const SHA256 = require('crypto-js/sha256')

class Block {
    constructor(index, timestamp, data, previousHash) {
        this.index = index
        this.timestamp = timestamp
        this.data = data
        this.previousHash = previousHash
        this.hash = this.calculateHash()
        this.nonce = 0
    }

    calculateHash() {
        return SHA256(this.index + this.previousHash + this.timestamp + JSON.stringify(this.data) + this.nonce).toString()
    }

    mine(difficulty) {

        console.log("mining block: " + this.index)
        console.log("... difficulty: " + difficulty)

        while(this.hash.substring(0, difficulty) !== Array(difficulty + 1).join("0")) {
            this.nonce++
            this.hash = this.calculateHash()
        }

        console.log("... block mined: " + this.hash)
        console.log("... nonce: " + this.nonce)
    }
}