Download images from shared Flickr album 1 by 1. It has the ability to resume downloads if it is interrupted. Also you can download images in different size options

flickr_download_album.rb

require 'mechanize'
require 'json'

ALBUM_URL = ARGV[0]
ALBUM_NAME = ARGV[1]
SIZE_TO_DOWNLOAD = ARGV[2]
if !ALBUM_URL || !ALBUM_NAME
  puts "Usage: ruby #{__FILE__} <album_url> <album_name> [size_to_download_image]"
  puts "size_to_download_image default 'o' which is original. Other available options in descending order of size k, h, l, c, m etc."
  exit!
end
SIZE_TO_DOWNLOAD = 'o'

class FlickrDownloader
  def initialize
    @client = Mechanize.new{|u| u.user_agent_alias="Mac Safari"}
    home_page = @client.get(ALBUM_URL)
    @photoset_id = home_page.uri.to_s.match(/sets\/(\d+)/)[1]
    @api_key = home_page.content.match(/root\.YUI_config\.flickr\.api\.site_key.*?"(.*)".*$/)[1]
    @per_page = 50
    @album = {"title" => ALBUM_NAME, "photo_urls" => []}
    @json_file = ALBUM_NAME + '.json'
  end

  def reset_token
    @api_key = @client.get(ALBUM_URL).content.match(/root\.YUI_config\.flickr\.api\.site_key.*?"(.*)".*$/)[1]
  end

  def fetch_photo_links
    links_file = JSON.parse(File.read(@json_file)) rescue nil
    return if links_file
    page = 1
    loop do
      puts "fetching links on page #{page}"
      photo_list_url = "https://api.flickr.com/services/rest?extras=can_addmeta%2Ccan_comment%2Ccan_download%2Ccan_share%2Ccontact%2Ccount_comments%2Ccount_faves%2Ccount_views%2Cdate_taken%2Cdate_upload%2Cdescription%2Cicon_urls_deep%2Cisfavorite%2Cispro%2Clicense%2Cmedia%2Cneeds_interstitial%2Cowner_name%2Cowner_datecreate%2Cpath_alias%2Crealname%2Crotation%2Csafety_level%2Csecret_k%2Csecret_h%2Curl_c%2Curl_f%2Curl_h%2Curl_k%2Curl_l%2Curl_m%2Curl_n%2Curl_o%2Curl_q%2Curl_s%2Curl_sq%2Curl_t%2Curl_z%2Cvisibility%2Cvisibility_source%2Co_dims%2Cis_marketplace_printable%2Cis_marketplace_licensable%2Cpubliceditability&per_page=#{@per_page}&page=#{page}&get_user_info=1&primary_photo_extras=url_c%2C%20url_h%2C%20url_k%2C%20url_l%2C%20url_m%2C%20url_n%2C%20url_o%2C%20url_q%2C%20url_s%2C%20url_sq%2C%20url_t%2C%20url_z%2C%20needs_interstitial%2C%20can_share&jump_to=&photoset_id=#{@photoset_id}&viewerNSID=&method=flickr.photosets.getPhotos&csrf=&api_key=#{@api_key}&format=json&hermes=1&hermesClient=1&reqId=53857556&nojsoncallback=1"
      photos = JSON.parse(@client.get(photo_list_url).content)
      if photos["stat"] != "ok"
        if photos["message"]['Invalid API Key']
          reset_token()
        else
          break
        end
      end

      photos['photoset']['photo'].each do |photo|
        @album["photo_urls"].push(photo["url_#{SIZE_TO_DOWNLOAD}_cdn"])
      end
      puts "fetched #{photos['photoset']['photo'].length} links from page"
      page += 1
    end
    puts "dumping links to #{@json_file}"
    File.open(@json_file, 'w') { |file| file.write @album.to_json }
  end

  def download_photos_from_links
    puts "reading links from #{@json_file}"
    links = JSON.parse(File.read(@json_file)) rescue nil
    fetch_photo_links if !links

    if !Dir.exists?(links["title"])
      puts "creating dir '#{links["title"]}'"
      Dir.mkdir(links["title"])
    end
    links["photo_urls"].each do |photo|
      file_path = links["title"] + "/" + File.basename(photo)
      puts "downloading #{photo}"
      @client.get(photo).save(file_path) if !File.exists?(file_path)
    end
  end
end

flickr_downloader = FlickrDownloader.new()
flickr_downloader.fetch_photo_links
flickr_downloader.download_photos_from_links