# mirror.py, by chaynes@indiana.edu

import image

def mirror(lst):
    """Copy the values in elements in the first half of lst into elements in the
    second half of lst, in reverse order.
    """
    for i in range(len(lst) / 2):
        lst[len(lst) - 1 - i] = lst[i]

def mirror_matrix(matrix):
    """Call the mirror function on each row of matrix."""
    for index in range(len(matrix)):
        row = matrix[index]
        mirror(row)

def main():
    """Show bonsai.jpg, and then show and save its mirror image."""
    m = image.read('bonsai.jpg')
    mirror_matrix(m)
    im = image.new(m)
    im.show()
    im.save('mirror.jpg')

if __name__ == '__main__':
    main()