a script to download images associated with a GSMLS ID

gsmls-image-downloader.rb

#!/usr/bin/env ruby

# gsmls-image-downloader.rb
# -------------------------
# When passed a GSMLS ID, this script will download all of the listing's 
# associated images.

require 'open-uri'

def download_image(mls_id)

  # i've seen URLs with these variants:
  # 
  #  http://imagehost.gsmls.com/pubhigh/80/2765180_0.jpg
  #    from http://new.gsmls.com/publicsite/common/media.jsp
  # 
  #  http://img.gsmls.com/imagedb/highres/80/2765180_0.jpg
  #    from the real estate agent reports
  # 
  # ...but they both seem to return the exact same image
  url_prefix = "http://imagehost.gsmls.com/pubhigh"

  # get last two digits of MLS ID; it's needed for the directory
  dir_name = mls_id[-2,2]

  num = 0
  loop do

    filename = "#{mls_id}_#{num}.jpg"
    image_url = "#{url_prefix}/#{dir_name}/#{filename}"

    begin
      # pull down the file
      temp_file = open(image_url, {
        "User-Agent" => "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0)", # heh
        "Referer" => "http://new.gsmls.com/publicsite/common/media.jsp"
      })

      # put all the images into a folder named the MLS ID.
      # only check the directory on the first iteration.
      Dir.mkdir(mls_id) unless FileTest.directory?(mls_id) if num == 0

      # write it out, overwriting any existing files
      open("#{mls_id}/#{filename}", "w+").write(temp_file.read)
      # puts "#{image_url} >> #{mls_id}/#{filename}"

      # set the ctime and mtime of the file to be the last-modified date of the HTTP header
      # FIXME: this doesn't seem to be working as expected.
      File.utime(temp_file.last_modified, temp_file.last_modified, "#{mls_id}/#{filename}")

      $stderr.putc "."
      $stderr.flush # flush the output after each char so it'll actually display

    rescue OpenURI::HTTPError
      # if we haven't downloaded any images yet and get an HTTP error, then 
      # there's obviously no photos for the listing.
      # TODO: more granular HTTP error checking
      if num < 1
        puts "No photos for MLS ID #{mls_id}"
      else
        $stderr.putc "\n"
        puts "Downloaded #{num} images for GSMLS ID #{mls_id}"
      end

      # either way, we're finished attempting to download images, so break out of the loop
      break
    end

    num += 1

    # be nice to the remote server
    sleep 0.5

  end # loop

end # download_image

#####

# basic input validation
if /^\d{3,}$/.match(ARGV[0])
  download_image(ARGV[0])
else
  $stderr.puts "Error parsing GSMLS ID #{ARGV[0]}."
end