import hashlib
import json

class TRBlock(object) :

    def __init__(self, index, timestamp, data, prevHash, nonce, target):
        '''
            Default constructor for creating a block.

            Parameters
            ----------
            index : int
                The index of the block
            timestamp: long
                Timestamp in epoch, number of seconds since 1 Jan 1970
            data : object
                The actual data that needs to be stored on block chain
            prevHash : str
                The hash of the previous block
            nonce : str
                The nonce which has been mined
            target: int
                Number of leading zeros
        '''
        self.index = index
        self.timestamp = timestamp
        self.data = data
        self.prevHash = prevHash
        self.nonce = nonce
        self.target = target

    def compute_hash(self):
        '''
            Compute sha1 hash and convert it into hexadecimal string, json.dumps
            uses ":" separator without space

            Returns
            -------
            str
                sha1 hash of the attributes converted into hexadecimal string
        '''
        return hashlib.sha1(json.dumps(self.__dict__, separators=(',', ':')) \
        .encode("utf-8")).hexdigest()


if __name__ == "__main__":
    block = TRBlock(0,1514528022,"Hello World", "000000000000000000000000000", \
    "Random nonce",8)
    print(block.compute_hash())