class ROTP::OTP::URI

def algorithm
  return unless %w[sha256 sha512].include?(@otp.digest)
  @otp.digest.upcase
end

def counter
  return if @otp.is_a?(TOTP)
  fail if @counter.nil?
  @counter
end

def digits
  return if @otp.digits == DEFAULT_DIGITS
  @otp.digits
end

def initialize(otp, account_name: nil, counter: nil)
  @otp = otp
  @account_name = account_name || ''
  @counter = counter
end

def issuer
  @otp.issuer&.strip&.tr(':', '_')
end

def label
  [issuer, @account_name.rstrip]
    .compact
    .map { |s| s.tr(':', '_') }
    .map { |s| ERB::Util.url_encode(s) }
    .join(':')
end

def parameters
  {
    secret: @otp.secret,
    issuer: issuer,
    algorithm: algorithm,
    digits: digits,
    period: period,
    counter: counter,
  }
    .merge(@otp.provisioning_params)
    .reject { |_, v| v.nil? }
    .map { |k, v| "#{k}=#{ERB::Util.url_encode(v)}" }
    .join('&')
end

def period
  return if @otp.is_a?(HOTP)
  return if @otp.interval == DEFAULT_INTERVAL
  @otp.interval
end

def to_s
  "otpauth://#{type}/#{label}?#{parameters}"
end

def type
  case @otp
  when TOTP then 'totp'
  when HOTP then 'hotp'
  end
end