// GetTransaction retrieves a specific transaction from the database, along with
// its added positional metadata.
func GetTransaction(db ethdb.Database, hash common.Hash) (*types.Transaction, common.Hash, uint64, uint64) {
	// Retrieve the transaction itself from the database
	data, _ := db.Get(hash.Bytes())
	if len(data) == 0 {
		return nil, common.Hash{}, 0, 0
	}
	var tx types.Transaction
	if err := rlp.DecodeBytes(data, &tx); err != nil {
		return nil, common.Hash{}, 0, 0
	}
	// Retrieve the blockchain positional metadata
	data, _ = db.Get(append(hash.Bytes(), txMetaSuffix...))
	if len(data) == 0 {
		return nil, common.Hash{}, 0, 0
	}
	var meta struct {
		BlockHash  common.Hash
		BlockIndex uint64
		Index      uint64
	}
	if err := rlp.DecodeBytes(data, &meta); err != nil {
		return nil, common.Hash{}, 0, 0
	}
	return &tx, meta.BlockHash, meta.BlockIndex, meta.Index
}

// WriteHeadFastBlockHash stores the fast head block's hash.
func WriteHeadFastBlockHash(db ethdb.Database, hash common.Hash) error {
	if err := db.Put(headFastKey, hash.Bytes()); err != nil {
		glog.Fatalf("failed to store last fast block's hash into database: %v", err)
		return err
	}
	return nil
}

// GetHeadFastBlockHash retrieves the hash of the current canonical head block during
// fast synchronization. The difference between this and GetHeadBlockHash is that
// whereas the last block hash is only updated upon a full block import, the last
// fast hash is updated when importing pre-processed blocks.
func GetHeadFastBlockHash(db ethdb.Database) common.Hash {
	data, _ := db.Get(headFastKey)
	if len(data) == 0 {
		return common.Hash{}
	}
	return common.BytesToHash(data)
}

// GetCanonicalHash retrieves a hash assigned to a canonical block number.
func GetCanonicalHash(db ethdb.Database, number uint64) common.Hash {
	data, _ := db.Get(append(blockNumPrefix, big.NewInt(int64(number)).Bytes()...))
	if len(data) == 0 {
		return common.Hash{}
	}
	return common.BytesToHash(data)
}

// WriteCanonicalHash stores the canonical hash for the given block number.
func WriteCanonicalHash(db ethdb.Database, hash common.Hash, number uint64) error {
	key := append(blockNumPrefix, big.NewInt(int64(number)).Bytes()...)
	if err := db.Put(key, hash.Bytes()); err != nil {
		glog.Fatalf("failed to store number to hash mapping into database: %v", err)
		return err
	}
	return nil
}

// GetReceipt returns a receipt by hash
func GetReceipt(db ethdb.Database, txHash common.Hash) *types.Receipt {
	data, _ := db.Get(append(receiptsPrefix, txHash[:]...))
	if len(data) == 0 {
		return nil
	}
	var receipt types.ReceiptForStorage
	err := rlp.DecodeBytes(data, &receipt)
	if err != nil {
		glog.V(logger.Core).Infoln("GetReceipt err:", err)
	}
	return (*types.Receipt)(&receipt)
}

// GetTd retrieves a block's total difficulty corresponding to the hash, nil if
// none found.
func GetTd(db ethdb.Database, hash common.Hash) *big.Int {
	data, _ := db.Get(append(append(blockPrefix, hash.Bytes()...), tdSuffix...))
	if len(data) == 0 {
		return nil
	}
	td := new(big.Int)
	if err := rlp.Decode(bytes.NewReader(data), td); err != nil {
		glog.V(logger.Error).Infof("invalid block total difficulty RLP for hash %x: %v", hash, err)
		return nil
	}
	return td
}

// [deprecated by the header/block split, remove eventually]
// GetBlockByHashOld returns the old combined block corresponding to the hash
// or nil if not found. This method is only used by the upgrade mechanism to
// access the old combined block representation. It will be dropped after the
// network transitions to eth/63.
func GetBlockByHashOld(db ethdb.Database, hash common.Hash) *types.Block {
	data, _ := db.Get(append(blockHashPrefix, hash[:]...))
	if len(data) == 0 {
		return nil
	}
	var block types.StorageBlock
	if err := rlp.Decode(bytes.NewReader(data), &block); err != nil {
		glog.V(logger.Error).Infof("invalid block RLP for hash %x: %v", hash, err)
		return nil
	}
	return (*types.Block)(&block)
}

// WriteBody serializes the body of a block into the database.
func WriteBody(db ethdb.Database, hash common.Hash, body *types.Body) error {
	data, err := rlp.EncodeToBytes(body)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, hash.Bytes()...), bodySuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store block body into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block body [%x…]", hash.Bytes()[:4])
	return nil
}

