"""Bounding-box math shared by grouping, tracking, capture, drawing."""
from __future__ import annotations

import math
from typing import Tuple

Bbox = Tuple[int, int, int, int]


def clamp_bbox(bbox: Bbox, w: int, h: int) -> Bbox:
    x1, y1, x2, y2 = bbox
    return max(0, x1), max(0, y1), min(w, x2), min(h, y2)


def expand_bbox(bbox: Bbox, w: int, h: int, sx: float = 0.8, sy: float = 1.5) -> Bbox:
    x1, y1, x2, y2 = bbox
    bw, bh = x2 - x1, y2 - y1
    cx, cy = (x1 + x2) // 2, (y1 + y2) // 2
    nw, nh = int(bw * (1 + sx)), int(bh * (1 + sy))
    nx1 = max(0, cx - nw // 2)
    ny1 = max(0, cy - nh // 2)
    return nx1, ny1, min(w, nx1 + nw), min(h, ny1 + nh)


def merge_boxes(a: Bbox, b: Bbox) -> Bbox:
    return (min(a[0], b[0]), min(a[1], b[1]), max(a[2], b[2]), max(a[3], b[3]))


def box_center(bbox: Bbox):
    return ((bbox[0] + bbox[2]) / 2, (bbox[1] + bbox[3]) / 2)


def box_distance(a: Bbox, b: Bbox) -> float:
    ca, cb = box_center(a), box_center(b)
    return math.hypot(ca[0] - cb[0], ca[1] - cb[1])