# Presenters are created by Controllers/Views and know the current state of the view and the model
# Can be used to filter away tangled logic in the view
# Also can be used to skin the controller

# An example of a presenter used to remove logic from view(this is a small example , views can get it even more bloated with logic)
# app/views/categories/index.html
<div class="images">
  <%if @category.image_url%>
    <%= link_to image_tag("/images/#{@category.id}.png") + "some extra text", category_path(@category), class: 'class-name', remote: true %>
  <%else%>
    <%= link_to image_tag("/images/default.png") + "some extra text", category_path(@category), class: 'class-name', remote: true %>
  <%end%>
<div>

# app/presenters/category_presenter.rb
class CategoryPresenter < BasePresenter
  presents :category

  def featured_image
    image_path = category.image_url ? category.id : "default"  
    link_to image_tag("/images/#{image_path}.png") + "some extra text", category_path(category), :class => 'class-name',     :remote => true
  end

  def top_brands
    @top_brands ||= category.top_brands
  end

  def top_keywords
    @top_keywords ||= category.top_keywords
  end
end

class BasePresenter
  def initialize(object, template)
    @object = object
    @template = template
  end

  def self.presents(name)
   define_method(name) do
     @object
   end
  end

  def method_missing?(*args, &block)
    @template.send(*args, &block)
  end
end

# app/views/category/index.html
<% present @category do |category_presenter|%>
<div class="images">
  <%= category_presenter.featured_image%>
<div>
<% end %>

# app/helpers/application_helper.rb
def present(object, klass = nil)
 klass ||= "#{object.class}Presenter".constantize
 presenter = object.new(object, self)
 yield(presenter)
end
  
# To access presenters from controller
# app/controllers/application_controller.rb
private
 def present(object, klass = nil)
   klass ||= "#{object.class}Presenter".constantize
   klass.new(object, view_context)
 end