module Papercrop
  module ModelExtension

    module ClassMethods

      # Initializes attachment cropping in your model
      #
      #   crop_attached_file :avatar
      #
      # You can also define an initial aspect ratio for the crop and preview box through opts[:aspect]
      #
      #   crop_attached_file :avatar, :aspect => "4:3"
      # 
      # Or unlock it
      # 
      #   crop_attached_file :avatar, :aspect => false
      #
      # @param attachment_name [Symbol] Name of the desired attachment to crop
      # @param opts [Hash]
      # @option opts [Range, String, FlaseClass] :aspect
      def crop_attached_file(attachment_name, opts = {})
        opts = opts.dup

        [:crop_x, :crop_y, :crop_w, :crop_h, :original_w, :original_h, :box_w, :aspect, :cropped_geometries].each do |a|
          attr_accessor :"#{attachment_name}_#{a}"
        end

        aspect = normalize_aspect opts[:aspect]

        send :define_method, :"#{attachment_name}_aspect" do
          aspect.first.to_f / aspect.last.to_f if aspect
        end

        if respond_to? :attachment_definitions
          # for Paperclip <= 3.4
          definitions = attachment_definitions
        else
          # for Paperclip >= 3.5
          definitions = Paperclip::Tasks::Attachments.instance.definitions_for(self)
        end

        processors = definitions[attachment_name][:processors] ||= []
        unless processors.include? :papercrop
          processors << :papercrop
        end

        after_update :"reprocess_to_crop_#{attachment_name}_attachment"
      end


      # Returns a valid and normalized value for aspect ratio
      # It will return 1.. if aspect is nil or a invalid string
      # @param aspect [Range, String, FalseClass]
      # 
      # @return [Range]
      def normalize_aspect(aspect)
        if aspect.kind_of?(String) && aspect =~ Papercrop::RegExp::ASPECT
          Range.new *aspect.split(':').map(&:to_i)
        elsif aspect.kind_of?(Range)
          return aspect.first.to_i..aspect.last.to_i
        elsif aspect == false
          return aspect
        else
          1..1
        end
      end
    end


    module InstanceMethods

      # Asks if the attachment received a crop process
      # @param  attachment_name [Symbol]
      #
      # @return [Boolean]
      def cropping?(attachment_name)
        !self.send(:"#{attachment_name}_crop_x").blank? &&
        !self.send(:"#{attachment_name}_crop_y").blank? &&
        !self.send(:"#{attachment_name}_crop_w").blank? &&
        !self.send(:"#{attachment_name}_crop_h").blank?
      end


      # Returns a Paperclip::Geometry object of a given attachment
      #
      # @param attachment_name [Symbol]
      # @param style = :original [Symbol] attachment style
      # @return [Paperclip::Geometry]
      def image_geometry(attachment_name, style = :original)
        @geometry                  ||= {}
        @geometry[attachment_name] ||= {}
        
        path = (self.send(attachment_name).options[:storage] == :filesystem) ? self.send(attachment_name).path(style) : self.send(attachment_name).url(style)
        
        @geometry[attachment_name][style] ||= Paperclip::Geometry.from_file(path)
      end


      # Uses method missing to responding the model callback
      def method_missing(method, *args)
        if method.to_s =~ Papercrop::RegExp::CALLBACK
          reprocess_cropped_attachment(
            method.to_s.scan(Papercrop::RegExp::CALLBACK).flatten.first.to_sym
          )
        else
          super
        end
      end


      # Sets all cropping attributes to nil
      # @param  attachment_name [Symbol]
      def reset_crop_attributes_of(attachment_name)
        [:crop_x, :crop_y, :crop_w, :crop_h].each do |a|
          self.send :"#{attachment_name}_#{a}=", nil
        end
      end

      private

        # Saves the attachment if the crop attributes are present
        # @param  attachment_name [Symbol]
        def reprocess_cropped_attachment(attachment_name)
          if cropping?(attachment_name)
            attachment_instance = send(attachment_name)
            attachment_instance.assign(attachment_instance)
            attachment_instance.save

            reset_crop_attributes_of(attachment_name)
          end
        end

    end
  end
end


# ActiveRecord support
if defined? ActiveRecord::Base
  ActiveRecord::Base.class_eval do
    extend  Papercrop::ModelExtension::ClassMethods
    include Papercrop::ModelExtension::InstanceMethods
  end
end


# Mongoid support
if defined? Mongoid::Document
  Mongoid::Document::ClassMethods.module_eval do
    include Papercrop::ModelExtension::ClassMethods
  end

  Mongoid::Document.module_eval do
    include Papercrop::ModelExtension::InstanceMethods
  end
end