RUBY / COMPASS: Save global javascript variable references to generated sprite names

compass.rb

# Store javascript references to sprites in spriteList.js
# Author: dan.tello@viget.com
on_sprite_saved do |file_path|
  # Path to file where sprite data is to be stored
  javascript_file = "public/javascripts/base/compass_sprites.js"
  path_segments = file_path.split('/public').last.split('/')
  file_name = path_segments.pop
  image_path = path_segments.join('/') + '/'
  base_folder = path_segments[2]
  parent_folder = path_segments[path_segments.length - 1]
  sprite_name = file_name.gsub(/\-(\w*)\.png/, "");

  # Prefix the sprite name with its parent foldername if the sprite
  # file is not a direct child of the base_folder.
  file_prefix = base_folder == parent_folder ? "" : parent_folder + "_"
  sprite_variable = "COMPASS.#{base_folder}.#{file_prefix}#{sprite_name}"
  javascript = File.read(javascript_file)

  # Create COMPASS object if it doesn't exist
  unless javascript =~ /COMPASS = \{\};/
    File.open(javascript_file, "a") do |f|
      f.write("COMPASS = {};\n")
    end
  end

  # Add the scope/section object if it doesn't exist
  unless javascript =~ /COMPASS\.#{base_folder} = \{\};/
    File.open(javascript_file, "a") do |f|
      f.write("\nCOMPASS.#{base_folder} = {};")
    end
  end

  # Add or replace the sprite reference
  if javascript =~ /#{sprite_variable} =\ /
    File.open(javascript_file, "w") do |f|
      f.puts javascript.gsub(/#{sprite_variable} = (.*);/, "#{sprite_variable} = '#{file_name}';")
    end
  else
    File.open(javascript_file, "a") do |f|
      f.write("\n#{sprite_variable} = '#{file_name}';")
    end
  end
end

compass_sprites.js

// Example of the generated output if
// file_path === '/public/images/clever_world/module/map/parts-s63d8b5c4ed.png'

COMPASS = {};
COMPASS.clever_world = {};
COMPASS.clever_world.map_parts = 'parts-s63d8b5c4ed.png';