {
		var blk *btcutil.Block
		blksha, buf, err := db.getBlkByHeight(height)
		if err != nil {
			return err
		}
		blk, err = btcutil.NewBlockFromBytes(buf)
		if err != nil {
			return err
		}

		for _, tx := range blk.MsgBlock().Transactions {
			err = db.unSpend(tx)
			if err != nil {
				return err
			}
		}
		// rather than iterate the list of tx backward, do it twice.
		for _, tx := range blk.Transactions() {
			var txUo txUpdateObj
			txUo.delete = true
			db.txUpdateMap[*tx.Sha()] = &txUo
		}
		db.lBatch().Delete(shaBlkToKey(blksha))
		db.lBatch().Delete(int64ToKey(height))
	}

	db.nextBlock = keepidx + 1

	return nil
}

// NotifyBlockDisconnected creates and marshals a JSON message to notify
// of a new block disconnected from the main chain.  The notification is sent
// to each connected wallet.
func (s *rpcServer) NotifyBlockDisconnected(block *btcutil.Block) {
	hash, err := block.Sha()
	if err != nil {
		rpcsLog.Error("Bad block; connected block notification dropped")
		return
	}

	// TODO: remove int32 type conversion.
	ntfn := btcws.NewBlockDisconnectedNtfn(hash.String(),
		int32(block.Height()))
	for ntfnChan, rc := range s.ws.connections {
		if rc.blockUpdates {
			ntfnChan <- ntfn
		}
	}
}

// addOrphanBlock adds the passed block (which is already determined to be
// an orphan prior calling this function) to the orphan pool.  It lazily cleans
// up any expired blocks so a separate cleanup poller doesn't need to be run.
// It also imposes a maximum limit on the number of outstanding orphan
// blocks and will remove the oldest received orphan block if the limit is
// exceeded.
func (b *BlockChain) addOrphanBlock(block *btcutil.Block) {
	// Remove expired orphan blocks.
	for _, oBlock := range b.orphans {
		if time.Now().After(oBlock.expiration) {
			b.removeOrphanBlock(oBlock)
			continue
		}

		// Update the oldest orphan block pointer so it can be discarded
		// in case the orphan pool fills up.
		if b.oldestOrphan == nil || oBlock.expiration.Before(b.oldestOrphan.expiration) {
			b.oldestOrphan = oBlock
		}
	}

	// Limit orphan blocks to prevent memory exhaustion.
	if len(b.orphans)+1 > maxOrphanBlocks {
		// Remove the oldest orphan to make room for the new one.
		b.removeOrphanBlock(b.oldestOrphan)
		b.oldestOrphan = nil
	}

	// Get the block sha.  It is safe to ignore the error here since any
	// errors would've been caught prior to calling this function.
	blockSha, _ := block.Sha()

	// Protect concurrent access.  This is intentionally done here instead
	// of near the top since removeOrphanBlock does its own locking and
	// the range iterator is not invalidated by removing map entries.
	b.orphanLock.Lock()
	b.orphanLock.Unlock()

	// Insert the block into the orphan map with an expiration time
	// 1 hour from now.
	expiration := time.Now().Add(time.Hour)
	oBlock := &orphanBlock{
		block:      block,
		expiration: expiration,
	}
	b.orphans[*blockSha] = oBlock

	// Add to previous hash lookup index for faster dependency lookups.
	prevHash := &block.MsgBlock().Header.PrevBlock
	b.prevOrphans[*prevHash] = append(b.prevOrphans[*prevHash], oBlock)

	return
}

// SubmitBlockAsync returns an instance of a type that can be used to get the
// result of the RPC at some future time by invoking the Receive function on the
// returned instance.
//
// See SubmitBlock for the blocking version and more details.
func (c *Client) SubmitBlockAsync(block *btcutil.Block, options *btcjson.SubmitBlockOptions) FutureSubmitBlockResult {
	blockHex := ""
	if block != nil {
		blockBytes, err := block.Bytes()
		if err != nil {
			return newFutureError(err)
		}

		blockHex = hex.EncodeToString(blockBytes)
	}

	id := c.NextID()
	cmd, err := btcjson.NewSubmitBlockCmd(id, blockHex, options)
	if err != nil {
		return newFutureError(err)
	}

	return c.sendCmd(cmd)
}

// checkBIP0030 ensures blocks do not contain duplicate transactions which
// 'overwrite' older transactions that are not fully spent.  This prevents an
// attack where a coinbase and all of its dependent transactions could be
// duplicated to effectively revert the overwritten transactions to a single
// confirmation thereby making them vulnerable to a double spend.
//
// For more details, see https://en.bitcoin.it/wiki/BIP_0030 and
// http://r6.ca/blog/20120206T005236Z.html.
func (b *BlockChain) checkBIP0030(node *blockNode, block *btcutil.Block) error {
	// Attempt to fetch duplicate transactions for all of the transactions
	// in this block from the point of view of the parent node.
	fetchList, err := block.TxShas()
	if err != nil {
		return nil
	}
	fetchSet := make(map[btcwire.ShaHash]bool)
	for _, txHash := range fetchList {
		fetchSet[*txHash] = true
	}
	txResults, err := b.fetchTxStore(node, fetchSet)
	if err != nil {
		return err
	}

