#16 Virtual Attributes (revised)

<div class="field">
  <%= f.label :name %><br />
  <%= f.text_field :name %>
</div>
<div class="field">
  <%= f.label :price_in_dollars %><br />
  <%= f.text_field :price_in_dollars %>
</div>
<div class="field">
  <%= f.label :released_at_text, "Release Date & Time" %><br />
  <%= f.text_field :released_at_text %>
</div>
<div class="field">
  <%= f.label :category_id %><br />
  <%= f.collection_select :category_id, Category.order(:name), :id, :name %>
  or create one:
  <%= f.text_field :new_category %>
</div>
<div class="field">
  <%= f.label :tag_names, "Tags (space separated)" %><br />
  <%= f.text_field :tag_names %>
</div>

class Product < ActiveRecord::Base
  attr_accessible :name, :price_in_dollars, :released_at_text, :category_id, :new_category, :tag_names
  belongs_to :category
  has_many :taggings
  has_many :tags, through: :taggings
  
  attr_writer :released_at_text, :tag_names
  attr_accessor :new_category
  
  validate :check_released_at_text
  
  before_save :save_released_at_text
  before_save :create_category
  before_save :save_tag_names
  
  def price_in_dollars
    price_in_cents.to_d/100 if price_in_cents
  end
  
  def price_in_dollars=(dollars)
    self.price_in_cents = dollars.to_d*100 if dollars.present?
  end
  
  def released_at_text
    @released_at_text || released_at.try(:strftime, "%Y-%m-%d %H:%M:%S")
  end
  
  def save_released_at_text
    self.released_at = Time.zone.parse(@released_at_text) if @released_at_text.present?
  end

  def check_released_at_text
    if @released_at_text.present? && Time.zone.parse(@released_at_text).nil?
      errors.add :released_at_text, "cannot be parsed"
    end
  rescue ArgumentError
    errors.add :released_at_text, "is out of range"
  end
  
  def create_category
    self.category = Category.create!(name: new_category) if new_category.present?
  end
  
  def tag_names
    @tag_names || tags.pluck(:name).join(" ")
  end
  
  def save_tag_names
    if @tag_names
      self.tags = @tag_names.split.map { |name| Tag.where(name: name).first_or_create! }
    end
  end
end