# Copyright 2019 The JAX 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
#
#     https://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 nn module."""

import collections
from functools import partial
import itertools
import unittest

from absl.testing import absltest
from absl.testing import parameterized

import scipy.stats

from jax._src import core
from jax._src import test_util as jtu
from jax._src import ad_checkpoint
from jax.test_util import check_grads
from jax import nn
from jax import random
import jax
import jax.numpy as jnp

from jax import config
config.parse_flags_with_absl()


class NNFunctionsTest(jtu.JaxTestCase):
  @jtu.skip_on_flag("jax_skip_slow_tests", True)
  def testSoftplusGrad(self):
    check_grads(nn.softplus, (1e-8,), order=4,
                rtol=1e-2 if jtu.device_under_test() == "tpu" else None)

  def testSoftplusGradZero(self):
    check_grads(nn.softplus, (0.,), order=1,
                rtol=1e-2 if jtu.device_under_test() == "tpu" else None)

  def testSoftplusGradInf(self):
    self.assertAllClose(
        1., jax.grad(nn.softplus)(float('inf')))

  def testSoftplusGradNegInf(self):
    check_grads(nn.softplus, (-float('inf'),), order=1,
                rtol=1e-2 if jtu.device_under_test() == "tpu" else None)

  def testSoftplusGradNan(self):
    check_grads(nn.softplus, (float('nan'),), order=1,
                rtol=1e-2 if jtu.device_under_test() == "tpu" else None)

  @parameterized.parameters([int, float] + jtu.dtypes.floating + jtu.dtypes.integer)
  def testSoftplusZero(self, dtype):
    self.assertEqual(jnp.log(dtype(2)), nn.softplus(dtype(0)))

  def testReluGrad(self):
    rtol = 1e-2 if jtu.device_under_test() == "tpu" else None
    check_grads(nn.relu, (1.,), order=3, rtol=rtol)
    check_grads(nn.relu, (-1.,), order=3, rtol=rtol)
    jaxpr = jax.make_jaxpr(jax.grad(nn.relu))(0.)
    self.assertGreaterEqual(len(jaxpr.jaxpr.eqns), 2)

  def testRelu6Grad(self):
    rtol = 1e-2 if jtu.device_under_test() == "tpu" else None
    check_grads(nn.relu6, (1.,), order=3, rtol=rtol)
    check_grads(nn.relu6, (-1.,), order=3, rtol=rtol)
    self.assertAllClose(jax.grad(nn.relu6)(0.), 0., check_dtypes=False)
    self.assertAllClose(jax.grad(nn.relu6)(6.), 0., check_dtypes=False)

  def testSoftplusValue(self):
    val = nn.softplus(89.)
    self.assertAllClose(val, 89., check_dtypes=False)

  @jtu.skip_on_flag("jax_skip_slow_tests", True)
  def testEluGrad(self):
    check_grads(nn.elu, (1e4,), order=4, eps=1.)

  def testEluValue(self):
    val = nn.elu(1e4)
    self.assertAllClose(val, 1e4, check_dtypes=False)

  def testGluValue(self):
    val = nn.glu(jnp.array([1.0, 0.0]), axis=0)
    self.assertAllClose(val, jnp.array([0.5]))

  @parameterized.parameters(False, True)
  def testGeluIntType(self, approximate):
    val_float = nn.gelu(jnp.array(-1.0), approximate=approximate)
    val_int = nn.gelu(jnp.array(-1), approximate=approximate)
    self.assertAllClose(val_float, val_int)

  @parameterized.parameters(False, True)
  def testGelu(self, approximate):
    def gelu_reference(x):
      return x * scipy.stats.norm.cdf(x)
    rng = jtu.rand_default(self.rng())
    args_maker = lambda: [rng((4, 5, 6), jnp.float32)]
    self._CheckAgainstNumpy(
      gelu_reference, partial(nn.gelu, approximate=approximate), args_maker,
      check_dtypes=False, tol=1e-3 if approximate else None)

  @parameterized.parameters(*itertools.product(
      (jnp.float32, jnp.bfloat16, jnp.float16),
      (partial(nn.gelu, approximate=False),
       partial(nn.gelu, approximate=True),
       nn.relu, nn.softplus, nn.sigmoid)))
  def testDtypeMatchesInput(self, dtype, fn):
    x = jnp.zeros((), dtype=dtype)
    out = fn(x)
    self.assertEqual(out.dtype, dtype)

  def testEluMemory(self):
    # see https://github.com/google/jax/pull/1640
    with jax.enable_checks(False):  # With checks we materialize the array
      jax.make_jaxpr(lambda: nn.elu(jnp.ones((10 ** 12,))))  # don't oom

  def testHardTanhMemory(self):
    # see https://github.com/google/jax/pull/1640
    with jax.enable_checks(False):  # With checks we materialize the array
      jax.make_jaxpr(lambda: nn.hard_tanh(jnp.ones((10 ** 12,))))  # don't oom

