Implement transactions

transaction.go

@@ -0,0 +1,73 @@
+package main
+
+import "log"
+
+const subsidy = 10
+
+// Transaction represents a Bitcoin transaction
+type Transaction struct {
+	Vin  []TXInput
+	Vout []TXOutput
+}
+
+// IsCoinbase checks whether the transaction is coinbase
+func (tx Transaction) IsCoinbase() bool {
+	return len(tx.Vin) == 1 && tx.Vin[0].Txid == -1 && tx.Vin[0].Vout == -1
+}
+
+// TXInput represents a transaction input
+type TXInput struct {
+	Txid      int
+	Vout      int
+	ScriptSig string
+}
+
+// TXOutput represents a transaction output
+type TXOutput struct {
+	Value        int
+	ScriptPubKey string
+}
+
+// Unlock checks if the output can be unlocked with the provided data
+func (out *TXOutput) Unlock(unlockingData string) bool {
+	return out.ScriptPubKey == unlockingData
+}
+
+// NewCoinbaseTX creates a new coinbase transaction
+func NewCoinbaseTX(to string) *Transaction {
+	txin := TXInput{-1, -1, "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"}
+	txout := TXOutput{subsidy, to}
+	tx := Transaction{[]TXInput{txin}, []TXOutput{txout}}
+
+	return &tx
+}
+
+// NewUTXOTransaction creates a new transaction
+func NewUTXOTransaction(from, to string, value int) *Transaction {
+	var inputs []TXInput
+	var outputs []TXOutput
+
+	acc, validOutputs := s.findUnspentOutputs(from, value)
+
+	if acc < value {
+		log.Panic("ERROR: Not enough funds")
+	}
+
+	// Build a list of inputs
+	for txid, outs := range validOutputs {
+		for _, out := range outs {
+			input := TXInput{txid, out, from}
+			inputs = append(inputs, input)
+		}
+	}
+
+	// Build a list of outputs
+	outputs = append(outputs, TXOutput{value, to})
+	if acc > value {
+		outputs = append(outputs, TXOutput{acc - value, from}) // a change
+	}
+
+	tx := Transaction{inputs, outputs}
+
+	return &tx
+}