#!/usr/bin/env python3
import argparse
import json
from pathlib import Path

import cv2


parser = argparse.ArgumentParser(description="Locate a template image inside a larger image.")
parser.add_argument("scene", type=Path)
parser.add_argument("template", type=Path)
parser.add_argument("output", type=Path)
args = parser.parse_args()

scene_color = cv2.imread(str(args.scene), cv2.IMREAD_COLOR)
scene_gray = cv2.imread(str(args.scene), cv2.IMREAD_GRAYSCALE)
template_gray = cv2.imread(str(args.template), cv2.IMREAD_GRAYSCALE)

if scene_color is None or scene_gray is None:
    raise SystemExit(f"could not read scene image: {args.scene}")
if template_gray is None:
    raise SystemExit(f"could not read template image: {args.template}")
if template_gray.shape[0] > scene_gray.shape[0] or template_gray.shape[1] > scene_gray.shape[1]:
    raise SystemExit("template image must not be larger than the scene image")