#!/usr/bin/ruby
#
# artspots-update downloads the latest submissions to Artspots and Jaxpad
# to a local directory.  The intention is to combine this script with
# standard Linux applications to get a dynamically updated wallpaper or
# screensaver.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#
# Copyright 2007, Nocte <nocte@hippie.nu>

# There are some extra requires here for rubyscript2exe
require 'rexml/document'
require 'net/http'
require 'tempfile'
require 'open-uri'
require 'optparse'
require 'time'

begin
  exit if RUBYSCRIPT2EXE.is_compiling?
rescue
  nil
end

use_jaxpad = false
prune_nr = 0

ARGV.options do |o|
    o.set_summary_indent('  ')
    o.banner = 'Usage: artspots-update [options]'

    o.on('-j', '--jaxpad', 
         'Download from Jaxpad instead of Artspots') { |use_jaxpad| }

    o.on('-p', '--prune=N', Integer,
         'Keep only the newest N images') { |prune_nr| }

    o.on('-v', '--version', 
         'Print version information') { puts 'artspots-update 1.1'; exit }

    o.on('-h', '--help', 
         'Show this help message') { puts o; exit }

    o.parse!
end

prune = (prune_nr.nil? == false and prune_nr > 0)
site  = (use_jaxpad ? 'jaxpad' : 'artspots')

if prune and prune_nr < 1
    puts "--prune must be a positive number"
    exit
end

dest_dir = File.join(ENV['HOME'] || ENV['USERPROFILE'], ".#{site}-cache")
src      = "http://#{site}.com/rss"
iurl     = "http://#{site}.com/image/"

if not File.directory?(dest_dir)
    begin
        Dir.mkdir(dest_dir) 
    rescue
        puts "Error: cannot create directory '#{dest_dir}'"
        exit
    end
end

Dir.chdir(dest_dir)
available  = Dir.glob("*.title").map!{|x| x.split('.')[0]}.sort
downloaded = []

#----------------------------------------------------------------------------

begin
    xml = REXML::Document.new(open(src){|f|f.read})
rescue
    puts "Cannot retrieve data from #{src}"
    exit
end
xml.elements.each('rss/channel/item') do |item|
    title = item.elements['title'].text
    id    = item.elements['link'].text.split('/')[-1]
    url   = item.elements['enclosure'].text
    pubd  = item.elements['pubDate'].text

    ext       = url.split('.')[-1]
    timestamp = Time.parse(pubd).to_i.to_s
    filename  = File.join(dest_dir, timestamp + '.' + ext)
    fileinfo  = File.join(dest_dir, timestamp + '.title')

    next if not available.empty? and timestamp.to_i <= available[-1].to_i
    break if prune and downloaded.length == prune_nr

    begin
        open(filename, "wb") { |file| file.write(open(url){|f|f.read}) }
        open(fileinfo, "w")  { |file| file.write("#{title}  (#{iurl}#{id})") }
        downloaded.push(timestamp)
    rescue
        puts "Failed to download #{url}"
    end
end

#----------------------------------------------------------------------------

if prune
    available = (available + downloaded).sort
    available[0,available.length - prune_nr].each { |id|
        ['.title', '.jpg', '.png', '.gif'].each { |ext|
          File.unlink(File.join(dest_dir, id + ext)) rescue nil
        }
    } unless available.length <= prune_nr
end