class CreateFavoriteForm
  include ActiveModel::Model

  validate :scoped_favorite_limit
  validate :favorable_is_uniq

  def initialize(user:, **params)
    @user = user
    @params = params.merge(user_id: @user.id)
  end

  def save
    favorite = Favorite.new(@params)
    return favorite.save if valid? && favorite.valid?
    promote_errors(favorite)
    false
  end

  private

  def scoped_favorite_limit
    if @user.favorites.where(favorable_type: @params[:favorable_type]).count > 99
      errors.add(:favorites, "too many favorites")
    end
  end

  def favorable_is_uniq
    if @user.favorites.where(favorable_type: @params[:favorable_type], favorable_id: @params[:favorable_id]).exists?
      errors.add(:favorites, "must be unique")
    end
  end

  def promote_errors(object)
    object.errors.each do |key, val|
      errors.add(key, val)
    end
  end
end