# Copyright 2022 The TensorFlow 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,
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# See the License for the specific language governing permissions and
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"""Quantization helpers."""
from typing import Any, Dict

import tensorflow as tf
import tensorflow_model_optimization as tfmot


class LayerQuantizerHelper(object):
  """Helper class that handles quantizers."""

  def __init__(self, *args, **kwargs):
    self._quantizers = {}
    self._quantizer_vars = {}
    super().__init__(*args, **kwargs)

  def _all_value_quantizer(self):
    return tfmot.quantization.keras.quantizers.AllValuesQuantizer(
        num_bits=8, per_axis=False, symmetric=False, narrow_range=False)

  def _moving_average_quantizer(self):
    return tfmot.quantization.keras.quantizers.MovingAverageQuantizer(
        num_bits=8, per_axis=False, symmetric=False, narrow_range=False)

  def _add_quantizer(self, name, all_value_quantizer=False):
    if all_value_quantizer:
      self._quantizers[name] = self._all_value_quantizer()
    else:
      self._quantizers[name] = self._moving_average_quantizer()

  def _apply_quantizer(self, name, inputs, training, **kwargs):
    return self._quantizers[name](
        inputs, training, self._quantizer_vars[name], **kwargs)

  def _build_quantizer_vars(self):
    for name in self._quantizers:
      self._quantizer_vars[name] = self._quantizers[name].build(
          tensor_shape=None, name=name, layer=self)


class NoOpActivation:
  """No-op activation which simply returns the incoming tensor.

  This activation is required to distinguish between `keras.activations.linear`
  which does the same thing. The main difference is that NoOpActivation should
  not have any quantize operation applied to it.
  """

  def __call__(self, x: tf.Tensor) -> tf.Tensor:
    return x

  def get_config(self) -> Dict[str, Any]:
    """Get a config of this object."""
    return {}

  def __eq__(self, other: Any) -> bool:
    if not other or not isinstance(other, NoOpActivation):
      return False

    return True

  def __ne__(self, other: Any) -> bool:
    return not self.__eq__(other)


def quantize_wrapped_layer(cls, quantize_config):

  def constructor(*arg, **kwargs):
    return tfmot.quantization.keras.QuantizeWrapperV2(
        cls(*arg, **kwargs), quantize_config)

  return constructor