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103 lines
2.5 KiB
103 lines
2.5 KiB
package main
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import (
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"encoding/hex"
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)
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// Blockchain keeps a sequence of Blocks
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type Blockchain struct {
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blocks []*Block
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}
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const genesisCoinbaseData = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"
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// NewBlockchain creates a new Blockchain with genesis Block
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func NewBlockchain(address string) *Blockchain {
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return &Blockchain{[]*Block{NewGenesisBlock()}}
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}
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// FindUnspentTransactions returns a list of transactions containing unspent outputs
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func (bc *Blockchain) FindUnspentTransactions(address string) []Transaction {
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var unspentTXs []Transaction
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spentTXOs := make(map[string][]int)
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for index := len(bc.blocks) - 1; index >= 0; index-- {
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block := bc.blocks[index]
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BreakTransaction:
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for _, tx := range block.Transactions {
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txId := hex.EncodeToString(tx.Id)
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idx := -1
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if spentTXOs[txId] != nil {
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idx = 0
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}
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for outIdx, txOutput := range tx.txOutput {
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if idx >= 0 && spentTXOs[txId][idx] == outIdx {
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idx++
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continue
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}
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if txOutput.address == address {
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unspentTXs = append(unspentTXs, *tx)
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continue BreakTransaction
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}
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}
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}
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}
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return unspentTXs
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}
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// FindUTXO finds and returns all unspent transaction outputs
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func (bc *Blockchain) FindUTXO(address string) []TXOutput {
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var UTXOs []TXOutput
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unspentTXs := bc.FindUnspentTransactions(address)
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for _, tx := range unspentTXs {
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for _, txOutput := range tx.txOutput {
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if txOutput.address == address {
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UTXOs = append(UTXOs, txOutput)
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break
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}
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}
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}
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return UTXOs
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}
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// FindSpendableOutputs finds and returns unspent outputs to reference in inputs
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func (bc *Blockchain) FindSpendableOutputs(address string, amount int) (int, map[string][]int) {
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unspentOutputs := make(map[string][]int)
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unspentTXs := bc.FindUnspentTransactions(address)
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accumulated := 0
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Work:
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for _, tx := range unspentTXs {
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txID := hex.EncodeToString(tx.ID)
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for outIdx, txOutput := range tx.txOutput {
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if txOutput.address == address && accumulated < amount {
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accumulated += txOutput.value
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unspentOutputs[txID] = append(unspentOutputs[txID], outIdx)
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if accumulated >= amount {
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break Work
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}
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}
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}
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}
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return accumulated, unspentOutputs
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}
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// CreateBlockchain creates a new blockchain DB
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func CreateBlockchain(address string) *Blockchain {
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// TODO: We assume we have not created any blockchain before.
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// In current bitcoin, we can check if we created a blockchain before accessing local db.
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cbtx := NewCoinbaseTX(address, genesisCoinbaseData)
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genesis := NewGenesisBlock(cbtx)
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bc := Blockchain{[]*Block{genesis}}
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return &bc
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}
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