  @parameterized.parameters([nn.softmax, nn.log_softmax])
  def testSoftmaxWhereMask(self, fn):
    x = jnp.array([5.5, 1.3, -4.2, 0.9])
    m = jnp.array([True, False, True, True])

    out = fn(x, where=m, initial=-jnp.inf)
    self.assertAllClose(out[m], fn(x[m]))

    probs = out if fn is nn.softmax else jnp.exp(out)
    self.assertAllClose(probs.sum(), 1.0)

    # TODO(mattjj): include log_softmax in these extra tests if/when we add a
    # custom_jvp rule for it (since otherwise it doesn't pass the numerical
    # checks below).
    if fn is nn.softmax and config.jax_softmax_custom_jvp:
      g_fun = lambda x: jnp.take(fn(x, where=m, initial=-jnp.inf),
                                jnp.array([0, 2, 3]))
      jtu.check_grads(g_fun, (x,), order=2)

  def testSoftmaxGrad(self):
    x = jnp.array([5.5, 1.3, -4.2, 0.9])
    jtu.check_grads(nn.softmax, (x,), order=2, atol=3e-3)

  def testSoftmaxGradResiduals(self):
    if not jax.config.jax_softmax_custom_jvp:
      raise unittest.SkipTest("only applies when upgrade flag enabled")
    x = jnp.array([5.5, 1.3, -4.2, 0.9])
    res = ad_checkpoint.saved_residuals(nn.softmax, x)
    self.assertLen(res, 1)

  def testSoftmaxGradFlag(self):
    x = jnp.array([5.5, 1.3, -4.2, 0.9])

    with jax.softmax_custom_jvp(False):
      res = ad_checkpoint.saved_residuals(nn.softmax, x)
    self.assertLen(res, 3)
    self.assertEqual(sum(a.size for a, _ in res), 6)

    with jax.softmax_custom_jvp(True):
      res = ad_checkpoint.saved_residuals(nn.softmax, x)
    self.assertLen(res, 1)
    self.assertEqual(sum(a.size for a, _ in res), 4)

  def testStandardizeWhereMask(self):
    x = jnp.array([5.5, 1.3, -4.2, 0.9])
    m = jnp.array([True, False, True, True])
    x_filtered = jnp.take(x, jnp.array([0, 2, 3]))

    out_masked = jnp.take(nn.standardize(x, where=m), jnp.array([0, 2, 3]))
    out_filtered = nn.standardize(x_filtered)

    self.assertAllClose(out_masked, out_filtered)

  def testOneHot(self):
    actual = nn.one_hot(jnp.array([0, 1, 2]), 3)
    expected = jnp.array([[1., 0., 0.],
                          [0., 1., 0.],
                          [0., 0., 1.]])
    self.assertAllClose(actual, expected, check_dtypes=False)

    actual = nn.one_hot(jnp.array([1, 2, 0]), 3)
    expected = jnp.array([[0., 1., 0.],
                          [0., 0., 1.],
                          [1., 0., 0.]])
    self.assertAllClose(actual, expected, check_dtypes=False)

  def testOneHotOutOfBound(self):
    actual = nn.one_hot(jnp.array([-1, 3]), 3)
    expected = jnp.array([[0., 0., 0.],
                          [0., 0., 0.]])
    self.assertAllClose(actual, expected, check_dtypes=False)

  def testOneHotNonArrayInput(self):
    actual = nn.one_hot([0, 1, 2], 3)
    expected = jnp.array([[1., 0., 0.],
                          [0., 1., 0.],
                          [0., 0., 1.]])
    self.assertAllClose(actual, expected, check_dtypes=False)

  def testOneHotCustomDtype(self):
    actual = nn.one_hot(jnp.array([0, 1, 2]), 3, dtype=jnp.bool_)
    expected = jnp.array([[True, False, False],
                          [False, True, False],
                          [False, False, True]])
    self.assertAllClose(actual, expected)

  def testOneHotConcretizationError(self):
    # https://github.com/google/jax/issues/3654
    msg = r"in jax.nn.one_hot argument `num_classes`"
    with self.assertRaisesRegex(core.ConcretizationTypeError, msg):
      jax.jit(nn.one_hot)(3, 5)

  def testOneHotAxis(self):
    expected = jnp.array([[0., 1., 0.],
                          [0., 0., 1.],
                          [1., 0., 0.]]).T

    actual = nn.one_hot(jnp.array([1, 2, 0]), 3, axis=0)
    self.assertAllClose(actual, expected, check_dtypes=False)

    actual = nn.one_hot(jnp.array([1, 2, 0]), 3, axis=-2)
    self.assertAllClose(actual, expected, check_dtypes=False)

  def testTanhExists(self):
    nn.tanh  # doesn't crash

  def testCustomJVPLeak(self):
    # https://github.com/google/jax/issues/8171
    @jax.jit
    def fwd():
      a = jnp.array(1.)

      def f(hx, _):
        hx = jax.nn.sigmoid(hx + a)
        return hx, None

      hx = jnp.array(0.)
      jax.lax.scan(f, hx, None, length=2)

    with jax.checking_leaks():
      fwd()  # doesn't crash

  def testCustomJVPLeak2(self):
    # https://github.com/google/jax/issues/8171
    # The above test uses jax.nn.sigmoid, as in the original #8171, but that
    # function no longer actually has a custom_jvp! So we inline the old def.

