# Copyright 2016 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.
# ==============================================================================
"""Tests for tf.keras models with callbacks, checkpointing with dist strategy."""

import tensorflow.compat.v2 as tf

import collections
import tempfile

from absl.testing import parameterized
import numpy as np

import keras
from keras import losses
from keras.distribute import distribute_strategy_test as keras_test_lib
from keras.distribute import distributed_training_utils_v1
from keras.distribute import optimizer_combinations


class Counter(keras.callbacks.Callback):
  """Counts the number of times each callback method was run.

  Attributes:
    method_counts: dict. Contains the counts of time  each callback method was
      run.
  """

  def __init__(self):
    self.method_counts = collections.defaultdict(int)
    methods_to_count = [
        'on_batch_begin', 'on_batch_end', 'on_epoch_begin', 'on_epoch_end',
        'on_predict_batch_begin', 'on_predict_batch_end', 'on_predict_begin',
        'on_predict_end', 'on_test_batch_begin', 'on_test_batch_end',
        'on_test_begin', 'on_test_end', 'on_train_batch_begin',
        'on_train_batch_end', 'on_train_begin', 'on_train_end'
    ]
    for method_name in methods_to_count:
      setattr(self, method_name,
              self.wrap_with_counts(method_name, getattr(self, method_name)))

  def wrap_with_counts(self, method_name, method):

    def _call_and_count(*args, **kwargs):
      self.method_counts[method_name] += 1
      return method(*args, **kwargs)

    return _call_and_count


class TestDistributionStrategyWithCallbacks(tf.test.TestCase,
                                            parameterized.TestCase):

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.all_strategy_combinations()))
  def test_callbacks_in_fit(self, distribution):
    with distribution.scope():
      model = keras_test_lib.get_model()
      model.compile(
          optimizer='sgd',
          loss='mse',
          metrics=['mae'])

    dataset = keras_test_lib.get_dataset(distribution)
    counter = Counter()

    epochs = 2
    steps_per_epoch = 5
    validation_steps = 3

    model.fit(
        dataset,
        epochs=epochs,
        steps_per_epoch=steps_per_epoch,
        verbose=0,
        validation_data=dataset,
        validation_steps=validation_steps,
        callbacks=[counter])

    if (isinstance(distribution, tf.compat.v1.distribute.experimental.TPUStrategy) and
        not tf.executing_eagerly()):
      # TPU Strategy can have multi step training, from extended.steps_per_run
      # if steps_per_run = 1, then num_batch_call_per_epoch = steps_per_epoch
      steps_per_run = distribution.extended.steps_per_run
      num_batch_call_per_epoch = steps_per_epoch // steps_per_run
      if steps_per_epoch % steps_per_run:
        num_batch_call_per_epoch += 1
    else:
      num_batch_call_per_epoch = steps_per_epoch

    self.assertDictEqual(
        counter.method_counts, {
            'on_batch_begin': epochs * num_batch_call_per_epoch,
            'on_batch_end': epochs * num_batch_call_per_epoch,
            'on_epoch_begin': epochs,
            'on_epoch_end': epochs,
            'on_test_batch_begin': epochs * validation_steps,
            'on_test_batch_end': epochs * validation_steps,
            'on_test_begin': epochs,
            'on_test_end': epochs,
            'on_train_batch_begin': epochs * num_batch_call_per_epoch,
            'on_train_batch_end': epochs * num_batch_call_per_epoch,
            'on_train_begin': 1,
            'on_train_end': 1
        })

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.all_strategy_combinations()))
  def test_callbacks_in_eval(self, distribution):
    with distribution.scope():
      model = keras_test_lib.get_model()
      model.compile(
          optimizer='sgd',
          loss='mse',
          metrics=['mae'])

    dataset = keras_test_lib.get_dataset(distribution)
    counter = Counter()

    model.evaluate(dataset, steps=5, callbacks=[counter])

    self.assertDictEqual(
        counter.method_counts, {
            'on_test_batch_begin': 5,
            'on_test_batch_end': 5,
            'on_test_begin': 1,
            'on_test_end': 1
        })

