import random
from collections.abc import Sequence

import mmcv
import numpy as np
from torch.nn.modules.utils import _pair

from ..registry import PIPELINES


def _init_lazy_if_proper(results, lazy):
    """Initialize lazy operation properly.

    Make sure that a lazy operation is properly initialized,
    and avoid a non-lazy operation accidentally getting mixed in.

    Required keys in results are "imgs" if "img_shape" not in results,
    otherwise, Required keys in results are "img_shape", add or modified keys
    are "img_shape", "lazy".
    Add or modified keys in "lazy" are "original_shape", "crop_bbox", "flip",
    "flip_direction", "interpolation".

    Args:
        results (dict): A dict stores data pipeline result.
        lazy (bool): Determine whether to apply lazy operation. Default: False.
    """

    if 'img_shape' not in results:
        results['img_shape'] = results['imgs'][0].shape[:2]
    if lazy:
        if 'lazy' not in results:
            img_h, img_w = results['img_shape']
            lazyop = dict()
            lazyop['original_shape'] = results['img_shape']
            lazyop['crop_bbox'] = np.array([0, 0, img_w, img_h],
                                           dtype=np.float32)
            lazyop['flip'] = False
            lazyop['flip_direction'] = None
            lazyop['interpolation'] = None
            results['lazy'] = lazyop
    else:
        assert 'lazy' not in results, 'Use Fuse after lazy operations'


@PIPELINES.register_module()
class Imgaug:
    """Imgaug augmentation.

    Adds custom transformations from imgaug library.
    Please visit `https://imgaug.readthedocs.io/en/latest/index.html`
    to get more information. Two demo configs could be found in tsn and i3d
    config folder.

    It's better to use uint8 images as inputs since imgaug works best with
    numpy dtype uint8 and isn't well tested with other dtypes. It should be
    noted that not all of the augmenters have the same input and output dtype,
    which may cause unexpected results.

    Required keys are "imgs", "img_shape"(if "gt_bboxes" is not None) and
    "modality", added or modified keys are "imgs", "img_shape", "gt_bboxes"
    and "proposals".

    It is worth mentioning that `Imgaug` will NOT create custom keys like
    "interpolation", "crop_bbox", "flip_direction", etc. So when using
    `Imgaug` along with other mmaction2 pipelines, we should pay more attention
    to required keys.

    Two steps to use `Imgaug` pipeline:
    1. Create initialization parameter `transforms`. There are three ways
        to create `transforms`.
        1) string: only support `default` for now.
            e.g. `transforms='default'`
        2) list[dict]: create a list of augmenters by a list of dicts, each
            dict corresponds to one augmenter. Every dict MUST contain a key
            named `type`. `type` should be a string(iaa.Augmenter's name) or
            an iaa.Augmenter subclass.
            e.g. `transforms=[dict(type='Rotate', rotate=(-20, 20))]`
            e.g. `transforms=[dict(type=iaa.Rotate, rotate=(-20, 20))]`
        3) iaa.Augmenter: create an imgaug.Augmenter object.
            e.g. `transforms=iaa.Rotate(rotate=(-20, 20))`
    2. Add `Imgaug` in dataset pipeline. It is recommended to insert imgaug
        pipeline before `Normalize`. A demo pipeline is listed as follows.
        ```
        pipeline = [
            dict(
                type='SampleFrames',
                clip_len=1,
                frame_interval=1,
                num_clips=16,
            ),
            dict(type='RawFrameDecode'),
            dict(type='Resize', scale=(-1, 256)),
            dict(
                type='MultiScaleCrop',
                input_size=224,
                scales=(1, 0.875, 0.75, 0.66),
                random_crop=False,
                max_wh_scale_gap=1,
                num_fixed_crops=13),
            dict(type='Resize', scale=(224, 224), keep_ratio=False),
            dict(type='Flip', flip_ratio=0.5),
            dict(type='Imgaug', transforms='default'),
            # dict(type='Imgaug', transforms=[
            #     dict(type='Rotate', rotate=(-20, 20))
            # ]),
            dict(type='Normalize', **img_norm_cfg),
            dict(type='FormatShape', input_format='NCHW'),
            dict(type='Collect', keys=['imgs', 'label'], meta_keys=[]),
            dict(type='ToTensor', keys=['imgs', 'label'])
        ]
        ```

    Args:
        transforms (str | list[dict] | :obj:`iaa.Augmenter`): Three different
            ways to create imgaug augmenter.
    """

    def __init__(self, transforms):
        import imgaug.augmenters as iaa

        if transforms == 'default':
            self.transforms = self.default_transforms()
        elif isinstance(transforms, list):
            assert all(isinstance(trans, dict) for trans in transforms)
            self.transforms = transforms
        elif isinstance(transforms, iaa.Augmenter):
            self.aug = self.transforms = transforms
        else:
            raise ValueError('transforms must be `default` or a list of dicts'
                             ' or iaa.Augmenter object')

        if not isinstance(transforms, iaa.Augmenter):
            self.aug = iaa.Sequential(
                [self.imgaug_builder(t) for t in self.transforms])

    def default_transforms(self):
        """Default transforms for imgaug."""

        return [
            dict(type='Rotate', rotate=(-30, 30)),
            dict(
                type='SomeOf',
                n=(0, 3),
                children=[
                    dict(
                        type='OneOf',
                        children=[
                            dict(type='GaussianBlur', sigma=(0, 0.5)),
                            dict(type='AverageBlur', k=(2, 7)),
                            dict(type='MedianBlur', k=(3, 11))
                        ]),
                    dict(
                        type='OneOf',
                        children=[
                            dict(
                                type='Dropout', p=(0.01, 0.1),
                                per_channel=0.5),
                            dict(
                                type='CoarseDropout',
                                p=(0.03, 0.15),
                                size_percent=(0.02, 0.05),
                                per_channel=0.2),
                        ]),
                    dict(
                        type='AdditiveGaussianNoise',
                        loc=0,
                        scale=(0.0, 0.05 * 255),
                        per_channel=0.5),
                ]),
        ]

    def imgaug_builder(self, cfg):
        """Import a module from imgaug.

        It follows the logic of :func:`build_from_cfg`. Use a dict object to
        create an iaa.Augmenter object.

        Args:
            cfg (dict): Config dict. It should at least contain the key "type".

        Returns:
            obj:`iaa.Augmenter`: The constructed imgaug augmenter.
        """
        import imgaug.augmenters as iaa

        assert isinstance(cfg, dict) and 'type' in cfg
        args = cfg.copy()

        obj_type = args.pop('type')
        if mmcv.is_str(obj_type):
            obj_cls = getattr(iaa, obj_type)
        elif issubclass(obj_type, iaa.Augmenter):
            obj_cls = obj_type
        else:
            raise TypeError(
                f'type must be a str or valid type, but got {type(obj_type)}')

        if 'children' in args:
            args['children'] = [
                self.imgaug_builder(child) for child in args['children']
            ]

        return obj_cls(**args)

    def __repr__(self):
        repr_str = self.__class__.__name__ + f'(transforms={self.aug})'
        return repr_str

    def __call__(self, results):
        assert results['modality'] == 'RGB', 'Imgaug only support RGB images.'
        in_type = results['imgs'][0].dtype.type

        cur_aug = self.aug.to_deterministic()

        results['imgs'] = [
            cur_aug.augment_image(frame) for frame in results['imgs']
        ]
        img_h, img_w, _ = results['imgs'][0].shape

        out_type = results['imgs'][0].dtype.type
        assert in_type == out_type, \
            ('Imgaug input dtype and output dtype are not the same. ',
             f'Convert from {in_type} to {out_type}')

