# Picasa album helper, by Hackerdude.
# For usage, see http://www.hackerdude.com/2006/02/27/parse-picasa-xml-with-rails/
#
# Distributed under the creative commons Attribution license.
# http://creativecommons.org/licenses/by/2.0/
# 
# This basically means, do whatever you want with it, give me credit for this piece
# of it.
# 
# If you do end up using it, I'd appreciate a line. Please email david at hackerdude
module PicasaAlbumHelper

  require 'net/http'
  require 'uri'
  require 'rexml/document'


  # Encapsulates the picasa album. Follows the same attribute
  # names as the XML payload
  class PicasaAlbum
    attr_accessor :firstImage, :lastImage, :albumName
    
    attr_reader :entries

    # A hash of entries keyed by their thumbnail name
    attr_reader :thumbnails

    def entries=(entries)
      @entries = entries
      # Set the thumbnails
      @thumbnails = {}
      @entries.each {|entry| 
        @thumbnails[entry.itemThumbnailImage] = entry
      }
    end

    # Creates the album out of a URL
    def self.create_album(base_url, index_path)
      result = PicasaAlbum.new()
      full_url = base_url+index_path
      url = URI.parse(full_url)
      res = Net::HTTP.get(url)
      #res = req.get(url.path)
      xml_string = res
      xml_doc = REXML::Document.new(xml_string)
      root_node = xml_doc.root
      result.albumName = root_node.elements["albumName"].text.strip
      entries = []
      images_node = root_node.elements["images"]
      images_node.each_element('image') { |imageElement| 
        fileEntry = PicasaFileEntry.new(imageElement)
        entries.push(fileEntry)
        result.firstImage = imageElement.elements["firstImage"].text.strip
        result.lastImage = imageElement.elements["lastImage"].text.strip
      }
      result.entries = entries;
      return result
    end

  end

  # Encapsulates a single file entry. Follows the same attribute
  # names as the XML payload.
  class PicasaFileEntry
    # Some simple metadata
    attr_accessor :isFirstImage, :isLastImage, :isPrevImage, :isNextImage,
      :itemLargeImage, :nextImage, :nextThumbnail, :prevImage, :prevThumbNail

    # The meat of this entry
    attr_accessor :itemWidth, :itemHeight, :itemName,
      :itemThumbnailImage, :itemThumbnailWidth, :itemThumbnailHeight,
      :itemCaption

    # The constructor needs an XML element to read the information from.
    def initialize(node)

      @itemWidth = node.elements["itemWidth"].text.strip
      @itemHeight = node.elements["itemHeight"].text.strip
      @itemName   = node.elements["itemName"].text.strip
      @itemThumbnailImage = node.elements["itemThumbnailImage"].text.strip
      @itemThumbnailWidth = node.elements["itemThumbnailWidth"].text.strip
      @itemCaption = node.elements["itemCaption"].text.strip
      @itemLargeImage = node.elements["itemLargeImage"].text.strip

    end
      
  end

  # Creates a slideshow using a picasa index.xml file.
  # 
  # == Usage: 
  # include lightbox.js in your page
  # 
  #   slideshow( "http://localhost:3000/", "images/travel/album1/index.xml", 
  #              { :max_per_row=3, :max_rows=4 } )
  def slideshow( base_url, index_file, options = {} )
    max_rows = options[:max_rows]
    max_rows = 9999 unless max_rows != nil
    max_per_row = options[:max_per_row]
    max_per_row = 10 unless max_per_row != nil

    fullURL = "#{base_url}#{index_file}"
    # Get the base path for the picasa album
    itemPath = /http:\/\/([^\/]*)\/(.*)\/([A-Za-z0-9.]*)/.match(fullURL)[2]

    # Get album info from picasa
    album = PicasaAlbum.create_album(base_url, index_file)
    album_thumbnails = album.thumbnails
    html_output=""

    # Now let's render those images.. 
    row = 0
    column = 0

    album_thumbnails.keys.each { |itemThumbnailImage| 
      column += 1
      if column > max_per_row then
        html_output += "<br/>"
        column = 0
        row+= 1
      end
      item = album_thumbnails[itemThumbnailImage]
      itemLargeImage = item.itemLargeImage
      itemCaption = item.itemCaption

      itemThumbnailImage = '' if itemThumbnailImage == nil
      itemCaption = '' if itemCaption == nil
      itemLargeImage = '' if itemLargeImage == nil

      html_output += "<a href=\"#{itemPath}/#{itemLargeImage}\" "
      html_output += "rel=\"lightbox\" "
      html_output += "title=\"#{itemCaption}\">"
      html_output += "<img src=\"#{itemPath}/#{itemThumbnailImage}\"></a> "
    }
    return html_output

  end

end