superhero_2_0.rb

require 'active_model'

class Superhero
  include ActiveModel::Validations
  @@total = []

  attr_reader :name, :age

  def initialize name, age
    @name = name

    @age = age
  end

  class << self
    def create name:, age:

      obj = new name, age
      @@total << obj
      obj
    end

    def all
      @@total
    end

    def find_by **args
      all.select { |element| element if condition element, **args }
    end

    def condition elem, **args
      if args[:name] && args[:age]
        elem.name == args[:name] && elem.age == args[:age]
      elsif args[:name]
        elem.name == args[:name]
      elsif args[:age]
        elem.age == args[:age]
      end
    end
  end

  validates :age, numericality: { integer: true, greater_than: 0 }
  validate :duplicate_names

  def duplicate_names
    all_names = Superhero.all.collect {|elem| elem.name}
    if all_names.count(name) >= 2
        errors.add(:name, "#{name} is already exists")
    end
  end

end

superhero1 = Superhero.create name: 'Jessy', age: 54
p superhero1.valid?
p superhero1.errors.messages

superhero2 = Superhero.create name: 'John McClane', age: 12
p superhero2.valid?
p superhero2.errors.messages



superhero3 = Superhero.create name: 'John McClane', age: 0
p superhero3.valid?
p superhero3.errors.messages


# p Superhero.all

# p Superhero.find_by name: 'John McClane', age: 0