class Student
    attr_accessor :id, :surname, :name, :patronymic, :phone, :telegram, :email, :git

    def self.valid_phone_number?(phone)
        phone.match?(/\A\+?[0-9]{10,15}\z/)
    end

    def initialize(args = {})
        @surname = args.fetch(:surname)
        @name = args.fetch(:name)
        @patronymic = args.fetch(:patronymic)

        @id = args[:id] || nil

        @phone = args[:phone]
        if @phone && !Student.valid_phone_number?(@phone)
            raise ArgumentError, "Invalid phone number format: #{@phone}"
        end
        
        @telegram = args[:telegram] || nil
        @email = args[:email] || nil
        @git = args[:git] || nil
    end

    def to_s
        "Student: #{@surname} #{@name} #{@patronymic}\n" \
        "ID: #{@id || 'N/A'}\n" \
        "Phone: #{@phone || 'N/A'}\n" \
        "Telegram: #{@telegram || 'N/A'}\n" \
        "Email: #{@email || 'N/A'}\n" \
        "Git: #{@git || 'N/A'}"
    end
  end