        if 'gt_bboxes' in results:
            from imgaug.augmentables import bbs
            bbox_list = [
                bbs.BoundingBox(
                    x1=bbox[0], y1=bbox[1], x2=bbox[2], y2=bbox[3])
                for bbox in results['gt_bboxes']
            ]
            bboxes = bbs.BoundingBoxesOnImage(
                bbox_list, shape=results['img_shape'])
            bbox_aug, *_ = cur_aug.augment_bounding_boxes([bboxes])
            results['gt_bboxes'] = [[
                max(bbox.x1, 0),
                max(bbox.y1, 0),
                min(bbox.x2, img_w),
                min(bbox.y2, img_h)
            ] for bbox in bbox_aug.items]
            if 'proposals' in results:
                bbox_list = [
                    bbs.BoundingBox(
                        x1=bbox[0], y1=bbox[1], x2=bbox[2], y2=bbox[3])
                    for bbox in results['proposals']
                ]
                bboxes = bbs.BoundingBoxesOnImage(
                    bbox_list, shape=results['img_shape'])
                bbox_aug, *_ = cur_aug.augment_bounding_boxes([bboxes])
                results['proposals'] = [[
                    max(bbox.x1, 0),
                    max(bbox.y1, 0),
                    min(bbox.x2, img_w),
                    min(bbox.y2, img_h)
                ] for bbox in bbox_aug.items]

        results['img_shape'] = (img_h, img_w)

        return results


@PIPELINES.register_module()
class Fuse:
    """Fuse lazy operations.

    Fusion order:
        crop -> resize -> flip

    Required keys are "imgs", "img_shape" and "lazy", added or modified keys
    are "imgs", "lazy".
    Required keys in "lazy" are "crop_bbox", "interpolation", "flip_direction".
    """

    def __call__(self, results):
        if 'lazy' not in results:
            raise ValueError('No lazy operation detected')
        lazyop = results['lazy']
        imgs = results['imgs']

        # crop
        left, top, right, bottom = lazyop['crop_bbox'].round().astype(int)
        imgs = [img[top:bottom, left:right] for img in imgs]

        # resize
        img_h, img_w = results['img_shape']
        if lazyop['interpolation'] is None:
            interpolation = 'bilinear'
        else:
            interpolation = lazyop['interpolation']
        imgs = [
            mmcv.imresize(img, (img_w, img_h), interpolation=interpolation)
            for img in imgs
        ]

        # flip
        if lazyop['flip']:
            for img in imgs:
                mmcv.imflip_(img, lazyop['flip_direction'])

        results['imgs'] = imgs
        del results['lazy']

        return results


@PIPELINES.register_module()
class RandomScale:
    """Resize images by a random scale.

    Required keys are "imgs", "img_shape", "modality", added or modified
    keys are "imgs", "img_shape", "keep_ratio", "scale_factor", "lazy",
    "scale", "resize_size". Required keys in "lazy" is None, added or
    modified key is "interpolation".

    Args:
        scales (tuple[int]): Tuple of scales to be chosen for resize.
        mode (str): Selection mode for choosing the scale. Options are "range"
            and "value". If set to "range", The short edge will be randomly
            chosen from the range of minimum and maximum on the shorter one
            in all tuples. Otherwise, the longer edge will be randomly chosen
            from the range of minimum and maximum on the longer one in all
            tuples. Default: 'range'.
    """

    def __init__(self, scales, mode='range', **kwargs):
        self.mode = mode
        if self.mode not in ['range', 'value']:
            raise ValueError(f"mode should be 'range' or 'value', "
                             f'but got {self.mode}')
        self.scales = scales
        self.kwargs = kwargs

    def select_scale(self, scales):
        num_scales = len(scales)
        if num_scales == 1:
            # specify a fixed scale
            scale = scales[0]
        elif num_scales == 2:
            if self.mode == 'range':
                scale_long = [max(s) for s in scales]
                scale_short = [min(s) for s in scales]
                long_edge = np.random.randint(
                    min(scale_long),
                    max(scale_long) + 1)
                short_edge = np.random.randint(
                    min(scale_short),
                    max(scale_short) + 1)
                scale = (long_edge, short_edge)
            elif self.mode == 'value':
                scale = random.choice(scales)
        else:
            if self.mode != 'value':
                raise ValueError("Only 'value' mode supports more than "
                                 '2 image scales')
            scale = random.choice(scales)

        return scale

    def __call__(self, results):
        scale = self.select_scale(self.scales)
        results['scale'] = scale
        resize = Resize(scale, **self.kwargs)
        results = resize(results)
        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}('
                    f'scales={self.scales}, mode={self.mode})')
        return repr_str


# Note, entity box transfroms are not added to: ThreeCrop, TenCrop,
# MultiGroupCrop.
@PIPELINES.register_module()
class EntityBoxRescale:
    """Rescale the entity box and proposals according to the image shape.

    Required keys are "proposals", "gt_bboxes", added or modified keys are
    "gt_bboxes". If original "proposals" is not None, "proposals" and
    will be added or modified.

    Args:
        scale_factor (np.ndarray): The scale factor used entity_box rescaling.
    """

    def __init__(self, scale_factor):
        self.scale_factor = scale_factor

    def __call__(self, results):
        scale_factor = np.concatenate([self.scale_factor, self.scale_factor])

        proposals = results['proposals']
        gt_bboxes = results['gt_bboxes']
        results['gt_bboxes'] = gt_bboxes * scale_factor

        if proposals is not None:
            assert proposals.shape[1] == 4, (
                'proposals shape should be in '
                f'(n, 4), but got {proposals.shape}')
            results['proposals'] = proposals * scale_factor

        return results

    def __repr__(self):
        return f'{self.__class__.__name__}(scale_factor={self.scale_factor})'


@PIPELINES.register_module()
class EntityBoxCrop:
    """Crop the entity boxes and proposals according to the cropped images.

    Required keys are "proposals", "gt_bboxes", added or modified keys are
    "gt_bboxes". If original "proposals" is not None, "proposals" will be
    modified.

    Args:
        crop_bbox(np.ndarray | None): The bbox used to crop the original image.
    """

    def __init__(self, crop_bbox):
        self.crop_bbox = crop_bbox

    def __call__(self, results):
        proposals = results['proposals']
        gt_bboxes = results['gt_bboxes']

        if self.crop_bbox is None:
            return results

        x1, y1, x2, y2 = self.crop_bbox
        img_w, img_h = x2 - x1, y2 - y1

        assert gt_bboxes.shape[-1] == 4
        gt_bboxes_ = gt_bboxes.copy()
        gt_bboxes_[..., 0::2] = np.clip(gt_bboxes[..., 0::2] - x1, 0,
                                        img_w - 1)
        gt_bboxes_[..., 1::2] = np.clip(gt_bboxes[..., 1::2] - y1, 0,
                                        img_h - 1)
        results['gt_bboxes'] = gt_bboxes_

        if proposals is not None:
            assert proposals.shape[-1] == 4
            proposals_ = proposals.copy()
            proposals_[..., 0::2] = np.clip(proposals[..., 0::2] - x1, 0,
                                            img_w - 1)
            proposals_[..., 1::2] = np.clip(proposals[..., 1::2] - y1, 0,
                                            img_h - 1)
            results['proposals'] = proposals_
        return results

    def __repr__(self):
        return f'{self.__class__.__name__}(crop_bbox={self.crop_bbox})'


@PIPELINES.register_module()
class EntityBoxFlip:
    """Flip the entity boxes and proposals with a probability.

    Reverse the order of elements in the given bounding boxes and proposals
    with a specific direction. The shape of them are preserved, but the
    elements are reordered. Only the horizontal flip is supported (seems
    vertical flipping makes no sense). Required keys are "proposals",
    "gt_bboxes", added or modified keys are "gt_bboxes". If "proposals"
    is not None, it will also be modified.

