Ruby - Credit Card

credit_card.rb

class CreditCard
  attr_accessor :card, :store

  def initialize(card_identifier)
    @card = card_identifier
    @store = {
        amex: {begins_with: ["34", "37"], number_length: ["15"]},
        discover: {begins_with: ["6011"], number_length: ["16"]},
        mastercard: {begins_with: ["51","52","53","54","55"], number_length: ["16"]},
        visa: {begins_with: ["4"], number_length: ["13", "16"]},
    }
  end

  def type
    puts check_type(card)
  end

  private
  def check_type(card_no)
    card_company_name = nil
    store.each do |card_name, params|
      card_company_name = card_name if starts_with(params, card_no) && params[:number_length].include?(card_no.to_s.length.to_s)
    end

    card_company_name
  end

  def starts_with(params, card_no)
    card_first_digits = card_no.to_s[0]

    return true if params[:begins_with].include?(card_first_digits)
    card_first_digits = card_no.to_s[0..1]

    return true if params[:begins_with].include?(card_first_digits)

    card_first_digits = card_no.to_s[0..3]

    return true if params[:begins_with].include?(card_first_digits)
  end
end

CreditCard.new(4111111111111111).type # :visa
CreditCard.new(4111111111111).type # :visa
CreditCard.new(4012888888881881).type # :visa
CreditCard.new(378282246310005).type # :amex
CreditCard.new(6011111111111117).type # :discover
CreditCard.new(5105105105105100).type # :mastercard
CreditCard.new(5105105105105106).type # :mastercard
CreditCard.new(9111111111111111).type # nil

TODOs(if time was enough):

1. add specs
2. multiple cards support