# rectangle.py
# Steve Marschner (srm2), Lillian Lee (ljl2), and Walker White
# March 13, 2015
"""Lecture Demo: Class to represent 2D rectangles."""


class Rectangle(object):
    """Instances represent rectangular regions of the plane.
    
    Instance variables:
        l: x coordinate of left edge   [float]
        r: x coordinate of right edge  [float]
        b: y coordinate of bottom edge [float]
        t: y coordinate of top edge    [float]
        
    For all Rectangles, l <= r and b <= t."""

    def __init__(self, l, r, b, t):
        """Initialzier: Creates the rectangle [l, r] x [b, t]
        
        Parameter l: left edge
        Precondition: l is a float
        
        Parameter r: right edge
        Precondition: r is a float, l <= r
        
        Parameter b: bottom edge
        Precondition: b is a float
        
        Parameter t: top edge
        Precondition: t is a float, b <= t"""
        self.l = l
        self.r = r
        self.b = b
        self.t = t

    def area(self):
        """Returns: area of the rectangle."""
        return (self.r - self.l) * (self.t - self.b)

    def intersection(self, other):
        """Returns: new Rectangle which is intersection of self with other.
        
        The result may be an "empty" rectangle
        
        Parameter other: the rectangle to intersect
        Precondition: other is a rectangle"""
        l = max(self.l, other.l)
        r = min(self.r, other.r)
        b = max(self.b, other.b)
        t = min(self.t, other.t)
        if (r < l):
            r = l
        if (t < b):
            t = b
        return Rectangle(l, r, b, t)
    
    def __str__(self):
        """Returns: String representation of this rectangle."""
        return "(%g, %g) x (%g, %g)" % (self.l, self.r, self.b, self.t)


def demo_rect():
    """Show off rectangle in action"""
    r1 = Rectangle(0., 1., 2., 3.)
    print r1.area()
    r2 = Rectangle(.5, 2., 2.5, 9.)
    print r2.area()
    r3 = r1.intersection(r2)
    r4 = r2.intersection(r1)
    print r3, r4

if __name__ == '__main__':
    demo_rect()