    Args:
        img_shape (tuple[int]): The img shape.
    """

    def __init__(self, img_shape):
        self.img_shape = img_shape
        assert mmcv.is_tuple_of(img_shape, int)

    def __call__(self, results):
        proposals = results['proposals']
        gt_bboxes = results['gt_bboxes']
        img_h, img_w = self.img_shape

        assert gt_bboxes.shape[-1] == 4
        gt_bboxes_ = gt_bboxes.copy()
        gt_bboxes_[..., 0::4] = img_w - gt_bboxes[..., 2::4] - 1
        gt_bboxes_[..., 2::4] = img_w - gt_bboxes[..., 0::4] - 1
        if proposals is not None:
            assert proposals.shape[-1] == 4
            proposals_ = proposals.copy()
            proposals_[..., 0::4] = img_w - proposals[..., 2::4] - 1
            proposals_[..., 2::4] = img_w - proposals[..., 0::4] - 1
        else:
            proposals_ = None

        results['proposals'] = proposals_
        results['gt_bboxes'] = gt_bboxes_
        return results

    def __repr__(self):
        repr_str = f'{self.__class__.__name__}(img_shape={self.img_shape})'
        return repr_str


@PIPELINES.register_module()
class RandomCrop:
    """Vanilla square random crop that specifics the output size.

    Required keys in results are "imgs" and "img_shape", added or
    modified keys are "imgs", "lazy"; Required keys in "lazy" are "flip",
    "crop_bbox", added or modified key is "crop_bbox".

    Args:
        size (int): The output size of the images.
        lazy (bool): Determine whether to apply lazy operation. Default: False.
    """

    def __init__(self, size, lazy=False):
        if not isinstance(size, int):
            raise TypeError(f'Size must be an int, but got {type(size)}')
        self.size = size
        self.lazy = lazy

    def __call__(self, results):
        """Performs the RandomCrop augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        _init_lazy_if_proper(results, self.lazy)

        img_h, img_w = results['img_shape']
        assert self.size <= img_h and self.size <= img_w

        y_offset = 0
        x_offset = 0
        if img_h > self.size:
            y_offset = int(np.random.randint(0, img_h - self.size))
        if img_w > self.size:
            x_offset = int(np.random.randint(0, img_w - self.size))

        if 'crop_quadruple' not in results:
            results['crop_quadruple'] = np.array(
                [0, 0, 1, 1],  # x, y, w, h
                dtype=np.float32)

        x_ratio, y_ratio = x_offset / img_w, y_offset / img_h
        w_ratio, h_ratio = self.size / img_w, self.size / img_h

        old_crop_quadruple = results['crop_quadruple']
        old_x_ratio, old_y_ratio = old_crop_quadruple[0], old_crop_quadruple[1]
        old_w_ratio, old_h_ratio = old_crop_quadruple[2], old_crop_quadruple[3]
        new_crop_quadruple = [
            old_x_ratio + x_ratio * old_w_ratio,
            old_y_ratio + y_ratio * old_h_ratio, w_ratio * old_w_ratio,
            h_ratio * old_x_ratio
        ]
        results['crop_quadruple'] = np.array(
            new_crop_quadruple, dtype=np.float32)

        new_h, new_w = self.size, self.size

        results['crop_bbox'] = np.array(
            [x_offset, y_offset, x_offset + new_w, y_offset + new_h])

        results['img_shape'] = (new_h, new_w)

        if not self.lazy:
            results['imgs'] = [
                img[y_offset:y_offset + new_h, x_offset:x_offset + new_w]
                for img in results['imgs']
            ]
        else:
            lazyop = results['lazy']
            if lazyop['flip']:
                raise NotImplementedError('Put Flip at last for now')

            # record crop_bbox in lazyop dict to ensure only crop once in Fuse
            lazy_left, lazy_top, lazy_right, lazy_bottom = lazyop['crop_bbox']
            left = x_offset * (lazy_right - lazy_left) / img_w
            right = (x_offset + new_w) * (lazy_right - lazy_left) / img_w
            top = y_offset * (lazy_bottom - lazy_top) / img_h
            bottom = (y_offset + new_h) * (lazy_bottom - lazy_top) / img_h
            lazyop['crop_bbox'] = np.array([(lazy_left + left),
                                            (lazy_top + top),
                                            (lazy_left + right),
                                            (lazy_top + bottom)],
                                           dtype=np.float32)

        # Process entity boxes
        if 'gt_bboxes' in results:
            assert not self.lazy
            entity_box_crop = EntityBoxCrop(results['crop_bbox'])
            results = entity_box_crop(results)

        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}(size={self.size}, '
                    f'lazy={self.lazy})')
        return repr_str


@PIPELINES.register_module()
class RandomResizedCrop:
    """Random crop that specifics the area and height-weight ratio range.

    Required keys in results are "imgs", "img_shape", "crop_bbox" and "lazy",
    added or modified keys are "imgs", "crop_bbox" and "lazy"; Required keys
    in "lazy" are "flip", "crop_bbox", added or modified key is "crop_bbox".

    Args:
        area_range (Tuple[float]): The candidate area scales range of
            output cropped images. Default: (0.08, 1.0).
        aspect_ratio_range (Tuple[float]): The candidate aspect ratio range of
            output cropped images. Default: (3 / 4, 4 / 3).
        lazy (bool): Determine whether to apply lazy operation. Default: False.
    """

    def __init__(self,
                 area_range=(0.08, 1.0),
                 aspect_ratio_range=(3 / 4, 4 / 3),
                 lazy=False):
        self.area_range = area_range
        self.aspect_ratio_range = aspect_ratio_range
        self.lazy = lazy
        if not mmcv.is_tuple_of(self.area_range, float):
            raise TypeError(f'Area_range must be a tuple of float, '
                            f'but got {type(area_range)}')
        if not mmcv.is_tuple_of(self.aspect_ratio_range, float):
            raise TypeError(f'Aspect_ratio_range must be a tuple of float, '
                            f'but got {type(aspect_ratio_range)}')

    @staticmethod
    def get_crop_bbox(img_shape,
                      area_range,
                      aspect_ratio_range,
                      max_attempts=10):
        """Get a crop bbox given the area range and aspect ratio range.

        Args:
            img_shape (Tuple[int]): Image shape
            area_range (Tuple[float]): The candidate area scales range of
                output cropped images. Default: (0.08, 1.0).
            aspect_ratio_range (Tuple[float]): The candidate aspect
                ratio range of output cropped images. Default: (3 / 4, 4 / 3).
                max_attempts (int): The maximum of attempts. Default: 10.
            max_attempts (int): Max attempts times to generate random candidate
                bounding box. If it doesn't qualified one, the center bounding
                box will be used.
        Returns:
            (list[int]) A random crop bbox within the area range and aspect
            ratio range.
        """
        assert 0 < area_range[0] <= area_range[1] <= 1
        assert 0 < aspect_ratio_range[0] <= aspect_ratio_range[1]

        img_h, img_w = img_shape
        area = img_h * img_w

        min_ar, max_ar = aspect_ratio_range
        aspect_ratios = np.exp(
            np.random.uniform(
                np.log(min_ar), np.log(max_ar), size=max_attempts))
        target_areas = np.random.uniform(*area_range, size=max_attempts) * area
        candidate_crop_w = np.round(np.sqrt(target_areas *
                                            aspect_ratios)).astype(np.int32)
        candidate_crop_h = np.round(np.sqrt(target_areas /
                                            aspect_ratios)).astype(np.int32)

        for i in range(max_attempts):
            crop_w = candidate_crop_w[i]
            crop_h = candidate_crop_h[i]
            if crop_h <= img_h and crop_w <= img_w:
                x_offset = random.randint(0, img_w - crop_w)
                y_offset = random.randint(0, img_h - crop_h)
                return x_offset, y_offset, x_offset + crop_w, y_offset + crop_h

