"""
Copyright (C) 2019 NVIDIA Corporation.  All rights reserved.
Licensed under the CC BY-NC-SA 4.0 license (https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode).
"""

import re
import importlib
import torch
from argparse import Namespace
import numpy as np
from PIL import Image
import os


# Converts a Tensor into a Numpy array
# |imtype|: the desired type of the converted numpy array
def tensor2im(image_tensor, imtype=np.uint8, normalize=True, tile=False):
    if isinstance(image_tensor, list):
        image_numpy = []
        for i in range(len(image_tensor)):
            image_numpy.append(tensor2im(image_tensor[i], imtype, normalize))
        return image_numpy

    if image_tensor.dim() == 4:
        # transform each image in the batch
        images_np = []
        for b in range(image_tensor.size(0)):
            one_image = image_tensor[b]
            one_image_np = tensor2im(one_image)
            images_np.append(one_image_np.reshape(1, *one_image_np.shape))
        images_np = np.concatenate(images_np, axis=0)
        return images_np

    if image_tensor.dim() == 2:
        image_tensor = image_tensor.unsqueeze(0)
    image_numpy = image_tensor.detach().cpu().float().numpy()
    if normalize:
        image_numpy = (np.transpose(image_numpy, (1, 2, 0)) + 1) / 2.0 * 255.0
    else:
        image_numpy = np.transpose(image_numpy, (1, 2, 0)) * 255.0
    image_numpy = np.clip(image_numpy, 0, 255)
    if image_numpy.shape[2] == 1:
        image_numpy = image_numpy[:, :, 0]
    return image_numpy.astype(imtype)


# Converts a one-hot tensor into a colorful label map
def tensor2label(label_tensor, n_label, imtype=np.uint8, tile=False):
    if label_tensor.dim() == 4:
        # transform each image in the batch
        images_np = []
        for b in range(label_tensor.size(0)):
            one_image = label_tensor[b]
            one_image_np = tensor2label(one_image, n_label, imtype)
            images_np.append(one_image_np.reshape(1, *one_image_np.shape))
        images_np = np.concatenate(images_np, axis=0)
        if tile:
            images_tiled = tile_images(images_np)
            return images_tiled
        else:
            images_np = images_np[0]
            return images_np

    if label_tensor.dim() == 1:
        return np.zeros((64, 64, 3), dtype=np.uint8)
    if n_label == 0:
        return tensor2im(label_tensor, imtype)
    label_tensor = label_tensor.cpu().float()
    if label_tensor.size()[0] > 1:
        label_tensor = label_tensor.max(0, keepdim=True)[1]
    label_tensor = Colorize(n_label)(label_tensor)
    label_numpy = np.transpose(label_tensor.numpy(), (1, 2, 0))
    result = label_numpy.astype(imtype)
    return result


def save_image(image_numpy, image_path, create_dir=False):
    if create_dir:
        os.makedirs(os.path.dirname(image_path), exist_ok=True)
    if len(image_numpy.shape) == 2:
        image_numpy = np.expand_dims(image_numpy, axis=2)
    if image_numpy.shape[2] == 1:
        image_numpy = np.repeat(image_numpy, 3, 2)
    image_pil = Image.fromarray(image_numpy)

    # save to png
    image_pil.save(image_path.replace('.jpg', '.png'))


def mkdirs(paths):
    if isinstance(paths, list) and not isinstance(paths, str):
        for path in paths:
            mkdir(path)
    else:
        mkdir(paths)


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


def atoi(text):
    return int(text) if text.isdigit() else text


def natural_keys(text):
    '''
    alist.sort(key=natural_keys) sorts in human order
    http://nedbatchelder.com/blog/200712/human_sorting.html
    (See Toothy's implementation in the comments)
    '''
    return [atoi(c) for c in re.split('(\d+)', text)]


def natural_sort(items):
    items.sort(key=natural_keys)


def str2bool(v):
    if v.lower() in ('yes', 'true', 't', 'y', '1'):
        return True
    elif v.lower() in ('no', 'false', 'f', 'n', '0'):
        return False
    else:
        raise argparse.ArgumentTypeError('Boolean value expected.')


def find_class_in_module(target_cls_name, module):
    target_cls_name = target_cls_name.replace('_', '').lower()
    clslib = importlib.import_module(module)
    cls = None
    for name, clsobj in clslib.__dict__.items():
        if name.lower() == target_cls_name:
            cls = clsobj

    if cls is None:
        print("In %s, there should be a class whose name matches %s in lowercase without underscore(_)" % (module, target_cls_name))
        exit(0)

    return cls


def save_network(net, label, epoch, opt):
    save_filename = '%s_net_%s.pth' % (epoch, label)
    save_path = os.path.join(opt.checkpoints_dir, opt.name, save_filename)
    torch.save(net.cpu().state_dict(), save_path)
    if len(opt.gpu_ids) and torch.cuda.is_available():
        net.cuda()


def load_network(net, label, epoch, opt):
    save_filename = '%s_net_%s.pth' % (epoch, label)
    save_dir = os.path.join(opt.checkpoints_dir, opt.name)
    save_path = os.path.join(save_dir, save_filename)
    weights = torch.load(save_path)
    net.load_state_dict(weights, strict=False)#
    return net