# Copyright 2018 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,
# 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.
# ==============================================================================
"""A simple network to use in tests and examples."""

import tensorflow.compat.v2 as tf

from keras.legacy_tf_layers import core
from keras.legacy_tf_layers import normalization
from keras.optimizers.legacy import optimizer_v2


def minimize_loss_example(optimizer, use_bias=False, use_callable_loss=True):
    """Example of non-distribution-aware legacy code."""

    def dataset_fn():
        dataset = tf.data.Dataset.from_tensors([[1.0]]).repeat()
        # TODO(isaprykin): batch with drop_remainder causes shapes to be
        # fully defined for TPU.  Remove this when XLA supports dynamic shapes.
        return dataset.batch(1, drop_remainder=True)

    layer = core.Dense(1, use_bias=use_bias)

    def model_fn(x):
        """A very simple model written by the user."""

        def loss_fn():
            y = tf.reshape(layer(x), []) - tf.constant(1.0)
            return y * y

        if isinstance(optimizer, optimizer_v2.OptimizerV2):
            return optimizer.minimize(
                loss_fn, lambda: layer.trainable_variables
            )
        elif use_callable_loss:
            return optimizer.minimize(loss_fn)
        else:
            return optimizer.minimize(loss_fn())

    return model_fn, dataset_fn, layer


def batchnorm_example(
    optimizer_fn,
    batch_per_epoch=1,
    momentum=0.9,
    renorm=False,
    update_ops_in_replica_mode=False,
):
    """Example of non-distribution-aware legacy code with batch
    normalization."""

    def dataset_fn():
        # input shape is [16, 8], input values are increasing in both
        # dimensions.
        return tf.data.Dataset.from_tensor_slices(
            [
                [
                    [float(x * 8 + y + z * 100) for y in range(8)]
                    for x in range(16)
                ]
                for z in range(batch_per_epoch)
            ]
        ).repeat()

    optimizer = optimizer_fn()
    batchnorm = normalization.BatchNormalization(
        renorm=renorm, momentum=momentum, fused=False
    )
    layer = core.Dense(1, use_bias=False)

    def model_fn(x):
        """A model that uses batchnorm."""

        def loss_fn():
            y = batchnorm(x, training=True)
            with tf.control_dependencies(
                tf.compat.v1.get_collection(tf.compat.v1.GraphKeys.UPDATE_OPS)
                if update_ops_in_replica_mode
                else []
            ):
                loss = tf.reduce_mean(
                    tf.reduce_sum(layer(y)) - tf.constant(1.0)
                )
            # `x` and `y` will be fetched by the gradient computation, but not
            # `loss`.
            return loss

        if isinstance(optimizer, optimizer_v2.OptimizerV2):
            return optimizer.minimize(
                loss_fn, lambda: layer.trainable_variables
            )

        # Callable loss.
        return optimizer.minimize(loss_fn)

    return model_fn, dataset_fn, batchnorm