// WriteHeader serializes a block header into the database.
func WriteHeader(db ethdb.Database, header *types.Header) error {
	data, err := rlp.EncodeToBytes(header)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, header.Hash().Bytes()...), headerSuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store header into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored header #%v [%x…]", header.Number, header.Hash().Bytes()[:4])
	return nil
}

// WriteTd serializes the total difficulty of a block into the database.
func WriteTd(db ethdb.Database, hash common.Hash, td *big.Int) error {
	data, err := rlp.EncodeToBytes(td)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, hash.Bytes()...), tdSuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store block total difficulty into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block total difficulty [%x…]: %v", hash.Bytes()[:4], td)
	return nil
}

// GetBlockReceipts retrieves the receipts generated by the transactions included
// in a block given by its hash.
func GetBlockReceipts(db ethdb.Database, hash common.Hash) types.Receipts {
	data, _ := db.Get(append(blockReceiptsPrefix, hash[:]...))
	if len(data) == 0 {
		return nil
	}
	storageReceipts := []*types.ReceiptForStorage{}
	if err := rlp.DecodeBytes(data, &storageReceipts); err != nil {
		glog.V(logger.Error).Infof("invalid receipt array RLP for hash %x: %v", hash, err)
		return nil
	}
	receipts := make(types.Receipts, len(storageReceipts))
	for i, receipt := range storageReceipts {
		receipts[i] = (*types.Receipt)(receipt)
	}
	return receipts
}

func getTransaction(chainDb ethdb.Database, txPool *core.TxPool, txHash common.Hash) (*types.Transaction, bool, error) {
	txData, err := chainDb.Get(txHash.Bytes())
	isPending := false
	tx := new(types.Transaction)

	if err == nil && len(txData) > 0 {
		if err := rlp.DecodeBytes(txData, tx); err != nil {
			return nil, isPending, err
		}
	} else {
		// pending transaction?
		tx = txPool.GetTransaction(txHash)
		isPending = true
	}

	return tx, isPending, nil
}

// WriteBlockReceipts stores all the transaction receipts belonging to a block
// as a single receipt slice. This is used during chain reorganisations for
// rescheduling dropped transactions.
func WriteBlockReceipts(db ethdb.Database, hash common.Hash, receipts types.Receipts) error {
	// Convert the receipts into their storage form and serialize them
	storageReceipts := make([]*types.ReceiptForStorage, len(receipts))
	for i, receipt := range receipts {
		storageReceipts[i] = (*types.ReceiptForStorage)(receipt)
	}
	bytes, err := rlp.EncodeToBytes(storageReceipts)
	if err != nil {
		return err
	}
	// Store the flattened receipt slice
	if err := db.Put(append(blockReceiptsPrefix, hash.Bytes()...), bytes); err != nil {
		glog.Fatalf("failed to store block receipts into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block receipts [%x…]", hash.Bytes()[:4])
	return nil
}

// WriteMapmapBloom writes each address included in the receipts' logs to the
// MIP bloom bin.
func WriteMipmapBloom(db ethdb.Database, number uint64, receipts types.Receipts) error {
	batch := db.NewBatch()
	for _, level := range MIPMapLevels {
		key := mipmapKey(number, level)
		bloomDat, _ := db.Get(key)
		bloom := types.BytesToBloom(bloomDat)
		for _, receipt := range receipts {
			for _, log := range receipt.Logs {
				bloom.Add(log.Address.Big())
			}
		}
		batch.Put(key, bloom.Bytes())
	}
	if err := batch.Write(); err != nil {
		return fmt.Errorf("mipmap write fail for: %d: %v", number, err)
	}
	return nil
}

// getTransactionBlockData fetches the meta data for the given transaction from the chain database. This is useful to
// retrieve block information for a hash. It returns the block hash, block index and transaction index.
func getTransactionBlockData(chainDb ethdb.Database, txHash common.Hash) (common.Hash, uint64, uint64, error) {
	var txBlock struct {
		BlockHash  common.Hash
		BlockIndex uint64
		Index      uint64
	}

	blockData, err := chainDb.Get(append(txHash.Bytes(), 0x0001))
	if err != nil {
		return common.Hash{}, uint64(0), uint64(0), err
	}

	reader := bytes.NewReader(blockData)
	if err = rlp.Decode(reader, &txBlock); err != nil {
		return common.Hash{}, uint64(0), uint64(0), err
	}

	return txBlock.BlockHash, txBlock.BlockIndex, txBlock.Index, nil
}

func addMipmapBloomBins(db ethdb.Database) (err error) {
	const mipmapVersion uint = 2

