# Copyright 2022 Google SwitchTransformers Authors and HuggingFace Inc. team.
#
# 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 SwitchTransformersConfig, is_torch_available
from transformers.testing_utils import (
    Expectations,
    require_tokenizers,
    require_torch,
    require_torch_accelerator,
    require_torch_bf16,
    slow,
    torch_device,
)

from ...generation.test_utils import GenerationTesterMixin
from ...test_configuration_common import ConfigTester
from ...test_modeling_common import ModelTesterMixin, ids_tensor
from ...test_pipeline_mixin import PipelineTesterMixin


if is_torch_available():
    import torch
    import torch.nn.functional as F

    from transformers import (
        AutoTokenizer,
        SwitchTransformersEncoderModel,
        SwitchTransformersForConditionalGeneration,
        SwitchTransformersModel,
        SwitchTransformersSparseMLP,
        SwitchTransformersTop1Router,
    )
    from transformers.models.switch_transformers.modeling_switch_transformers import (
        load_balancing_loss_func,
        router_z_loss_func,
    )


class SwitchTransformersModelTester:
    def __init__(
        self,
        parent,
        vocab_size=99,
        batch_size=13,
        encoder_seq_length=7,
        decoder_seq_length=9,
        # For common tests
        is_training=True,
        use_attention_mask=True,
        use_labels=True,
        hidden_size=32,
        num_hidden_layers=2,
        num_attention_heads=4,
        d_ff=37,
        relative_attention_num_buckets=8,
        dropout_rate=0.1,
        initializer_factor=0.002,
        eos_token_id=1,
        pad_token_id=0,
        decoder_start_token_id=0,
        decoder_layers=None,
        sparse_step=1,
        num_sparse_decoder_layers=2,
        num_sparse_encoder_layers=2,
        expert_capacity=100,
        router_jitter_noise=0.0,
    ):
        self.parent = parent
        self.batch_size = batch_size
        self.encoder_seq_length = encoder_seq_length
        self.decoder_seq_length = decoder_seq_length
        # For common tests
        self.seq_length = self.decoder_seq_length
        self.is_training = is_training
        self.use_attention_mask = use_attention_mask
        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.d_ff = d_ff
        self.relative_attention_num_buckets = relative_attention_num_buckets
        self.dropout_rate = dropout_rate
        self.initializer_factor = initializer_factor
        self.eos_token_id = eos_token_id
        self.pad_token_id = pad_token_id
        self.decoder_start_token_id = decoder_start_token_id
        self.scope = None
        self.decoder_layers = decoder_layers
        self.sparse_step = sparse_step
        self.num_sparse_decoder_layers = num_sparse_decoder_layers
        self.num_sparse_encoder_layers = num_sparse_encoder_layers
        self.expert_capacity = expert_capacity
        self.router_jitter_noise = router_jitter_noise

    def prepare_config_and_inputs(self):
        input_ids = ids_tensor([self.batch_size, self.encoder_seq_length], self.vocab_size)
        decoder_input_ids = ids_tensor([self.batch_size, self.decoder_seq_length], self.vocab_size)

        attention_mask = None
        decoder_attention_mask = None
        if self.use_attention_mask:
            attention_mask = ids_tensor([self.batch_size, self.encoder_seq_length], vocab_size=2)
            decoder_attention_mask = ids_tensor([self.batch_size, self.decoder_seq_length], vocab_size=2)

        lm_labels = None
        if self.use_labels:
            lm_labels = ids_tensor([self.batch_size, self.decoder_seq_length], self.vocab_size)

        config = self.get_config()

        return (
            config,
            input_ids,
            decoder_input_ids,
            attention_mask,
            decoder_attention_mask,
            lm_labels,
        )

    def get_pipeline_config(self):
        return SwitchTransformersConfig(
            vocab_size=166,  # switch_transformers forces 100 extra tokens
            d_model=self.hidden_size,
            d_ff=self.d_ff,
            d_kv=self.hidden_size // self.num_attention_heads,
            num_layers=self.num_hidden_layers,
            num_decoder_layers=self.decoder_layers,
            num_heads=self.num_attention_heads,
            relative_attention_num_buckets=self.relative_attention_num_buckets,
            dropout_rate=self.dropout_rate,
            initializer_factor=self.initializer_factor,
            eos_token_id=self.eos_token_id,
            bos_token_id=self.pad_token_id,
            pad_token_id=self.pad_token_id,
            decoder_start_token_id=self.decoder_start_token_id,
            expert_capacity=self.expert_capacity,
            router_jitter_noise=self.router_jitter_noise,
        )

