bradford-hamilton

module Crystal::Blockchain
  blockchain = [] of NamedTuple(
    index: Int32,
    timestamp: String,
    data: String,
    hash: String,
    prev_hash: String
  )
end

bradford-hamilton

module Block
  extend self
end

bradford-hamilton

def create(index, timestamp, data, prev_hash)
  block = {
    index: index,
    timestamp: timestamp,
    data: data,
    prev_hash: prev_hash
  }
  block.merge({ hash: self.calculate_hash(block) })
end

bradford-hamilton

def calculate_hash(block)
  plain_text = "
    #{block[:index]}
    #{block[:timestamp]}
    #{block[:data]}
    #{block[:prev_hash]}
  "
  sha256 = OpenSSL::Digest.new("SHA256")
  sha256.update(plain_text)
  sha256.to_s

bradford-hamilton

blockchain << Block.create(0, Time.now.to_s, "Genesis block's data!", "")

bradford-hamilton

blockchain << Block.create(0, Time.now.to_s, "Genesis block's data!", "")

get "/" do
  blockchain.to_json
end

Kemal.run

bradford-hamilton

blockchain = [] of NamedTuple(
  index: Int32,
  timestamp: String,
  data: String,
  hash: String,
  prev_hash: String,
  difficulty: Int32,
  nonce: String
)

bradford-hamilton

def create(index, timestamp, data, prev_hash)
  block = {
    index: index,
    timestamp: timestamp,
    data: data,
    prev_hash: prev_hash
    difficulty: self.difficulty,
    nonce: ""
  }
end

bradford-hamilton

def difficulty
  3
end

bradford-hamilton

def generate(last_block, data)
  new_block = self.create(
    last_block[:index] + 1,
    Time.now.to_s,
    data,
    last_block[:hash]
  )

  i = 0