#! /usr/bin/env python

from optparse import OptionParser
import os
import sys, string, time
import random

def changeWallpaper(filename):
  cmd = string.join(["gconftool -s /desktop/gnome/background/picture_filename -t string \"",filename,"\""],'')
  os.system(cmd) # execute system command

# Parse commandline arguments
parser = OptionParser()
parser.add_option("-f", "--folder", dest="folder", help="use wallpapers from FOLDER", metavar="FOLDER")
parser.add_option("-i", "--interval", type="float", dest="interval", default=300, help="time interval in seconds", metavar="INTERVAL")
parser.add_option("-m", "--mode", type="string", dest="wallpaper_mode", default="centered", help="Wallpaper can be displayed in several modes: none, wallpaper, centered, scaled, stretched, zoom")
parser.add_option("-d", "--default", dest="default_image", help="specify default image when program is killed", metavar="FILENAME", default="nothing.gif")
parser.add_option("-c", "--bg-color-mode", dest="bg_color_mode", default="solid", help="Background Color Options: solid, hg (horizontal gradient, vg (vertical gradient)",metavar="COLOR_MODE")

(options, args) = parser.parse_args()

# Validate for presence of valid folder
if options.folder is None:
  raise ValueError, "No valid folder specified"
if not(os.path.isdir(options.folder)):
  raise ValueError, "The folder specified is not valid"

# Set Background Color Mode
if options.bg_color_mode == "vg":
  cmd = "gconftool -s /desktop/gnome/background/color_shading_type -t string \"vertical-gradient\""
  os.system(cmd) # execute system command
elif options.bg_color_mode == "hg":
  cmd = "gconftool -s /desktop/gnome/background/color_shading_type -t string \"horizontal-gradient\""
  os.system(cmd) # execute system command
else:
  cmd = "gconftool -s /desktop/gnome/background/color_shading_type -t string \"solid\""
  os.system(cmd) # execute system command

# Set wallpaper display mode
cmd = string.join(["gconftool -s /desktop/gnome/background/picture_options -t string \"", options.wallpaper_mode ,"\""],'')
os.system(cmd) # execute system command

# Make list of images
imagefilelist = [filename for filename in os.listdir(options.folder)
if (filename.lower().endswith("jpg")
    or filename.lower().endswith("png")
    or filename.lower().endswith("gif"))]

imagefilelist = [string.join([os.path.normpath(options.folder),imgFile],"/") for imgFile in imagefilelist]

# Validate for presence of images
if (len(imagefilelist) == 0):
  raise ValueError, "Folder does not contain any image files"

count=0 #init index
random.shuffle(imagefilelist) #randomize wallpaper order
try:
  while (True):
    if (count < len(imagefilelist) -1):
      count = count + 1
    else:
      count = 0

    time.sleep(options.interval)
    changeWallpaper(imagefilelist[count])
except KeyboardInterrupt:
  print options.default_image
  cmd = string.join(["gconftool -s /desktop/gnome/background/picture_filename -t string \"", options.default_image ,"\""],'')
  os.system(cmd) # execute system command
  pass