import os, subprocess
import numpy as np
from matplotlib import pyplot as plt
import torch
import cv2


def ensure_dir(path):
    if not os.path.exists(path):
        os.makedirs(path)


def imagesc(nd_array):
    plt.figure(figsize=(10, 10))
    plt.imshow(nd_array)
    plt.colorbar()
    plt.show()


def imread(img):
    # return RGB image
    try:
        im = cv2.imread(img)
    except Exception as e:
        print(e)
        return None
    im = im[..., ::-1] / 255.
    return im


def imwrite(img, name):
    # write RGB image, img is in RGB format
    cv2.imwrite(name, img[..., ::-1] * 255.)


def stereoRead(img: str):
    im = imread(img)
    H, W, _ = im.shape
    assert W % 2 == 0, '%s is not a side-by-side stereo image' % img
    left = im[:, :W // 2, ...]
    right = im[:, W // 2:, ...]
    return left, right


def stereoWright(left: np.ndarray, right: np.ndarray, name: str):
    im = np.concatenate((left, right), axis=1)
    imwrite(im, name)


def exeCmd(cmd=None):
    print(cmd)
    return subprocess.check_call(cmd, shell=True)


def img2tensor(img, cuda=True):
    img_t = np.expand_dims(img.transpose(2, 0, 1), axis=0)
    img_t = torch.from_numpy(img_t.astype(np.float32))
    if cuda:
        img_t = img_t.cuda(non_blocking=True)
    return img_t


def tensor2img(img_t):
    if len(img_t.shape) == 4:
        img = img_t[0].detach().cpu().numpy()
    elif len(img_t.shape) == 3:
        img = img_t.detach().cpu().numpy()
    else:
        raise NotImplementedError
    img = img.transpose(1, 2, 0)
    return img


def cal_padding(L, window_size):
    padding_left, padding_right = 0, 0
    if L%window_size != 0:
        total = window_size-L%window_size
        padding_left = total//2
        padding_right = total - padding_left
    return padding_left, padding_right

def requires_grad(model, flag=True):
    for p in model.parameters():
        p.requires_grad = flag