# --------------------------------------------------------
# SiamMask
# Licensed under The MIT License
# Written by Qiang Wang (wangqiang2015 at ia.ac.cn)
# --------------------------------------------------------
import numpy as np
from collections import namedtuple

Corner = namedtuple('Corner', 'x1 y1 x2 y2')
BBox = Corner
Center = namedtuple('Center', 'x y w h')


def corner2center(corner):
    """
    :param corner: Corner or np.array 4*N
    :return: Center or 4 np.array N
    """
    if isinstance(corner, Corner):
        x1, y1, x2, y2 = corner
        return Center((x1 + x2) * 0.5, (y1 + y2) * 0.5, (x2 - x1), (y2 - y1))
    else:
        x1, y1, x2, y2 = corner[0], corner[1], corner[2], corner[3]
        x = (x1 + x2) * 0.5
        y = (y1 + y2) * 0.5
        w = x2 - x1
        h = y2 - y1
        return x, y, w, h


def center2corner(center):
    """
    :param center: Center or np.array 4*N
    :return: Corner or np.array 4*N
    """
    if isinstance(center, Center):
        x, y, w, h = center
        return Corner(x - w * 0.5, y - h * 0.5, x + w * 0.5, y + h * 0.5)
    else:
        x, y, w, h = center[0], center[1], center[2], center[3]
        x1 = x - w * 0.5
        y1 = y - h * 0.5
        x2 = x + w * 0.5
        y2 = y + h * 0.5
        return x1, y1, x2, y2


def cxy_wh_2_rect(pos, sz):
    return np.array([pos[0]-sz[0]/2, pos[1]-sz[1]/2, sz[0], sz[1]])  # 0-index


def get_axis_aligned_bbox(region):
    nv = region.size
    if nv == 8:
        cx = np.mean(region[0::2])
        cy = np.mean(region[1::2])
        x1 = min(region[0::2])
        x2 = max(region[0::2])
        y1 = min(region[1::2])
        y2 = max(region[1::2])
        A1 = np.linalg.norm(region[0:2] - region[2:4]) * np.linalg.norm(region[2:4] - region[4:6])
        A2 = (x2 - x1) * (y2 - y1)
        s = np.sqrt(A1 / A2)
        w = s * (x2 - x1) + 1
        h = s * (y2 - y1) + 1
    else:
        x = region[0]
        y = region[1]
        w = region[2]
        h = region[3]
        cx = x+w/2
        cy = y+h/2

    return cx, cy, w, h