        # Fallback
        crop_size = min(img_h, img_w)
        x_offset = (img_w - crop_size) // 2
        y_offset = (img_h - crop_size) // 2
        return x_offset, y_offset, x_offset + crop_size, y_offset + crop_size

    def __call__(self, results):
        """Performs the RandomResizeCrop augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        _init_lazy_if_proper(results, self.lazy)

        img_h, img_w = results['img_shape']

        left, top, right, bottom = self.get_crop_bbox(
            (img_h, img_w), self.area_range, self.aspect_ratio_range)
        new_h, new_w = bottom - top, right - left

        if 'crop_quadruple' not in results:
            results['crop_quadruple'] = np.array(
                [0, 0, 1, 1],  # x, y, w, h
                dtype=np.float32)

        x_ratio, y_ratio = left / img_w, top / img_h
        w_ratio, h_ratio = new_w / img_w, new_h / img_h

        old_crop_quadruple = results['crop_quadruple']
        old_x_ratio, old_y_ratio = old_crop_quadruple[0], old_crop_quadruple[1]
        old_w_ratio, old_h_ratio = old_crop_quadruple[2], old_crop_quadruple[3]
        new_crop_quadruple = [
            old_x_ratio + x_ratio * old_w_ratio,
            old_y_ratio + y_ratio * old_h_ratio, w_ratio * old_w_ratio,
            h_ratio * old_x_ratio
        ]
        results['crop_quadruple'] = np.array(
            new_crop_quadruple, dtype=np.float32)

        results['crop_bbox'] = np.array([left, top, right, bottom])
        results['img_shape'] = (new_h, new_w)

        if not self.lazy:
            results['imgs'] = [
                img[top:bottom, left:right] for img in results['imgs']
            ]
        else:
            lazyop = results['lazy']
            if lazyop['flip']:
                raise NotImplementedError('Put Flip at last for now')

            # record crop_bbox in lazyop dict to ensure only crop once in Fuse
            lazy_left, lazy_top, lazy_right, lazy_bottom = lazyop['crop_bbox']
            left = left * (lazy_right - lazy_left) / img_w
            right = right * (lazy_right - lazy_left) / img_w
            top = top * (lazy_bottom - lazy_top) / img_h
            bottom = bottom * (lazy_bottom - lazy_top) / img_h
            lazyop['crop_bbox'] = np.array([(lazy_left + left),
                                            (lazy_top + top),
                                            (lazy_left + right),
                                            (lazy_top + bottom)],
                                           dtype=np.float32)

        if 'gt_bboxes' in results:
            assert not self.lazy
            entity_box_crop = EntityBoxCrop(results['crop_bbox'])
            results = entity_box_crop(results)
        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}('
                    f'area_range={self.area_range}, '
                    f'aspect_ratio_range={self.aspect_ratio_range}, '
                    f'lazy={self.lazy})')
        return repr_str


@PIPELINES.register_module()
class MultiScaleCrop:
    """Crop images with a list of randomly selected scales.

    Randomly select the w and h scales from a list of scales. Scale of 1 means
    the base size, which is the minimal of image weight and height. The scale
    level of w and h is controlled to be smaller than a certain value to
    prevent too large or small aspect ratio.
    Required keys are "imgs", "img_shape", added or modified keys are "imgs",
    "crop_bbox", "img_shape", "lazy" and "scales". Required keys in "lazy" are
    "crop_bbox", added or modified key is "crop_bbox".

    Args:
        input_size (int | tuple[int]): (w, h) of network input.
        scales (tuple[float]): Weight and height scales to be selected.
        max_wh_scale_gap (int): Maximum gap of w and h scale levels.
            Default: 1.
        random_crop (bool): If set to True, the cropping bbox will be randomly
            sampled, otherwise it will be sampler from fixed regions.
            Default: False.
        num_fixed_crops (int): If set to 5, the cropping bbox will keep 5
            basic fixed regions: "upper left", "upper right", "lower left",
            "lower right", "center". If set to 13, the cropping bbox will
            append another 8 fix regions: "center left", "center right",
            "lower center", "upper center", "upper left quarter",
            "upper right quarter", "lower left quarter", "lower right quarter".
            Default: 5.
        lazy (bool): Determine whether to apply lazy operation. Default: False.
    """

    def __init__(self,
                 input_size,
                 scales=(1, ),
                 max_wh_scale_gap=1,
                 random_crop=False,
                 num_fixed_crops=5,
                 lazy=False):
        self.input_size = _pair(input_size)
        if not mmcv.is_tuple_of(self.input_size, int):
            raise TypeError(f'Input_size must be int or tuple of int, '
                            f'but got {type(input_size)}')

        if not isinstance(scales, tuple):
            raise TypeError(f'Scales must be tuple, but got {type(scales)}')

        if num_fixed_crops not in [5, 13]:
            raise ValueError(f'Num_fix_crops must be in {[5, 13]}, '
                             f'but got {num_fixed_crops}')

        self.scales = scales
        self.max_wh_scale_gap = max_wh_scale_gap
        self.random_crop = random_crop
        self.num_fixed_crops = num_fixed_crops
        self.lazy = lazy

    def __call__(self, results):
        """Performs the MultiScaleCrop augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        _init_lazy_if_proper(results, self.lazy)

        img_h, img_w = results['img_shape']
        base_size = min(img_h, img_w)
        crop_sizes = [int(base_size * s) for s in self.scales]

        candidate_sizes = []
        for i, h in enumerate(crop_sizes):
            for j, w in enumerate(crop_sizes):
                if abs(i - j) <= self.max_wh_scale_gap:
                    candidate_sizes.append([w, h])

        crop_size = random.choice(candidate_sizes)
        for i in range(2):
            if abs(crop_size[i] - self.input_size[i]) < 3:
                crop_size[i] = self.input_size[i]

        crop_w, crop_h = crop_size

        if self.random_crop:
            x_offset = random.randint(0, img_w - crop_w)
            y_offset = random.randint(0, img_h - crop_h)
        else:
            w_step = (img_w - crop_w) // 4
            h_step = (img_h - crop_h) // 4
            candidate_offsets = [
                (0, 0),  # upper left
                (4 * w_step, 0),  # upper right
                (0, 4 * h_step),  # lower left
                (4 * w_step, 4 * h_step),  # lower right
                (2 * w_step, 2 * h_step),  # center
            ]
            if self.num_fixed_crops == 13:
                extra_candidate_offsets = [
                    (0, 2 * h_step),  # center left
                    (4 * w_step, 2 * h_step),  # center right
                    (2 * w_step, 4 * h_step),  # lower center
                    (2 * w_step, 0 * h_step),  # upper center
                    (1 * w_step, 1 * h_step),  # upper left quarter
                    (3 * w_step, 1 * h_step),  # upper right quarter
                    (1 * w_step, 3 * h_step),  # lower left quarter
                    (3 * w_step, 3 * h_step)  # lower right quarter
                ]
                candidate_offsets.extend(extra_candidate_offsets)
            x_offset, y_offset = random.choice(candidate_offsets)

        new_h, new_w = crop_h, crop_w

        results['crop_bbox'] = np.array(
            [x_offset, y_offset, x_offset + new_w, y_offset + new_h])
        results['img_shape'] = (new_h, new_w)
        results['scales'] = self.scales

        if 'crop_quadruple' not in results:
            results['crop_quadruple'] = np.array(
                [0, 0, 1, 1],  # x, y, w, h
                dtype=np.float32)

        x_ratio, y_ratio = x_offset / img_w, y_offset / img_h
        w_ratio, h_ratio = new_w / img_w, new_h / img_h

        old_crop_quadruple = results['crop_quadruple']
        old_x_ratio, old_y_ratio = old_crop_quadruple[0], old_crop_quadruple[1]
        old_w_ratio, old_h_ratio = old_crop_quadruple[2], old_crop_quadruple[3]
        new_crop_quadruple = [
            old_x_ratio + x_ratio * old_w_ratio,
            old_y_ratio + y_ratio * old_h_ratio, w_ratio * old_w_ratio,
            h_ratio * old_x_ratio
        ]
        results['crop_quadruple'] = np.array(
            new_crop_quadruple, dtype=np.float32)

        if not self.lazy:
            results['imgs'] = [
                img[y_offset:y_offset + new_h, x_offset:x_offset + new_w]
                for img in results['imgs']
            ]
        else:
            lazyop = results['lazy']
            if lazyop['flip']:
                raise NotImplementedError('Put Flip at last for now')

