/**
* @param BlockInterface $block
* @param TransactionSerializerInterface $txSerializer
* @return BlockData
*/
public function parseUtxos(BlockInterface $block, TransactionSerializerInterface $txSerializer)
{
$blockData = new BlockData();
$unknown = [];
$hashStorage = new HashStorage();
// Record every Outpoint required for the block.
foreach ($block->getTransactions() as $t => $tx) {
if ($tx->isCoinbase()) {
continue;
}
foreach ($tx->getInputs() as $in) {
$outpoint = $in->getOutPoint();
$unknown[$outpoint->getTxId()->getBinary() . $outpoint->getVout()] = $outpoint;
}
}
foreach ($block->getTransactions() as $tx) {
/** @var BufferInterface $buffer */
$buffer = $txSerializer->serialize($tx);
$hash = Hash::sha256d($buffer)->flip();
$hashStorage->attach($tx, $hash);
$hashBin = $hash->getBinary();
foreach ($tx->getOutputs() as $i => $out) {
$lookup = $hashBin . $i;
if (isset($unknown[$lookup])) {
// Remove unknown outpoints which consume this output
$outpoint = $unknown[$lookup];
$utxo = new Utxo($outpoint, $out);
unset($unknown[$lookup]);
} else {
// Record new utxos which are not consumed in the same block
$utxo = new Utxo(new OutPoint($hash, $i), $out);
$blockData->remainingNew[] = $utxo;
}
// All utxos produced are stored
$blockData->parsedUtxos[] = $utxo;
}
}
$blockData->requiredOutpoints = array_values($unknown);
$blockData->hashStorage = $hashStorage;
return $blockData;
}
/**
* @param BlockInterface $block
* @param TransactionSerializerInterface $txSerializer
* @return Buffer
* @throws MerkleTreeEmpty
*/
public function calcMerkleRoot(BlockInterface $block, TransactionSerializerInterface $txSerializer)
{
$hashFxn = function ($value) {
return hash('sha256', hash('sha256', $value, true), true);
};
$txCount = count($block->getTransactions());
if ($txCount === 0) {
// TODO: Probably necessary. Should always have a coinbase at least.
throw new MerkleTreeEmpty('Cannot compute Merkle root of an empty tree');
}
if ($txCount === 1) {
$transaction = $block->getTransaction(0);
$serialized = $txSerializer->serialize($transaction);
$binary = $hashFxn($serialized->getBinary());
} else {
// Create a fixed size Merkle Tree
$tree = new FixedSizeTree($txCount + $txCount % 2, $hashFxn);
// Compute hash of each transaction
$last = '';
foreach ($block->getTransactions() as $i => $transaction) {
$last = $txSerializer->serialize($transaction)->getBinary();
$tree->set($i, $last);
}
// Check if we need to repeat the last hash (odd number of transactions)
if (!($txCount % 2 === 0)) {
$tree->set($txCount, $last);
}
$binary = $tree->hash();
}
return (new Buffer($binary))->flip();
}
