#copyright (c) 2021 PaddlePaddle Authors. All Rights Reserve.
#
#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.

import paddle
import paddle.nn as nn
import paddle.nn.functional as F

from paddle.nn import L1Loss
from paddle.nn import MSELoss as L2Loss
from paddle.nn import SmoothL1Loss


class DistanceLoss(nn.Layer):
    """
    DistanceLoss:
        mode: loss mode
    """

    def __init__(self, mode="l2", **kargs):
        super().__init__()
        assert mode in ["l1", "l2", "smooth_l1"]
        if mode == "l1":
            self.loss_func = nn.L1Loss(**kargs)
        elif mode == "l2":
            self.loss_func = nn.MSELoss(**kargs)
        elif mode == "smooth_l1":
            self.loss_func = nn.SmoothL1Loss(**kargs)
        self.mode = mode

    def forward(self, x, y):
        loss = self.loss_func(x, y)
        return {"loss_{}".format(self.mode): loss}