            # record crop_bbox in lazyop dict to ensure only crop once in Fuse
            lazy_left, lazy_top, lazy_right, lazy_bottom = lazyop['crop_bbox']
            left = x_offset * (lazy_right - lazy_left) / img_w
            right = (x_offset + new_w) * (lazy_right - lazy_left) / img_w
            top = y_offset * (lazy_bottom - lazy_top) / img_h
            bottom = (y_offset + new_h) * (lazy_bottom - lazy_top) / img_h
            lazyop['crop_bbox'] = np.array([(lazy_left + left),
                                            (lazy_top + top),
                                            (lazy_left + right),
                                            (lazy_top + bottom)],
                                           dtype=np.float32)

        if 'gt_bboxes' in results:
            assert not self.lazy
            entity_box_crop = EntityBoxCrop(results['crop_bbox'])
            results = entity_box_crop(results)

        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}('
                    f'input_size={self.input_size}, scales={self.scales}, '
                    f'max_wh_scale_gap={self.max_wh_scale_gap}, '
                    f'random_crop={self.random_crop}, '
                    f'num_fixed_crops={self.num_fixed_crops}, '
                    f'lazy={self.lazy})')
        return repr_str


@PIPELINES.register_module()
class Resize:
    """Resize images to a specific size.

    Required keys are "imgs", "img_shape", "modality", added or modified
    keys are "imgs", "img_shape", "keep_ratio", "scale_factor", "lazy",
    "resize_size". Required keys in "lazy" is None, added or modified key is
    "interpolation".

    Args:
        scale (float | Tuple[int]): If keep_ratio is True, it serves as scaling
            factor or maximum size:
            If it is a float number, the image will be rescaled by this
            factor, else if it is a tuple of 2 integers, the image will
            be rescaled as large as possible within the scale.
            Otherwise, it serves as (w, h) of output size.
        keep_ratio (bool): If set to True, Images will be resized without
            changing the aspect ratio. Otherwise, it will resize images to a
            given size. Default: True.
        interpolation (str): Algorithm used for interpolation:
            "nearest" | "bilinear". Default: "bilinear".
        lazy (bool): Determine whether to apply lazy operation. Default: False.
    """

    def __init__(self,
                 scale,
                 keep_ratio=True,
                 interpolation='bilinear',
                 lazy=False):
        if isinstance(scale, float):
            if scale <= 0:
                raise ValueError(f'Invalid scale {scale}, must be positive.')
        elif isinstance(scale, tuple):
            max_long_edge = max(scale)
            max_short_edge = min(scale)
            if max_short_edge == -1:
                # assign np.inf to long edge for rescaling short edge later.
                scale = (np.inf, max_long_edge)
        else:
            raise TypeError(
                f'Scale must be float or tuple of int, but got {type(scale)}')
        self.scale = scale
        self.keep_ratio = keep_ratio
        self.interpolation = interpolation
        self.lazy = lazy

    def __call__(self, results):
        """Performs the Resize augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """

        _init_lazy_if_proper(results, self.lazy)

        if 'scale_factor' not in results:
            results['scale_factor'] = np.array([1, 1], dtype=np.float32)
        img_h, img_w = results['img_shape']

        if self.keep_ratio:
            new_w, new_h = mmcv.rescale_size((img_w, img_h), self.scale)
        else:
            new_w, new_h = self.scale

        self.scale_factor = np.array([new_w / img_w, new_h / img_h],
                                     dtype=np.float32)

        results['img_shape'] = (new_h, new_w)
        results['keep_ratio'] = self.keep_ratio
        results['scale_factor'] = results['scale_factor'] * self.scale_factor

        if not self.lazy:
            results['imgs'] = [
                mmcv.imresize(
                    img, (new_w, new_h), interpolation=self.interpolation)
                for img in results['imgs']
            ]
        else:
            lazyop = results['lazy']
            if lazyop['flip']:
                raise NotImplementedError('Put Flip at last for now')
            lazyop['interpolation'] = self.interpolation

        if 'gt_bboxes' in results:
            assert not self.lazy
            entity_box_rescale = EntityBoxRescale(self.scale_factor)
            results = entity_box_rescale(results)

        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}('
                    f'scale={self.scale}, keep_ratio={self.keep_ratio}, '
                    f'interpolation={self.interpolation}, '
                    f'lazy={self.lazy})')
        return repr_str


@PIPELINES.register_module()
class RandomRescale:
    """Randomly resize images so that the short_edge is resized to a specific
    size in a given range. The scale ratio is unchanged after resizing.

    Required keys are "imgs", "img_shape", "modality", added or modified
    keys are "imgs", "img_shape", "keep_ratio", "scale_factor", "resize_size",
    "short_edge".

    Args:
        scale_range (tuple[int]): The range of short edge length. A closed
            interval.
        interpolation (str): Algorithm used for interpolation:
            "nearest" | "bilinear". Default: "bilinear".
    """

    def __init__(self, scale_range, interpolation='bilinear'):
        self.scale_range = scale_range
        # make sure scale_range is legal, first make sure the type is OK
        assert mmcv.is_tuple_of(scale_range, int)
        assert len(scale_range) == 2
        assert scale_range[0] < scale_range[1]
        assert np.all([x > 0 for x in scale_range])

        self.keep_ratio = True
        self.interpolation = interpolation

    def __call__(self, results):
        """Performs the Resize augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        short_edge = np.random.randint(self.scale_range[0],
                                       self.scale_range[1] + 1)
        resize = Resize((-1, short_edge),
                        keep_ratio=True,
                        interpolation=self.interpolation,
                        lazy=False)
        results = resize(results)

        results['short_edge'] = short_edge
        return results

    def __repr__(self):
        scale_range = self.scale_range
        repr_str = (f'{self.__class__.__name__}('
                    f'scale_range=({scale_range[0]}, {scale_range[1]}), '
                    f'interpolation={self.interpolation})')
        return repr_str


@PIPELINES.register_module()
class Flip:
    """Flip the input images with a probability.

    Reverse the order of elements in the given imgs with a specific direction.
    The shape of the imgs is preserved, but the elements are reordered.
    Required keys are "imgs", "img_shape", "modality", added or modified
    keys are "imgs", "lazy" and "flip_direction". Required keys in "lazy" is
    None, added or modified key are "flip" and "flip_direction". The Flip
    augmentation should be placed after any cropping / reshaping augmentations,
    to make sure crop_quadruple is calculated properly.

