blockchain.js

const Block = require('./block')

class Blockchain {
    constructor(difficulty = 1) {
        this.blocks = [new Block()]
        this.index = 1
        this.difficulty = difficulty
    }

    getLastBlock() {
        return this.blocks[this.blocks.length - 1]
    }

    addBlock(data) {
        const index = this.index
        const difficulty = this.difficulty
        const previousHash = this.getLastBlock().hash

        const block = new Block(index, previousHash, data, difficulty)

        this.index++
        this.blocks.push(block)
    }

    isValid() {
        for (let i = 1; i < this.blocks.length; i++) {
            const currentBlock = this.blocks[i]
            const previousBlock = this.blocks[i - 1]

            if (currentBlock.hash !== currentBlock.generateHash()) {
                return false
            }

            if (currentBlock.index !== previousBlock.index + 1) {
                return false
            }

            if (currentBlock.previousHash !== previousBlock.hash) {
                return false
            }
        }
        return true
    }
}

module.exports = Blockchain