import cv2

from config import *
from helpers import clamp, box_center, box_wh

# Template matching fallback
# =========================

def _crop_safe(img, x1, y1, x2, y2):
    h, w = img.shape[:2]
    x1 = int(clamp(x1, 0, w - 1))
    y1 = int(clamp(y1, 0, h - 1))
    x2 = int(clamp(x2, 0, w))
    y2 = int(clamp(y2, 0, h))
    if x2 <= x1 + 1 or y2 <= y1 + 1:
        return None
    return img[y1:y2, x1:x2]


def tm_update_template(gray_eff, box_eff):
    if gray_eff is None or box_eff is None:
        return None
    cx, cy = box_center(box_eff)
    half = TM_TEMPLATE_SIZE // 2
    patch = _crop_safe(gray_eff, cx - half, cy - half, cx + half, cy + half)
    if patch is None:
        return None
    if patch.shape[0] < 12 or patch.shape[1] < 12:
        return None
    return patch.copy()


def tm_search(gray_eff, template, pred_center, miss_streak):
    if (not TM_ENABLE) or gray_eff is None or template is None or pred_center is None:
        return None
    h, w = gray_eff.shape[:2]
    cx, cy = float(pred_center[0]), float(pred_center[1])
    scale = TM_SEARCH_SCALE_BASE + TM_SEARCH_SCALE_PER_MISS * float(miss_streak)
    th, tw = template.shape[:2]
    win_w = int(max(tw * scale, tw + 20))
    win_h = int(max(th * scale, th + 20))
    x1 = int(cx - win_w / 2)
    y1 = int(cy - win_h / 2)
    x2 = int(cx + win_w / 2)
    y2 = int(cy + win_h / 2)
    roi = _crop_safe(gray_eff, x1, y1, x2, y2)
    if roi is None or roi.shape[0] < th + 2 or roi.shape[1] < tw + 2:
        return None
    res = cv2.matchTemplate(roi, template, cv2.TM_CCOEFF_NORMED)
    _, maxv, _, maxl = cv2.minMaxLoc(res)
    if maxv < TM_MIN_SCORE:
        return None
    bx = x1 + maxl[0]
    by = y1 + maxl[1]
    mcx = bx + tw / 2
    mcy = by + th / 2
    return (mcx, mcy, float(maxv), tw, th)


# =========================