class Line():
    """ I should change this to a named tuple... """
    def __init__(self, p1, p2):
        self.p1 = p1
        self.p2 = p2
        
    def plot(self):
        line(self.p1.x, self.p1.y, self.p1.z,
             self.p2.x, self.p2.y, self.p2.z)
    
    def lerp(self, other, t):
        p1 = PVector.lerp(self.p1, other.p1, t)
        p2 = PVector.lerp(self.p2, other.p2, t)
        return Line(p1, p2)
    
def line_instersect(line_a, line_b):     
    """
    code adapted from Bernardo Fontes 
    https://github.com/berinhard/sketches/
    """
       
    x1, y1 = line_a.p1.x, line_a.p1.y
    x2, y2 = line_a.p2.x, line_a.p2.y
    x3, y3 = line_b.p1.x, line_b.p1.y
    x4, y4 = line_b.p2.x, line_b.p2.y
        
    try:
        uA = ((x4-x3)*(y1-y3) - (y4-y3)*(x1-x3)) / ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
        uB = ((x2-x1)*(y1-y3) - (y2-y1)*(x1-x3)) / ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
    except ZeroDivisionError:
        return
        
    if not(0 <= uA <= 1 and 0 <= uB <= 1):
        return
        
    x = line_a.p1.x + uA * (line_a.p2.x - line_a.p1.x)
    y = line_a.p1.y + uA * (line_a.p2.y - line_a.p1.y)
        
    return PVector(x, y)


def edges(poly_points):
    return pairwise(poly_points) + [(poly_points[-1], poly_points[0])]   

def pairwise(iterable):
    import itertools
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = itertools.tee(iterable)
    next(b, None)
    return zip(a, b) 

def min_max(points):
        points = iter(points)
        try:
            p = points.next()
            min_x, min_y = max_x, max_y = p.x, p.y
        except StopIteration:
            raise ValueError, "min_max requires at least one point"
        for p in points:
            if p.x < min_x:
                min_x = p.x
            elif p.x > max_x:
                max_x = p.x
            if p.y < min_y:
                min_y = p.y
            elif p.y > max_y:
                max_y = p.y
        return (PVector(min_x, min_y),
                PVector(max_x, max_y))
        
def par_hatch(points, divisions, *sides):
        vectors = [PVector(p.x, p.y, p.z) for p in points]
        lines = []
        if not sides: sides = [0]
        for s in sides:
            a, b = vectors[-1 + s], vectors[+0 + s]
            d, c = vectors[-2 + s], vectors[-3 + s]
            for i in range(1, divisions):
                s0 = PVector.lerp(a, b, i/float(divisions))
                s1 = PVector.lerp(d, c, i/float(divisions))
                lines.append(Line(s0, s1)) 
        return lines