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Blockchain.js
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Blockchain.js
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/* ===== SHA256 with Crypto-js ===============================
| Learn more: Crypto-js: https://github.com/brix/crypto-js |
| =========================================================*/
const SHA256 = require('crypto-js/sha256');
var Promise = require('bluebird');
//Importing levelSandbox class
const LevelSandboxClass = require('./LevelSandbox.js');
const BlockClass = require('./Block.js');
// Creating the levelSandbox class object
/* ===== Blockchain Class ==========================
| Class with a constructor for new blockchain |
| ================================================*/
class Blockchain{
constructor(){
this.chain = new LevelSandboxClass.LevelSandbox();
// this.addGenesusBlock().then(console.log);
}
addGenesusBlock(){
// console.log("entered addGenesusBlock with new Block ");
var newBlock = new BlockClass.Block("Genesus");
newBlock.previousBlockHash = "0x0";
newBlock.height =0;
newBlock.time = new Date().getTime().toString().slice(0,-3);
newBlock.hash = SHA256(JSON.stringify(newBlock)).toString();
var self = this;
// console.log('before returning addGenesusBlock');
return new Promise((resolve, reject) => {
self.chain.addLevelDBData(newBlock.height, newBlock).then((result)=>{
resolve(result);
});
});
}
// Add new block
addBlock(newBlock){
// console.log("entered addBlock with new Block " + JSON.stringify(newBlock));
var self = this;
var newBlock_self = newBlock;
return new Promise ((resolve, reject)=> {
self.get_last_block()
.then((gotGenesusBlock)=>{
// console.log('gotGenesusBlock');
var last_block = gotGenesusBlock;
var prev_hash = last_block.hash;
var height = last_block.height;
newBlock.previousBlockHash = prev_hash;
newBlock.time = new Date().getTime().toString().slice(0,-3);
newBlock.height = height + 1;
newBlock.hash = SHA256(JSON.stringify(newBlock)).toString();
self.chain.addLevelDBData(newBlock.height, newBlock)
.then((value)=>{
resolve(value);
});
},
(noGenesusBlock)=>{
// console.log('noGenesusBlock');
self.addGenesusBlock().then((last_block)=>{
var prev_hash = last_block.hash;
var height = last_block.height;
newBlock.previousBlockHash = prev_hash;
newBlock.time = new Date().getTime().toString().slice(0,-3);
newBlock.height = height+1;
newBlock.hash = SHA256(JSON.stringify(newBlock)).toString();
self.chain.addLevelDBData(newBlock.height, newBlock)
.then((value)=>{
resolve(value);
});
});
});
});
}
get_last_block(){
// console.log("entered get_last_block");
let self = this;
return new Promise((resolve, reject ) => {
self.getBlockHeight()
.then((height)=>
{
if (height === 0){
reject("No Genesus Block");
}else{
self.getBlock(height-1)
.then((value)=>{
// console.log("Get last Block Resolves: " + JSON.stringify(value));
resolve(value);
});
}
});
});
}
getBlock(key){
let self = this;
return new Promise(function(resolve, reject) {
self.chain.getLevelDBData(key).then(
(value) => {
console.log('getLevelDBData in getBlock : ', value );
resolve(value);
},(error)=>{
if (error.type == 'NotFoundError') {
console.log('NotFoundError');
reject(error);
}
else {
reject(error);
console.log('else NotFoundError');
}
}
);
});
}
// Get block height
getBlockHeight(){
//console.log("Get Block Height Returns ");
return new Promise((resolve, reject)=>{
this.chain.getBlocksCount().then((count)=>{
resolve(count);
});
});
}
validateBlock(blockHeight){
let self = this;
return new Promise((resolve, reject) =>{
self.getBlock(blockHeight).then((block)=>{
resolve(self.validateBlockObject(block));
});
});
}
validateBlockObject(block){
let blockHash = block.hash;
block.hash = '';
let validBlockHash = SHA256(JSON.stringify(block)).toString();
block.hash = blockHash;
return blockHash === validBlockHash;
}
validateChain(){
let self = this;
var not_valid_blocks = [];
var previous_block = null ;
return new Promise(function(resolve, reject){
self.chain.db.createReadStream()
.on('data', function (data) {
// console.log("GOT DATA in validate Chain!!!!");
// console.log(data);
// validateBlockObject(data, )
var currentBlock = JSON.parse(data.value);
if (self.validateBlockObject(currentBlock)){
if (previous_block === null || currentBlock.previousBlockHash === previous_block.hash){
console.log("block: ", currentBlock, " is valid.");
}else{
console.log("block with height : ", currentBlock.height, " is not valid as its previous block hash changed.");
not_valid_blocks.push(currentBlock);
}
}else{
console.log("block with height : ", currentBlock.height, " is not valid as it contnets changed.");
not_valid_blocks.push(currentBlock)
}
previous_block = currentBlock;
})
.on('error', function (err) {
reject(err)
})
.on('close', function () {
console.log("Done validateChain");
resolve(not_valid_blocks.length === 0);
});
});
}
}
module.exports.Blockchain = Blockchain;
//testing
// var bc = new Blockchain();
// // console.log( "created block chain");
// // console.log('created nBlock : ' + JSON.stringify(nBlock));
// bc.addBlock(new BlockClass.Block('test1'))
// .then(()=>{
// // console.log("Reached This Point");
// bc.addBlock(new BlockClass.Block('test2'))
// .then(()=>{
// // console.log("Added Second Block");
// bc.addBlock(new BlockClass.Block('test3'))
// .then(()=>{
// bc.getBlockHeight()
// .then((height)=>{
// bc.validateChain();
// });
// });
// });
// });