Implemented image reference update

_plugins/image-reference-update.rb

@@ -0,0 +1,102 @@
+require 'uri'
+require 'faraday'
+require 'yaml'
+
+class Localizer
+
+  IMAGE_FIELDS = ["media_artist_url"]
+
+  attr_reader :post_directory, :image_directory
+
+  def initialize(post_directory, image_directory)
+    @post_directory = post_directory
+    @image_directory = image_directory
+  end
+
+
+  def localize_images
+    Dir.foreach(@post_directory) do |file|
+      next if !(file.end_with?('md') || file.end_with?('.markdown'))
+      transform_file("#{@post_directory}#{File::SEPARATOR}#{file}")
+    end
+  end
+
+
+  private
+
+
+  def local_image_filename(url)
+    uri = URI(url)
+    "#{image_directory}#{File::SEPARATOR}#{File.basename(uri.path)}"
+  end
+
+
+  # downloads the file locally if it hasn't already been downloaded
+  def ensure_local_image(url, local_file)
+    return local_file if File.exist?(local_file)
+
+    connection = Faraday.new do |faraday|
+      faraday.adapter(Faraday.default_adapter)
+    end
+    response = download_file_helper(connection, url)
+    File.open(local_file, 'wb') { |file| file << response.body }
+
+    local_file
+  end
+
+  # helper to make sure that we can follow redirects, which can be important for
+  # many of the cloud file sharing services out there.
+  def download_file_helper(connection, url)
+    response = connection.get do |req|
+      req.url(url)
+    end
+
+    case response.status
+    when 302
+      download_file_helper(connection, response['Location'])
+    when 200
+      response
+    else
+      raise "Error downloading file: #{response.status}"
+    end
+  end
+
+
+  def transform_file(file)
+    puts "Transforming #{file}"
+    contents = File.read(file, encoding: 'UTF-8')
+
+    # Step 1: get all the images that must be downloaded
+    yaml = YAML.load(contents)
+
+    yaml['talks'].each do |talk|
+     IMAGE_FIELDS.each do |image_field|
+
+      image_url = talk[image_field]
+
+      next unless !image_url.nil? && (image_url.start_with?('http') || image_url.start_with?('https'))
+
+      local_image = local_image_filename(image_url)
+
+      begin
+        ensure_local_image(image_url, local_image)
+      rescue
+        puts "Error downloading locally for image: #{image_url}"
+        next
+      end
+
+      # talk[image_field] = local_image
+      contents = contents.gsub(image_url,"/"+local_image)
+
+     end
+    end
+
+    # Step 3: replace the file itself
+    File.unlink(file)
+    File.open(file, "w", encoding: "UTF-8") { |file| file.puts contents }
+  end
+
+end
+
+localizer = Localizer.new('_posts', 'images')
+localizer.localize_images