    def get_config(self):
        return SwitchTransformersConfig(
            vocab_size=self.vocab_size,
            d_model=self.hidden_size,
            d_ff=self.d_ff,
            d_kv=self.hidden_size // self.num_attention_heads,
            num_layers=self.num_hidden_layers,
            num_decoder_layers=self.decoder_layers,
            num_heads=self.num_attention_heads,
            relative_attention_num_buckets=self.relative_attention_num_buckets,
            dropout_rate=self.dropout_rate,
            initializer_factor=self.initializer_factor,
            eos_token_id=self.eos_token_id,
            bos_token_id=self.pad_token_id,
            pad_token_id=self.pad_token_id,
            decoder_start_token_id=self.decoder_start_token_id,
            sparse_step=self.sparse_step,
            num_sparse_encoder_layers=self.num_sparse_encoder_layers,
            num_sparse_decoder_layers=self.num_sparse_decoder_layers,
        )

    def check_prepare_lm_labels_via_shift_left(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        model = SwitchTransformersModel(config=config)
        model.to(torch_device)
        model.eval()

        # make sure that lm_labels are correctly padded from the right
        lm_labels.masked_fill_((lm_labels == self.decoder_start_token_id), self.eos_token_id)

        # add casaul pad token mask
        triangular_mask = torch.tril(lm_labels.new_ones(lm_labels.shape)).logical_not()
        lm_labels.masked_fill_(triangular_mask, self.pad_token_id)
        decoder_input_ids = model._shift_right(lm_labels)

        for i, (decoder_input_ids_slice, lm_labels_slice) in enumerate(zip(decoder_input_ids, lm_labels)):
            # first item
            self.parent.assertEqual(decoder_input_ids_slice[0].item(), self.decoder_start_token_id)
            if i < decoder_input_ids_slice.shape[-1]:
                if i < decoder_input_ids.shape[-1] - 1:
                    # items before diagonal
                    self.parent.assertListEqual(
                        decoder_input_ids_slice[1 : i + 1].tolist(), lm_labels_slice[:i].tolist()
                    )
                # pad items after diagonal
                if i < decoder_input_ids.shape[-1] - 2:
                    self.parent.assertListEqual(
                        decoder_input_ids_slice[i + 2 :].tolist(), lm_labels_slice[i + 1 : -1].tolist()
                    )
            else:
                # all items after square
                self.parent.assertListEqual(decoder_input_ids_slice[1:].tolist(), lm_labels_slice[:-1].tolist())

    def create_and_check_model(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        model = SwitchTransformersModel(config=config)
        model.to(torch_device)
        model.eval()
        result = model(
            input_ids=input_ids,
            decoder_input_ids=decoder_input_ids,
            attention_mask=attention_mask,
            decoder_attention_mask=decoder_attention_mask,
        )
        result = model(input_ids=input_ids, decoder_input_ids=decoder_input_ids)
        decoder_output = result.last_hidden_state
        decoder_past = result.past_key_values
        encoder_output = result.encoder_last_hidden_state

        self.parent.assertEqual(encoder_output.size(), (self.batch_size, self.encoder_seq_length, self.hidden_size))
        self.parent.assertEqual(decoder_output.size(), (self.batch_size, self.decoder_seq_length, self.hidden_size))
        # There should be `num_layers` key value embeddings stored in decoder_past
        self.parent.assertEqual(len(decoder_past), config.num_layers)

    def create_and_check_with_lm_head(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        model = SwitchTransformersForConditionalGeneration(config=config).to(torch_device).eval()
        outputs = model(
            input_ids=input_ids,
            decoder_input_ids=decoder_input_ids,
            decoder_attention_mask=decoder_attention_mask,
            labels=lm_labels,
            output_attentions=True,
            output_router_logits=True,
            output_hidden_states=True,
        )
        self.parent.assertEqual(len(outputs), 15)
        self.parent.assertEqual(outputs["logits"].size(), (self.batch_size, self.decoder_seq_length, self.vocab_size))
        self.parent.assertEqual(outputs["loss"].size(), ())

    def create_and_check_decoder_model_past(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        model = SwitchTransformersModel(config=config).get_decoder().to(torch_device).eval()
        # first forward pass
        outputs = model(input_ids, use_cache=True, output_router_logits=False)
        outputs_use_cache_conf = model(input_ids, output_router_logits=False)
        outputs_no_past = model(input_ids, use_cache=False, output_router_logits=False)

        self.parent.assertTrue(len(outputs) == len(outputs_use_cache_conf))
        self.parent.assertTrue(len(outputs) == len(outputs_no_past) + 1)

        output, past_key_values = outputs.to_tuple()

        # create hypothetical next token and extent to next_input_ids
        next_tokens = ids_tensor((self.batch_size, 1), config.vocab_size)

