# 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.

from .hook import Hook
from .builder import HOOKS


@HOOKS.register()
class OptimizerHook(Hook):
    def __init__(self, priority=1):
        self.priority = priority
        
    def train_iter_end(self, trainer):
        for i_opt in range(len(trainer.optimizer)):
            trainer.optimizer[i_opt].clear_grad()

        loss = 0
        for key, value in trainer.outputs.items():
            if 'loss' in key:
                loss += value
        loss.backward()
        
        for i_opt in range(len(trainer.optimizer)):
            trainer.optimizer[i_opt].step()

        if 'loss' not in trainer.outputs:
            trainer.outputs['loss'] = loss