	// Examine the resulting data about the requested transactions.
	for _, txD := range txResults {
		switch txD.Err {
		// A duplicate transaction was not found.  This is the most
		// common case.
		case btcdb.TxShaMissing:
			continue

		// A duplicate transaction was found.  This is only allowed if
		// the duplicate transaction is fully spent.
		case nil:
			if !isTransactionSpent(txD) {
				str := fmt.Sprintf("tried to overwrite "+
					"transaction %v at block height %d "+
					"that is not fully spent", txD.Hash,
					txD.BlockHeight)
				return RuleError(str)
			}

		// Some other unexpected error occurred.  Return it now.
		default:
			return txD.Err
		}
	}

	return nil
}

// NotifyBlockDisconnected creates and marshals a JSON message to notify
// of a new block disconnected from the main chain.  The notification is sent
// to each connected wallet.
func (s *rpcServer) NotifyBlockDisconnected(block *btcutil.Block) {
	var id interface{} = "btcd:blockdisconnected"
	hash, err := block.Sha()
	if err != nil {
		log.Error("Bad block; connected block notification dropped.")
		return
	}
	ntfn := btcjson.Reply{
		Result: struct {
			Hash   string `json:"hash"`
			Height int64  `json:"height"`
		}{
			Hash:   hash.String(),
			Height: block.Height(),
		},
		Id: &id,
	}
	m, _ := json.Marshal(ntfn)
	s.ws.walletNotificationMaster <- m
}

// getPrevNodeFromBlock returns a block node for the block previous to the
// passed block (the passed block's parent).  When it is already in the memory
// block chain, it simply returns it.  Otherwise, it loads the previous block
// from the block database, creates a new block node from it, and returns it.
// The returned node will be nil if the genesis block is passed.
func (b *BlockChain) getPrevNodeFromBlock(block *btcutil.Block) (*blockNode, error) {
	// Genesis block.
	prevHash := &block.MsgBlock().Header.PrevBlock
	if prevHash.IsEqual(zeroHash) {
		return nil, nil
	}

	// Return the existing previous block node if it's already there.
	if bn, ok := b.index[*prevHash]; ok {
		return bn, nil
	}

	// Dynamically load the previous block from the block database, create
	// a new block node for it, and update the memory chain accordingly.
	prevBlockNode, err := b.loadBlockNode(prevHash)
	if err != nil {
		return nil, err
	}
	return prevBlockNode, nil
}

// logBlockHeight logs a new block height as an information message to show
// progress to the user.  In order to prevent spam, it limits logging to one
// message every 10 seconds with duration and totals included.
func (b *blockManager) logBlockHeight(block *btcutil.Block) {
	b.receivedLogBlocks++
	b.receivedLogTx += int64(len(block.MsgBlock().Transactions))

	now := time.Now()
	duration := now.Sub(b.lastBlockLogTime)
	if duration < time.Second*10 {
		return
	}

	// Truncate the duration to 10s of milliseconds.
	durationMillis := int64(duration / time.Millisecond)
	tDuration := 10 * time.Millisecond * time.Duration(durationMillis/10)

	// Log information about new block height.
	blockStr := "blocks"
	if b.receivedLogBlocks == 1 {
		blockStr = "block"
	}
	txStr := "transactions"
	if b.receivedLogTx == 1 {
		txStr = "transaction"
	}
	bmgrLog.Infof("Processed %d %s in the last %s (%d %s, height %d, %s)",
		b.receivedLogBlocks, blockStr, tDuration, b.receivedLogTx,
		txStr, block.Height(), block.MsgBlock().Header.Timestamp)

	b.receivedLogBlocks = 0
	b.receivedLogTx = 0
	b.lastBlockLogTime = now
}

func GetExodusTransactions(block *btcutil.Block) []*btcutil.Tx {
	var txs []*btcutil.Tx

	for _, tx := range block.Transactions() {
		mtx := tx.MsgTx()
		for _, txOut := range mtx.TxOut {
			// Extract the address from the script pub key
			addrs, _ := GetAddrs(txOut.PkScript)
			// Check each output address and if there's an address going to the exodus address
			// we add it to tx slice
			for _, addr := range addrs {
				if addr.Addr == ExodusAddress {
					txs = append(txs, tx)
					// Continue, we don't care if there are more exodus addresses
					continue
				}
			}
		}
	}

	return txs
}