global processed_txids, transaction_id

sk = SigningKey.from_pem(open(sk_filename).read())

vk = sk.get_verifying_key()

pk = str(base64.b64encode(vk.to_string()), encoding='utf8')

timestamp = str(int(time.time()-300))

leaders = db.query("SELECT * FROM leaders WHERE pk = %s AND timestamp > %s", pk, timestamp)

if not leaders:

election(sk_filename)

else:

# leader = leaders[0]

transactions = db.query("SELECT * FROM transactions WHERE id > %s ORDER BY id ASC LIMIT 20", transaction_id)

random.shuffle(transactions)

for transaction in transactions:

if transaction.txid in processed_txids:

continue

data = json.loads(transaction.data)

sender = data["transaction"]["sender"]

receiver = data["transaction"]["receiver"]

amount = data["transaction"]["amount"]

signature = data["signature"]

chain_txids = set()

sender_blocks = lastest_block(sender)

receiver_blocks = lastest_block(receiver)

if len(set(sender_blocks+receiver_blocks)) >= 1:

if len(set(sender_blocks+receiver_blocks)) == 1:

txs = db.query("SELECT * FROM graph WHERE hash = %s", (sender_blocks+receiver_blocks)[0])

else:

txs = db.query("SELECT * FROM graph WHERE hash IN %s", set(sender_blocks+receiver_blocks))

for tx in txs:

tx_data = json.loads(tx.data)

txid = tx_data["transaction"]["txid"]

chain_txids.add(txid)

processed_txids.add(txid)

if transaction.txid in chain_txids:

continue

from_block = sender_blocks[-1] if sender_blocks else sender

to_block = receiver_blocks[-1] if receiver_blocks else receiver

# query from_block and to_block

# get balance and calcuate

# update transaction's from_block and to_block

data["from_block"] = from_block

data["to_block"] = to_block

data["sender_balance"] = ""

data["receiver_balance"] = ""

data["leader_publickey"] = pk

vk2 = VerifyingKey.from_string(base64.b64decode(sender), curve=NIST384p)

assert vk2.verify(base64.b64decode(signature), json.dumps(data["transaction"]).encode('utf-8'))

# signature = sk.sign(json.dumps(transaction).encode('utf-8'))

# data = {"transaction": transaction, "signature": str(base64.b64encode(signature), encoding="utf-8")}

for nonce in range(100000000):

block_hash = hashlib.sha256((json.dumps(data) + pk + str(nonce)).encode('utf8')).hexdigest()

if block_hash < certain_value:

print("tx", nonce, block_hash)

try:

# query if any node taken from_block or to_block

db.execute("INSERT INTO graph (hash, from_block, to_block, sender, receiver, nonce, data) VALUES (%s, %s, %s, %s, %s, %s, %s)", block_hash, from_block, to_block, sender, receiver, nonce, transaction.data)

# db.execute("INSERT INTO graph (hash, from_block, to_block, sender, receiver, nonce, data, transaction_id, timestamp) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s)", block_hash, from_block, to_block, sender, receiver, nonce, transaction.data, transaction.id, int(time.time()))

processed_txids.add(transaction.txid)

break

except:

pass

time.sleep(1)

transaction_id += 20