require 'thor'
require 'nokogiri'
require 'fileutils'

module IphotoBackup
  class CLI < Thor
    IPHOTO_ALBUM_PATH = "~/Pictures/iPhoto Library.photolibrary/AlbumData.xml"
    DEFAULT_OUTPUT_DIRECTORY = "~/Google Drive/Dropbox"

    desc "export iPhoto albums", "exports iPhoto albums into target directory"
    option :filter, aliases: '-e', default: '.*'
    option :output, aliases: '-o', default: DEFAULT_OUTPUT_DIRECTORY
    def export
      each_album do |folder_name, album_info|
        say "\n\nProcessing Roll: #{folder_name}..."

        album_images = value_for_dictionary_key('KeyList', album_info).css('string').map(&:content)
        album_images.each do |image_id|
          image_info = info_for_image image_id
          source_path = value_for_dictionary_key('ImagePath', image_info).content

          target_path = File.join(File.expand_path(options[:output]), folder_name, File.basename(source_path))
          target_dir = File.dirname target_path
          FileUtils.mkdir_p(target_dir) unless Dir.exists?(target_dir)

          if FileUtils.uptodate?(source_path, [ target_path ])
            say "  copying #{source_path} to #{target_path}"
            FileUtils.copy source_path, target_path, preserve: true
          else
            print '.'
          end
        end
      end
    end
    default_command :export

    private

    def each_album(&block)
      albums = value_for_dictionary_key("List of Rolls").children.select {|n| n.name == 'dict' }
      albums.each do |album_info|
        folder_name = value_for_dictionary_key('RollName', album_info).content

        if folder_name.match(album_filter)
          yield folder_name, album_info
        else
          say "\n\n#{folder_name} does not match the filter: #{album_filter.inspect}"
        end
      end
    end

    def info_for_image(image_id)
      value_for_dictionary_key image_id, master_images
    end

    def value_for_dictionary_key(key, dictionary = root_dictionary)
      key_node = dictionary.children.find {|n| n.name == 'key' && n.content == key }
      next_element key_node
    end

    # find next available sibling element
    def next_element(node)
      element_node = node
      while element_node != nil  do
        element_node = element_node.next_sibling
        break if element_node.element?
      end
      element_node
    end

    def album_filter
      @album_filter ||= Regexp.new(options[:filter])
    end

    def master_images
      @master_images ||= value_for_dictionary_key "Master Image List"
    end

    def root_dictionary
      @root_dictionary ||= begin
        file = File.expand_path IPHOTO_ALBUM_PATH
        doc = Nokogiri.XML(File.read(file))
        doc.child.children.find {|n| n.name == 'dict' }
      end
    end
  end
end