# Copyright 2017 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.training.evaluation."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import os

import numpy as np

from tensorflow.python.framework import constant_op
from tensorflow.python.framework import dtypes
from tensorflow.python.framework import ops
from tensorflow.python.framework import random_seed
from tensorflow.python.layers import layers
from tensorflow.python.ops import array_ops
from tensorflow.python.ops import math_ops
from tensorflow.python.ops import metrics
from tensorflow.python.ops import state_ops
from tensorflow.python.ops import variable_scope
from tensorflow.python.ops.losses import losses
from tensorflow.python.platform import test
from tensorflow.python.training import basic_session_run_hooks
from tensorflow.python.training import evaluation
from tensorflow.python.training import gradient_descent
from tensorflow.python.training import monitored_session
from tensorflow.python.training import saver
from tensorflow.python.training import training

_USE_GLOBAL_STEP = 0


def logistic_classifier(inputs):
  return layers.dense(inputs, 1, activation=math_ops.sigmoid)


def local_variable(init_value, name):
  return variable_scope.get_variable(
      name,
      dtype=dtypes.float32,
      initializer=init_value,
      trainable=False,
      collections=[ops.GraphKeys.LOCAL_VARIABLES])


class EvaluateOnceTest(test.TestCase):

  def setUp(self):
    super(EvaluateOnceTest, self).setUp()

    # Create an easy training set:
    np.random.seed(0)

    self._inputs = np.zeros((16, 4))
    self._labels = np.random.randint(0, 2, size=(16, 1)).astype(np.float32)

    for i in range(16):
      j = int(2 * self._labels[i] + np.random.randint(0, 2))
      self._inputs[i, j] = 1

  def _train_model(self, checkpoint_dir, num_steps):
    """Trains a simple classification model.

    Note that the data has been configured such that after around 300 steps,
    the model has memorized the dataset (e.g. we can expect %100 accuracy).

    Args:
      checkpoint_dir: The directory where the checkpoint is written to.
      num_steps: The number of steps to train for.
    """
    with ops.Graph().as_default():
      random_seed.set_random_seed(0)
      tf_inputs = constant_op.constant(self._inputs, dtype=dtypes.float32)
      tf_labels = constant_op.constant(self._labels, dtype=dtypes.float32)

      tf_predictions = logistic_classifier(tf_inputs)
      loss_op = losses.log_loss(labels=tf_labels, predictions=tf_predictions)

      optimizer = gradient_descent.GradientDescentOptimizer(learning_rate=1.0)
      train_op = optimizer.minimize(loss_op,
                                    training.get_or_create_global_step())

      with monitored_session.MonitoredTrainingSession(
          checkpoint_dir=checkpoint_dir,
          hooks=[basic_session_run_hooks.StopAtStepHook(num_steps)]) as session:
        loss = None
        while not session.should_stop():
          _, loss = session.run([train_op, loss_op])

        if num_steps >= 300:
          assert loss < .015

  def testEvaluatePerfectModel(self):
    checkpoint_dir = os.path.join(self.get_temp_dir(),
                                  'evaluate_perfect_model_once')

    # Train a Model to completion:
    self._train_model(checkpoint_dir, num_steps=300)

    # Run
    inputs = constant_op.constant(self._inputs, dtype=dtypes.float32)
    labels = constant_op.constant(self._labels, dtype=dtypes.float32)
    logits = logistic_classifier(inputs)
    predictions = math_ops.round(logits)

    accuracy, update_op = metrics.accuracy(
        predictions=predictions, labels=labels)

    checkpoint_path = saver.latest_checkpoint(checkpoint_dir)

    final_ops_values = evaluation._evaluate_once(
        checkpoint_path=checkpoint_path,
        eval_ops=update_op,
        final_ops={'accuracy': accuracy},
        hooks=[evaluation._StopAfterNEvalsHook(1),])
    self.assertTrue(final_ops_values['accuracy'] > .99)

  def testEvalOpAndFinalOp(self):
    checkpoint_dir = os.path.join(self.get_temp_dir(), 'eval_ops_and_final_ops')

    # Train a model for a single step to get a checkpoint.
    self._train_model(checkpoint_dir, num_steps=1)
    checkpoint_path = saver.latest_checkpoint(checkpoint_dir)

    # Create the model so we have something to restore.
    inputs = constant_op.constant(self._inputs, dtype=dtypes.float32)
    logistic_classifier(inputs)

    num_evals = 5
    final_increment = 9.0

    my_var = local_variable(0.0, name='MyVar')
    eval_ops = state_ops.assign_add(my_var, 1.0)
    final_ops = array_ops.identity(my_var) + final_increment

    final_ops_values = evaluation._evaluate_once(
        checkpoint_path=checkpoint_path,
        eval_ops=eval_ops,
        final_ops={'value': final_ops},
        hooks=[evaluation._StopAfterNEvalsHook(num_evals),])
    self.assertEqual(final_ops_values['value'], num_evals + final_increment)

  def testOnlyFinalOp(self):
    checkpoint_dir = os.path.join(self.get_temp_dir(), 'only_final_ops')

    # Train a model for a single step to get a checkpoint.
    self._train_model(checkpoint_dir, num_steps=1)
    checkpoint_path = saver.latest_checkpoint(checkpoint_dir)

    # Create the model so we have something to restore.
    inputs = constant_op.constant(self._inputs, dtype=dtypes.float32)
    logistic_classifier(inputs)

    final_increment = 9.0

    my_var = local_variable(0.0, name='MyVar')
    final_ops = array_ops.identity(my_var) + final_increment

    final_ops_values = evaluation._evaluate_once(
        checkpoint_path=checkpoint_path, final_ops={'value': final_ops})
    self.assertEqual(final_ops_values['value'], final_increment)


if __name__ == '__main__':
  test.main()
