# Licensed under the Python License (see http://www.python.org/psf/license/)
# Copyright (C) 2008 Pierre Duquesne <stackp@online.fr>
 
import sys
 
class Spinner:
    """A class to show a spinning ascii animation on a character terminal.
 
    It informs the user that some processing is being done.
    """
 
    def __init__(self, message=''):
        self.message = message
        self.symbols = list('-\|/')
        self.nsym = len(self.symbols)
        self.n = 0
 
    def spin(self):
        print '\r', self.message + self.symbols[self.n],
        sys.stdout.flush()
        self.n = (self.n + 1) % self.nsym
 
    def stop(self, stop_message=''):
        print '\r', self.message + stop_message
 
    def set_message(self, message):
        self.message = message
 
 
class DummySpinner:
    """A class that mock Spinner and do not spin.
 
    To be used when output is not a character terminal (e.g. a log file). 
    For example::
 
        if sys.stdout.isatty():
            s = Spinner()
        else:
            s = DummySpinner()
 
    """   
    def __init__(self, message=''):
        self.message = message
 
    def spin(self):
        pass
 
    def stop(self, stop_message=''):
        print self.message + stop_message
 
    def set_message(self, message):
        self.message = message
 
 
if __name__ == "__main__":
 
    import time
 
    def test():
        if sys.stdout.isatty():
            s = Spinner()
        else:
            s = DummySpinner()
 
        # simple usage
        for i in range(10):
            s.spin()
            time.sleep(0.1)
 
        s.set_message('Initialization ... ')
        for i in range(10):
            s.spin()
            time.sleep(0.1)
        s.stop('Done')
 
        s.set_message('Loading ... ')
        for i in range(10):
            s.spin()
            time.sleep(0.1)
        s.stop('Done')
 
    test()