import argparse
import cv2 as cv
import numpy as np

parser = argparse.ArgumentParser(description="Find bright spots in an image.")
parser.add_argument("image_path", help="path of the image file.")
parser.add_argument("--threshold", type=int, default=0,
                    help="Threshold for binary threshold. Set to 0 to use"
                    " automatic thresholding.")
parser.add_argument("--contour-area-lower-bound", type=int, default=0.01,
                    help="lower bound for contour area.")
parser.add_argument("--contour-area-upper-bound", type=int, default=100,
                    help="upper bound for contour area.")
parser.add_argument("--arc-length-lower-bound", type=int, default=0,
                    help="lower bound for contour arc length.")
parser.add_argument("--arc-length-upper-bound", type=int, default=80,
                    help="upper bound for contour arc length.")
parser.add_argument("--contour-color",
                    choices=["red", "green", "blue", "black", "white"],
                    default="red",
                    help="color of the contours.")
parser.add_argument("--contour-thickness", type=int, default=2,
                    help="thickness of the contour.")
args = parser.parse_args()

image = cv.imread(args.image_path)
cv.imshow("Image", image)
print("Press key to continue...")
cv.waitKey(0)

image_gray = cv.cvtColor(image, cv.COLOR_RGB2GRAY)
image_blurred = cv.GaussianBlur(image_gray, (11, 11), 0)

if args.threshold == 0:
    # Automatic thresholding with Otsu's method
    threshold, mask = cv.threshold(image_gray, 0, 255,
                                   cv.THRESH_BINARY+cv.THRESH_OTSU)
else:
    threshold, mask = cv.threshold(image_gray, args.threshold, 255,
                                   cv.THRESH_BINARY)

cv.imshow("Image", mask)
print("\nThresholded image")
print("Press key to continue...")
cv.waitKey(0)
_, contours, hierarchy = cv.findContours(mask, cv.RETR_TREE,
                                         cv.CHAIN_APPROX_SIMPLE)
print("\nFound {} contours.".format(len(contours)))

def filter_contour(contour):
    area = cv.contourArea(contour)
    arc_length = cv.arcLength(contour, closed=True)
    return (area > args.contour_area_lower_bound
            and area < args.contour_area_upper_bound
            and arc_length > args.arc_length_lower_bound
            and arc_length < args.arc_length_upper_bound)

filtered_contours = list(filter(filter_contour, contours))

# Set color
if args.contour_color == "red":
    color = (0, 0, 255)
elif args.contour_color == "green":
    color = (0, 255, 0)
elif args.contour_color == "blue":
    color = (255, 0, 0)
elif args.contour_color == "black":
    color = (0, 0, 0)
elif args.contour_color == "white":
    color = (255, 255, 255)

cv.drawContours(image, filtered_contours, -1, color, args.contour_thickness)
cv.imshow("Image", image)
print("Found {} spots.".format(len(filtered_contours)))
print("Press key to exit...")
cv.waitKey(0)