# coding=utf-8
# Copyright Iz Beltagy, Matthew E. Peters, Arman Cohan and The HuggingFace Inc. team. 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.


import unittest

from transformers import LEDConfig, is_tf_available
from transformers.testing_utils import require_tf, slow

from .test_configuration_common import ConfigTester
from .test_modeling_tf_common import TFModelTesterMixin, ids_tensor


if is_tf_available():
    import tensorflow as tf

    from transformers import TFLEDForConditionalGeneration, TFLEDModel


@require_tf
class TFLEDModelTester:
    config_cls = LEDConfig
    config_updates = {}
    hidden_act = "gelu"

    def __init__(
        self,
        parent,
        batch_size=13,
        seq_length=7,
        is_training=True,
        use_labels=False,
        vocab_size=99,
        hidden_size=32,
        num_hidden_layers=5,
        num_attention_heads=4,
        intermediate_size=37,
        hidden_dropout_prob=0.1,
        attention_probs_dropout_prob=0.1,
        max_position_embeddings=20,
        eos_token_id=2,
        pad_token_id=1,
        bos_token_id=0,
        attention_window=4,
    ):
        self.parent = parent
        self.batch_size = batch_size
        self.seq_length = seq_length
        self.is_training = is_training
        self.use_labels = use_labels
        self.vocab_size = vocab_size
        self.hidden_size = hidden_size
        self.num_hidden_layers = num_hidden_layers
        self.num_attention_heads = num_attention_heads
        self.intermediate_size = intermediate_size

        self.hidden_dropout_prob = hidden_dropout_prob
        self.attention_probs_dropout_prob = attention_probs_dropout_prob
        self.max_position_embeddings = max_position_embeddings
        self.eos_token_id = eos_token_id
        self.pad_token_id = pad_token_id
        self.bos_token_id = bos_token_id
        self.attention_window = attention_window

        # `ModelTesterMixin.test_attention_outputs` is expecting attention tensors to be of size
        # [num_attention_heads, encoder_seq_length, encoder_key_length], but TFLongformerSelfAttention
        # returns attention of shape [num_attention_heads, encoder_seq_length, self.attention_window + 1]
        # because its local attention only attends to `self.attention_window` and one before and one after
        self.key_length = self.attention_window + 1

        # because of padding `encoder_seq_length`, is different from `seq_length`. Relevant for
        # the `test_attention_outputs` and `test_hidden_states_output` tests
        self.encoder_seq_length = (
            self.seq_length + (self.attention_window - self.seq_length % self.attention_window) % self.attention_window
        )

    def prepare_config_and_inputs_for_common(self):
        input_ids = ids_tensor([self.batch_size, self.seq_length - 1], self.vocab_size)
        eos_tensor = tf.expand_dims(tf.constant([self.eos_token_id] * self.batch_size), 1)
        input_ids = tf.concat([input_ids, eos_tensor], axis=1)

        decoder_input_ids = ids_tensor([self.batch_size, self.seq_length], self.vocab_size)

        config = self.config_cls(
            vocab_size=self.vocab_size,
            d_model=self.hidden_size,
            encoder_layers=self.num_hidden_layers,
            decoder_layers=self.num_hidden_layers,
            encoder_attention_heads=self.num_attention_heads,
            decoder_attention_heads=self.num_attention_heads,
            encoder_ffn_dim=self.intermediate_size,
            decoder_ffn_dim=self.intermediate_size,
            dropout=self.hidden_dropout_prob,
            attention_dropout=self.attention_probs_dropout_prob,
            max_position_embeddings=self.max_position_embeddings,
            eos_token_ids=[2],
            bos_token_id=self.bos_token_id,
            pad_token_id=self.pad_token_id,
            decoder_start_token_id=self.pad_token_id,
            attention_window=self.attention_window,
            **self.config_updates,
        )
        inputs_dict = prepare_led_inputs_dict(config, input_ids, decoder_input_ids)
        global_attention_mask = tf.concat(
            [tf.zeros_like(input_ids)[:, :-1], tf.ones_like(input_ids)[:, -1:]],
            axis=-1,
        )
        inputs_dict["global_attention_mask"] = global_attention_mask
        return config, inputs_dict

    def check_decoder_model_past_large_inputs(self, config, inputs_dict):
        model = TFLEDModel(config=config).get_decoder()
        input_ids = inputs_dict["input_ids"]

        input_ids = input_ids[:1, :]
        attention_mask = inputs_dict["attention_mask"][:1, :]
        self.batch_size = 1