        # append to next input_ids and
        next_input_ids = torch.cat([input_ids, next_tokens], dim=-1)

        output_from_no_past = model(next_input_ids, output_router_logits=False)["last_hidden_state"]
        output_from_past = model(next_tokens, past_key_values=past_key_values, output_router_logits=False)[
            "last_hidden_state"
        ]

        # select random slice
        random_slice_idx = ids_tensor((1,), output_from_past.shape[-1]).item()
        output_from_no_past_slice = output_from_no_past[:, -1, random_slice_idx].detach()
        output_from_past_slice = output_from_past[:, 0, random_slice_idx].detach()

        # test that outputs are equal for slice
        self.parent.assertTrue(torch.allclose(output_from_past_slice, output_from_no_past_slice, atol=1e-3))

    def create_and_check_decoder_model_attention_mask_past(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        model = SwitchTransformersModel(config=config).get_decoder()
        model.to(torch_device)
        model.eval()

        # create attention mask
        attn_mask = torch.ones(input_ids.shape, dtype=torch.long, device=torch_device)

        half_seq_length = input_ids.shape[-1] // 2
        attn_mask[:, half_seq_length:] = 0

        # first forward pass
        output, past_key_values = model(
            input_ids, attention_mask=attn_mask, use_cache=True, output_router_logits=False
        ).to_tuple()

        # create hypothetical next token and extent to next_input_ids
        next_tokens = ids_tensor((self.batch_size, 1), config.vocab_size)

        # change a random masked slice from input_ids
        random_seq_idx_to_change = ids_tensor((1,), half_seq_length).item() + 1
        random_other_next_tokens = ids_tensor((self.batch_size, 1), config.vocab_size).squeeze(-1)
        input_ids[:, -random_seq_idx_to_change] = random_other_next_tokens

        # append to next input_ids and attn_mask
        next_input_ids = torch.cat([input_ids, next_tokens], dim=-1)
        attn_mask = torch.cat(
            [attn_mask, torch.ones((attn_mask.shape[0], 1), dtype=torch.long, device=torch_device)],
            dim=1,
        )

        # get two different outputs
        output_from_no_past = model(next_input_ids, attention_mask=attn_mask, output_router_logits=False)[
            "last_hidden_state"
        ]
        output_from_past = model(
            next_tokens, past_key_values=past_key_values, attention_mask=attn_mask, output_router_logits=False
        )["last_hidden_state"]

        # select random slice
        random_slice_idx = ids_tensor((1,), output_from_past.shape[-1]).item()
        output_from_no_past_slice = output_from_no_past[:, -1, random_slice_idx].detach()
        output_from_past_slice = output_from_past[:, 0, random_slice_idx].detach()

        # test that outputs are equal for slice
        self.parent.assertTrue(torch.allclose(output_from_past_slice, output_from_no_past_slice, atol=1e-3))

    def create_and_check_decoder_model_past_large_inputs(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        model = SwitchTransformersModel(config=config).get_decoder().to(torch_device).eval()
        # first forward pass
        outputs = model(input_ids, attention_mask=attention_mask, use_cache=True, output_router_logits=False)

        output, past_key_values = outputs.to_tuple()

        # create hypothetical multiple next token and extent to next_input_ids
        next_tokens = ids_tensor((self.batch_size, 3), config.vocab_size)
        next_mask = ids_tensor((self.batch_size, 3), vocab_size=2)

        # append to next input_ids and
        next_input_ids = torch.cat([input_ids, next_tokens], dim=-1)
        next_attention_mask = torch.cat([attention_mask, next_mask], dim=-1)

        output_from_no_past = model(next_input_ids, attention_mask=next_attention_mask, output_router_logits=False)[
            "last_hidden_state"
        ]
        output_from_past = model(
            next_tokens,
            attention_mask=next_attention_mask,
            past_key_values=past_key_values,
            output_router_logits=False,
        )["last_hidden_state"]

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

        self.parent.assertTrue(output_from_past_slice.shape[1] == next_tokens.shape[1])

        # test that outputs are equal for slice
        self.parent.assertTrue(torch.allclose(output_from_past_slice, output_from_no_past_slice, atol=1e-3))

