#!/usr/bin/env python3
import random
import math
def circle(ctx,x,y,r):
    ctx.arc(x,y,r,0,math.pi*2.)
    ctx.stroke()

def circle_fill(ctx,x,y,r):
    ctx.arc(x,y,r,0,math.pi*2.)
    ctx.fill()

def draw_crater(ctx,x,y,r):
    for n in range(3):
        off_x = random.uniform(-0.01, 0.01)
        off_y = random.uniform(-0.01, 0.01)
        ctx.arc(x + off_x, y + off_y, r, 0, math.pi*2.)
        ctx.fill()

def moon_shade(ctx, phase, nothern=True):
    #phase=-0.4
    #x_max = 0.7 
    x_max = 1.
    # the shadow always has to "hug" one side - pick which
    ctx.move_to(0.5, 0.0)
    if phase > 0:
        ctx.curve_to(-0.2, 0, -0.2, 1, 0.5, 1)
    elif phase < 0: 
        ctx.curve_to(1.2, 0, 1.2, 1, 0.5, 1)
    else:
        return
    #ctx.close_path()
    #ctx.fill()

    #ctx.move_to(0.5, 0.0)
    #ctx.curve_to(x_max*phase, 0.5-(0.5*phase), x_max*phase, 0.5+(0.5*phase), 0.5, 1)
    #ctx.curve_to(0.5 + (x_max*phase), 0.5+(0.5*phase), 0.5+ (x_max*phase), 0.5-(0.5*phase), 0.5, 0)

    # helper x is the same for both points
    h_x = abs(x_max * phase)
    h_y = abs(h_x - 0.5)

    #y_c = (phase * 0.5) 
    #ctx.curve_to(x_max*phase, 0.5+abs(0.5*phase-0.5), (x_max*phase), 0.5-abs(0.5*phase-0.5), 0.5, 0)
    ctx.curve_to(h_x, 0.5 + h_y, h_x, 0.5-h_y, 0.5, 0)
    #ctx.close_path()
    ctx.fill()


def random_color():
    red = random.uniform(0, 1)
    green = random.uniform(0, 1)
    blue = random.uniform(0, 1)
    return red, green, blue