img_convert.rb

#!/usr/bin/env ruby

require 'nokogiri'
require 'uri'

# opens every file in the given dir tree and converts any html img tags to rails image_tag calls
#
# example usage: 
# ruby convert.rb ~/my_rails_app/app/views
#
# ***be careful and backup before using this***
#

raise "no directory tree given" if ARGV.first.nil?

path = "#{ARGV.first}/**/*"

@count = {
  :files_open => 0,
  :files_revised => 0,
  :tags => 0
}

class RailsImageTag
  
  def initialize(img)
    @img = img
  end
  
  # construct and return the erb containing the new image_tag call
  def to_erb
    uri_parts = URI.parse(@img['src']).path.split('/')
    asset_name = ""
    if uri_parts[uri_parts.length - 2] != "images"
      asset_name = uri_parts[uri_parts.length - 2] + "/" + uri_parts[uri_parts.length - 1]
    else
      asset_name = uri_parts.last
    end
    "<%= image_tag('#{asset_name}', #{options_to_erb}) %>"
  end
  
  # convert the img tag params to image_tag options
  def options_to_erb
    @img.attributes.collect{|k,v| "#{k}: '#{v}'" if !v.blank? and k != 'src' }.compact.join(', ')
  end
  
end

class HtmlDoc
  
  def initialize(filename)
    @name = filename
    file = File.open(@name)
    @doc = Nokogiri::HTML(file)
    @content = File.open(@name) { |f| f.read }
  end
  
  # overwrite the file with new contents
  def write_file
    puts "writing #{@name}"
    File.open(@name, "w") {|f| f.write(@content) }
  end
  
  # convert a single file and record stats to <em>log</em>
  def convert_img_tags!(log)
    log[:files_open] += 1
    file_marked = false
    @doc.xpath("//img").each do |img| 
      file_marked = true
      log[:tags] += 1
      replaced = RailsImageTag.new(img).to_erb
      puts "original: #{img.to_s}, replaced: #{replaced}"
      @content = @content.gsub(img.to_s, replaced)
      #img.replace(replaced)
    end

    if file_marked
      log[:files_revised] += 1
      write_file
    end
  end
  
end

Dir.glob(path).each { |filename| HtmlDoc.new(filename).convert_img_tags!(@count) if File.file?(filename) }

p "***********************************"
p "#{@count[:files_open]} files opened"
p "#{@count[:files_revised]} files revised"
p "#{@count[:tags]} tags replaced"