# Copyright 2021 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 the distributed values library."""

from absl.testing import parameterized

from tensorflow.python.distribute import combinations
from tensorflow.python.distribute import test_util as ds_test_util
from tensorflow.python.distribute import values as values_lib
from tensorflow.python.eager import context
from tensorflow.python.eager import def_function
from tensorflow.python.eager import test
from tensorflow.python.framework import constant_op
from tensorflow.python.framework import dtypes
from tensorflow.python.framework import tensor_spec
from tensorflow.python.framework import test_util
from tensorflow.python.ops import array_ops
from tensorflow.python.ops import control_flow_ops
from tensorflow.python.util import nest


class PerReplicaTest(test.TestCase, parameterized.TestCase):

  @combinations.generate(combinations.combine(mode=["eager"]))
  def testTypeSpec(self):
    vals = (constant_op.constant(1.),)
    per_replica = values_lib.PerReplica(vals)

    spec = per_replica._type_spec
    self.assertEqual(spec._value_specs,
                     (tensor_spec.TensorSpec([], dtypes.float32),))

  @combinations.generate(combinations.combine(mode=["eager"]))
  def testTypeSpecRoundTrip(self):
    vals = (constant_op.constant(1.),)
    per_replica = values_lib.PerReplica(vals)

    spec = per_replica._type_spec
    tensor_list = spec._to_components(per_replica)
    reconstructed = spec._from_components(tensor_list)

    self.assertAllEqual(per_replica.values, reconstructed.values)

  @combinations.generate(combinations.combine(mode=["eager"]))
  def testTypeSpecNest(self):
    vals = (constant_op.constant(1.), constant_op.constant([5., 6.0]),)
    per_replica = values_lib.PerReplica(vals)

    # Note: nest.map_structure exercises nest.flatten and
    # nest.pack_sequence_as.
    result = nest.map_structure(
        lambda t: t + 10, per_replica, expand_composites=True)

    self.assertLen(result.values, 2)
    self.assertAllEqual(result.values[0], 11.)
    self.assertAllEqual(result.values[1], [15., 16.0])

  @test_util.run_in_graph_and_eager_modes
  def testIsGraphTensor(self):
    per_replica = values_lib.PerReplica((constant_op.constant(1.),))
    for t in nest.flatten(per_replica, expand_composites=True):
      self.assertEqual(hasattr(t, "graph"), not context.executing_eagerly())

  @combinations.generate(combinations.combine(mode=["eager"]))
  def testDoesNotTriggerFunctionTracing(self):
    traces = []

    @def_function.function
    def f(x):
      traces.append(None)  # Only happens on trace.
      return x

    per_replica = values_lib.PerReplica((constant_op.constant(1.),))

    # Trace once.
    f(per_replica)
    self.assertNotEmpty(traces)
    del traces[:]

    per_replica_spec = per_replica._type_spec
    for _ in range(5):
      vals = per_replica_spec._to_components(per_replica)
      vals = [v * 2 for v in vals]
      per_replica = per_replica_spec._from_components(vals)

      output = f(per_replica)
      self.assertIsInstance(output, values_lib.PerReplica)
      self.assertAllEqual(output._values, per_replica._values)
      self.assertEmpty(traces)  # Make sure we're not re-tracing `f`.

  @combinations.generate(combinations.combine(mode=["eager"]))
  def testFunctionCanReturnPerReplica(self):
    f = def_function.function(lambda x: x)
    x = values_lib.PerReplica((constant_op.constant(1.),))
    y = f(x)
    self.assertIsNot(x, y)
    nest.map_structure(self.assertAllEqual, x, y, expand_composites=True)
    self.assertEqual(x._type_spec, y._type_spec)

  @test_util.run_in_graph_and_eager_modes
  def testCondWithTensorValues(self):
    per_replica_1 = values_lib.PerReplica((constant_op.constant("a"),))
    per_replica_2 = values_lib.PerReplica((constant_op.constant(["b", "c"]),))
    condition = array_ops.placeholder_with_default(True, [])

    result = control_flow_ops.cond(
        condition, lambda: per_replica_1, lambda: per_replica_2)

    self.assertLen(result.values, 1)
    self.assertAllEqual(result.values[0], "a")

  @test_util.run_in_graph_and_eager_modes
  def testCondWithValuesConvertibleToTensor(self):
    per_replica_1 = values_lib.PerReplica(("a",))
    per_replica_2 = values_lib.PerReplica(("b",))
    condition = array_ops.placeholder_with_default(True, [])

    result = control_flow_ops.cond(
        condition, lambda: per_replica_1, lambda: per_replica_2)

    self.assertLen(result.values, 1)
    self.assertAllEqual(result.values[0], "a")

  @test_util.build_as_function_and_v1_graph
  def testCondWithValuesNotConvertibleToTensor(self):
    per_replica_1 = values_lib.PerReplica(({"a"},))
    per_replica_2 = values_lib.PerReplica(({"b", "c"},))
    condition = array_ops.placeholder(dtypes.bool, [])

    with self.assertRaisesRegex(TypeError, "Could not build a TypeSpec for"):
      control_flow_ops.cond(
          condition, lambda: per_replica_1, lambda: per_replica_2)

if __name__ == "__main__":
  ds_test_util.main()