# Copyright (c) 2022 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.
#
# The file has been adapted from the file:
#     https://github.com/laekov/fastmoe/blob/master/fmoe/gates/base_gate.py
#     Git commit hash: 295a615aacce7e54a37e7935274ba15e901c78e4
# We retain the following license from the original files:
#     Copyright 2021, Jiaao He. All rights reserved.
#   Licensed under the Apache License, Version 2.0 (the "License").

import paddle.nn as nn


class BaseGate(nn.Layer):
    def __init__(self, num_expert, group=None):
        super().__init__()
        self.world_size = group.nranks if group is not None else 1
        self.num_expert = num_expert
        self.tot_expert = self.world_size * num_expert
        self.loss = None

    def forward(self, x):
        raise NotImplementedError("Please implement the forward function.")

    def set_loss(self, loss):
        self.loss = loss

    def get_loss(self, clear=True):
        loss = self.loss
        if clear:
            self.loss = None
        return loss