    @slow
    def create_and_check_generate_with_past_key_values(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        r"""
        This test does not pass for small models due to precision errors. It is therefore only run for slightly larger models.
        """
        model = (
            SwitchTransformersForConditionalGeneration.from_pretrained("google/switch-base-8").to(torch_device).eval()
        )
        torch.manual_seed(0)
        output_without_past_cache = model.generate(
            input_ids[:1], num_beams=2, max_length=5, do_sample=True, use_cache=False
        )
        torch.manual_seed(0)
        output_with_past_cache = model.generate(input_ids[:1], num_beams=2, max_length=5, do_sample=True)
        self.parent.assertTrue(torch.all(output_with_past_cache == output_without_past_cache))

    def create_and_check_model_fp16_forward(
        self,
        config,
        input_ids,
        decoder_input_ids,
        attention_mask,
        decoder_attention_mask,
        lm_labels,
    ):
        model = SwitchTransformersModel(config=config).to(torch_device).half().eval()
        output = model(input_ids, decoder_input_ids=input_ids, attention_mask=attention_mask)["last_hidden_state"]
        self.parent.assertFalse(torch.isnan(output).any().item())

    def check_resize_embeddings_switch_transformers_v1_1(
        self,
        config,
    ):
        prev_vocab_size = config.vocab_size

        config.tie_word_embeddings = False
        model = SwitchTransformersForConditionalGeneration(config=config).to(torch_device).eval()
        model.resize_token_embeddings(prev_vocab_size - 10)

        self.parent.assertEqual(model.get_input_embeddings().weight.shape[0], prev_vocab_size - 10)
        self.parent.assertEqual(model.get_output_embeddings().weight.shape[0], prev_vocab_size - 10)
        self.parent.assertEqual(model.config.vocab_size, prev_vocab_size - 10)

    def prepare_config_and_inputs_for_common(self):
        config_and_inputs = self.prepare_config_and_inputs()
        (
            config,
            input_ids,
            decoder_input_ids,
            attention_mask,
            decoder_attention_mask,
            lm_labels,
        ) = config_and_inputs

        inputs_dict = {
            "input_ids": input_ids,
            "attention_mask": attention_mask,
            "decoder_input_ids": decoder_input_ids,
            "decoder_attention_mask": decoder_attention_mask,
            "use_cache": False,
            "output_router_logits": False,
        }
        return config, inputs_dict


@require_torch
class SwitchTransformersModelTest(ModelTesterMixin, GenerationTesterMixin, PipelineTesterMixin, unittest.TestCase):
    all_model_classes = (
        (SwitchTransformersModel, SwitchTransformersForConditionalGeneration) if is_torch_available() else ()
    )
    pipeline_model_mapping = (
        {
            "feature-extraction": SwitchTransformersModel,
        }
        if is_torch_available()
        else {}
    )

    test_resize_embeddings = True
    is_encoder_decoder = True
    # The small SWITCH_TRANSFORMERS model needs higher percentages for CPU/MP tests
    model_split_percents = [0.5, 0.8, 0.9]
    # `SwitchTransformers` is a MOE in which not all experts will get gradients because they are not all used in a single forward pass
    test_all_params_have_gradient = False

    def setUp(self):
        self.model_tester = SwitchTransformersModelTester(self)
        self.config_tester = ConfigTester(self, config_class=SwitchTransformersConfig, d_model=37)

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

    def test_shift_right(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.check_prepare_lm_labels_via_shift_left(*config_and_inputs)

    def test_model(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_model(*config_and_inputs)

    def test_model_v1_1(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        # check that gated gelu feed forward and different word embeddings work
        config = config_and_inputs[0]
        config.tie_word_embeddings = False
        config.feed_forward_proj = "gated-gelu"
        self.model_tester.create_and_check_model(config, *config_and_inputs[1:])

    def test_config_and_model_silu_gated(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        config = config_and_inputs[0]
        config.feed_forward_proj = "gated-silu"
        self.model_tester.create_and_check_model(*config_and_inputs)

    def test_with_lm_head(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_with_lm_head(*config_and_inputs)

    def test_decoder_model_past(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_decoder_model_past(*config_and_inputs)

    def test_decoder_model_past_with_attn_mask(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_decoder_model_attention_mask_past(*config_and_inputs)

    def test_decoder_model_past_with_3d_attn_mask(self):
        (
            config,
            input_ids,
            decoder_input_ids,
            attention_mask,
            decoder_attention_mask,
            lm_labels,
        ) = self.model_tester.prepare_config_and_inputs()

        attention_mask = ids_tensor(
            [self.model_tester.batch_size, self.model_tester.encoder_seq_length, self.model_tester.encoder_seq_length],
            vocab_size=2,
        )
        decoder_attention_mask = ids_tensor(
            [self.model_tester.batch_size, self.model_tester.decoder_seq_length, self.model_tester.decoder_seq_length],
            vocab_size=2,
        )

        self.model_tester.create_and_check_decoder_model_attention_mask_past(
            config,
            input_ids,
            decoder_input_ids,
            attention_mask,
            decoder_attention_mask,
            lm_labels,
        )

    # overwrite because T5 doesn't accept position ids as input and expects `decoder_input_ids`
    def test_custom_4d_attention_mask(self):
        for model_class in self.all_generative_model_classes:
            config, input_dict = self.model_tester.prepare_config_and_inputs_for_common()
            model = model_class(config).to(device=torch_device, dtype=torch.float32)

