module Base64Token

# File lib/base64_token.rb, line 33
def encryption_key=(key)
  @encryption_key = key
  @crypto_box = nil
end

# File lib/base64_token.rb, line 14
def generate(**hash)
  json = JSON.generate(hash)
  cipher = encrypt(json)
  Base64.urlsafe_encode64(cipher)
end

# File lib/base64_token.rb, line 27
def generate_key
  Base64.strict_encode64(
    RbNaCl::Random.random_bytes(RbNaCl::SecretBox.key_bytes)
  )
end

# File lib/base64_token.rb, line 20
def parse(token)
  return {} if !token || token.strip.empty?
  cipher = base64_decode(token)
  json = decrypt(cipher)
  JSON.parse(json).map { |k, v| [k.to_sym, v] }.to_h
end

# File lib/base64_token.rb, line 44
def base64_decode(string)
  Base64.urlsafe_decode64(string)
rescue ArgumentError => e
  raise Error, e.message
end

# File lib/base64_token.rb, line 56
def crypto_box
  @crypto_box ||= begin
    unless @encryption_key
      raise ConfigurationError, 'Encryption key not set.'
    end

    key = Base64.decode64(@encryption_key)
    RbNaCl::SimpleBox.from_secret_key(key)
  end
end

# File lib/base64_token.rb, line 50
def decrypt(ciphertext)
  crypto_box.decrypt(ciphertext)
rescue RbNaCl::CryptoError, RbNaCl::LengthError => e
  raise Error, e.message
end

# File lib/base64_token.rb, line 40
def encrypt(plaintext)
  crypto_box.encrypt(plaintext)
end