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.all_strategy_combinations()))
  def test_callbacks_in_predict(self, distribution):
    with distribution.scope():
      model = keras_test_lib.get_model()
      model.compile(
          optimizer='sgd',
          loss='mse',
          metrics=['mae'])

    dataset = keras_test_lib.get_dataset(distribution)
    counter = Counter()

    model.predict(
        keras_test_lib.get_predict_dataset(dataset),
        steps=5,
        callbacks=[counter])

    self.assertDictEqual(
        counter.method_counts, {
            'on_predict_batch_begin': 5,
            'on_predict_batch_end': 5,
            'on_predict_begin': 1,
            'on_predict_end': 1
        })


class TestDistributionStrategyErrorCases(tf.test.TestCase, parameterized.TestCase):

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
          ],
          mode=['graph']))
  def test_validating_dataset_input_tensors_with_shape_mismatch(
      self, distribution):
    with self.cached_session():
      a = tf.constant([1, 2], shape=(1, 2))
      b = tf.constant([[1, 2], [1, 2]], shape=(2, 2))
      x = tf.distribute.DistributedValues((a, b))
      y = tf.distribute.DistributedValues((a, a))
      # Removed device and input tensor shape details from the error message
      # since the order of the device and the corresponding input tensor shape
      # is not deterministic over different runs.
      with self.assertRaisesRegex(
          ValueError, 'Input tensor shapes do not match for '
          'distributed tensor inputs '
          'DistributedValues:.+'):
        with distribution.scope():
          distributed_training_utils_v1.validate_distributed_dataset_inputs(
              distribution, x, y)

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
          ],
          mode=['graph', 'eager']))
  def test_validating_dataset_input_tensors_with_dtype_mismatch(
      self, distribution):
    with self.cached_session():
      a = tf.constant([1, 2], shape=(1, 2), dtype=tf.int32)
      b = tf.constant([1, 2], shape=(1, 2), dtype=tf.float64)
      x = tf.distribute.DistributedValues((a, b))
      y = tf.distribute.DistributedValues((a, a))
      # Removed device and input tensor dtype details from the error message
      # since the order of the device and the corresponding input tensor dtype
      # is not deterministic over different runs.
      with self.assertRaisesRegex(
          ValueError, 'Input tensor dtypes do not match for '
          'distributed tensor inputs '
          'DistributedValues:.+'):
        with distribution.scope():
          distributed_training_utils_v1.validate_distributed_dataset_inputs(
              distribution, x, y)

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
          ],
          mode=['graph', 'eager']))
  def test_unsupported_features(self, distribution, mode):
    with self.cached_session():
      with distribution.scope():
        model = keras_test_lib.get_model()
        optimizer = tf.compat.v1.train.GradientDescentOptimizer(0.001)
        loss = 'mse'
        metrics = ['mae']
        model.compile(
            optimizer,
            loss,
            metrics=metrics)

      dataset = keras_test_lib.get_dataset(distribution)
      # Test with validation split
      with self.assertRaises(ValueError):
        model.fit(
            dataset,
            epochs=1,
            steps_per_epoch=2,
            verbose=0,
            validation_split=0.5,
            validation_steps=2)

      # Test with sample weight.
      sample_weight = np.random.random((10,))
      with self.assertRaises(ValueError):
        model.fit(
            dataset,
            epochs=1,
            steps_per_epoch=2,
            verbose=0,
            sample_weight=sample_weight)

      # Test with not specifying the `steps` argument for dataset with infinite
      # cardinality.
      dataset = dataset.repeat()
      with self.assertRaises(ValueError):
        model.fit(dataset, epochs=1, verbose=0)
      with self.assertRaises(ValueError):
        model.evaluate(dataset, verbose=0)

      with self.assertRaises(ValueError):
        model.predict(dataset, verbose=0)

