Desktop Changer

on findNextDesktopPicture(dektop_pictures_folder)
    tell application "Finder"
        set set_next to false
        repeat with each_file in folder dektop_pictures_folder
            if set_next is true then
                set desktop picture to each_file
                return
            end if
            if (each_file as POSIX file) is (desktop picture as POSIX file) then
                set set_next to true
            end if
        end repeat
        set desktop picture to first file of folder dektop_pictures_folder
    end tell

end findNextDesktopPicture

on changeDesktopPicture(dektop_pictures_folder)
    tell application "Finder"
        -- Pokud Finder nezná cestu k obrázku na ploše
        if desktop picture is missing value then
            set desktop picture to first file of folder dektop_pictures_folder
        else
            my findNextDesktopPicture(dektop_pictures_folder)
        end if
    end tell
end changeDesktopPicture

on run argv
    --display dialog first item of argv
    tell application "Finder"
        set dektop_pictures_folder to first item of argv as POSIX file

        -- Zkontrolovat, zda dodaná složka existuje
        if not (exists dektop_pictures_folder) then
            return
        end if
        -- Zkontrolovat, zda v zadané složce něco je
        if (count (every file in folder dektop_pictures_folder)) is less than 1 then
            return
        end if

        my changeDesktopPicture(dektop_pictures_folder)
    end tell
end run