    Args:
        flip_ratio (float): Probability of implementing flip. Default: 0.5.
        direction (str): Flip imgs horizontally or vertically. Options are
            "horizontal" | "vertical". Default: "horizontal".
        flip_label_map (Dict[int, int] | None): Transform the label of the
            flipped image with the specific label. Default: None.
        lazy (bool): Determine whether to apply lazy operation. Default: False.
    """
    _directions = ['horizontal', 'vertical']

    def __init__(self,
                 flip_ratio=0.5,
                 direction='horizontal',
                 flip_label_map=None,
                 lazy=False):
        if direction not in self._directions:
            raise ValueError(f'Direction {direction} is not supported. '
                             f'Currently support ones are {self._directions}')
        self.flip_ratio = flip_ratio
        self.direction = direction
        self.flip_label_map = flip_label_map
        self.lazy = lazy

    def __call__(self, results):
        """Performs the Flip augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        _init_lazy_if_proper(results, self.lazy)
        modality = results['modality']
        if modality == 'Flow':
            assert self.direction == 'horizontal'

        flip = np.random.rand() < self.flip_ratio

        results['flip'] = flip
        results['flip_direction'] = self.direction

        if self.flip_label_map is not None and flip:
            results['label'] = self.flip_label_map.get(results['label'],
                                                       results['label'])

        if not self.lazy:
            if flip:
                for i, img in enumerate(results['imgs']):
                    mmcv.imflip_(img, self.direction)
                lt = len(results['imgs'])
                for i in range(0, lt, 2):
                    # flow with even indexes are x_flow, which need to be
                    # inverted when doing horizontal flip
                    if modality == 'Flow':
                        results['imgs'][i] = mmcv.iminvert(results['imgs'][i])

            else:
                results['imgs'] = list(results['imgs'])
        else:
            lazyop = results['lazy']
            if lazyop['flip']:
                raise NotImplementedError('Use one Flip please')
            lazyop['flip'] = flip
            lazyop['flip_direction'] = self.direction

        if 'gt_bboxes' in results and flip:
            assert not self.lazy and self.direction == 'horizontal'
            entity_box_flip = EntityBoxFlip(results['img_shape'])
            results = entity_box_flip(results)

        return results

    def __repr__(self):
        repr_str = (
            f'{self.__class__.__name__}('
            f'flip_ratio={self.flip_ratio}, direction={self.direction}, '
            f'flip_label_map={self.flip_label_map}, lazy={self.lazy})')
        return repr_str


@PIPELINES.register_module()
class Normalize:
    """Normalize images with the given mean and std value.

    Required keys are "imgs", "img_shape", "modality", added or modified
    keys are "imgs" and "img_norm_cfg". If modality is 'Flow', additional
    keys "scale_factor" is required

    Args:
        mean (Sequence[float]): Mean values of different channels.
        std (Sequence[float]): Std values of different channels.
        to_bgr (bool): Whether to convert channels from RGB to BGR.
            Default: False.
        adjust_magnitude (bool): Indicate whether to adjust the flow magnitude
            on 'scale_factor' when modality is 'Flow'. Default: False.
    """

    def __init__(self, mean, std, to_bgr=False, adjust_magnitude=False):
        if not isinstance(mean, Sequence):
            raise TypeError(
                f'Mean must be list, tuple or np.ndarray, but got {type(mean)}'
            )

        if not isinstance(std, Sequence):
            raise TypeError(
                f'Std must be list, tuple or np.ndarray, but got {type(std)}')

        self.mean = np.array(mean, dtype=np.float32)
        self.std = np.array(std, dtype=np.float32)
        self.to_bgr = to_bgr
        self.adjust_magnitude = adjust_magnitude

    def __call__(self, results):
        modality = results['modality']

        if modality == 'RGB':
            n = len(results['imgs'])
            h, w, c = results['imgs'][0].shape
            imgs = np.empty((n, h, w, c), dtype=np.float32)
            for i, img in enumerate(results['imgs']):
                imgs[i] = img

            for img in imgs:
                mmcv.imnormalize_(img, self.mean, self.std, self.to_bgr)

            results['imgs'] = imgs
            results['img_norm_cfg'] = dict(
                mean=self.mean, std=self.std, to_bgr=self.to_bgr)
            return results
        if modality == 'Flow':
            num_imgs = len(results['imgs'])
            assert num_imgs % 2 == 0
            assert self.mean.shape[0] == 2
            assert self.std.shape[0] == 2
            n = num_imgs // 2
            h, w = results['imgs'][0].shape
            x_flow = np.empty((n, h, w), dtype=np.float32)
            y_flow = np.empty((n, h, w), dtype=np.float32)
            for i in range(n):
                x_flow[i] = results['imgs'][2 * i]
                y_flow[i] = results['imgs'][2 * i + 1]
            x_flow = (x_flow - self.mean[0]) / self.std[0]
            y_flow = (y_flow - self.mean[1]) / self.std[1]
            if self.adjust_magnitude:
                x_flow = x_flow * results['scale_factor'][0]
                y_flow = y_flow * results['scale_factor'][1]
            imgs = np.stack([x_flow, y_flow], axis=-1)
            results['imgs'] = imgs
            args = dict(
                mean=self.mean,
                std=self.std,
                to_bgr=self.to_bgr,
                adjust_magnitude=self.adjust_magnitude)
            results['img_norm_cfg'] = args
            return results
        raise NotImplementedError

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}('
                    f'mean={self.mean}, '
                    f'std={self.std}, '
                    f'to_bgr={self.to_bgr}, '
                    f'adjust_magnitude={self.adjust_magnitude})')
        return repr_str


@PIPELINES.register_module()
class ColorJitter:
    """Randomly distort the brightness, contrast, saturation and hue of images,
    and add PCA based noise into images.

    Note: The input images should be in RGB channel order.

    Code Reference:
    https://gluon-cv.mxnet.io/_modules/gluoncv/data/transforms/experimental/image.html
    https://mxnet.apache.org/api/python/docs/_modules/mxnet/image/image.html#LightingAug

    If specified to apply color space augmentation, it will distort the image
    color space by changing brightness, contrast and saturation. Then, it will
    add some random distort to the images in different color channels.
    Note that the input images should be in original range [0, 255] and in RGB
    channel sequence.

    Required keys are "imgs", added or modified keys are "imgs", "eig_val",
    "eig_vec", "alpha_std" and "color_space_aug".

    Args:
        color_space_aug (bool): Whether to apply color space augmentations. If
            specified, it will change the brightness, contrast, saturation and
            hue of images, then add PCA based noise to images. Otherwise, it
            will directly add PCA based noise to images. Default: False.
        alpha_std (float): Std in the normal Gaussian distribution of alpha.
        eig_val (np.ndarray | None): Eigenvalues of [1 x 3] size for RGB
            channel jitter. If set to None, it will use the default
            eigenvalues. Default: None.
        eig_vec (np.ndarray | None): Eigenvectors of [3 x 3] size for RGB
            channel jitter. If set to None, it will use the default
            eigenvectors. Default: None.
    """

    def __init__(self,
                 color_space_aug=False,
                 alpha_std=0.1,
                 eig_val=None,
                 eig_vec=None):
        if eig_val is None:
            # note that the data range should be [0, 255]
            self.eig_val = np.array([55.46, 4.794, 1.148], dtype=np.float32)
        else:
            self.eig_val = eig_val

        if eig_vec is None:
            self.eig_vec = np.array([[-0.5675, 0.7192, 0.4009],
                                     [-0.5808, -0.0045, -0.8140],
                                     [-0.5836, -0.6948, 0.4203]],
                                    dtype=np.float32)
        else:
            self.eig_vec = eig_vec

        self.alpha_std = alpha_std
        self.color_space_aug = color_space_aug

    @staticmethod
    def brightness(img, delta):
        """Brightness distortion.

        Args:
            img (np.ndarray): An input image.
            delta (float): Delta value to distort brightness.
                It ranges from [-32, 32).

        Returns:
            np.ndarray: A brightness distorted image.
        """
        if np.random.rand() > 0.5:
            img = img + np.float32(delta)
        return img

    @staticmethod
    def contrast(img, alpha):
        """Contrast distortion.

        Args:
            img (np.ndarray): An input image.
            alpha (float): Alpha value to distort contrast.
                It ranges from [0.6, 1.4).

        Returns:
            np.ndarray: A contrast distorted image.
        """
        if np.random.rand() > 0.5:
            img = img * np.float32(alpha)
        return img

    @staticmethod
    def saturation(img, alpha):
        """Saturation distortion.

        Args:
            img (np.ndarray): An input image.
            alpha (float): Alpha value to distort the saturation.
                It ranges from [0.6, 1.4).

