#!/usr/bin/env python
#
# Author  : Ahmed Obied (amaobied@ucalgary.ca)
# Date    : Jan. 17th 2008
# Purpose : Calculates the area of a circle or the volume
#           and surface area of a sphere.
#

# constant for pi
PI = 3.141592654

def circle_area(radius):
    """
    Purpose    : calculates the area of a circle 
    Parameters : radius - the radius of the circle
    Returns    : the area
    """
    return PI * radius * radius

def sphere_volume(radius):
    """
    Purpose    : calculates the volume of a sphere
    Parameters : radius - the radius of the sphere
    Returns    : the volume
    """        
    return 4.0 / 3.0 * PI * radius * radius * radius

def sphere_surface_area(radius):
    """
    Purpose    : calculates the surface area of a sphere
    Parameters : radius - the radius of the sphere
    Returns    : the surface area
    """
    return 4 * PI * radius * radius

def sphere_calc(radius):
    """
    Purpose    : calls the sphere_volumen and sphere_surface_area functions
    Parameters : radius - the radius of the sphere
    Returns    : the volume and the surface area
    """
    return (sphere_volume(radius), sphere_surface_area(radius))

if __name__ == '__main__':
    """ Main Entry """
    while True:
        
        # print the banner
        print '\nWelcome to circle and sphere calculator'
        print '(c)ircle\'s surface area'
        print '(s)phere\'s surface area and volume'
        print '(q)uit the program'

        # get the choice
        choice = raw_input('Enter choice now: ')

        # based on the given choice, take the appropriate action
        if choice == 'C' or choice == 'c':

            # get the radius and calculate the area
            radius = float(raw_input('Enter the radius of the circle: '))
            print 'The area of the cicle with radius %.2f is %.2f' % \
                  (radius, circle_area(radius))
        elif choice == 'S' or choice == 's':

            # get the radius and calculate the volumen and area
            radius = float(raw_input('Enter the radius of the sphere: '))
            volume, area = sphere_calc(radius)
            print 'The surface area of the cicle with radius %4.2f is %4.2f ' \
                  'and the volume is %4.2f' % (radius, area, volume)

        # if 'Q' or 'q' is entered then we break out of the while loop to quit the program
        elif choice == 'Q' or choice == 'q':
            print 'Quiting program.'
            break