Check Blockchain's validity for toutsurlebitcoin.fr

BlockchainValidity.java

public boolean isFirstBlockValid() {
  Block firstBlock = blocks.get(0);

  if (firstBlock.getIndex() != 0) {
    return false;
  }

  if (firstBlock.getPreviousHash() != null) {
    return false;
  }

  if (firstBlock.getHash() == null || 
      !Block.calculateHash(firstBlock).equals(firstBlock.getHash())) {
    return false;
  }

  return true;
}

public boolean isValidNewBlock(Block newBlock, Block previousBlock) {
  if (newBlock != null  &&  previousBlock != null) {
    if (previousBlock.getIndex() + 1 != newBlock.getIndex()) {
      return false;
    }

    if (newBlock.getPreviousHash() == null  || 
        !newBlock.getPreviousHash().equals(previousBlock.getHash())) {
      return false;
    }

    if (newBlock.getHash() == null  ||  
        !Block.calculateHash(newBlock).equals(newBlock.getHash())) {
      return false;
    }

    return true;
  }

  return false;
}

public boolean isBlockChainValid() {
  if (!isFirstBlockValid()) {
    return false;
  }

  for (int i = 1; i < blocks.size(); i++) {
    Block currentBlock = blocks.get(i);
    Block previousBlock = blocks.get(i - 1);

    if (!isValidNewBlock(currentBlock, previousBlock)) {
      return false;
    }
  }

  return true;
}