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
              tf.__internal__.distribute.combinations.one_device_strategy,
          ],
          mode=['graph', 'eager']))
  def test_distribution_strategy_on_subclassed_model(
      self, distribution):
    with distribution.scope():

      class _SimpleMLP(keras.Model):

        def __init__(self, num_labels):
          super(_SimpleMLP, self).__init__()
          self.dense = keras.layers.Dense(num_labels)

        def call(self, inputs):
          return self.dense(inputs)

      model = _SimpleMLP(3)

      if not tf.executing_eagerly():
        with self.assertRaisesRegex(
            ValueError,
            'We currently do not support distribution strategy with a '
            '`Sequential` model that is created without `input_shape`/'
            '`input_dim` set in its first layer or a subclassed model.'):
          model.compile(
              'sgd')
      else:
        model.compile(
            'sgd')

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
              tf.__internal__.distribute.combinations.one_device_strategy,
          ],
          mode=['graph', 'eager']))
  def test_distribution_strategy_on_deferred_sequential_model(
      self, distribution):
    with distribution.scope():
      model = keras.models.Sequential()
      model.add(keras.layers.Dense(16, activation='relu'))
      model.add(keras.layers.Dense(3, activation='softmax'))

      if tf.executing_eagerly():
        model.compile(
            'sgd')
      else:
        with self.assertRaisesRegex(
            ValueError,
            'We currently do not support distribution strategy with a '
            '`Sequential` model that is created without '
            '`input_shape`/`input_dim` set in its first layer or '
            'a subclassed model.'):
          model.compile(
              'sgd')

  @tf.__internal__.distribute.combinations.generate(
      keras_test_lib.all_strategy_combinations_minus_default())
  def test_standalone_loss_without_loss_reduction(self, distribution):
    with distribution.scope():
      loss_object = losses.MeanSquaredError()

      with self.assertRaisesRegex(
          ValueError, 'Please use `tf.keras.losses.Reduction.SUM` or '
          '`tf.keras.losses.Reduction.NONE`'):
        y = np.asarray([1, 0])
        loss_object(y, y)


class TestDistributionStrategyWithLossMasking(tf.test.TestCase,
                                              parameterized.TestCase):

  # TODO(priyag): Enable all strategies for this test. Currently it does not
  # work for TPU due to some invalid datatype.
  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
          ],
          mode=['graph', 'eager'],
          optimizer=optimizer_combinations
          .gradient_descent_optimizer_keras_v2_fn
      ))
  def test_masking(self, distribution, optimizer):
    with self.cached_session():
      np.random.seed(1337)
      x = np.array([[[1], [1]], [[0], [0]]])
      with distribution.scope():
        model = keras.models.Sequential()
        model.add(keras.layers.Masking(mask_value=0, input_shape=(2, 1)))
        model.add(
            keras.layers.TimeDistributed(
                keras.layers.Dense(1, kernel_initializer='one')))
        model.compile(
            loss='mse',
            optimizer=optimizer())
      y = np.array([[[1], [1]], [[1], [1]]])
      dataset = tf.data.Dataset.from_tensor_slices((x, y))
      dataset = dataset.repeat(100)
      dataset = dataset.batch(10)
      hist = model.fit(x=dataset, epochs=1, steps_per_epoch=2)
      self.assertEqual(hist.history['loss'][0], 0)


class TestDistributionStrategyWithNormalizationLayer(tf.test.TestCase,
                                                     parameterized.TestCase):

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.all_strategy_combinations(),
          tf.__internal__.test.combinations.combine(
              fused=[True, False],
              optimizer=optimizer_combinations
              .gradient_descent_optimizer_keras_v2_fn)))
  def test_batchnorm_correctness(self, distribution, fused, optimizer):
    with self.cached_session():
      with distribution.scope():
        model = keras.models.Sequential()
        norm = keras.layers.BatchNormalization(
            input_shape=(
                10,
                20,
                30,
            ), momentum=0.8, fused=fused)
        model.add(norm)
        model.compile(
            loss='mse',
            optimizer=optimizer())

