blockchain.py

import os
import json
import hashlib
import datetime
from huggingface_hub import (upload_file,HfApi)

token_self = os.environ['HF_TOKEN']
api = HfApi(token=token_self)

class Blockchain:

    def __init__(self,chain_load,load=None,create=None):
        global main_chain
        main_chain=chain_load
        
        self.pending_transactions = []
        self.trans_data_out = []
        if load == None or load=="":
            self.chain = []
            self.create_block(proof=1, previous_hash='0',chain_n=create)
        elif load != None and load !="":
            #r = requests.get(load) 
            lod = json.loads(load)
            self.chain = lod
    def reset(self,create=None):
        self.chain = []
        self.pending_transactions = []
        self.create_block(proof=1, previous_hash='0',chain_n=create)
    def create_block(self, proof, previous_hash,chain_r=None,chain_n=None):
        if chain_r=="" or chain_r==None:
            chain_r=f"{main_chain.split('datasets/',1)[1].split('/raw',1)[0]}"
        if chain_n !="" and chain_n !=None:
            chain_n = f"{main_chain.split('main/',1)[1]}{chain_n}"
        if chain_n=="" or chain_n==None:
            chain_n=chain_d
        block = {'index': len(self.chain) + 1,
                'timestamp': str(datetime.datetime.now()),
                'transactions': self.pending_transactions,
                'proof': proof,
                'previous_hash': previous_hash}
        if self.block_valid(block) == True:
            
            self.pending_transactions = []
            self.chain.append(block)
            json_object = json.dumps(self.chain, indent=4)
            with open("tmp.json", "w") as outfile:
                outfile.write(json_object)
            try: 
                api.upload_file(
                path_or_fileobj="tmp.json",
                path_in_repo=chain_n,
                repo_id=chain_r,
                token=token_self,
                repo_type="dataset",
                )
                os.remove("tmp.json")
        
            except Exception as e:
                print(e)
                pass         
            return block
        else:
            block = {"Not Valid"}
            print("not Valid")
            return block
    def print_previous_block(self):
        return self.chain[-1]
    def new_transaction(self, block):
        print (f'block::{block}')
        trans_data = {
            'name': block[0]['name'],
            'recipient': block[0]['recipient'],
            'amount': block[0]['amount'],
            'balance': block[0]['balance'], 
            'index': block[0]['index'],
            'timestamp': block[0]['timestamp'],
            'proof': block[0]['proof'],
            'previous_hash': block[0]['previous_hash']
        }
        self.trans_data_out.append(trans_data)
        self.pending_transactions.append(block)
    def proof_of_work(self, previous_proof):
        new_proof = 1
        check_proof = False
        while check_proof is False:
            hash_operation = hashlib.sha256(
                str(new_proof**2 - previous_proof**2).encode()).hexdigest()
            if hash_operation[:5] == '00000':
                check_proof = True
            else:
                new_proof += 1
        return new_proof

    def hash(self, block):
        encoded_block = json.dumps(block, sort_keys=True).encode()
        return hashlib.sha256(encoded_block).hexdigest() 
    def block_valid(self, block):
        print (block)
        #prev_block=len(self.chain)
        if len(self.chain) > 0:
            prev_block = len(self.chain)-1
            previous_block = self.chain[prev_block]
            print (previous_block)
            out=True
            ind=None
            mes=None
            if block['previous_hash'] != self.hash(previous_block):
                out=False
                #ind=block_index
                mes='Hash'
    
            previous_proof = previous_block['proof']
            proof = block['proof']
            hash_operation = hashlib.sha256(
                str(proof**2 - previous_proof**2).encode()).hexdigest()
    
            if hash_operation[:5] != '00000':
                out=False
                #ind=block_index+1
                mes='Proof'
            previous_block = block
        else: 
            out = True
        return out 

    def chain_valid(self, chain):
        previous_block = chain[0]
        block_index = 1 
        out=True
        ind=None
        mes=None
        while block_index < len(chain):
            block = chain[block_index]
            if block['previous_hash'] != self.hash(previous_block):
                out=False
                ind=block_index
                mes='Hash'
                break

            previous_proof = previous_block['proof']
            proof = block['proof']
            hash_operation = hashlib.sha256(
                str(proof**2 - previous_proof**2).encode()).hexdigest()

            if hash_operation[:5] != '00000':
                out=False
                ind=block_index+1
                mes='Proof'
                break
            previous_block = block
            block_index += 1
        
        return out, ind, mes