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blockchain.js
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blockchain.js
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const Block = require('./block');
const cryptoHash = require('./cryptoHash');
class Blockchain{
constructor(){
this.chain =[Block.genesis()];
}
addBlock({data}){
const newBlock = Block.mineBlock({
prevBlock: this.chain[this.chain.length-1],
data:data
});
this.chain.push(newBlock);
}
replaceChain(chain){
if(chain.length <= this.chain.length){
console.error("The incoming chain is not longer");
return;
}
if(!Blockchain.isValidChain(chain)){
console.error("Incoming chain is not valid");
return;
}
this.chain = chain;
}
static isValidChain(chain){
if(JSON.stringify(chain[0]) != JSON.stringify(Block.genesis())){
return false;
}
for(let i=1;i<chain.length;i++){
const {timestamp,prevHash,hash,data,nonce, difficulty} = chain[i];
const realLastHash = chain[i-1].hash;
const validatedHash = cryptoHash(timestamp,data,prevHash,nonce,difficulty);
const lastDifficulty = chain[i-1].difficulty;
if(prevHash !== realLastHash){
return false;
}
if(hash !== validatedHash){
return false;
}
if(Math.abs(lastDifficulty-difficulty)>1){
return false;
}
}
return true;
}
}
const blockchain = new Blockchain();
// blockchain.addBlock({data:"King"});
// blockchain.addBlock({data:"Kohli"});
// console.log(blockchain);
// for(let i=0;i<1000;i++){
// blockchain.addBlock({data:`Block ${i}`});
// console.log(blockchain.chain[blockchain.chain.length-1]);
// }
// console.log(blockchain);
// const result = Blockchain.isValidChain(blockchain.chain);
// console.log(result)
module.exports = Blockchain;