path: root/actionpack/lib/action_view/digestor.rb

require 'active_support/core_ext'
require 'logger'

module ActionView
  class Digestor
    EXPLICIT_DEPENDENCY = /# Template Dependency: ([^ ]+)/

    # Matches:
    #   render partial: "comments/comment", collection: commentable.comments
    #   render "comments/comments"
    #   render 'comments/comments'
    #   render('comments/comments')
    #
    #   render(@topic)         => render("topics/topic")
    #   render(topics)         => render("topics/topic")
    #   render(message.topics) => render("topics/topic")
    RENDER_DEPENDENCY = /
      render\s?                # render, followed by an optional space
      \(?                      # start a optional parenthesis for the render call
      (partial:)?\s?           # naming the partial, used with collection -- 1st capture
      ([@a-z"'][@a-z_\/\."']+) # the template name itself -- 2nd capture
    /x

    cattr_accessor(:cache)  { Hash.new }
    cattr_accessor(:logger, instance_reader: true) { ActionView::Base.logger }

    def self.digest(name, format, finder, options = {})
      cache["#{name}.#{format}"] ||= new(name, format, finder, options).digest
    end

    attr_reader :name, :format, :finder, :options

    def initialize(name, format, finder, options = {})
      @name, @format, @finder, @options = name, format, finder, options
    end

    def digest
      Digest::MD5.hexdigest("#{name}.#{format}-#{source}-#{dependency_digest}").tap do |digest|
        logger.try :info, "Cache digest for #{name}.#{format}: #{digest}"
      end
    rescue ActionView::MissingTemplate
      logger.try :error, "Couldn't find template for digesting: #{name}.#{format}"
      ''
    end

    def dependencies
      render_dependencies + explicit_dependencies
    rescue ActionView::MissingTemplate
      [] # File doesn't exist, so no dependencies
    end

    def nested_dependencies
      dependencies.collect do |dependency|
        dependencies = Digestor.new(dependency, format, finder, partial: true).nested_dependencies
        dependencies.any? ? { dependency => dependencies } : dependency
      end
    end


    private
      def logical_name
        name.gsub(%r|/_|, "/")
      end
      
      def directory
        name.split("/").first
      end

      def partial?
        options[:partial] || name.include?("/_")
      end

      def source
        @source ||= finder.find(logical_name, [], partial?, formats: [ format ]).source
      end


      def dependency_digest
        dependencies.collect do |template_name|
          Digestor.digest(template_name, format, finder, partial: true)
        end.join("-")
      end

      def render_dependencies
        source.scan(RENDER_DEPENDENCY).
          collect(&:second).uniq.

          # render(@topic)         => render("topics/topic")
          # render(topics)         => render("topics/topic")
          # render(message.topics) => render("topics/topic")
          collect { |name| name.sub(/\A@?([a-z]+\.)*([a-z_]+)\z/) { "#{$2.pluralize}/#{$2.singularize}" } }.

          # render("headline") => render("message/headline")
          collect { |name| name.include?("/") ? name : "#{directory}/#{name}" }.
          
          # replace quotes from string renders
          collect { |name| name.gsub(/["']/, "") }
      end

      def explicit_dependencies
        source.scan(EXPLICIT_DEPENDENCY).flatten.uniq
      end
  end
end