            (
                input_ids,
                _,
                input_ids_shared_prefix,
                mask_shared_prefix,
                _,
            ) = self._get_custom_4d_mask_test_data()

            logits = model.forward(
                decoder_input_ids=input_ids,
                input_ids=input_dict["input_ids"][:3],
            ).logits
            # logits.shape == torch.Size([3, 4, ...])

            logits_shared_prefix = model(
                input_ids=input_dict["input_ids"][:1],
                decoder_input_ids=input_ids_shared_prefix,
                decoder_attention_mask=mask_shared_prefix,
            )[0]
            # logits_shared_prefix.shape == torch.Size([1, 6, ...])

            out_last_tokens = logits[:, -1, :]  # last tokens in each batch line
            out_shared_prefix_last_tokens = logits_shared_prefix[0, -3:, :]  # last three tokens

            # comparing softmax-normalized logits:
            normalized_0 = F.softmax(out_last_tokens)
            normalized_1 = F.softmax(out_shared_prefix_last_tokens)
            torch.testing.assert_close(normalized_0, normalized_1, rtol=1e-3, atol=1e-4)

    def test_decoder_model_past_with_large_inputs(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_decoder_model_past_large_inputs(*config_and_inputs)

    def test_generate_with_past_key_values(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_generate_with_past_key_values(*config_and_inputs)

    @unittest.skipIf(torch_device == "cpu", "Can't do half precision")
    def test_model_fp16_forward(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_model_fp16_forward(*config_and_inputs)

    def test_v1_1_resize_embeddings(self):
        config = self.model_tester.prepare_config_and_inputs()[0]
        self.model_tester.check_resize_embeddings_switch_transformers_v1_1(config)

    @slow
    def test_model_from_pretrained(self):
        model_name = "google/switch-base-8"
        model = SwitchTransformersModel.from_pretrained(model_name, use_safetensors=False)
        self.assertIsNotNone(model)

    @unittest.skip(
        reason="This architecture has tied weights by default and there is no way to remove it, check: https://github.com/huggingface/transformers/pull/31771#issuecomment-2210915245"
    )
    def test_load_save_without_tied_weights(self):
        pass

    @unittest.skip("TODO ARTHUR later on this will be fixed with t5 modular refactor")
    def test_retain_grad_hidden_states_attentions(self):
        pass

    @unittest.skip(reason="SwitchTransformers has no separate base model without a head.")
    def test_model_base_model_prefix(self):
        pass


class SwitchTransformersEncoderOnlyModelTester:
    def __init__(
        self,
        parent,
        vocab_size=99,
        batch_size=13,
        encoder_seq_length=7,
        # For common tests
        use_attention_mask=True,
        hidden_size=32,
        num_hidden_layers=2,
        num_attention_heads=4,
        d_ff=37,
        relative_attention_num_buckets=8,
        is_training=False,
        dropout_rate=0.1,
        initializer_factor=0.002,
        is_encoder_decoder=False,
        eos_token_id=1,
        pad_token_id=0,
        scope=None,
    ):
        self.parent = parent
        self.batch_size = batch_size
        self.encoder_seq_length = encoder_seq_length
        # For common tests
        self.seq_length = self.encoder_seq_length
        self.use_attention_mask = use_attention_mask
        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.d_ff = d_ff
        self.relative_attention_num_buckets = relative_attention_num_buckets
        self.dropout_rate = dropout_rate
        self.initializer_factor = initializer_factor
        self.eos_token_id = eos_token_id
        self.pad_token_id = pad_token_id
        self.is_encoder_decoder = is_encoder_decoder
        self.scope = None
        self.is_training = is_training

    def prepare_config_and_inputs(self):
        input_ids = ids_tensor([self.batch_size, self.encoder_seq_length], self.vocab_size)

        attention_mask = None
        if self.use_attention_mask:
            attention_mask = ids_tensor([self.batch_size, self.encoder_seq_length], vocab_size=2)

        config = SwitchTransformersConfig(
            vocab_size=self.vocab_size,
            d_model=self.hidden_size,
            d_ff=self.d_ff,
            d_kv=self.hidden_size // self.num_attention_heads,
            num_layers=self.num_hidden_layers,
            num_heads=self.num_attention_heads,
            relative_attention_num_buckets=self.relative_attention_num_buckets,
            dropout_rate=self.dropout_rate,
            initializer_factor=self.initializer_factor,
            eos_token_id=self.eos_token_id,
            bos_token_id=self.pad_token_id,
            pad_token_id=self.pad_token_id,
            is_encoder_decoder=self.is_encoder_decoder,
        )

