import hashlib
import pickle
import csv
from binascii import unhexlify


def swap_order(d, wsz=4, gsz=2 ):
    return "".join(["".join([m[i:i+gsz] for i in range(wsz-gsz,-gsz,-gsz)]) for m in [d[i:i+wsz] for i in range(0,len(d),wsz)]])


def calculate_blockhash(serialized_block):
    a = hashlib.sha256(hashlib.sha256(serialized_block).digest()).hexdigest()
    return swap_order(a, len(a))


def read_csv(path):
    result = []
    with open(path, newline="\n") as csv_file:
        reader = csv.reader(csv_file, delimiter=',')
        for row in reader:
            result.append(row)
    return result


# Block #400000


class Block:
    def __init__(self, transactions, lastblockhash, difficulty):
        self.transactions = transactions
        self.blockhash = ""
        self.lastblockhash = lastblockhash
        self.difficulty = difficulty
        self.nonce = 0

    def proof_of_work(self):
        current_hash = calculate_blockhash(pickle.dumps(self))
        while int(current_hash, 16) >= self.difficulty:
            self.nonce += 1
            # print(current_hash)
            current_hash = calculate_blockhash(pickle.dumps(self))
        self.blockhash = current_hash
        return current_hash

    def __str__(self):
        result = ""
        result += "Last Blockhash: " + str(self.lastblockhash) + "\n"
        result += "Own Blockhash : " + str(self.blockhash) + "\n"
        result += "Nonce         : " + str(self.nonce) +"\n"
        result += "Transactions  : " +"\n"
        for t in self.transactions:
            result += t[0] + ", " + t[1] + ", " + t[2]
        result += "\n"
        return result


# Read the transactions
transactions = read_csv("buchhaltung.csv")

# Define the difficulty
mant = 3
exp = 71
difficulty = mant * 10**exp

# Create the Genesis Block
genesis = Block([], 0, difficulty)
current_blockhash = genesis.proof_of_work()
print("Genesis Blockhash: ")
print(genesis)
blocks = [genesis]
for transaction in transactions:
    current_block = Block([transaction], current_blockhash, difficulty)
    current_blockhash = current_block.proof_of_work()
    print(current_block)
    blocks.append(current_block)