        # first forward pass
        outputs = model(input_ids, attention_mask=attention_mask, use_cache=True)

        output, past_key_values = outputs.to_tuple()
        past_key_values = past_key_values[1]

        # create hypothetical next token and extent to next_input_ids
        next_tokens = ids_tensor((self.batch_size, 3), config.vocab_size)
        next_attn_mask = tf.cast(ids_tensor((self.batch_size, 3), 2), tf.int8)

        # append to next input_ids and
        next_input_ids = tf.concat([input_ids, next_tokens], axis=-1)
        next_attention_mask = tf.concat([attention_mask, next_attn_mask], axis=-1)

        output_from_no_past = model(next_input_ids, attention_mask=next_attention_mask)[0]
        output_from_past = model(next_tokens, attention_mask=next_attention_mask, past_key_values=past_key_values)[0]

        self.parent.assertEqual(next_tokens.shape[1], output_from_past.shape[1])

        # select random slice
        random_slice_idx = int(ids_tensor((1,), output_from_past.shape[-1]))
        output_from_no_past_slice = output_from_no_past[:, -3:, random_slice_idx]
        output_from_past_slice = output_from_past[:, :, random_slice_idx]

        # test that outputs are equal for slice
        tf.debugging.assert_near(output_from_past_slice, output_from_no_past_slice, rtol=1e-3)


def prepare_led_inputs_dict(
    config,
    input_ids,
    decoder_input_ids,
    attention_mask=None,
    decoder_attention_mask=None,
):
    if attention_mask is None:
        attention_mask = tf.cast(tf.math.not_equal(input_ids, config.pad_token_id), tf.int8)
    if decoder_attention_mask is None:
        decoder_attention_mask = tf.cast(tf.math.not_equal(decoder_input_ids, config.pad_token_id), tf.int8)
    return {
        "input_ids": input_ids,
        "attention_mask": attention_mask,
        "decoder_input_ids": decoder_input_ids,
        "decoder_attention_mask": decoder_attention_mask,
    }


@require_tf
class TFLEDModelTest(TFModelTesterMixin, unittest.TestCase):
    all_model_classes = (TFLEDForConditionalGeneration, TFLEDModel) if is_tf_available() else ()
    all_generative_model_classes = (TFLEDForConditionalGeneration,) if is_tf_available() else ()
    is_encoder_decoder = True
    test_pruning = False

    def setUp(self):
        self.model_tester = TFLEDModelTester(self)
        self.config_tester = ConfigTester(self, config_class=LEDConfig)

    def test_config(self):
        self.config_tester.run_common_tests()

    def test_decoder_model_past_large_inputs(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs_for_common()
        self.model_tester.check_decoder_model_past_large_inputs(*config_and_inputs)

    def test_model_common_attributes(self):
        config, inputs_dict = self.model_tester.prepare_config_and_inputs_for_common()

        for model_class in self.all_model_classes:
            model = model_class(config)
            assert isinstance(model.get_input_embeddings(), tf.keras.layers.Layer)
            x = model.get_output_layer_with_bias()
            assert x is None
            name = model.get_prefix_bias_name()
            assert name is None

    def test_attention_outputs(self):
        config, inputs_dict = self.model_tester.prepare_config_and_inputs_for_common()
        inputs_dict["global_attention_mask"] = tf.zeros_like(inputs_dict["attention_mask"])
        num_global_attn_indices = 2
        inputs_dict["global_attention_mask"] = tf.where(
            tf.range(self.model_tester.seq_length)[None, :] < num_global_attn_indices,
            1,
            inputs_dict["global_attention_mask"],
        )

        config.return_dict = True
        seq_length = self.model_tester.seq_length
        encoder_seq_length = self.model_tester.encoder_seq_length

        def check_decoder_attentions_output(outputs):
            decoder_attentions = outputs.decoder_attentions
            self.assertEqual(len(decoder_attentions), self.model_tester.num_hidden_layers)
            self.assertListEqual(
                list(decoder_attentions[0].shape[-3:]),
                [self.model_tester.num_attention_heads, seq_length, seq_length],
            )

        def check_encoder_attentions_output(outputs):
            attentions = [t.numpy() for t in outputs.encoder_attentions]
            global_attentions = [t.numpy() for t in outputs.encoder_global_attentions]
            self.assertEqual(len(attentions), self.model_tester.num_hidden_layers)
            self.assertEqual(len(global_attentions), self.model_tester.num_hidden_layers)
            self.assertListEqual(
                list(attentions[0].shape[-3:]),
                [self.model_tester.num_attention_heads, encoder_seq_length, seq_length],
            )
            self.assertListEqual(
                list(global_attentions[0].shape[-3:]),
                [self.model_tester.num_attention_heads, encoder_seq_length, num_global_attn_indices],
            )

