# Copyright 2019, The TensorFlow Authors.
#
# 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 QuantileAdaptiveClipSumQuery."""

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

from absl.testing import parameterized

import numpy as np
import tensorflow.compat.v1 as tf

from tensorflow_privacy.privacy.dp_query import quantile_adaptive_clip_sum_query
from tensorflow_privacy.privacy.dp_query import test_utils

tf.enable_eager_execution()


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

  def test_sum_no_clip_no_noise(self):
    record1 = tf.constant([2.0, 0.0])
    record2 = tf.constant([-1.0, 1.0])

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=10.0,
        noise_multiplier=0.0,
        target_unclipped_quantile=1.0,
        learning_rate=0.0,
        clipped_count_stddev=0.0,
        expected_num_records=2.0)
    query_result, _ = test_utils.run_query(query, [record1, record2])
    result = query_result.numpy()
    expected = [1.0, 1.0]
    self.assertAllClose(result, expected)

  def test_sum_with_clip_no_noise(self):
    record1 = tf.constant([-6.0, 8.0])  # Clipped to [-3.0, 4.0].
    record2 = tf.constant([4.0, -3.0])  # Not clipped.

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=5.0,
        noise_multiplier=0.0,
        target_unclipped_quantile=1.0,
        learning_rate=0.0,
        clipped_count_stddev=0.0,
        expected_num_records=2.0)

    query_result, _ = test_utils.run_query(query, [record1, record2])
    result = query_result.numpy()
    expected = [1.0, 1.0]
    self.assertAllClose(result, expected)

  def test_sum_with_noise(self):
    record1, record2 = 2.71828, 3.14159
    stddev = 1.0
    clip = 5.0

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=clip,
        noise_multiplier=stddev / clip,
        target_unclipped_quantile=1.0,
        learning_rate=0.0,
        clipped_count_stddev=0.0,
        expected_num_records=2.0)

    noised_sums = []
    for _ in range(1000):
      query_result, _ = test_utils.run_query(query, [record1, record2])
      noised_sums.append(query_result.numpy())

    result_stddev = np.std(noised_sums)
    self.assertNear(result_stddev, stddev, 0.1)

  def test_adaptation_target_zero(self):
    record1 = tf.constant([8.5])
    record2 = tf.constant([-7.25])

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=10.0,
        noise_multiplier=0.0,
        target_unclipped_quantile=0.0,
        learning_rate=1.0,
        clipped_count_stddev=0.0,
        expected_num_records=2.0,
        geometric_update=False)

    global_state = query.initial_global_state()

    initial_clip = global_state.sum_state.l2_norm_clip
    self.assertAllClose(initial_clip, 10.0)

    # On the first two iterations, nothing is clipped, so the clip goes down
    # by 1.0 (the learning rate). When the clip reaches 8.0, one record is
    # clipped, so the clip goes down by only 0.5. After two more iterations,
    # both records are clipped, and the clip norm stays there (at 7.0).

    expected_sums = [1.25, 1.25, 0.75, 0.25, 0.0]
    expected_clips = [9.0, 8.0, 7.5, 7.0, 7.0]
    for expected_sum, expected_clip in zip(expected_sums, expected_clips):
      actual_sum, global_state = test_utils.run_query(query, [record1, record2],
                                                      global_state)

      actual_clip = global_state.sum_state.l2_norm_clip

      self.assertAllClose(actual_clip.numpy(), expected_clip)
      self.assertAllClose(actual_sum.numpy(), (expected_sum,))

  def test_adaptation_target_zero_geometric(self):
    record1 = tf.constant([5.0])
    record2 = tf.constant([-2.5])

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=16.0,
        noise_multiplier=0.0,
        target_unclipped_quantile=0.0,
        learning_rate=np.log(2.0),  # Geometric steps in powers of 2.
        clipped_count_stddev=0.0,
        expected_num_records=2.0,
        geometric_update=True)

    global_state = query.initial_global_state()

    initial_clip = global_state.sum_state.l2_norm_clip
    self.assertAllClose(initial_clip, 16.0)

    # For two iterations, nothing is clipped, so the clip is cut in half.
    # Then one record is clipped, so the clip goes down by only sqrt(2.0) to
    # 4 / sqrt(2.0). Still only one record is clipped, so it reduces to 2.0.
    # Now both records are clipped, and the clip norm stays there (at 2.0).

    four_div_root_two = 4 / np.sqrt(2.0)  # approx 2.828

    expected_sums = [2.5, 2.5, 1.5, four_div_root_two - 2.5, 0.0]
    expected_clips = [8.0, 4.0, four_div_root_two, 2.0, 2.0]
    for expected_sum, expected_clip in zip(expected_sums, expected_clips):
      actual_sum, global_state = test_utils.run_query(query, [record1, record2],
                                                      global_state)

      actual_clip = global_state.sum_state.l2_norm_clip

      self.assertAllClose(actual_clip.numpy(), expected_clip)
      self.assertAllClose(actual_sum.numpy(), (expected_sum,))

  def test_adaptation_target_one(self):
    record1 = tf.constant([-1.5])
    record2 = tf.constant([2.75])

