import copy
import warnings

import numpy as np
import torch
from mmcv import ConfigDict
from mmcv.ops import nms

from ..bbox import bbox_mapping_back


def merge_aug_proposals(aug_proposals, img_metas, cfg):
    """Merge augmented proposals (multiscale, flip, etc.)

    Args:
        aug_proposals (list[Tensor]): proposals from different testing
            schemes, shape (n, 5). Note that they are not rescaled to the
            original image size.

        img_metas (list[dict]): list of image info dict where each dict has:
            'img_shape', 'scale_factor', 'flip', and may also contain
            'filename', 'ori_shape', 'pad_shape', and 'img_norm_cfg'.
            For details on the values of these keys see
            `mmdet/datasets/pipelines/formatting.py:Collect`.

        cfg (dict): rpn test config.

    Returns:
        Tensor: shape (n, 4), proposals corresponding to original image scale.
    """

    cfg = copy.deepcopy(cfg)

    # deprecate arguments warning
    if 'nms' not in cfg or 'max_num' in cfg or 'nms_thr' in cfg:
        warnings.warn(
            'In rpn_proposal or test_cfg, '
            'nms_thr has been moved to a dict named nms as '
            'iou_threshold, max_num has been renamed as max_per_img, '
            'name of original arguments and the way to specify '
            'iou_threshold of NMS will be deprecated.')
    if 'nms' not in cfg:
        cfg.nms = ConfigDict(dict(type='nms', iou_threshold=cfg.nms_thr))
    if 'max_num' in cfg:
        if 'max_per_img' in cfg:
            assert cfg.max_num == cfg.max_per_img, f'You set max_num and ' \
                f'max_per_img at the same time, but get {cfg.max_num} ' \
                f'and {cfg.max_per_img} respectively' \
                f'Please delete max_num which will be deprecated.'
        else:
            cfg.max_per_img = cfg.max_num
    if 'nms_thr' in cfg:
        assert cfg.nms.iou_threshold == cfg.nms_thr, f'You set ' \
            f'iou_threshold in nms and ' \
            f'nms_thr at the same time, but get ' \
            f'{cfg.nms.iou_threshold} and {cfg.nms_thr}' \
            f' respectively. Please delete the nms_thr ' \
            f'which will be deprecated.'

    recovered_proposals = []
    for proposals, img_info in zip(aug_proposals, img_metas):
        img_shape = img_info['img_shape']
        scale_factor = img_info['scale_factor']
        flip = img_info['flip']
        flip_direction = img_info['flip_direction']
        _proposals = proposals.clone()
        _proposals[:, :4] = bbox_mapping_back(_proposals[:, :4], img_shape,
                                              scale_factor, flip,
                                              flip_direction)
        recovered_proposals.append(_proposals)
    aug_proposals = torch.cat(recovered_proposals, dim=0)
    merged_proposals, _ = nms(aug_proposals[:, :4].contiguous(),
                              aug_proposals[:, -1].contiguous(),
                              cfg.nms.iou_threshold)
    scores = merged_proposals[:, 4]
    _, order = scores.sort(0, descending=True)
    num = min(cfg.max_per_img, merged_proposals.shape[0])
    order = order[:num]
    merged_proposals = merged_proposals[order, :]
    return merged_proposals


def merge_aug_bboxes(aug_bboxes, aug_scores, img_metas, rcnn_test_cfg):
    """Merge augmented detection bboxes and scores.

    Args:
        aug_bboxes (list[Tensor]): shape (n, 4*#class)
        aug_scores (list[Tensor] or None): shape (n, #class)
        img_shapes (list[Tensor]): shape (3, ).
        rcnn_test_cfg (dict): rcnn test config.

    Returns:
        tuple: (bboxes, scores)
    """
    recovered_bboxes = []
    for bboxes, img_info in zip(aug_bboxes, img_metas):
        img_shape = img_info[0]['img_shape']
        scale_factor = img_info[0]['scale_factor']
        flip = img_info[0]['flip']
        flip_direction = img_info[0]['flip_direction']
        bboxes = bbox_mapping_back(bboxes, img_shape, scale_factor, flip,
                                   flip_direction)
        recovered_bboxes.append(bboxes)
    bboxes = torch.stack(recovered_bboxes).mean(dim=0)
    if aug_scores is None:
        return bboxes
    else:
        scores = torch.stack(aug_scores).mean(dim=0)
        return bboxes, scores


def merge_aug_scores(aug_scores):
    """Merge augmented bbox scores."""
    if isinstance(aug_scores[0], torch.Tensor):
        return torch.mean(torch.stack(aug_scores), dim=0)
    else:
        return np.mean(aug_scores, axis=0)


def merge_aug_masks(aug_masks, img_metas, rcnn_test_cfg, weights=None):
    """Merge augmented mask prediction.

    Args:
        aug_masks (list[ndarray]): shape (n, #class, h, w)
        img_shapes (list[ndarray]): shape (3, ).
        rcnn_test_cfg (dict): rcnn test config.

    Returns:
        tuple: (bboxes, scores)
    """
    recovered_masks = []
    for mask, img_info in zip(aug_masks, img_metas):
        flip = img_info[0]['flip']
        flip_direction = img_info[0]['flip_direction']
        if flip:
            if flip_direction == 'horizontal':
                mask = mask[:, :, :, ::-1]
            elif flip_direction == 'vertical':
                mask = mask[:, :, ::-1, :]
            else:
                raise ValueError(
                    f"Invalid flipping direction '{flip_direction}'")
        recovered_masks.append(mask)

    if weights is None:
        merged_masks = np.mean(recovered_masks, axis=0)
    else:
        merged_masks = np.average(
            np.array(recovered_masks), axis=0, weights=np.array(weights))
    return merged_masks