      # centered on 5.0, variance 10.0
      x = np.random.normal(loc=5.0, scale=10.0, size=(1000, 10, 20, 30))
      x = x.astype('float32')
      dataset = tf.data.Dataset.from_tensor_slices((x, x))
      dataset = dataset.repeat(100)
      dataset = keras_test_lib.batch_wrapper(dataset, 32, distribution)

      predict_dataset = tf.data.Dataset.from_tensor_slices(x)
      predict_dataset = predict_dataset.repeat(100)
      predict_dataset = keras_test_lib.batch_wrapper(predict_dataset, 32,
                                                     distribution)

      model.fit(dataset, epochs=4, verbose=0, steps_per_epoch=10)
      out = model.predict(predict_dataset, steps=2)
      out -= keras.backend.eval(norm.beta)
      out /= keras.backend.eval(norm.gamma)
      np.testing.assert_allclose(out.mean(), 0.0, atol=1e-1)
      np.testing.assert_allclose(out.std(), 1.0, atol=1e-1)

# TODO(b/146181571): Enable this for all distribution strategies once
# DistributedVariable.assign() returns a variable for MirroredStrategy.
  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.tpu_strategy_combinations(),
          tf.__internal__.test.combinations.combine(
              optimizer=optimizer_combinations
              .gradient_descent_optimizer_keras_v2_fn)))
  def test_batchnorm_correctness_with_renorm(self, distribution, optimizer):
    with self.cached_session():
      with distribution.scope():
        model = keras.models.Sequential()
        norm = keras.layers.BatchNormalization(
            input_shape=(
                10,
                20,
                30,
            ), momentum=0.8, fused=False, renorm=True)
        model.add(norm)
        model.compile(
            loss='mse',
            optimizer=optimizer())

      # centered on 5.0, variance 10.0
      x = np.random.normal(loc=5.0, scale=10.0, size=(1000, 10, 20, 30))
      x = x.astype('float32')
      dataset = tf.data.Dataset.from_tensor_slices((x, x))
      dataset = dataset.repeat(100)
      dataset = keras_test_lib.batch_wrapper(dataset, 32, distribution)

      predict_dataset = tf.data.Dataset.from_tensor_slices(x)
      predict_dataset = predict_dataset.repeat(100)
      predict_dataset = keras_test_lib.batch_wrapper(predict_dataset, 32,
                                                     distribution)

      model.fit(dataset, epochs=4, verbose=0, steps_per_epoch=10)
      out = model.predict(predict_dataset, steps=2)
      out -= keras.backend.eval(norm.beta)
      out /= keras.backend.eval(norm.gamma)
      np.testing.assert_allclose(out.mean(), 0.0, atol=1e-1)
      np.testing.assert_allclose(out.std(), 1.0, atol=1e-1)


class TestDistributionStrategySaveLoadWeights(tf.test.TestCase,
                                              parameterized.TestCase):

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.all_strategy_combinations_minus_default(),
          tf.__internal__.test.combinations.combine(
              optimizer=optimizer_combinations.rmsprop_optimizer_keras_v2_fn)))
  def test_save_load_h5(self, distribution, optimizer):
    with self.cached_session():
      dataset = keras_test_lib.get_dataset(distribution)
      with distribution.scope():
        model = keras_test_lib.get_model()
        model.compile(
            optimizer(),
            'mse')
        model.fit(dataset, epochs=1, steps_per_epoch=1)

        weights_file = tempfile.mktemp('.h5')
        model.save_weights(weights_file)

        model_2 = keras_test_lib.get_model()
        model_2.compile(
            optimizer(),
            'mse')
        model_2.load_weights(weights_file)
        model_2.predict(
            keras_test_lib.get_predict_dataset(distribution), steps=2)
        model_2.fit(dataset, epochs=1, steps_per_epoch=1)