    @jax.custom_jvp
    def sigmoid(x):
      one = jnp.float32(1)
      return jax.lax.div(one, jax.lax.add(one, jax.lax.exp(jax.lax.neg(x))))
    sigmoid.defjvps(lambda g, ans, x: g * ans * (jnp.float32(1) - ans))

    @jax.jit
    def fwd():
      a = jnp.array(1., 'float32')

      def f(hx, _):
        hx = sigmoid(hx + a)
        return hx, None

      hx = jnp.array(0., 'float32')
      jax.lax.scan(f, hx, None, length=2)

    with jax.checking_leaks():
      fwd()  # doesn't crash


InitializerRecord = collections.namedtuple(
  "InitializerRecord",
  ["name", "initializer", "shapes", "dtypes"])

ALL_SHAPES = [(2,), (2, 2), (2, 3), (3, 2), (2, 3, 4), (4, 3, 2), (2, 3, 4, 5)]

def initializer_record(name, initializer, dtypes, min_dims=2, max_dims=4):
  shapes = [shape for shape in ALL_SHAPES
            if min_dims <= len(shape) <= max_dims]
  return InitializerRecord(name, initializer, shapes, dtypes)

INITIALIZER_RECS = [
    initializer_record("uniform", nn.initializers.uniform, jtu.dtypes.floating, 1),
    initializer_record("normal", nn.initializers.normal, jtu.dtypes.inexact, 1),
    initializer_record("he_normal", nn.initializers.he_normal, jtu.dtypes.inexact),
    initializer_record("he_uniform", nn.initializers.he_uniform, jtu.dtypes.inexact),
    initializer_record("glorot_normal", nn.initializers.glorot_normal, jtu.dtypes.inexact),
    initializer_record("glorot_uniform", nn.initializers.glorot_uniform, jtu.dtypes.inexact),
    initializer_record("lecun_normal", nn.initializers.lecun_normal, jtu.dtypes.inexact),
    initializer_record("lecun_uniform", nn.initializers.lecun_uniform, jtu.dtypes.inexact),
    initializer_record("orthogonal", nn.initializers.orthogonal, jtu.dtypes.floating, 2, 2),
    initializer_record("delta_orthogonal", nn.initializers.delta_orthogonal, jtu.dtypes.floating, 4, 4)
]


class NNInitializersTest(jtu.JaxTestCase):
  @parameterized.parameters(itertools.chain.from_iterable(
    jtu.sample_product_testcases(
      [dict(initializer=rec.initializer())],
      shape=rec.shapes,
      dtype=rec.dtypes
    )
    for rec in INITIALIZER_RECS
  ))
  def testInitializer(self, initializer, shape, dtype):
    rng = random.PRNGKey(0)
    val = initializer(rng, shape, dtype)

    self.assertEqual(shape, jnp.shape(val))
    self.assertEqual(jax.dtypes.canonicalize_dtype(dtype), jnp.dtype(val))

  @parameterized.parameters(itertools.chain.from_iterable(
    jtu.sample_product_testcases(
      [dict(initializer_provider=rec.initializer)],
      shape=rec.shapes,
      dtype=rec.dtypes
    )
    for rec in INITIALIZER_RECS
  ))
  def testInitializerProvider(self, initializer_provider, shape, dtype):
    rng = random.PRNGKey(0)
    initializer = initializer_provider(dtype=dtype)
    val = initializer(rng, shape)

    self.assertEqual(shape, jnp.shape(val))
    self.assertEqual(jax.dtypes.canonicalize_dtype(dtype), jnp.dtype(val))

  def testVarianceScalingMultiAxis(self):
    rng = random.PRNGKey(0)
    shape = (2, 3, 4, 5)
    initializer = nn.initializers.variance_scaling(
      scale=1.0, mode='fan_avg', distribution='truncated_normal',
      in_axis=(0, 1), out_axis=(-2, -1))
    val = initializer(rng, shape)

    self.assertEqual(shape, jnp.shape(val))

  def testVarianceScalingBatchAxis(self):
    rng = random.PRNGKey(0)
    shape = (2, 3, 4, 5)
    initializer = nn.initializers.variance_scaling(
      scale=1.0, mode='fan_avg', distribution='truncated_normal',
      in_axis=0, out_axis=(2, 3), batch_axis=1)
    val = initializer(rng, shape)

    self.assertEqual(shape, jnp.shape(val))

  def testVarianceScalingError(self):
    rng = random.PRNGKey(0)
    shape = (5,)
    initializer = nn.initializers.variance_scaling(
      scale=1.0, mode='fan_avg', distribution='truncated_normal')

    with self.assertRaisesRegex(
      ValueError,
      "Can't compute input and output sizes of a 1"
      "-dimensional weights tensor. Must be at least 2D."
    ):
      initializer(rng, shape)


if __name__ == "__main__":
  absltest.main(testLoader=jtu.JaxTestLoader())
