Clean up and refactor proofofwork.go

block.go

@@ -13,18 +13,15 @@ type Block struct {
 	Nonce         int
 }
 
-// Prove obtains proof of work
-func (b *Block) Prove() {
-	nonce, hash := Prove(b)
-
-	b.Hash = hash[:]
-	b.Nonce = nonce
-}
-
 // NewBlock creates and returns Block
 func NewBlock(data string, prevBlockHash []byte) *Block {
 	block := &Block{time.Now().Unix(), []byte(data), prevBlockHash, []byte{}, 0}
-	block.Prove()
+	pow := NewProofOfWork(block)
+	nonce, hash := pow.Run()
+
+	block.Hash = hash[:]
+	block.Nonce = nonce
+
 	return block
 }
 

proofofwork.go

@@ -3,35 +3,45 @@ package main
 import (
 	"bytes"
 	"crypto/sha256"
-	"encoding/binary"
 	"fmt"
-	"log"
 	"math"
 	"math/big"
 )
 
 var (
-	target   big.Int
 	maxNonce = math.MaxInt64
 )
 
 const targetBits = 12
 
-func setTarget() {
+// ProofOfWork represents a proof-of-work
+type ProofOfWork struct {
+	block  *Block
+	target big.Int
+}
+
+// NewProofOfWork builds and returns a ProofOfWork
+func NewProofOfWork(b *Block) *ProofOfWork {
 	targetBytes := make([]byte, 32)
+	target := big.Int{}
+
 	numOfZeros := targetBits / 4
 	targetBytes[numOfZeros-1] = 1
 	target.SetBytes(targetBytes)
+
+	pow := &ProofOfWork{b, target}
+
+	return pow
 }
 
-func prepareData(block *Block, nonce int) []byte {
+func (pow *ProofOfWork) prepareData(nonce int) []byte {
 	data := bytes.Join(
 		[][]byte{
-			block.PrevBlockHash,
-			block.Data,
-			intToHex(block.Timestamp),
-			intToHex(int64(targetBits)),
-			intToHex(int64(nonce)),
+			pow.block.PrevBlockHash,
+			pow.block.Data,
+			IntToHex(pow.block.Timestamp),
+			IntToHex(int64(targetBits)),
+			IntToHex(int64(nonce)),
 		},
 		[]byte{},
 	)
@@ -39,32 +49,21 @@ func prepareData(block *Block, nonce int) []byte {
 	return data
 }
 
-func intToHex(num int64) []byte {
-	buff := new(bytes.Buffer)
-	err := binary.Write(buff, binary.BigEndian, num)
-	if err != nil {
-		log.Panic(err)
-	}
-
-	return buff.Bytes()
-}
-
-// Prove ...
-func Prove(block *Block) (int, []byte) {
-	setTarget()
+// Run performs a proof-of-work
+func (pow *ProofOfWork) Run() (int, []byte) {
 	var hashInt big.Int
 	var hash [32]byte
 	nonce := 0
 
-	fmt.Printf("Mining the block containing \"%s\"\n", block.Data)
+	fmt.Printf("Mining the block containing \"%s\"\n", pow.block.Data)
 	for nonce < maxNonce {
-		data := prepareData(block, nonce)
+		data := pow.prepareData(nonce)
 
 		hash = sha256.Sum256(data)
 		fmt.Printf("\r%x", hash)
 		hashInt.SetBytes(hash[:])
 
-		if hashInt.Cmp(&target) == -1 {
+		if hashInt.Cmp(&pow.target) == -1 {
 			break
 		} else {
 			nonce++
@@ -75,16 +74,15 @@ func Prove(block *Block) (int, []byte) {
 	return nonce, hash[:]
 }
 
-// ConfirmProof ..
-func ConfirmProof(block *Block, nonce int) bool {
-	setTarget()
+// ConfirmProof confirms that the proof is correct
+func (pow *ProofOfWork) ConfirmProof(nonce int) bool {
 	var hashInt big.Int
 
-	data := prepareData(block, nonce)
+	data := pow.prepareData(nonce)
 	hash := sha256.Sum256(data)
 	hashInt.SetBytes(hash[:])
 
-	confirmation := hashInt.Cmp(&target) == -1
+	confirmation := hashInt.Cmp(&pow.target) == -1
 
 	return confirmation
 }

utils.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	"log"
+)
+
+// IntToHex converts an int64 to a byte array
+func IntToHex(num int64) []byte {
+	buff := new(bytes.Buffer)
+	err := binary.Write(buff, binary.BigEndian, num)
+	if err != nil {
+		log.Panic(err)
+	}
+
+	return buff.Bytes()
+}