	// check if the version is set. We ignore data for now since there's
	// only one version so we can easily ignore it for now
	var data []byte
	data, _ = db.Get([]byte("setting-mipmap-version"))
	if len(data) > 0 {
		var version uint
		if err := rlp.DecodeBytes(data, &version); err == nil && version == mipmapVersion {
			return nil
		}
	}

	defer func() {
		if err == nil {
			var val []byte
			val, err = rlp.EncodeToBytes(mipmapVersion)
			if err == nil {
				err = db.Put([]byte("setting-mipmap-version"), val)
			}
			return
		}
	}()
	latestBlock := core.GetBlock(db, core.GetHeadBlockHash(db))
	if latestBlock == nil { // clean database
		return
	}

	tstart := time.Now()
	glog.V(logger.Info).Infoln("upgrading db log bloom bins")
	for i := uint64(0); i <= latestBlock.NumberU64(); i++ {
		hash := core.GetCanonicalHash(db, i)
		if (hash == common.Hash{}) {
			return fmt.Errorf("chain db corrupted. Could not find block %d.", i)
		}
		core.WriteMipmapBloom(db, i, core.GetBlockReceipts(db, hash))
	}
	glog.V(logger.Info).Infoln("upgrade completed in", time.Since(tstart))
	return nil
}

// WriteReceipts stores a batch of transaction receipts into the database.
func WriteReceipts(db ethdb.Database, receipts types.Receipts) error {
	batch := db.NewBatch()

	// Iterate over all the receipts and queue them for database injection
	for _, receipt := range receipts {
		storageReceipt := (*types.ReceiptForStorage)(receipt)
		data, err := rlp.EncodeToBytes(storageReceipt)
		if err != nil {
			return err
		}
		if err := batch.Put(append(receiptsPrefix, receipt.TxHash.Bytes()...), data); err != nil {
			return err
		}
	}
	// Write the scheduled data into the database
	if err := batch.Write(); err != nil {
		glog.Fatalf("failed to store receipts into database: %v", err)
		return err
	}
	return nil
}

// WriteTransactions stores the transactions associated with a specific block
// into the given database. Beside writing the transaction, the function also
// stores a metadata entry along with the transaction, detailing the position
// of this within the blockchain.
func WriteTransactions(db ethdb.Database, block *types.Block) error {
	batch := db.NewBatch()

	// Iterate over each transaction and encode it with its metadata
	for i, tx := range block.Transactions() {
		// Encode and queue up the transaction for storage
		data, err := rlp.EncodeToBytes(tx)
		if err != nil {
			return err
		}
		if err := batch.Put(tx.Hash().Bytes(), data); err != nil {
			return err
		}
		// Encode and queue up the transaction metadata for storage
		meta := struct {
			BlockHash  common.Hash
			BlockIndex uint64
			Index      uint64
		}{
			BlockHash:  block.Hash(),
			BlockIndex: block.NumberU64(),
			Index:      uint64(i),
		}
		data, err = rlp.EncodeToBytes(meta)
		if err != nil {
			return err
		}
		if err := batch.Put(append(tx.Hash().Bytes(), txMetaSuffix...), data); err != nil {
			return err
		}
	}
	// Write the scheduled data into the database
	if err := batch.Write(); err != nil {
		glog.Fatalf("failed to store transactions into database: %v", err)
		return err
	}
	return nil
}

// upgradeChainDatabase ensures that the chain database stores block split into
// separate header and body entries.
func upgradeChainDatabase(db ethdb.Database) error {
	// Short circuit if the head block is stored already as separate header and body
	data, err := db.Get([]byte("LastBlock"))
	if err != nil {
		return nil
	}
	head := common.BytesToHash(data)

	if block := core.GetBlockByHashOld(db, head); block == nil {
		return nil
	}
	// At least some of the database is still the old format, upgrade (skip the head block!)
	glog.V(logger.Info).Info("Old database detected, upgrading...")

	if db, ok := db.(*ethdb.LDBDatabase); ok {
		blockPrefix := []byte("block-hash-")
		for it := db.NewIterator(); it.Next(); {
			// Skip anything other than a combined block
			if !bytes.HasPrefix(it.Key(), blockPrefix) {
				continue
			}
			// Skip the head block (merge last to signal upgrade completion)
			if bytes.HasSuffix(it.Key(), head.Bytes()) {
				continue
			}
			// Load the block, split and serialize (order!)
			block := core.GetBlockByHashOld(db, common.BytesToHash(bytes.TrimPrefix(it.Key(), blockPrefix)))

			if err := core.WriteTd(db, block.Hash(), block.DeprecatedTd()); err != nil {
				return err
			}
			if err := core.WriteBody(db, block.Hash(), &types.Body{block.Transactions(), block.Uncles()}); err != nil {
				return err
			}
			if err := core.WriteHeader(db, block.Header()); err != nil {
				return err
			}
			if err := db.Delete(it.Key()); err != nil {
				return err
			}
		}
		// Lastly, upgrade the head block, disabling the upgrade mechanism
		current := core.GetBlockByHashOld(db, head)

		if err := core.WriteTd(db, current.Hash(), current.DeprecatedTd()); err != nil {
			return err
		}
		if err := core.WriteBody(db, current.Hash(), &types.Body{current.Transactions(), current.Uncles()}); err != nil {
			return err
		}
		if err := core.WriteHeader(db, current.Header()); err != nil {
			return err
		}
	}
	return nil
}