        return config, input_ids, attention_mask

    def create_and_check_model(self, config, input_ids, attention_mask):
        model = SwitchTransformersEncoderModel(config=config)
        model.to(torch_device)
        model.eval()
        result = model(
            input_ids=input_ids,
            attention_mask=attention_mask,
        )
        result = model(input_ids=input_ids)
        encoder_output = result.last_hidden_state

        self.parent.assertEqual(encoder_output.size(), (self.batch_size, self.encoder_seq_length, self.hidden_size))

    def create_and_check_model_fp16_forward(self, config, input_ids, attention_mask):
        model = SwitchTransformersEncoderModel(config=config).to(torch_device).half().eval()
        output = model(input_ids, attention_mask=attention_mask)["last_hidden_state"]
        self.parent.assertFalse(torch.isnan(output).any().item())

    def prepare_config_and_inputs_for_common(self):
        config_and_inputs = self.prepare_config_and_inputs()
        config, input_ids, attention_mask = config_and_inputs

        inputs_dict = {
            "input_ids": input_ids,
            "attention_mask": attention_mask,
        }
        return config, inputs_dict


class SwitchTransformersEncoderOnlyModelTest(ModelTesterMixin, unittest.TestCase):
    all_model_classes = (SwitchTransformersEncoderModel,) if is_torch_available() else ()

    test_resize_embeddings = False

    def setUp(self):
        self.model_tester = SwitchTransformersEncoderOnlyModelTester(self)
        self.config_tester = ConfigTester(self, config_class=SwitchTransformersConfig, d_model=37)

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

    def test_model(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_model(*config_and_inputs)

    @unittest.skipIf(torch_device == "cpu", "Can't do half precision")
    def test_model_fp16_forward(self):
        config_and_inputs = self.model_tester.prepare_config_and_inputs()
        self.model_tester.create_and_check_model_fp16_forward(*config_and_inputs)

    @unittest.skip(
        reason="This architecture has tied weights by default and there is no way to remove it, check: https://github.com/huggingface/transformers/pull/31771#issuecomment-2210915245"
    )
    def test_load_save_without_tied_weights(self):
        pass


def use_task_specific_params(model, task):
    model.config.update(model.config.task_specific_params[task])


@require_torch
class TestAsymmetricSwitchTransformers(unittest.TestCase):
    def build_model_and_check_forward_pass(self, **kwargs):
        tester = SwitchTransformersModelTester(self, **kwargs)
        config, *inputs = tester.prepare_config_and_inputs()
        (
            input_ids,
            decoder_input_ids,
            attention_mask,
            decoder_attention_mask,
            lm_labels,
        ) = inputs
        model = SwitchTransformersForConditionalGeneration(config=config).to(torch_device).eval()
        outputs = model(
            input_ids=input_ids,
            decoder_input_ids=decoder_input_ids,
            decoder_attention_mask=decoder_attention_mask,
            labels=lm_labels,
            output_router_logits=False,
        )
        # outputs = model(*inputs)
        assert len(outputs) == 4
        assert outputs["logits"].size() == (tester.batch_size, tester.decoder_seq_length, tester.vocab_size)
        assert outputs["loss"].size() == ()
        return model

    def test_small_decoder(self):
        # num_hidden_layers is passed to SwitchTransformersConfig as num_layers
        model = self.build_model_and_check_forward_pass(decoder_layers=1, num_hidden_layers=2)
        assert len(model.encoder.block) == 2
        assert len(model.decoder.block) == 1

    def test_defaulting_to_symmetry(self):
        # num_hidden_layers is passed to SwitchTransformersConfig as num_layers
        model = self.build_model_and_check_forward_pass(num_hidden_layers=2)
        assert len(model.decoder.block) == len(model.encoder.block) == 2


@require_torch
class SwitchTransformerRouterTest(unittest.TestCase):
    r"""
    Switch Transformers has different blocks from classic transformer based models.
    The Swift MLP contains a Router class, that has to be tested to check if it is correctly implemented

    Original implementation of the routers here:

