import json
from hashlib import sha256

class BlockchainError(Exception): pass

class blockchain:
    def __init__(self):
        self.blockchain=[]
        self.transactionbyffer=[]
    def newgenesis(self, data):
        if len(self.blockchain)==0:
            temp={"id":0, "data":data, "transactions":[], "roothash":0}
            temp0=json.dumps(temp)
            temp0=sha256(temp0.encode()).hexdigest()
            temp["hash"]=temp0
            self.blockchain.append(temp)
        else:
            raise BlockchainError()
    def setbc(self, bc):
        self.blockchain=bc
    def addtx(self, data):
        self.transactionbyffer.append(data)
    def newblock(self, data):
        temp0={"id":len(self.blockchain), "data":data, "transactions":json.dumps(self.transactionbyffer), "roothash":self.blockchain[len(self.blockchain)-1]["hash"]}
        temp1=json.dumps(temp0)
        temp1=sha256(temp1.encode()).hexdigest()
        temp0["hash"]=temp1
        self.blockchain.append(temp0)
        self.transactionbyffer=[]
    def checkblocks(self):
        correct=1
        index=0
        for block in self.blockchain:
            temp0=json.dumps({"id":block["id"], "data":block["data"], "transactions":block["transactions"], "roothash":block["roothash"]})
            temp0=sha256(temp0.encode()).hexdigest()
            if block["id"]!=self.blockchain[block["id"]]["id"]:
                correct=0
            if block["id"]!=0:
                if self.blockchain[block["id"]-1]["hash"]!=block["roothash"]:
                    correct=0
            if block["hash"]!=temp0:
                correct=0
            index=index+1
        return correct