import _winreg
import re
from os import listdir
import ctypes

wallDir = 'c:\\wallpaper\\';
wallPaperLocation = ('Control Panel\\Desktop')
key = _winreg.OpenKey(_winreg.HKEY_CURRENT_USER, wallPaperLocation, 0, _winreg.KEY_ALL_ACCESS)
files = []
for file in listdir(wallDir):
    g = re.match("^.+\.jpg$", file, re.IGNORECASE)
    if g:
        files.append(file) 

v = _winreg.QueryValueEx(key, 'WallPaper')
print v[0]
g = re.match("^.+\\\(.+)$", v[0])
oldname = ""
if g:
    oldname =  g.group(1)
else:
    print "No Match"
    sys.exit(1)

print oldname
print files

if len(files) > 0:

    #find idx of old name
    oidx = -1
    n = 0
    for file in files:
        if file == oldname:
            oidx = n
            break
        else:
            n += 1

    idx = 0
    if oidx >= 0:
        idx = (oidx + 1) % len(files)

    
    print "Setting"

    ctypes.windll.user32.SystemParametersInfoA(20, 0, wallDir + files[idx], 0)

    _winreg.SetValueEx(key, 'WallPaper', 0, _winreg.REG_SZ, wallDir + files[idx])
    _winreg.FlushKey(key)
    _winreg.CloseKey(key)