    """

    config = SwitchTransformersConfig(
        num_experts=2,
        hidden_size=8,
        d_ff=16,
        router_jitter_noise=0.0,
        expert_capacity=4,
        num_heads=4,
    )

    def test_equivalency_balancy_loss(self):
        r"""
        This test checks if the balancy loss is correctly implemented
        as in the original implementation of the Switch Transformer .
        """
        router_probs = torch.Tensor(
            [
                [0.35490513, 0.60419905],
                [0.4275843, 0.23061597],
                [0.32985854, 0.43953657],
                [0.25099766, 0.27730572],
                [0.7678207, 0.71474564],
            ]
        )

        expert_indices = torch.Tensor([[0], [1], [1], [0], [0]]).to(torch.int32)

        loss = load_balancing_loss_func(router_probs, expert_indices)
        self.assertAlmostEqual(loss.item(), 0.8741045, places=5)

    def test_equivalency_router_z_loss(self):
        r"""
        This test checks if the router z loss is correctly implemented
        as in the original implementation of the Switch Transformer .
        """
        logits = torch.Tensor(
            [
                [
                    [-4.2124424, 3.891939, -3.6481273, 1.8849981],
                    [0.32625437, 2.918651, 0.84758997, -4.556842],
                    [-3.32062, 4.6977115, -0.15439987, 0.44086337],
                    [3.4467149, 4.3436565, -4.7224274, -4.264637],
                    [-2.224406, -2.5318158, -1.3832569, 1.1891162],
                    [-2.320062, -0.44705987, 4.289819, -0.00662684],
                ],
                [
                    [0.99470854, -0.6992364, 0.25503993, 4.2952085],
                    [3.5937333, -3.2408535, -4.298278, 4.426601],
                    [0.7669008, 2.6588762, 2.4505413, 4.6051874],
                    [0.23330331, -3.0845237, 0.6262374, -2.9865491],
                    [0.7595146, -2.1099675, -4.155346, -2.8326452],
                    [2.3771453, 1.004138, -3.1781673, 0.7581556],
                ],
            ]
        )

        loss = router_z_loss_func(logits)
        self.assertAlmostEqual(loss.item(), 13.786719, places=5)

    def test_equivalency_token_chose_masked_router(self):
        r"""
        This test tests the equivalency between the `SwitchTransformersTop1Router`
        originally implemented from here: TODO: provide link
        """

        input_tokens = torch.Tensor(
            [
                [
                    [0.6433916, 0.18188512, 0.02240455, 0.563781],
                    [0.5526401, 0.0958724, 0.34253013, 0.03644359],
                    [0.08744538, 0.7909105, 0.35205448, 0.53364205],
                ],
                [
                    [0.02900076, 0.4168595, 0.5802449, 0.91486526],
                    [0.27414513, 0.14991808, 0.9383501, 0.5209162],
                    [0.51207185, 0.90618336, 0.7309413, 0.95533276],
                ],
            ]
        )

        model = SwitchTransformersTop1Router(self.config)

        model.classifier.weight = torch.nn.Parameter(
            torch.Tensor(
                [
                    [0.02008116, 0.00620062],
                    [-0.00811031, -0.00031623],
                    [-0.03542127, 0.02703803],
                    [0.02335377, -0.02971946],
                ],
            ).t()
        )

        expert_index, _, router_logits = model(input_tokens)
        router_probs = torch.softmax(router_logits, dim=-1)

        router_z_loss = router_z_loss_func(router_logits)
        auxiliary_loss = load_balancing_loss_func(router_probs, torch.argmax(expert_index, dim=-1))

        self.assertAlmostEqual(router_z_loss.item(), 0.25389, places=5)
        self.assertAlmostEqual(auxiliary_loss.item(), 1.000, places=5)
        #
        # self.assertTrue(torch.allclose(expert_index.bool().unsqueeze(-1), expected_dispatch_mask))

    def test_max_routing_capacity(self):
        model = SwitchTransformersTop1Router(self.config)
        seq_len = 128
        batch_size = 4
        hidden_states = torch.stack(batch_size * [torch.rand((seq_len, self.config.hidden_size))])

        _, _, router_probs = model.forward(hidden_states)
        expert_index = torch.argmax(router_probs, dim=-1)
        expert_index = torch.nn.functional.one_hot(expert_index, num_classes=self.config.num_experts)

        token_priority = torch.cumsum(expert_index, dim=-2)
        expert_capacity_mask = token_priority <= self.config.expert_capacity
        expert_index = expert_index * expert_capacity_mask

        assert torch.sum(expert_index) <= batch_size * self.config.num_experts * self.config.expert_capacity


@slow
@require_torch
@require_tokenizers
class SwitchTransformerModelIntegrationTests(unittest.TestCase):
    @require_torch_accelerator
    @require_torch_bf16
    def test_small_logits(self):
        r"""
        Logits testing to check implementation consistency between `t5x` implementation
        and `transformers` implementation of Switch-C transformers. We only check the logits
        of the first batch.
        """
        model = SwitchTransformersModel.from_pretrained(
            "google/switch-base-8", use_safetensors=False, dtype=torch.bfloat16
        ).to(torch_device)
        input_ids = torch.ones((32, 64), dtype=torch.long).to(torch_device)
        decoder_input_ids = torch.ones((32, 64), dtype=torch.long).to(torch_device)

