From 3e491be4d7bfd102e8c7f60c7e21767c194592d3 Mon Sep 17 00:00:00 2001
From: Ivan Kuznetsov <me@jeiwan.ru>
Date: Sun, 17 Sep 2017 11:49:59 +0700
Subject: [PATCH] Use the UTXO set to send coins

---
 blockchain.go  | 71 --------------------------------------------------
 cli_send.go    |  3 ++-
 transaction.go |  6 ++---
 utxo_set.go    | 31 ++++++++++++++++++++++
 4 files changed, 36 insertions(+), 75 deletions(-)

diff --git a/blockchain.go b/blockchain.go
index 2faa7c6..fa68abc 100644
--- a/blockchain.go
+++ b/blockchain.go
@@ -95,31 +95,6 @@ func NewBlockchain() *Blockchain {
 	return &bc
 }
 
-// FindSpendableOutputs finds and returns unspent outputs to reference in inputs
-func (bc *Blockchain) FindSpendableOutputs(pubKeyHash []byte, amount int) (int, map[string][]int) {
-	unspentOutputs := make(map[string][]int)
-	unspentTXs := bc.FindUnspentTransactions(pubKeyHash)
-	accumulated := 0
-
-Work:
-	for _, tx := range unspentTXs {
-		txID := hex.EncodeToString(tx.ID)
-
-		for outIdx, out := range tx.Vout {
-			if out.IsLockedWithKey(pubKeyHash) && accumulated < amount {
-				accumulated += out.Value
-				unspentOutputs[txID] = append(unspentOutputs[txID], outIdx)
-
-				if accumulated >= amount {
-					break Work
-				}
-			}
-		}
-	}
-
-	return accumulated, unspentOutputs
-}
-
 // FindTransaction finds a transaction by its ID
 func (bc *Blockchain) FindTransaction(ID []byte) (Transaction, error) {
 	bci := bc.Iterator()
@@ -141,52 +116,6 @@ func (bc *Blockchain) FindTransaction(ID []byte) (Transaction, error) {
 	return Transaction{}, errors.New("Transaction is not found")
 }
 
-// FindUnspentTransactions returns a list of transactions containing unspent outputs
-func (bc *Blockchain) FindUnspentTransactions(pubKeyHash []byte) []Transaction {
-	var unspentTXs []Transaction
-	spentTXOs := make(map[string][]int)
-	bci := bc.Iterator()
-
-	for {
-		block := bci.Next()
-
-		for _, tx := range block.Transactions {
-			txID := hex.EncodeToString(tx.ID)
-
-		Outputs:
-			for outIdx, out := range tx.Vout {
-				// Was the output spent?
-				if spentTXOs[txID] != nil {
-					for _, spentOutIdx := range spentTXOs[txID] {
-						if spentOutIdx == outIdx {
-							continue Outputs
-						}
-					}
-				}
-
-				if out.IsLockedWithKey(pubKeyHash) {
-					unspentTXs = append(unspentTXs, *tx)
-				}
-			}
-
-			if tx.IsCoinbase() == false {
-				for _, in := range tx.Vin {
-					if in.UsesKey(pubKeyHash) {
-						inTxID := hex.EncodeToString(in.Txid)
-						spentTXOs[inTxID] = append(spentTXOs[inTxID], in.Vout)
-					}
-				}
-			}
-		}
-
-		if len(block.PrevBlockHash) == 0 {
-			break
-		}
-	}
-
-	return unspentTXs
-}
-
 // FindAllUTXO finds all unspent transaction outputs and returns transactions with spent outputs removed
 func (bc *Blockchain) FindAllUTXO() map[string]TXOutputs {
 	UTXO := make(map[string]TXOutputs)
diff --git a/cli_send.go b/cli_send.go
index f9c45d6..3528611 100644
--- a/cli_send.go
+++ b/cli_send.go
@@ -14,9 +14,10 @@ func (cli *CLI) send(from, to string, amount int) {
 	}
 
 	bc := NewBlockchain()
+	UTXOSet := UTXOSet{bc}
 	defer bc.db.Close()
 
-	tx := NewUTXOTransaction(from, to, amount, bc)
+	tx := NewUTXOTransaction(from, to, amount, &UTXOSet)
 	cbTx := NewCoinbaseTX(from, "")
 	txs := []*Transaction{cbTx, tx}
 
diff --git a/transaction.go b/transaction.go
index 90950cc..e2fac83 100644
--- a/transaction.go
+++ b/transaction.go
@@ -185,7 +185,7 @@ func NewCoinbaseTX(to, data string) *Transaction {
 }
 
 // NewUTXOTransaction creates a new transaction
-func NewUTXOTransaction(from, to string, amount int, bc *Blockchain) *Transaction {
+func NewUTXOTransaction(from, to string, amount int, UTXOSet *UTXOSet) *Transaction {
 	var inputs []TXInput
 	var outputs []TXOutput
 
@@ -195,7 +195,7 @@ func NewUTXOTransaction(from, to string, amount int, bc *Blockchain) *Transactio
 	}
 	wallet := wallets.GetWallet(from)
 	pubKeyHash := HashPubKey(wallet.PublicKey)
-	acc, validOutputs := bc.FindSpendableOutputs(pubKeyHash, amount)
+	acc, validOutputs := UTXOSet.FindSpendableOutputs(pubKeyHash, amount)
 
 	if acc < amount {
 		log.Panic("ERROR: Not enough funds")
@@ -222,7 +222,7 @@ func NewUTXOTransaction(from, to string, amount int, bc *Blockchain) *Transactio
 
 	tx := Transaction{nil, inputs, outputs}
 	tx.ID = tx.Hash()
-	bc.SignTransaction(&tx, wallet.PrivateKey)
+	UTXOSet.Blockchain.SignTransaction(&tx, wallet.PrivateKey)
 
 	return &tx
 }
diff --git a/utxo_set.go b/utxo_set.go
index 0ee851d..74e7fec 100644
--- a/utxo_set.go
+++ b/utxo_set.go
@@ -110,3 +110,34 @@ func (u UTXOSet) FindUTXO(pubKeyHash []byte) []TXOutput {
 
 	return UTXOs
 }
+
+// FindSpendableOutputs finds and returns unspent outputs to reference in inputs
+func (u UTXOSet) FindSpendableOutputs(pubkeyHash []byte, amount int) (int, map[string][]int) {
+	unspentOutputs := make(map[string][]int)
+	accumulated := 0
+	db := u.Blockchain.db
+
+	err := db.View(func(tx *bolt.Tx) error {
+		b := tx.Bucket([]byte(utxoBucket))
+		c := b.Cursor()
+
+		for k, v := c.First(); k != nil; k, v = c.Next() {
+			txID := hex.EncodeToString(k)
+			outs := DeserializeOutputs(v)
+
+			for outIdx, out := range outs.Outputs {
+				if out.IsLockedWithKey(pubkeyHash) && accumulated < amount {
+					accumulated += out.Value
+					unspentOutputs[txID] = append(unspentOutputs[txID], outIdx)
+				}
+			}
+		}
+
+		return nil
+	})
+	if err != nil {
+		log.Panic(err)
+	}
+
+	return accumulated, unspentOutputs
+}