ruby_blockchain_example.rb

# require './blockchain.rb'; Blockchain.demo
require 'digest'

class Blockchain

    DIFFICULTY = '00000'.freeze
    attr_reader :blocks

    def initialize
        @blocks = []
        data = 'first block ayy lmao'
        time = Time.now.utc
        prev_hash = 0
        index = 0
        hash_block(data, time, prev_hash, index)
    end

    def add_block(data)
        time = Time.now.utc
        prev_hash = @blocks.last
        index = @blocks.size
        hash_block(data, time, prev_hash, index)
    end

    def self.demo
        bc = Blockchain.new
        bc.add_block('lorem ipsum dolor sit amet')
        bc.add_block('consectetur adipiscing elit')
        bc.add_block('sed do eiusmod tempor incididunt')
        bc.add_block('ut labore et dolore magna aliqua')
        bc.blocks
    end

    private

    def hash_block(data, time, prev_hash, index)
        hash = ''
        nonce = 0
        log("hashing block #{index}...")
        until(is_hash_valid(hash))
            hash = Digest::SHA256.hexdigest("#{data}#{time}#{prev_hash}#{index}#{nonce}")
            nonce += 1
        end
        log("hashed block #{index}: #{nonce} iterations")
        @blocks << hash
    end

    def is_hash_valid(hash)
        hash.start_with? DIFFICULTY
    end

    def log(s)
        puts s
    end

end