import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;


public class Block {

   public static final double COINBASE = 25; 

   private byte[] hash;
   private byte[] prevBlockHash;
   private Transaction coinbase;
   private ArrayList<Transaction> txs;

   // address to which the coinbase transaction would go
   public Block(byte[] prevHash, RSAKey address) {
      prevBlockHash = prevHash;
      coinbase = new Transaction(COINBASE, address);
      txs = new ArrayList<Transaction>();
   }

   public Transaction getCoinbase() {
      return coinbase;
   }

   public byte[] getHash() {
      return hash;
   }

   public byte[] getPrevBlockHash() {
      return prevBlockHash;
   }

   public ArrayList<Transaction> getTransactions() {
      return txs;
   }

   public Transaction getTransaction(int index) {
      return txs.get(index);
   }

   public void addTransaction(Transaction tx) {
      txs.add(tx);
   }

   public byte[] getRawBlock() {
      ArrayList<Byte> rawBlock = new ArrayList<Byte>();
      if (prevBlockHash != null)
         for (int i = 0; i < prevBlockHash.length; i++)
            rawBlock.add(prevBlockHash[i]);
      for (int i = 0; i < txs.size(); i++) {
         byte[] rawTx = txs.get(i).getRawTx();
         for (int j = 0; j < rawTx.length; j++) {
            rawBlock.add(rawTx[j]);
         }
      }
      byte[] raw = new byte[rawBlock.size()];
      for (int i = 0; i < raw.length; i++)
         raw[i] = rawBlock.get(i);
      return raw;
   }

   public void finalize() {
      try {
         MessageDigest md = MessageDigest.getInstance("SHA-256");
         md.update(getRawBlock());
         hash = md.digest();
      } catch(NoSuchAlgorithmException x) {
         x.printStackTrace(System.err);
      }
   }
}