<reponame>MaximProshin/nncf
"""
 Copyright (c) 2019-2022 Intel Corporation
 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 typing import Tuple

from nncf.common.graph import NNCFNode
from nncf.common.sparsity.statistics import ConstSparsityStatistics
from nncf.common.statistics import NNCFStatistics
from nncf.torch.compression_method_api import PTCompressionAlgorithmController
from nncf.torch.nncf_network import NNCFNetwork
from nncf.torch.sparsity.layers import BinaryMask
from nncf.torch.sparsity.base_algo import BaseSparsityAlgoBuilder, BaseSparsityAlgoController
from nncf.torch.sparsity.collector import PTSparseModelStatisticsCollector
from nncf.torch.algo_selector import PT_COMPRESSION_ALGORITHMS


@PT_COMPRESSION_ALGORITHMS.register('const_sparsity')
class ConstSparsityBuilder(BaseSparsityAlgoBuilder):
    def create_weight_sparsifying_operation(self, target_module_node: NNCFNode, compression_lr_multiplier: float):
        return BinaryMask(target_module_node.layer_attributes.get_weight_shape())

    def _build_controller(self, model: NNCFNetwork) -> PTCompressionAlgorithmController:
        return ConstSparsityController(model, self._sparsified_module_info)

    def _are_frozen_layers_allowed(self) -> Tuple[bool, str]:
        return True, 'Frozen layers are allowed for const sparsity'


class ConstSparsityController(BaseSparsityAlgoController):
    def freeze(self):
        pass

    def set_sparsity_level(self, sparsity_level: float):
        pass

    def statistics(self, quickly_collected_only: bool = False) -> NNCFStatistics:
        collector = PTSparseModelStatisticsCollector(self.model, self.sparsified_module_info)
        model_statistics = collector.collect()
        stats = ConstSparsityStatistics(model_statistics)

        nncf_stats = NNCFStatistics()
        nncf_stats.register('const_sparsity', stats)
        return nncf_stats