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.all_strategy_combinations_minus_default(),
          tf.__internal__.test.combinations.combine(
              optimizer=optimizer_combinations.rmsprop_optimizer_keras_v2_fn)))
  def test_save_load_trackable(self, distribution, optimizer):
    # TODO(b/123533246): Enable the test for TPU once bug is fixed
    if (isinstance(distribution,
                   (tf.distribute.experimental.TPUStrategy, tf.compat.v1.distribute.experimental.TPUStrategy)) and
        distribution.extended.steps_per_run > 1):
      self.skipTest('MultiStep TPU Strategy deadlocks with optimizer restore.')
    with self.cached_session():
      dataset = keras_test_lib.get_dataset(distribution)
      with distribution.scope():
        model = keras_test_lib.get_model()
        model.compile(
            optimizer(),
            'mse')
        model.fit(dataset, epochs=1, steps_per_epoch=1)

        weights_file = tempfile.mktemp()
        model.save_weights(weights_file)

        model_2 = keras_test_lib.get_model()
        model_2.compile(
            optimizer(),
            'mse')
        model_2.load_weights(weights_file)
        model_2.predict(
            keras_test_lib.get_predict_dataset(distribution), steps=2)
        model_2.fit(dataset, epochs=1, steps_per_epoch=1)


class TestDistributionStrategyValidation(tf.test.TestCase, parameterized.TestCase):

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.times(
          keras_test_lib.all_strategy_combinations_minus_default()))
  def test_layer_outside_scope(self, distribution):
    with self.cached_session():
      with self.assertRaisesRegex(
          ValueError, 'was not created in the distribution strategy'):
        x = keras.layers.Input(shape=(3,), name='input')
        y = keras.layers.Dense(4, name='dense')(x)
        with distribution.scope():
          model = keras.Model(x, y)
          optimizer = tf.compat.v1.train.GradientDescentOptimizer(0.001)
          loss = 'mse'
          metrics = ['mae', keras.metrics.CategoricalAccuracy()]
          model.compile(
              optimizer,
              loss,
              metrics=metrics)

  @tf.__internal__.distribute.combinations.generate(
      keras_test_lib.all_strategy_combinations_minus_default())
  def test_model_outside_scope(self, distribution):
    with self.cached_session():
      with self.assertRaisesRegex(
          ValueError, 'was not created in the distribution strategy'):
        x = keras.layers.Input(shape=(3,), name='input')
        y = keras.layers.Dense(4, name='dense')(x)
        model = keras.Model(x, y)
        with distribution.scope():
          optimizer = tf.compat.v1.train.GradientDescentOptimizer(0.001)
          loss = 'mse'
          metrics = ['mae', keras.metrics.CategoricalAccuracy()]
          model.compile(optimizer, loss, metrics=metrics)


class TestDistributionStrategyWithStaticShapes(tf.test.TestCase,
                                               parameterized.TestCase):

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
          ],
          mode=['graph', 'eager']))
  def test_input_batch_size_not_divisible_by_num_replicas(self, distribution):
    with distribution.scope():
      with self.assertRaisesRegex(
          ValueError, r'The `batch_size` argument \(5\) must be divisible by '
          r'the number of replicas \(2\)'):
        keras.layers.Input(shape=(3,), batch_size=5, name='input')

  @tf.__internal__.distribute.combinations.generate(
      tf.__internal__.test.combinations.combine(
          distribution=[
              tf.__internal__.distribute.combinations.mirrored_strategy_with_gpu_and_cpu,
          ],
          mode=['graph', 'eager']))
  def test_static_input_batch_size(self, distribution):
    inputs = np.zeros((10, 3), dtype=np.float32)
    targets = np.zeros((10, 4), dtype=np.float32)
    dataset = tf.data.Dataset.from_tensor_slices((inputs, targets))
    dataset = dataset.repeat(100)
    dataset = dataset.batch(10, drop_remainder=True)

    with distribution.scope():
      x = keras.layers.Input(shape=(3,), batch_size=10, name='input')
      y = keras.layers.Dense(4, name='dense')(x)
      model = keras.Model(x, y)
      model.compile(optimizer='sgd', loss='mse', metrics=['mae'])

    model.fit(dataset, epochs=1, steps_per_epoch=5)
    model.evaluate(dataset, steps=5)
    model.predict(dataset)


if __name__ == '__main__':
  tf.__internal__.distribute.multi_process_runner.test_main()