        # fmt: off
        expectations = Expectations(
            {
                (None, None): [
                    -0.204102, -0.193359, 0.523438, -0.296875, 0.108887,
                    0.0211182, 0.605469, -0.100586, -0.0551758, 0.296875,
                    0.0090332, 0.174805, 0.139648, -0.170898, -0.0981445,
                    0.0245361, 0.0373535, 0.050293, -0.212891, 0.129883,
                    0.390625, -0.203125, -0.122559, -0.180664, 0.0437012,
                    -0.349609, -0.0250244, -0.104004, -0.15918, -0.133789
                ],
                ("cuda", 8): [
                    -0.2051, -0.1914, 0.5352, -0.2988, 0.1108, 0.0200, 0.6094, -0.1025,
                    -0.0549, 0.2988, -0.0018, 0.1758, 0.1348, -0.1689, -0.1035, 0.0266,
                    0.0383, 0.0493, -0.2119, 0.1328, 0.3906, -0.2041, -0.1240, -0.1836,
                    0.0454, -0.3477, -0.0256, -0.1050, -0.1572, -0.1338
                ],
            }
        )
        EXPECTED_MEAN_LOGITS = torch.tensor(expectations.get_expectation()).to(torch_device, dtype=torch.bfloat16)
        # fmt: on

        hf_logits = model(input_ids, decoder_input_ids=decoder_input_ids).last_hidden_state
        hf_logits = hf_logits[0, 0, :30]

        torch.testing.assert_close(hf_logits, EXPECTED_MEAN_LOGITS, rtol=6e-3, atol=9e-3)

    @unittest.skip(
        "Unless we stop stripping left and right by default for all special tokens, the expected ids obtained here will not match the original ones. Wait for https://github.com/huggingface/transformers/pull/23909 to be merged"
    )
    def test_small_generate(self):
        # Generate test using the smalled switch-C model.

        model = SwitchTransformersForConditionalGeneration.from_pretrained(
            "google/switch-base-8", dtype=torch.bfloat16
        ).eval()
        tokenizer = AutoTokenizer.from_pretrained("google-t5/t5-small", use_fast=False, legacy=False)
        model = model.to(torch_device)

        input_ids = tokenizer(
            "The human walks into a bar and orders a <extra_id_0>", return_tensors="pt"
        ).input_ids.to(torch_device)
        sequences = model.generate(input_ids)
        output_str = tokenizer.batch_decode(sequences, skip_special_tokens=True)[0]
        self.assertEqual(output_str, "drink.")

        input_ids = tokenizer(
            "A <extra_id_0> walks into a bar and orders a <extra_id_1> with <extra_id_2> pinch of <extra_id_3>.",
            return_tensors="pt",
        ).input_ids.to(torch_device)
        sequences = model.generate(input_ids)
        output_str = tokenizer.batch_decode(sequences, skip_special_tokens=False)[0]

        EXPECTED_OUTPUT = "<pad><extra_id_0> man<extra_id_1> beer<extra_id_2> a<extra_id_3> whiskey<extra_id_4>.</s>"
        self.assertEqual(output_str, EXPECTED_OUTPUT)

    @unittest.skip(
        "Unless we stop stripping left and right by default for all special tokens, the expected ids obtained here will not match the original ones. Wait for https://github.com/huggingface/transformers/pull/23909 to be merged"
    )
    def test_small_batch_generate(self):
        BATCH_SIZE = 4
        model = SwitchTransformersForConditionalGeneration.from_pretrained(
            "google/switch-base-8", dtype=torch.bfloat16
        ).eval()
        tokenizer = AutoTokenizer.from_pretrained("google-t5/t5-small", use_fast=False, legacy=False)

        inputs = [
            "A <extra_id_0> walks into a bar and orders a <extra_id_1> with <extra_id_2> pinch of <extra_id_3>."
        ] * BATCH_SIZE
        encoded_input = tokenizer.batch_encode_plus(inputs, return_tensors="pt")

        sequences = model.generate(**encoded_input)
        batch_output = tokenizer.batch_decode(sequences, skip_special_tokens=False)

        for i in range(0, BATCH_SIZE, 2):
            self.assertEqual(batch_output[i], batch_output[i + 1])


@require_torch
class SwitchTransformersSparseMLPTests(unittest.TestCase):
    def test_token_dropping(self):
        r"""
        This test checks if the token dropping actually drops tokens.
        """
        config = SwitchTransformersConfig(expert_capacity=0)  # we drop everything
        moe = SwitchTransformersSparseMLP(config)
        dropped_token_results = moe(torch.randn(2, 3, 768))[0]

        assert (dropped_token_results == 0).all(), f"Some tokens not dropped: {dropped_token_results}."
