bpsc101.py

import hashlib
import json
from time import time
from urllib.parse import urlparse

from flask import Flask, jsonify, request

class Smart_Blockchain:
    def __init__(self):
        self.current_transactions = []
        self.chain = []

        # Create the genesis block
        self.new_block(previous_hash='1')

    def new_block(self, previous_hash):
        """
        Create a new Block in the Smart Blockchain
        :param previous_hash: Hash of previous Block
        :return: New Block
        """

        block = {
            'index': len(self.chain) + 1,
            'timestamp': time(),
            'transactions': self.current_transactions,
            'previous_hash': previous_hash or self.hash(self.chain[-1]),
        }

        # Reset the current list of transactions
        self.current_transactions = []

        self.chain.append(block)
        return block


    def new_transaction(self, sender, amount, recipient):
        """
        Creates a new transaction to go into the next mined Block
        :param sender: Address of the Sender
        :param amount_send: The amount sent by the sender
        :param bpsc: Address of the Smart contract (bpsc)
        :param amount_bpsc: The amount received by bpsc (Transaction fees)
        :param recipient: Address of the Recipient
        :param amount_receive: The amount received by the recipient
        :return: The index of the Block that will hold this transaction
        """
        self.current_transactions.append({
            'sender': sender,
            'amount_send': amount,
             
            'bpsc': 'bpsc_wallet_address', # Block Producer Smart Contract (bpsc)
            'amount_bpsc': amount * 0.00005, # Transaction fees
            
            'recipient': recipient,
            'amount_receive': amount * 0.99995,
        })

        return self.last_block['index'] + 1
        

    @property
    def last_block(self):
        return self.chain[-1]


    @staticmethod
    def hash(block):
        """
        Creates a SHA-256 hash of a Block
        :param block: Block
        """

        # We must make sure that the Dictionary is Ordered, or we'll have inconsistent hashes
        block_string = json.dumps(block, sort_keys=True).encode()
        return hashlib.sha256(block_string).hexdigest()


# Instantiate the Node
app = Flask(__name__)

# Instantiate the Smart_Blockchain
blockchain = Smart_Blockchain()


@app.route('/mine', methods=['GET'])
def mine():
    last_block = blockchain.last_block

    # Forge the new Block by adding it to the chain
    previous_hash = blockchain.hash(last_block)
    block = blockchain.new_block(previous_hash)

    response = {
        'message': "New Block Forged",
        'index': block['index'],
        'transactions': block['transactions'],
        'previous_hash': block['previous_hash'],
    }
    return jsonify(response), 200


@app.route('/transactions/new', methods=['POST'])
def new_transaction():
    values = request.get_json()

    # Check that the required fields are in the POST'ed data
    required = ['sender', 'amount', 'recipient']
    if not all(k in values for k in required):
        return 'Missing values', 400

    # Create a new Transaction
    index = blockchain.new_transaction(values['sender'], values['amount'], values['recipient'])
    
    response = {'message': f'Transaction will be added to Block {index}'}
    return jsonify(response), 201


@app.route('/chain', methods=['GET'])
def full_chain():
    response = {
        'chain': blockchain.chain,
        'length': len(blockchain.chain),
    }
    return jsonify(response), 200


if __name__ == '__main__':
    from argparse import ArgumentParser

    parser = ArgumentParser()
    parser.add_argument('-p', '--port', default=5000, type=int, help='port to listen on')
    args = parser.parse_args()
    port = args.port

    app.run(host='0.0.0.0', port=port)