import cv2 as cv
import numpy as np


def click_event(event, x, y, flags, params):
    if event == cv.EVENT_LBUTTONDOWN:
        # print(x, ' ', y)
        cv.circle(img_copy, (int(x), int(y)), 10, [0, 255, 255], -1)
        cv.imshow('image', img_copy)
        vertexes.append([x, y])
        if len(vertexes) == 4:
            add_img_in_area()


def add_img_in_area():
    dst_points = np.array(vertexes, dtype=float)
    src_points = np.array([[0, 0], [bakery_w, 0], [bakery_w, bakery_h], [0, bakery_h]], dtype=float)

    mat_h = cv.findHomography(src_points, dst_points)[0]
    image_transformed_h = cv.warpPerspective(bakery, mat_h, (img_w, img_h))

    mask = np.zeros(img.shape[:2], dtype="uint8")
    cv.fillPoly(mask, np.int32([dst_points]), (255, 255, 255))

    bg_with_black_space = cv.bitwise_and(img, img, mask=cv.bitwise_not(mask))

    result = bg_with_black_space + image_transformed_h

    cv.imshow('image', result)
    vertexes.clear()


if __name__ == '__main__':
    vertexes = []
    img = cv.imread('../img/billboards.jpg')
    img_copy = img.copy()
    bakery = cv.imread('../img/bakery.jpg')
    bakery_h, bakery_w = bakery.shape[0:2]
    img_h, img_w = img.shape[0:2]
    cv.imshow('image', img)
    cv.setMouseCallback('image', click_event)
    cv.waitKey(0)
    cv.destroyAllWindows()