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=0.0,
        noise_multiplier=0.0,
        target_unclipped_quantile=1.0,
        learning_rate=1.0,
        clipped_count_stddev=0.0,
        expected_num_records=2.0,
        geometric_update=False)

    global_state = query.initial_global_state()

    initial_clip = global_state.sum_state.l2_norm_clip
    self.assertAllClose(initial_clip, 0.0)

    # On the first two iterations, both are clipped, so the clip goes up
    # by 1.0 (the learning rate). When the clip reaches 2.0, only one record is
    # clipped, so the clip goes up by only 0.5. After two more iterations,
    # both records are clipped, and the clip norm stays there (at 3.0).

    expected_sums = [0.0, 0.0, 0.5, 1.0, 1.25]
    expected_clips = [1.0, 2.0, 2.5, 3.0, 3.0]
    for expected_sum, expected_clip in zip(expected_sums, expected_clips):
      actual_sum, global_state = test_utils.run_query(query, [record1, record2],
                                                      global_state)

      actual_clip = global_state.sum_state.l2_norm_clip

      self.assertAllClose(actual_clip.numpy(), expected_clip)
      self.assertAllClose(actual_sum.numpy(), (expected_sum,))

  def test_adaptation_target_one_geometric(self):
    record1 = tf.constant([-1.5])
    record2 = tf.constant([3.0])

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=0.5,
        noise_multiplier=0.0,
        target_unclipped_quantile=1.0,
        learning_rate=np.log(2.0),  # Geometric steps in powers of 2.
        clipped_count_stddev=0.0,
        expected_num_records=2.0,
        geometric_update=True)

    global_state = query.initial_global_state()

    initial_clip = global_state.sum_state.l2_norm_clip
    self.assertAllClose(initial_clip, 0.5)

    # On the first two iterations, both are clipped, so the clip is doubled.
    # When the clip reaches 2.0, only one record is clipped, so the clip is
    # multiplied by sqrt(2.0). Still only one is clipped so it increases to 4.0.
    # Now both records are clipped, and the clip norm stays there (at 4.0).

    two_times_root_two = 2 * np.sqrt(2.0)  # approx 2.828

    expected_sums = [0.0, 0.0, 0.5, two_times_root_two - 1.5, 1.5]
    expected_clips = [1.0, 2.0, two_times_root_two, 4.0, 4.0]
    for expected_sum, expected_clip in zip(expected_sums, expected_clips):
      actual_sum, global_state = test_utils.run_query(query, [record1, record2],
                                                      global_state)

      actual_clip = global_state.sum_state.l2_norm_clip

      self.assertAllClose(actual_clip.numpy(), expected_clip)
      self.assertAllClose(actual_sum.numpy(), (expected_sum,))

  @parameterized.named_parameters(('start_low_arithmetic', True, False),
                                  ('start_low_geometric', True, True),
                                  ('start_high_arithmetic', False, False),
                                  ('start_high_geometric', False, True))
  def test_adaptation_linspace(self, start_low, geometric):
    # `num_records` records equally spaced from 0 to 10 in 0.1 increments.
    # Test that we converge to the correct median value and bounce around it.
    num_records = 21
    records = [
        tf.constant(x)
        for x in np.linspace(0.0, 10.0, num=num_records, dtype=np.float32)
    ]

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=(1.0 if start_low else 10.0),
        noise_multiplier=0.0,
        target_unclipped_quantile=0.5,
        learning_rate=1.0,
        clipped_count_stddev=0.0,
        expected_num_records=num_records,
        geometric_update=geometric)

    global_state = query.initial_global_state()

    for t in range(50):
      _, global_state = test_utils.run_query(query, records, global_state)

      actual_clip = global_state.sum_state.l2_norm_clip

      if t > 40:
        self.assertNear(actual_clip, 5.0, 0.25)

  @parameterized.named_parameters(('start_low_arithmetic', True, False),
                                  ('start_low_geometric', True, True),
                                  ('start_high_arithmetic', False, False),
                                  ('start_high_geometric', False, True))
  def test_adaptation_all_equal(self, start_low, geometric):
    # `num_records` equal records. Test that we converge to that record and
    # bounce around it. Unlike the linspace test, the quantile-matching
    # objective is very sharp at the optimum so a decaying learning rate is
    # necessary.
    num_records = 20
    records = [tf.constant(5.0)] * num_records

    learning_rate = tf.Variable(1.0)

    query = quantile_adaptive_clip_sum_query.QuantileAdaptiveClipSumQuery(
        initial_l2_norm_clip=(1.0 if start_low else 10.0),
        noise_multiplier=0.0,
        target_unclipped_quantile=0.5,
        learning_rate=learning_rate,
        clipped_count_stddev=0.0,
        expected_num_records=num_records,
        geometric_update=geometric)

    global_state = query.initial_global_state()

    for t in range(50):
      tf.assign(learning_rate, 1.0 / np.sqrt(t + 1))
      _, global_state = test_utils.run_query(query, records, global_state)

      actual_clip = global_state.sum_state.l2_norm_clip

      if t > 40:
        self.assertNear(actual_clip, 5.0, 0.5)


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