import my_extension as me


def grayscale(x, y, neighbors):
    r, g, b = neighbors[(x, y)]
    val = int(0.3 * r + 0.6 * g + 0.1 * b)
    return (val, val, val)

    
def blur(x, y, neighbors):
    totalr = 0
    num = 0
    for coord in neighbors:
        r, g, b = neighbors[coord]
        totalr += r
        num += 1
    val = int(totalr / num)
    return (val, val, val)
    
    
def threshold(x, y, neighbors):
    if neighbors[(x, y)][0] > 128:
        return (255, 255, 255)
    else:
        return (0, 0, 0)
    
    
def edge_detect(x, y, n):
    if len(n) < 9:
        return (0, 0, 0)     # Ignore edges
    else:
        # Sobel edge detection: https://en.wikipedia.org/wiki/Sobel_operator
        x_plus = n[(x - 1, y - 1)][0] + 2 * n[(x - 1, y)][0] + n[(x - 1, y + 1)][0]
        x_minus = n[(x + 1, y - 1)][0] + 2 * n[(x + 1, y)][0] + n[(x + 1, y + 1)][0]
        y_plus = n[(x - 1, y - 1)][0] + 2 * n[(x, y - 1)][0] + n[(x + 1, y - 1)][0]
        y_minus = n[(x - 1, y + 1)][0] + 2 * n[(x, y + 1)][0] + n[(x + 1, y + 1)][0]
        G = int(((x_plus - x_minus) ** 2 + (y_plus - y_minus) ** 2) ** 0.5 / 8.0)
        return (G, G, G)
        
    
    
#I = load_image("apple.png")     # Creates and returns an me.Image object.
# Could also be done as 
I = me.Image("apple.jpg")
# but the above method forces you to create (in C++) a Python object -- 
# this'll be useful in the next lab.

# Make sure your apply method creates an (internal) copy of the image before applying your operation --
# some of them (blur and edge-detect in particular) won't work if you're updating the image "in-place"


print("I =", I)                                 # (Image Object 211x239)
print("I['width'] =", I["width"])               # 211
print("I['height'] =", I["height"])             # 239
print("I['foo'] =", I["foo"])                   # None
print("applying grayscale...", end="");     I.apply(grayscale, 0);      I.save("apple_gray.png");   print("done!")     
print("blurring...", end="");               I.apply(blur, 3);           I.save("apple_blur.png");   print("done!")
print("thresholding...", end="");           I.apply(threshold, 0);      I.save("apple_thresh.png"); print("done!")
print("edge-detection...", end="");         I.apply(edge_detect, 1);    I.save("apple_edges.png");  print("done!")