NevCoin/src/main/java/tech/nevets/nevcoin/Block.java

package tech.nevets.nevcoin;

import tech.nevets.nevcoin.transactions.Transaction;
import tech.nevets.nevcoin.util.StringUtil;

import java.util.ArrayList;
import java.util.Date;

public class Block {

    public String hash;
    public String previousHash;
    public String merkleRoot;
    public ArrayList<Transaction> transactions = new ArrayList<Transaction>();
    //private String data;
    private long timeStamp;
    private int nonce;

    public Block(String previousHash) {
        //this.data = data;
        this.previousHash = previousHash;
        this.timeStamp = new Date().getTime();
        this.hash = calculateHash();
    }

    public String calculateHash() {
        String calculatedHash = StringUtil.applySha256(
                previousHash
                + Long.toString(timeStamp)
                + Integer.toString(nonce)
                + merkleRoot
                //+ data
                );
        return calculatedHash;
    }

    public void mineBlock(int difficulty) {
        merkleRoot = StringUtil.getMerkleRoot(transactions);
        String target = StringUtil.getDifficultyString(difficulty);

        while (!hash.substring(0, difficulty).equals(target)) {
            nonce ++;
            hash = calculateHash();
        }
        System.out.println("Block mined: " + hash);
    }

    public boolean addTransaction(Transaction transaction) {
        if (transaction == null) return false;
        if (!"0".equals(previousHash)) {
            if (transaction.processTransaction() != true) {
                System.out.println("Transaction failed to process. Discarded.");
                return false;
            }
        }

        transactions.add(transaction);
        System.out.println("Transaction Successfully added to Block");
        return true;
    }
}