        Returns:
            np.ndarray: A saturation distorted image.
        """
        if np.random.rand() > 0.5:
            gray = img * np.array([0.299, 0.587, 0.114], dtype=np.float32)
            gray = np.sum(gray, 2, keepdims=True)
            gray *= (1.0 - alpha)
            img = img * alpha
            img = img + gray
        return img

    @staticmethod
    def hue(img, alpha):
        """Hue distortion.

        Args:
            img (np.ndarray): An input image.
            alpha (float): Alpha value to control the degree of rotation
                for hue. It ranges from [-18, 18).

        Returns:
            np.ndarray: A hue distorted image.
        """
        if np.random.rand() > 0.5:
            u = np.cos(alpha * np.pi)
            w = np.sin(alpha * np.pi)
            bt = np.array([[1.0, 0.0, 0.0], [0.0, u, -w], [0.0, w, u]],
                          dtype=np.float32)
            tyiq = np.array([[0.299, 0.587, 0.114], [0.596, -0.274, -0.321],
                             [0.211, -0.523, 0.311]],
                            dtype=np.float32)
            ityiq = np.array([[1.0, 0.956, 0.621], [1.0, -0.272, -0.647],
                              [1.0, -1.107, 1.705]],
                             dtype=np.float32)
            t = np.dot(np.dot(ityiq, bt), tyiq).T
            t = np.array(t, dtype=np.float32)
            img = np.dot(img, t)
        return img

    def __call__(self, results):
        imgs = results['imgs']
        out = []
        if self.color_space_aug:
            bright_delta = np.random.uniform(-32, 32)
            contrast_alpha = np.random.uniform(0.6, 1.4)
            saturation_alpha = np.random.uniform(0.6, 1.4)
            hue_alpha = np.random.uniform(-18, 18)
            jitter_coin = np.random.rand()
            for img in imgs:
                img = self.brightness(img, delta=bright_delta)
                if jitter_coin > 0.5:
                    img = self.contrast(img, alpha=contrast_alpha)
                    img = self.saturation(img, alpha=saturation_alpha)
                    img = self.hue(img, alpha=hue_alpha)
                else:
                    img = self.saturation(img, alpha=saturation_alpha)
                    img = self.hue(img, alpha=hue_alpha)
                    img = self.contrast(img, alpha=contrast_alpha)
                out.append(img)
        else:
            out = imgs

        # Add PCA based noise
        alpha = np.random.normal(0, self.alpha_std, size=(3, ))
        rgb = np.array(
            np.dot(self.eig_vec * alpha, self.eig_val), dtype=np.float32)
        rgb = rgb[None, None, ...]

        results['imgs'] = [img + rgb for img in out]
        results['eig_val'] = self.eig_val
        results['eig_vec'] = self.eig_vec
        results['alpha_std'] = self.alpha_std
        results['color_space_aug'] = self.color_space_aug

        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}('
                    f'color_space_aug={self.color_space_aug}, '
                    f'alpha_std={self.alpha_std}, '
                    f'eig_val={self.eig_val}, '
                    f'eig_vec={self.eig_vec})')
        return repr_str


@PIPELINES.register_module()
class CenterCrop:
    """Crop the center area from images.

    Required keys are "imgs", "img_shape", added or modified keys are "imgs",
    "crop_bbox", "lazy" and "img_shape". Required keys in "lazy" is
    "crop_bbox", added or modified key is "crop_bbox".

    Args:
        crop_size (int | tuple[int]): (w, h) of crop size.
        lazy (bool): Determine whether to apply lazy operation. Default: False.
    """

    def __init__(self, crop_size, lazy=False):
        self.crop_size = _pair(crop_size)
        self.lazy = lazy
        if not mmcv.is_tuple_of(self.crop_size, int):
            raise TypeError(f'Crop_size must be int or tuple of int, '
                            f'but got {type(crop_size)}')

    def __call__(self, results):
        """Performs the CenterCrop augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        _init_lazy_if_proper(results, self.lazy)

        img_h, img_w = results['img_shape']
        crop_w, crop_h = self.crop_size

        left = (img_w - crop_w) // 2
        top = (img_h - crop_h) // 2
        right = left + crop_w
        bottom = top + crop_h
        new_h, new_w = bottom - top, right - left

        results['crop_bbox'] = np.array([left, top, right, bottom])
        results['img_shape'] = (new_h, new_w)

        if 'crop_quadruple' not in results:
            results['crop_quadruple'] = np.array(
                [0, 0, 1, 1],  # x, y, w, h
                dtype=np.float32)

        x_ratio, y_ratio = left / img_w, top / img_h
        w_ratio, h_ratio = new_w / img_w, new_h / img_h

        old_crop_quadruple = results['crop_quadruple']
        old_x_ratio, old_y_ratio = old_crop_quadruple[0], old_crop_quadruple[1]
        old_w_ratio, old_h_ratio = old_crop_quadruple[2], old_crop_quadruple[3]
        new_crop_quadruple = [
            old_x_ratio + x_ratio * old_w_ratio,
            old_y_ratio + y_ratio * old_h_ratio, w_ratio * old_w_ratio,
            h_ratio * old_x_ratio
        ]
        results['crop_quadruple'] = np.array(
            new_crop_quadruple, dtype=np.float32)

        if not self.lazy:
            results['imgs'] = [
                img[top:bottom, left:right] for img in results['imgs']
            ]
        else:
            lazyop = results['lazy']
            if lazyop['flip']:
                raise NotImplementedError('Put Flip at last for now')

            # record crop_bbox in lazyop dict to ensure only crop once in Fuse
            lazy_left, lazy_top, lazy_right, lazy_bottom = lazyop['crop_bbox']
            left = left * (lazy_right - lazy_left) / img_w
            right = right * (lazy_right - lazy_left) / img_w
            top = top * (lazy_bottom - lazy_top) / img_h
            bottom = bottom * (lazy_bottom - lazy_top) / img_h
            lazyop['crop_bbox'] = np.array([(lazy_left + left),
                                            (lazy_top + top),
                                            (lazy_left + right),
                                            (lazy_top + bottom)],
                                           dtype=np.float32)

        if 'gt_bboxes' in results:
            assert not self.lazy
            entity_box_crop = EntityBoxCrop(results['crop_bbox'])
            results = entity_box_crop(results)

        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}(crop_size={self.crop_size}, '
                    f'lazy={self.lazy})')
        return repr_str


@PIPELINES.register_module()
class ThreeCrop:
    """Crop images into three crops.

    Crop the images equally into three crops with equal intervals along the
    shorter side.
    Required keys are "imgs", "img_shape", added or modified keys are "imgs",
    "crop_bbox" and "img_shape".

    Args:
        crop_size(int | tuple[int]): (w, h) of crop size.
    """

    def __init__(self, crop_size):
        self.crop_size = _pair(crop_size)
        if not mmcv.is_tuple_of(self.crop_size, int):
            raise TypeError(f'Crop_size must be int or tuple of int, '
                            f'but got {type(crop_size)}')

    def __call__(self, results):
        """Performs the ThreeCrop augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        _init_lazy_if_proper(results, False)

        imgs = results['imgs']
        img_h, img_w = results['imgs'][0].shape[:2]
        crop_w, crop_h = self.crop_size
        assert crop_h == img_h or crop_w == img_w

        if crop_h == img_h:
            w_step = (img_w - crop_w) // 2
            offsets = [
                (0, 0),  # left
                (2 * w_step, 0),  # right
                (w_step, 0),  # middle
            ]
        elif crop_w == img_w:
            h_step = (img_h - crop_h) // 2
            offsets = [
                (0, 0),  # top
                (0, 2 * h_step),  # down
                (0, h_step),  # middle
            ]

        cropped = []
        crop_bboxes = []
        for x_offset, y_offset in offsets:
            bbox = [x_offset, y_offset, x_offset + crop_w, y_offset + crop_h]
            crop = [
                img[y_offset:y_offset + crop_h, x_offset:x_offset + crop_w]
                for img in imgs
            ]
            cropped.extend(crop)
            crop_bboxes.extend([bbox for _ in range(len(imgs))])

        crop_bboxes = np.array(crop_bboxes)
        results['imgs'] = cropped
        results['crop_bbox'] = crop_bboxes
        results['img_shape'] = results['imgs'][0].shape[:2]

        return results

    def __repr__(self):
        repr_str = f'{self.__class__.__name__}(crop_size={self.crop_size})'
        return repr_str


@PIPELINES.register_module()
class TenCrop:
    """Crop the images into 10 crops (corner + center + flip).

