# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.

import numbers

import cv2
import numpy as np
import PIL
import torch
from torchvision.transforms import functional as tvf


def _is_tensor_clip(clip):
    return torch.is_tensor(clip) and clip.ndimension() == 4


def crop_clip(clip, min_h, min_w, h, w):
    if isinstance(clip[0], np.ndarray) or isinstance(clip[0], torch.Tensor):
        if clip[0].shape[-1] == 3:
            cropped = [img[min_h : min_h + h, min_w : min_w + w, :] for img in clip]
        else:
            assert clip[0].shape[0] == 3
            cropped = [img[:, min_h : min_h + h, min_w : min_w + w] for img in clip]

    elif isinstance(clip[0], PIL.Image.Image):
        cropped = [img.crop((min_w, min_h, min_w + w, min_h + h)) for img in clip]

    else:
        raise TypeError(
            "Expected numpy.ndarray or PIL.Image or torch.Tensor):" + "but got list of {0}".format(type(clip[0]))
        )
    return cropped


def resize_clip(clip, size, interpolation="bilinear"):
    if isinstance(clip[0], np.ndarray) or isinstance(clip[0], torch.Tensor):
        if isinstance(size, numbers.Number):
            if clip[0].shape[-1] == 3:
                im_h, im_w, im_c = clip[0].shape
            else:
                assert clip[0].shape[0] == 3
                im_c, im_h, im_w = clip[0].shape
            # Min spatial dim already matches minimal size
            if (im_w <= im_h and im_w == size) or (im_h <= im_w and im_h == size):
                return clip
            new_h, new_w = get_resize_sizes(im_h, im_w, size)
            size = (new_w, new_h)
        else:
            size = size[0], size[1]

        if isinstance(clip[0], np.ndarray):
            if interpolation == "bilinear":
                np_inter = cv2.INTER_LINEAR
            else:
                np_inter = cv2.INTER_NEAREST
            scaled = [cv2.resize(img, size, interpolation=np_inter) for img in clip]
        else:  # isinstance(clip[0], torch.Tensor)
            if interpolation == "bilinear":
                np_inter = tvf.InterpolationMode.BILINEAR
            else:
                np_inter = tvf.InterpolationMode.NEAREST
            size = (size[1], size[0])  # torchvision transformers expect the size in (h, w) order.
            scaled = [tvf.resize(img, size, interpolation=np_inter) for img in clip]
    elif isinstance(clip[0], PIL.Image.Image):
        if isinstance(size, numbers.Number):
            im_w, im_h = clip[0].size
            # Min spatial dim already matches minimal size
            if (im_w <= im_h and im_w == size) or (im_h <= im_w and im_h == size):
                return clip
            new_h, new_w = get_resize_sizes(im_h, im_w, size)
            size = (new_w, new_h)
        else:
            size = size[1], size[0]
        if interpolation == "bilinear":
            pil_inter = PIL.Image.BILINEAR
        else:
            pil_inter = PIL.Image.NEAREST
        scaled = [img.resize(size, pil_inter) for img in clip]
    else:
        raise TypeError(
            "Expected numpy.ndarray or PIL.Image or torch.Tensor" + "but got list of {0}".format(type(clip[0]))
        )
    return scaled


def get_resize_sizes(im_h, im_w, size):
    if im_w < im_h:
        ow = size
        oh = int(size * im_h / im_w)
    else:
        oh = size
        ow = int(size * im_w / im_h)
    return oh, ow


def normalize(clip, mean, std, inplace=False):
    if not _is_tensor_clip(clip):
        raise TypeError("tensor is not a torch clip.")

    if not inplace:
        clip = clip.clone()

    dtype = clip.dtype
    mean = torch.as_tensor(mean, dtype=dtype, device=clip.device)
    std = torch.as_tensor(std, dtype=dtype, device=clip.device)
    clip.sub_(mean[:, None, None, None]).div_(std[:, None, None, None])

    return clip