require 'nokogiri'

module Trackman
  module Scaffold
    module ContentSaver      
      def self.included(base)
        class << base; attr_accessor :nodes_to_remove, :nodes_to_edit, :mappings; end
        base.nodes_to_remove = {}
        base.nodes_to_edit = {}

        if defined?(Rails)
          base.mappings = { :maintenance => '503', :maintenance_error => '503-error', :not_found => '404', :error => '500' }
        else
          base.mappings = {}
        end
        base.extend ClassMethods
      end

      module ClassMethods
        def edit selector, &block
          raise 'block parameter is mandatory' unless block_given?
          nodes_to_edit[selector] = block
        end
        def remove selector, &predicate
          nodes_to_remove[selector] = predicate
        end
      end

      protected
        def remove_nodes doc
          self.class.nodes_to_remove.each do |selector, predicate| 
            nodes = doc.search(selector)
            i = 0;
            unless predicate.nil?
              nodes = nodes.select { |n| r = predicate.call(n, i); i +=1;r } 
            end
            nodes.each{|n| n.remove }
          end
          doc
        end

        def edit_nodes doc
          self.class.nodes_to_edit.each do |selector, block|
            doc.search(selector).each_with_index { |n, i| block.call(n, i) }
          end
          doc
        end
        def xslt
          @xslt ||= Nokogiri::XSLT(File.open("#{File.dirname(__FILE__)}/pretty-print.xslt"))
        end
        
        def new_content
          html = Nokogiri::HTML(response.body)
          
          edit_nodes html
          remove_nodes html
          
          xslt.apply_to(html).to_s
        end 
        
        def cache key
          @cache ||= {}
          @cache[key] || yield
        end

        def render_filters
          response.body = cache(params[:action]) { new_content }
        end
        
        def save_filters
          to_write = self.class.mappings[params[:action].to_sym]
          unless to_write.nil?
            path = "/public/#{to_write}.html"
            result = cache(params[:action]) { new_content }
            File.open(Rails.root.to_s + path, 'w') { |f| f.write(result) } 
          end
        end
    end
  end
end