/
blockchain.go
221 lines (174 loc) · 4.31 KB
/
blockchain.go
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package blockchain
import (
"encoding/hex"
"fmt"
"github.com/dgraph-io/badger"
"os"
"runtime"
)
const (
dbPath = "./tmp/blocks"
dbFile = "./tmp/blocks/MANIFEST"
genesisData = "First Transaction from Genesis"
)
type BlockChain struct {
LastHash []byte
Database *badger.DB
}
type BlockChainIterator struct {
CurrentHash []byte
Database *badger.DB
}
func (chain *BlockChain) AddBlock(transaction []*Transaction) {
var lastHash []byte
err := chain.Database.View(func(txn *badger.Txn) error {
item, err := txn.Get([]byte("lh"))
Handle(err)
lastHash, err = item.Value()
return err
})
Handle(err)
newBlock := CreateBlock(transaction, lastHash)
err = chain.Database.Update(func(txn *badger.Txn) error {
err := txn.Set(newBlock.Hash, newBlock.Serialize())
Handle(err)
err = txn.Set([]byte("lh"), newBlock.Hash)
chain.LastHash = newBlock.Hash
return err
})
Handle(err)
}
func DBexists() bool {
if _, err := os.Stat(dbFile); os.IsNotExist(err) {
return false
}
return true
}
func InitBlockChain(address string) *BlockChain {
var lastHash []byte
if DBexists() {
fmt.Println("Blockchain already exixsts")
runtime.Goexit()
}
opts := badger.DefaultOptions
opts.Dir = dbPath
opts.ValueDir = dbPath
db, err := badger.Open(opts)
Handle(err)
err = db.Update(func(txn *badger.Txn) error {
cbtx := CoinbaseTx(address, genesisData)
genesis := Genesis(cbtx)
fmt.Println("Genesis created")
err = txn.Set(genesis.Hash, genesis.Serialize())
Handle(err)
err = txn.Set([]byte("lh"), genesis.Hash)
return err
})
Handle(err)
blockchain := BlockChain{lastHash, db}
return &blockchain
}
func ContinueBlockChain(address string) *BlockChain {
if DBexists() == false {
fmt.Println("No existing blockchain found, create one!")
runtime.Goexit()
}
var lastHash []byte
opts := badger.DefaultOptions
opts.Dir = dbPath
opts.ValueDir = dbPath
db, err := badger.Open(opts)
Handle(err)
err = db.Update(func(txn *badger.Txn) error {
item, err := txn.Get([]byte("lh"))
Handle(err)
lastHash, err = item.Value()
return err
})
Handle(err)
chain := BlockChain{lastHash, db}
return &chain
}
func (chain *BlockChain) Iterator() *BlockChainIterator {
iter := &BlockChainIterator{chain.LastHash, chain.Database}
return iter
}
func (iter *BlockChainIterator) Next() *Block {
var block *Block
err := iter.Database.View(func(txn *badger.Txn) error {
item, err := txn.Get(iter.CurrentHash)
encodedBlock, err := item.Value()
block = Deserialize(encodedBlock)
return err
})
Handle(err)
iter.CurrentHash = block.PrevHash
return block
}
func (chain *BlockChain) FindUnspentTransactions(address string) []Transaction {
var unspentTxs []Transaction
spentTXOs := make(map[string][]int)
iter := chain.Iterator()
for {
block := iter.Next()
for _, tx := range block.Transactions {
txID := hex.EncodeToString(tx.ID)
Outputs:
for outIdx, out := range tx.Outputs {
if spentTXOs[txID] != nil {
for _, spentOut := range spentTXOs[txID] {
if spentOut == outIdx {
continue Outputs
}
}
}
if out.CanBeUnlocked(address) {
unspentTxs = append(unspentTxs, *tx)
}
}
if tx.IsCoinbase() == false {
for _, in := range tx.Inputs {
if in.CanUnlock(address) {
inTxID := hex.EncodeToString(in.ID)
spentTXOs[inTxID] = append(spentTXOs[inTxID], in.Out)
}
}
}
}
if len(block.PrevHash) == 0 {
break
}
}
return unspentTxs
}
func (chain *BlockChain) FindUTXO(address string) []TxOutput {
var UTXOs []TxOutput
unspentTransactions := chain.FindUnspentTransactions(address)
for _, tx := range unspentTransactions {
for _, out := range tx.Outputs {
if out.CanBeUnlocked(address) {
UTXOs = append(UTXOs, out)
}
}
}
return UTXOs
}
func (chain *BlockChain) FindSpendableOutputs(address string, amount int) (int, map[string][]int) {
unspentOuts := make(map[string][]int)
unspentTxs := chain.FindUnspentTransactions(address)
accumulated := 0
Work:
for _, tx := range unspentTxs {
txID := hex.EncodeToString(tx.ID)
for outIdx, out := range tx.Outputs {
if out.CanBeUnlocked(address) && accumulated < amount {
accumulated += out.Value
unspentOuts[txID] = append(unspentOuts[txID], outIdx)
if accumulated >= amount {
break Work
}
}
}
}
return accumulated, unspentOuts
}