class CreditCardValidator < ActiveModel::EachValidator

  def validate_each(record, attribute, value)
    unless valid?(value.to_s, options)
      record.errors[attribute] << options.fetch(:message, I18n.t("active_validation.errors.messages.credit_card"))
    end
  end

  private

  DEFAULT_LENGTHS = {
    american_express: [15], diners_club: [14, 16], discover: [16], jcb: [16],
    laser: [16, 17, 18, 19], maestro: [12, 13, 14, 15, 16, 17, 18, 19],
    mastercard: [16], solo: [16, 18, 19], unionpay: [16, 17, 18, 19], visa: [16]
  }

  DEFAULT_PREFIXES = {
    american_express: ["34", "37"],
    diners_club: ["300", "301", "302", "303", "304", "305", "36", "54", "55"],
    discover: [
      "6011", "622126", "622127", "622128", "622129", "62213", "62214", "62215",
      "62216", "62217", "62218", "62219", "6222", "6223", "6224", "6225", "6226",
      "6227", "6228", "62290", "62291", "622920", "622921", "622922", "622923",
      "622924", "622925", "644", "645", "646", "647", "648", "649", "65"
    ],
    jcb: ["3528", "3529", "353", "354", "355", "356", "357", "358"],
    laser: ["6304", "6706", "6771", "6709"],
    maestro: [
      "5018", "5020", "5038", "6304", "6759", "6761", "6762", "6763", "6764",
      "6765", "6766"
    ],
    mastercard: ["51", "52", "53", "54", "55"],
    solo: ["6334", "6767"],
    unionpay: [
      "622126", "622127", "622128", "622129", "62213", "62214", "62215", "62216",
      "62217", "62218", "62219", "6222", "6223", "6224", "6225", "6226", "6227", "6228",
      "62290", "62291", "622920", "622921", "622922", "622923", "622924", "622925"
    ],
    visa: ["4"]
  }

  def valid_format?(value, options)
    value =~ (options.fetch(:strict, false) ? /^[0-9]+$/ : /^[0-9 -.]+$/)
  end

  def valid_length?(value, options)
    return(false) unless value.present?

    current_card = options.fetch(:card, :all)
    value_size = value.size

    case current_card
    when :amex
      DEFAULT_LENGTHS.fetch(:american_express).include?(value_size)
    when :all
      value_size_range = DEFAULT_LENGTHS.values.flatten.uniq.sort
      value_size.between?(value_size_range.first, value_size_range.last)
    else
      DEFAULT_LENGTHS.fetch(current_card).include?(value_size)
    end
  end

  def valid_prefix?(value, options)
    current_card = options.fetch(:card, :all)

    case current_card
    when :amex
      DEFAULT_PREFIXES.fetch(:american_express).any? { |p| value.start_with?(p) }
    when :all
      result = false
      DEFAULT_LENGTHS.each do |key, values|
        if values.include?(value.size)
          break if result = DEFAULT_PREFIXES.fetch(key).any? { |p| value.start_with?(p) }
        end
      end
      result
    else
      DEFAULT_PREFIXES.fetch(current_card).any? { |p| value.start_with?(p) }
    end
  end

  def valid?(value, options)
    striped_value = value.gsub(/\D/, "")

    valid_format?(value, options) &&
    valid_length?(striped_value, options) &&
    valid_prefix?(striped_value, options)
  end

end