        for model_class in self.all_model_classes:
            inputs_dict["output_attentions"] = True
            inputs_dict["use_cache"] = False
            config.output_hidden_states = False
            model = model_class(config)
            outputs = model(self._prepare_for_class(inputs_dict, model_class))
            out_len = len(outputs)
            self.assertEqual(config.output_hidden_states, False)
            check_encoder_attentions_output(outputs)

            if self.is_encoder_decoder:
                model = model_class(config)
                outputs = model(self._prepare_for_class(inputs_dict, model_class))
                self.assertEqual(config.output_hidden_states, False)
                check_decoder_attentions_output(outputs)

            # Check that output attentions can also be changed via the config
            del inputs_dict["output_attentions"]
            config.output_attentions = True
            model = model_class(config)
            outputs = model(self._prepare_for_class(inputs_dict, model_class))
            self.assertEqual(config.output_hidden_states, False)
            check_encoder_attentions_output(outputs)

            # Check attention is always last and order is fine
            inputs_dict["output_attentions"] = True
            config.output_hidden_states = True
            model = model_class(config)
            outputs = model(self._prepare_for_class(inputs_dict, model_class))

            self.assertEqual(out_len + (2 if self.is_encoder_decoder else 1), len(outputs))
            self.assertEqual(model.config.output_hidden_states, True)
            check_encoder_attentions_output(outputs)

    @slow
    def test_saved_model_with_attentions_output(self):
        # longformer has special attentions which are not
        # compatible in graph mode
        pass

    @slow
    def test_saved_model_with_hidden_states_output(self):
        # TODO(JPLU, PVP) this test should pass!!! PVP:
        # IMO there is a problem with the signature check.
        # Test passes for TFLEDModel, but not for TFLEDForConditionalGeneration
        # IMO the reason is that the tensor variable name cannot be changed
        # from decoder_input_ids -> input_ids, which poses a BIG restrictions
        pass


def _assert_tensors_equal(a, b, atol=1e-12, prefix=""):
    """If tensors not close, or a and b arent both tensors, raise a nice Assertion error."""
    if a is None and b is None:
        return True
    try:
        if tf.debugging.assert_near(a, b, atol=atol):
            return True
        raise
    except Exception:
        msg = "{} != {}".format(a, b)
        if prefix:
            msg = prefix + ": " + msg
        raise AssertionError(msg)


def _long_tensor(tok_lst):
    return tf.constant(tok_lst, dtype=tf.int32)


TOLERANCE = 1e-4


@slow
@require_tf
class TFLEDModelIntegrationTest(unittest.TestCase):
    def test_inference_no_head(self):
        model = TFLEDForConditionalGeneration.from_pretrained("allenai/led-base-16384").led

        # change to intended input here
        input_ids = _long_tensor([512 * [0, 31414, 232, 328, 740, 1140, 12695, 69]])
        decoder_input_ids = _long_tensor([128 * [0, 31414, 232, 328, 740, 1140, 12695, 69]])
        inputs_dict = prepare_led_inputs_dict(model.config, input_ids, decoder_input_ids)
        output = model(**inputs_dict)[0]
        expected_shape = (1, 1024, 768)
        self.assertEqual(output.shape, expected_shape)
        # change to expected output here
        expected_slice = tf.convert_to_tensor(
            [[2.3050, 2.8279, 0.6531], [-1.8457, -0.1455, -3.5661], [-1.0186, 0.4586, -2.2043]],
        )
        tf.debugging.assert_near(output[:, :3, :3], expected_slice, atol=TOLERANCE)

    def test_inference_with_head(self):
        model = TFLEDForConditionalGeneration.from_pretrained("allenai/led-base-16384")

        # change to intended input here
        input_ids = _long_tensor([512 * [0, 31414, 232, 328, 740, 1140, 12695, 69]])
        decoder_input_ids = _long_tensor([128 * [0, 31414, 232, 328, 740, 1140, 12695, 69]])
        inputs_dict = prepare_led_inputs_dict(model.config, input_ids, decoder_input_ids)
        output = model(**inputs_dict)[0]
        expected_shape = (1, 1024, model.config.vocab_size)
        self.assertEqual(output.shape, expected_shape)
        # change to expected output here
        expected_slice = tf.convert_to_tensor(
            [[33.6507, 6.4572, 16.8089], [5.8739, -2.4238, 11.2902], [-3.2139, -4.3149, 4.2783]],
        )
        tf.debugging.assert_near(output[:, :3, :3], expected_slice, atol=TOLERANCE)

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