server.py

from uuid import uuid4

import sys

from blockchain import Blockchain

from flask import Flask, jsonify, request

# Instantiate our Node
app = Flask(__name__)

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

# Instantiate the Blockchain
blockchain = Blockchain()

@app.route('/mine', methods=['GET'])
def mine():
    # Run proof of work algorithm to get the next proof
    last_block = blockchain.last_block
    last_proof = last_block['proof']
    proof = blockchain.proof_of_work(last_proof)

    # We must receive a reward for finding the proof.
    # The sender is '0' to signify that this node has mined a new coin
    blockchain.new_transaction(
        sender='0',
        recipient=node_identifier,
        amount=1,
    )

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

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

@app.route('/transactions/new', methods=['POST'])
def new_transaction():
    values = request.get_json()
    print(values)
    # Check that the required fields are in the POST'ed data
    required = ['sender', 'recipient', 'amount']
    if not all(k in values for k in required):
        return 'Missing parameters', 400

    # Crate a new transaction
    index = blockchain.new_transaction(values['sender'], values['recipient'], values['amount'])

    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


@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__':
    from argparse import ArgumentParser
    parser = ArgumentParser()
    parser.add_argument('-p', '--port', default=5000, type=int, help='port listening')
    args = parser.parse_args()
    port = args.port
    app.run(host='0.0.0.0', port=port)