node.py

# -*- coding: utf-8 -*-
"""
@Author: Ken Ng
@Date: 2018-07-04 18:38:14
@Last Modified by:   Ken Ng
@Last Modified time: 2018-07-04 18:38:14
"""
from flask import (
    Flask,
    jsonify,
    request
)
from blockchain import Blockchain
from uuid import uuid4
from argparse import ArgumentParser
from params import ADDRESS, DEFAULT_PORT


# Initiate our node
app = Flask(__name__)

# Generate a globally unique address for this node
node_id = str(uuid4()).replace('-', '')

# Initiate the blockchain
blockchain = Blockchain()


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

    # award
    # sender is 0 referring a new coin
    blockchain.new_transaction(
        sender="0",
        recipient=node_id,
        amount=1
    )

    # forge the new block into the chain
    new_block = blockchain.new_block(proof)
    response = {
        'message': 'New Block Forged',
        'index': new_block['index'],
        'transactions': new_block['transactions'],
        'proof': new_block['proof'],
        'previous_hash': new_block['previous_hash']
    }
    return jsonify(response), 200


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

    # checking
    required_field = ['sender', 'recipient', 'amount']
    if not all(k in transaction for k in required_field):
        return 'Missing values', 400

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


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


@app.route('/nodes_register', methods=['POST'])
def register_nodes():
    values = request.get_json()
    nodes = values.get('nodes')
    if nodes is None:
        return "Error: Please supply a valid list of nodes", 400
    for node in nodes:
        blockchain.register_node(node)
    response = {
        'message': 'New nodes have been added',
        'total_nodes': list(blockchain.nodes),
    }
    return jsonify(response), 201


@app.route('/nodes/resolve', methods=['GET'])
def consensus():
    replaced = blockchain.resolve_conflicts()

    if replaced:
        response = {
            'message': 'Our chain was replaced',
            'new_chain': blockchain.chain
        }
    else:
        response = {
            'message': 'Our chain is authoritative',
            'chain': blockchain.chain
        }
    return jsonify(response), 200


if __name__ == '__main__':
    parser = ArgumentParser()
    parser.add_argument(
        '-p', '--port', default=DEFAULT_PORT, type=int, help='port to listen on'
    )
    args = parser.parse_args()
    port = args.port
    app.run(host=ADDRESS, port=port)