qortal/src/qora/block/BlockChain.java

package qora.block;

import java.math.BigDecimal;
import java.sql.SQLException;

import data.block.BlockData;
import qora.assets.Asset;
import repository.BlockRepository;
import repository.DataException;
import repository.Repository;
import repository.RepositoryManager;

/**
 * Class representing the blockchain as a whole.
 *
 */
public class BlockChain {

	/**
	 * Minimum Qora balance.
	 */
	public static final BigDecimal MIN_BALANCE = BigDecimal.valueOf(1L).setScale(8);
	/**
	 * Maximum Qora balance.
	 */
	public static final BigDecimal MAX_BALANCE = BigDecimal.valueOf(10_000_000_000L).setScale(8);
	/**
	 * Minimum target time between blocks, in seconds.
	 */
	public static final long MIN_BLOCK_TIME = 60;
	/**
	 * Maximum target time between blocks, in seconds.
	 */
	public static final long MAX_BLOCK_TIME = 300;

	/**
	 * Some sort start-up/initialization/checking method.
	 * 
	 * @throws SQLException
	 */
	public static void validate() throws DataException {
		// Check first block is Genesis Block
		if (!isGenesisBlockValid())
			rebuildBlockchain();
	}

	private static boolean isGenesisBlockValid() throws DataException {
		BlockRepository blockRepository = RepositoryManager.getRepository().getBlockRepository();

		int blockchainHeight = blockRepository.getBlockchainHeight();
		if (blockchainHeight < 1)
			return false;

		BlockData blockData = blockRepository.fromHeight(1);
		if (blockData == null)
			return false;

		return GenesisBlock.isGenesisBlock(blockData);
	}

	private static void rebuildBlockchain() throws DataException {
		// (Re)build repository
		Repository repository = RepositoryManager.getRepository();
		repository.rebuild();

		// Add Genesis Block
		GenesisBlock genesisBlock = new GenesisBlock(repository);
		genesisBlock.process();

		// Add QORA asset.
		// NOTE: Asset's transaction reference is Genesis Block's generator signature which doesn't exist as a transaction!
		// TODO construct Asset(repository, AssetData) then .save()?
		Asset qoraAsset = new Asset(Asset.QORA, genesisBlock.getGenerator().getAddress(), "Qora", "This is the simulated Qora asset.", 10_000_000_000L, true,
				genesisBlock.getBlockData().getGeneratorSignature());
		qoraAsset.save();

		repository.saveChanges();
	}

	/**
	 * Return Qora balance adjusted to within min/max limits.
	 */
	public static BigDecimal minMaxBalance(BigDecimal balance) {
		if (balance.compareTo(MIN_BALANCE) < 0)
			return MIN_BALANCE;

		if (balance.compareTo(MAX_BALANCE) > 0)
			return MAX_BALANCE;

		return balance;
	}

}