    Crop the four corners and the center part of the image with the same
    given crop_size, and flip it horizontally.
    Required keys are "imgs", "img_shape", added or modified keys are "imgs",
    "crop_bbox" and "img_shape".

    Args:
        crop_size(int | tuple[int]): (w, h) of crop size.
    """

    def __init__(self, crop_size):
        self.crop_size = _pair(crop_size)
        if not mmcv.is_tuple_of(self.crop_size, int):
            raise TypeError(f'Crop_size must be int or tuple of int, '
                            f'but got {type(crop_size)}')

    def __call__(self, results):
        """Performs the TenCrop augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        _init_lazy_if_proper(results, False)

        imgs = results['imgs']

        img_h, img_w = results['imgs'][0].shape[:2]
        crop_w, crop_h = self.crop_size

        w_step = (img_w - crop_w) // 4
        h_step = (img_h - crop_h) // 4

        offsets = [
            (0, 0),  # upper left
            (4 * w_step, 0),  # upper right
            (0, 4 * h_step),  # lower left
            (4 * w_step, 4 * h_step),  # lower right
            (2 * w_step, 2 * h_step),  # center
        ]

        img_crops = list()
        crop_bboxes = list()
        for x_offset, y_offsets in offsets:
            crop = [
                img[y_offsets:y_offsets + crop_h, x_offset:x_offset + crop_w]
                for img in imgs
            ]
            flip_crop = [np.flip(c, axis=1).copy() for c in crop]
            bbox = [x_offset, y_offsets, x_offset + crop_w, y_offsets + crop_h]
            img_crops.extend(crop)
            img_crops.extend(flip_crop)
            crop_bboxes.extend([bbox for _ in range(len(imgs) * 2)])

        crop_bboxes = np.array(crop_bboxes)
        results['imgs'] = img_crops
        results['crop_bbox'] = crop_bboxes
        results['img_shape'] = results['imgs'][0].shape[:2]

        return results

    def __repr__(self):
        repr_str = f'{self.__class__.__name__}(crop_size={self.crop_size})'
        return repr_str


@PIPELINES.register_module()
class MultiGroupCrop:
    """Randomly crop the images into several groups.

    Crop the random region with the same given crop_size and bounding box
    into several groups.
    Required keys are "imgs", added or modified keys are "imgs", "crop_bbox"
    and "img_shape".

    Args:
        crop_size(int | tuple[int]): (w, h) of crop size.
        groups(int): Number of groups.
    """

    def __init__(self, crop_size, groups):
        self.crop_size = _pair(crop_size)
        self.groups = groups
        if not mmcv.is_tuple_of(self.crop_size, int):
            raise TypeError('Crop size must be int or tuple of int, '
                            f'but got {type(crop_size)}')

        if not isinstance(groups, int):
            raise TypeError(f'Groups must be int, but got {type(groups)}.')

        if groups <= 0:
            raise ValueError('Groups must be positive.')

    def __call__(self, results):
        """Performs the MultiGroupCrop augmentation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        imgs = results['imgs']
        img_h, img_w = imgs[0].shape[:2]
        crop_w, crop_h = self.crop_size

        img_crops = []
        crop_bboxes = []
        for _ in range(self.groups):
            x_offset = random.randint(0, img_w - crop_w)
            y_offset = random.randint(0, img_h - crop_h)

            bbox = [x_offset, y_offset, x_offset + crop_w, y_offset + crop_h]
            crop = [
                img[y_offset:y_offset + crop_h, x_offset:x_offset + crop_w]
                for img in imgs
            ]
            img_crops.extend(crop)
            crop_bboxes.extend([bbox for _ in range(len(imgs))])

        crop_bboxes = np.array(crop_bboxes)
        results['imgs'] = img_crops
        results['crop_bbox'] = crop_bboxes
        results['img_shape'] = results['imgs'][0].shape[:2]

        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}'
                    f'(crop_size={self.crop_size}, '
                    f'groups={self.groups})')
        return repr_str


@PIPELINES.register_module()
class AudioAmplify:
    """Amplify the waveform.

    Required keys are "audios", added or modified keys are "audios",
    "amplify_ratio".

    Args:
        ratio (float): The ratio used to amplify the audio waveform.
    """

    def __init__(self, ratio):
        if isinstance(ratio, float):
            self.ratio = ratio
        else:
            raise TypeError('Amplification ratio should be float.')

    def __call__(self, results):
        """Perfrom the audio amplification.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """

        assert 'audios' in results
        results['audios'] *= self.ratio
        results['amplify_ratio'] = self.ratio

        return results

    def __repr__(self):
        repr_str = f'{self.__class__.__name__}(ratio={self.ratio})'
        return repr_str


@PIPELINES.register_module()
class MelSpectrogram:
    """MelSpectrogram. Transfer an audio wave into a melspectogram figure.

    Required keys are "audios", "sample_rate", "num_clips", added or modified
    keys are "audios".

    Args:
        window_size (int): The window size in milisecond. Default: 32.
        step_size (int): The step size in milisecond. Default: 16.
        n_mels (int): Number of mels. Default: 80.
        fixed_length (int): The sample length of melspectrogram maybe not
            exactly as wished due to different fps, fix the length for batch
            collation by truncating or padding. Default: 128.
    """

    def __init__(self,
                 window_size=32,
                 step_size=16,
                 n_mels=80,
                 fixed_length=128):
        if all(
                isinstance(x, int)
                for x in [window_size, step_size, n_mels, fixed_length]):
            self.window_size = window_size
            self.step_size = step_size
            self.n_mels = n_mels
            self.fixed_length = fixed_length
        else:
            raise TypeError('All arguments should be int.')

    def __call__(self, results):
        """Perform MelSpectrogram transformation.

        Args:
            results (dict): The resulting dict to be modified and passed
                to the next transform in pipeline.
        """
        try:
            import librosa
        except ImportError:
            raise ImportError('Install librosa first.')
        signals = results['audios']
        sample_rate = results['sample_rate']
        n_fft = int(round(sample_rate * self.window_size / 1000))
        hop_length = int(round(sample_rate * self.step_size / 1000))
        melspectrograms = list()
        for clip_idx in range(results['num_clips']):
            clip_signal = signals[clip_idx]
            mel = librosa.feature.melspectrogram(
                y=clip_signal,
                sr=sample_rate,
                n_fft=n_fft,
                hop_length=hop_length,
                n_mels=self.n_mels)
            if mel.shape[0] >= self.fixed_length:
                mel = mel[:self.fixed_length, :]
            else:
                mel = np.pad(
                    mel, ((0, mel.shape[-1] - self.fixed_length), (0, 0)),
                    mode='edge')
            melspectrograms.append(mel)

        results['audios'] = np.array(melspectrograms)
        return results

    def __repr__(self):
        repr_str = (f'{self.__class__.__name__}'
                    f'(window_size={self.window_size}), '
                    f'step_size={self.step_size}, '
                    f'n_mels={self.n_mels}, '
                    f'fixed_length={self.fixed_length})')
        return repr_str
