# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from ppdet.core.workspace import register, create
from .meta_arch import BaseArch
import paddle
import paddle.nn.functional as F

__all__ = ['RetinaNet']


@register
class RetinaNet(BaseArch):
    __category__ = 'architecture'

    def __init__(self, backbone, neck, head):
        super(RetinaNet, self).__init__()
        self.backbone = backbone
        self.neck = neck
        self.head = head

    @classmethod
    def from_config(cls, cfg, *args, **kwargs):
        backbone = create(cfg['backbone'])

        kwargs = {'input_shape': backbone.out_shape}
        neck = create(cfg['neck'], **kwargs)

        kwargs = {'input_shape': neck.out_shape}
        head = create(cfg['head'], **kwargs)

        return {
            'backbone': backbone,
            'neck': neck,
            'head': head,
        }

    def _forward(self):
        body_feats = self.backbone(self.inputs)
        neck_feats = self.neck(body_feats)

        if self.training:
            return self.head(neck_feats, self.inputs)
        else:
            head_outs = self.head(neck_feats)
            bbox, bbox_num, nms_keep_idx = self.head.post_process(
                head_outs, self.inputs['im_shape'], self.inputs['scale_factor'])

            if self.use_extra_data:
                extra_data = {}  # record the bbox output before nms, such like scores and nms_keep_idx
                """extra_data:{
                            'scores': predict scores,
                            'nms_keep_idx': bbox index before nms,
                           }
                           """
                preds_logits = self.head.decode_cls_logits(head_outs[0])
                preds_scores = F.sigmoid(preds_logits)
                extra_data['logits'] = preds_logits
                extra_data['scores'] = preds_scores
                extra_data['nms_keep_idx'] = nms_keep_idx  # bbox index before nms
                return {'bbox': bbox, 'bbox_num': bbox_num, "extra_data": extra_data}
            else:
                return {'bbox': bbox, 'bbox_num': bbox_num}

    def get_loss(self):
        return self._forward()

    def get_pred(self):
        return self._forward()
