main.py

'''
Main.py - driver file to be ran as main user interaction. This will handle the
interaction in the form of a menu option and do various tasks based on the selection.
This file also handles the state and maintenance of the blockchain.
'''
from BlockchainClass import Blockchain
from BlockClass import Block

import hashlib  


def create_transaction():
    ''' Create the transaction object and handle inputs into the object.
        returns: dictionary of transaction object
    '''
    transaction_object = {'to': None, 'from': None, 'amt': None}
    transaction_object['to'] = input('To? ').strip()
    transaction_object['from'] = input('From? ').strip()
    transaction_object['amt'] = input('Amount? ').strip()
    
    return transaction_object


def main():
    print('*******************************')
    print('  *Entering the Blockchain     ')
    print('*******************************')
    
    blockchain = Blockchain()
    
    # State information is outside user interface loop
    current_block = Block(index=blockchain.current_length + 1, previous_hash=blockchain.genesis_block.hash)
    prev_block = blockchain.get_last_block()

    # User interface loop operates until they're finished
    while True:
      
        print('\n\nMENU:---------------------------------')
        print("\t '.' - exit the program")
        print("\t 'T/t' - Create a new transaction")
        print("\t 'mine' - mine the current block")
        print("\t 'chain' - display the entire chain")
        print("\t 'block' - display the current block")
        print("\t 'V/v' - check blockchain is valid")
        print('--------------------------------------')
        option = input('Please select a menu option: ').strip().lower()
        
        # Handle each case
        if option == '.':
            print('*Exiting the Blockchain*')
            break
        elif option == 't': 
            transaction_object = create_transaction()
            try: 
                current_block.add_transaction(transaction_object)   
            except Exception as err:
                print(err)
        
        elif option == 'mine':
            # Mine current block and add to ledger
            try:
                result = current_block.mine()
                print(result)
               
                blockchain.append_block(current_block)
            
                # adjust pointers and state of chain
                prev_block._next_block = current_block
                prev_block = current_block
                current_block = Block(index=blockchain.current_length + 1, previous_hash=prev_block.hash)
            except Exception as err:
                print(err)
            
            
        elif option == 'chain':
            blockchain.display()
        elif option == 'block':
            current_block.display()
            
        elif option == 'v':
            result = blockchain.check_validity()
            print(result)
            
        else:
            print('Invalid Argument: ', option, '\n please try again')
        
if __name__ == "__main__":
    main()