feat: add initial implementation of mining

blockchain/blockchain.go

@@ -2,6 +2,8 @@ package blockchain
 
 import (
 	"encoding/json"
+	"log"
+	"strings"
 
 	"github.com/stinkymonkeyph/gopher-blocks/constants"
 )
@@ -33,3 +35,45 @@ func (bc *Blockchain) AddTransactionToTransactionPool(txn *Transaction) {
 	txn.Status = constants.STATUS_PENDING
 	bc.TransactionPool = append(bc.TransactionPool, txn)
 }
+
+func (bc *Blockchain) AddBlock(b *Block) {
+	m := map[string]bool{}
+	for _, txn := range b.Transactions {
+		m[txn.TransactioHash] = true
+	}
+
+	for idx, txn := range bc.TransactionPool {
+		_, ok := m[txn.TransactioHash]
+
+		if ok {
+			bc.TransactionPool = append(bc.TransactionPool[:idx], bc.TransactionPool[idx+1:]...)
+		}
+	}
+
+	bc.Blocks = append(bc.Blocks, b)
+}
+
+func (bc *Blockchain) ProofOfWorkMining(minerAddress string) {
+	nonce := 0
+	for {
+		prevHash := bc.Blocks[len(bc.Blocks)-1].Hash()
+		guessBlock := NewBlock(prevHash, nonce)
+
+		for _, txn := range bc.TransactionPool {
+			tx := NewTransaction(txn.From, txn.To, txn.Value, txn.Data)
+			guessBlock.AddTransactionToTheBlock(tx)
+		}
+
+		zeroes := strings.Repeat("0", constants.MINING_DIFFICULTY)
+		guessHash := guessBlock.Hash()
+
+		if zeroes == guessHash[2:2+constants.MINING_DIFFICULTY] {
+			rewardTxn := NewTransaction(constants.BLOCKCHAIN_REWARD_ADDRESS, minerAddress, constants.MINING_REWARD, []byte{})
+			guessBlock.Transactions = append(guessBlock.Transactions, rewardTxn)
+			bc.AddBlock(guessBlock)
+			log.Printf(bc.ToJSON(), "\n\n")
+			nonce = 0
+			continue
+		}
+	}
+}

blockchain/transaction.go

@@ -1,16 +1,21 @@
 package blockchain
 
 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"math"
+
+	"github.com/stinkymonkeyph/gopher-blocks/constants"
 )
 
 type Transaction struct {
-	From   string `json:"from"`
-	To     string `json:"to"`
-	Value  uint64 `json:"value"`
-	Data   []byte `json:"data"`
-	Status string `json:"status"`
+	From           string `json:"from"`
+	To             string `json:"to"`
+	Value          uint64 `json:"value"`
+	Data           []byte `json:"data"`
+	Status         string `json:"status"`
+	TransactioHash string `json:"transaction_hash"`
 }
 
 func NewTransaction(from string, to string, value uint64, data []byte) *Transaction {
@@ -19,7 +24,7 @@ func NewTransaction(from string, to string, value uint64, data []byte) *Transact
 	t.To = to
 	t.Value = value
 	t.Data = data
-
+	t.TransactioHash = ""
 	return t
 }
 
@@ -46,3 +51,17 @@ func (t *Transaction) VerifyTransaction() bool {
 
 	return true
 }
+
+func (t *Transaction) Hash() string {
+	ts, err := json.Marshal(t)
+
+	if err != nil {
+		panic("Something went wrong while serializing transaction object")
+	}
+
+	sum := sha256.Sum256(ts)
+	hex := hex.EncodeToString(sum[:32])
+	hex = constants.HEX_PREFIX + hex
+
+	return hex
+}

constants/constants.go

@@ -1,9 +1,14 @@
 package constants
 
 const (
-	BLOCKCHAIN_NAME = "GopherBlocks"
-	HEX_PREFIX      = "0x"
-	STATUS_SUCCESS  = "success"
-	STATUS_FAILED   = "failed"
-	STATUS_PENDING  = "pending"
+	BLOCKCHAIN_NAME           = "GopherBlocks"
+	HEX_PREFIX                = "0x"
+	STATUS_SUCCESS            = "success"
+	STATUS_FAILED             = "failed"
+	STATUS_PENDING            = "pending"
+	MINING_DIFFICULTY         = 4
+	MINING_REWARD             = 1200 * DECIMAL
+	CURRENCY_NAME             = "gopher"
+	DECIMAL                   = 100
+	BLOCKCHAIN_REWARD_ADDRESS = "Gopher_Reward_Pool"
 )

main.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"log"
+	"sync"
+	"time"
 
 	"github.com/stinkymonkeyph/gopher-blocks/blockchain"
 	"github.com/stinkymonkeyph/gopher-blocks/constants"
@@ -12,7 +14,17 @@ func init() {
 }
 
 func main() {
+
+	var wg sync.WaitGroup
+
 	block := blockchain.NewBlock("0x0", 0)
+	transaction1 := blockchain.NewTransaction("0x1", "0x2", 12, []byte{})
 	bc := blockchain.NewBlockchain(block)
 	log.Print(bc.ToJSON())
+
+	wg.Add(1)
+	go bc.ProofOfWorkMining("alice")
+	time.Sleep(2000)
+	bc.AddTransactionToTransactionPool(transaction1)
+	wg.Wait()
 }