# Copyright 2020 The HuggingFace 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 random
import warnings
from collections.abc import Mapping
from dataclasses import dataclass
from random import randint
from typing import Any, Callable, Dict, List, NewType, Optional, Tuple, Union

import numpy as np

from ..models.bert import BertTokenizer, BertTokenizerFast
from ..tokenization_utils_base import PreTrainedTokenizerBase
from ..utils import PaddingStrategy


InputDataClass = NewType("InputDataClass", Any)

"""
A DataCollator is a function that takes a list of samples from a Dataset and collate them into a batch, as a dictionary
of PyTorch/TensorFlow tensors or NumPy arrays.
"""
DataCollator = NewType("DataCollator", Callable[[List[InputDataClass]], Dict[str, Any]])


class DataCollatorMixin:
    def __call__(self, features, return_tensors=None):
        if return_tensors is None:
            return_tensors = self.return_tensors
        if return_tensors == "tf":
            return self.tf_call(features)
        elif return_tensors == "pt":
            return self.torch_call(features)
        elif return_tensors == "np":
            return self.numpy_call(features)
        else:
            raise ValueError(f"Framework '{return_tensors}' not recognized!")


def default_data_collator(features: List[InputDataClass], return_tensors="pt") -> Dict[str, Any]:
    """
    Very simple data collator that simply collates batches of dict-like objects and performs special handling for
    potential keys named:

        - `label`: handles a single value (int or float) per object
        - `label_ids`: handles a list of values per object

    Does not do any additional preprocessing: property names of the input object will be used as corresponding inputs
    to the model. See glue and ner for example of how it's useful.
    """

    # In this function we'll make the assumption that all `features` in the batch
    # have the same attributes.
    # So we will look at the first element as a proxy for what attributes exist
    # on the whole batch.

    if return_tensors == "pt":
        return torch_default_data_collator(features)
    elif return_tensors == "tf":
        return tf_default_data_collator(features)
    elif return_tensors == "np":
        return numpy_default_data_collator(features)


@dataclass
class DefaultDataCollator(DataCollatorMixin):
    """
    Very simple data collator that simply collates batches of dict-like objects and performs special handling for
    potential keys named:

        - `label`: handles a single value (int or float) per object
        - `label_ids`: handles a list of values per object

    Does not do any additional preprocessing: property names of the input object will be used as corresponding inputs
    to the model. See glue and ner for example of how it's useful.

    This is an object (like other data collators) rather than a pure function like default_data_collator. This can be
    helpful if you need to set a return_tensors value at initialization.

    Args:
        return_tensors (`str`):
            The type of Tensor to return. Allowable values are "np", "pt" and "tf".
    """

    return_tensors: str = "pt"

    def __call__(self, features: List[Dict[str, Any]], return_tensors=None) -> Dict[str, Any]:
        if return_tensors is None:
            return_tensors = self.return_tensors
        return default_data_collator(features, return_tensors)


def torch_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
    import torch

    if not isinstance(features[0], Mapping):
        features = [vars(f) for f in features]
    first = features[0]
    batch = {}

    # Special handling for labels.
    # Ensure that tensor is created with the correct type
    # (it should be automatically the case, but let's make sure of it.)
    if "label" in first and first["label"] is not None:
        label = first["label"].item() if isinstance(first["label"], torch.Tensor) else first["label"]
        dtype = torch.long if isinstance(label, int) else torch.float
        batch["labels"] = torch.tensor([f["label"] for f in features], dtype=dtype)
    elif "label_ids" in first and first["label_ids"] is not None:
        if isinstance(first["label_ids"], torch.Tensor):
            batch["labels"] = torch.stack([f["label_ids"] for f in features])
        else:
            dtype = torch.long if type(first["label_ids"][0]) is int else torch.float
            batch["labels"] = torch.tensor([f["label_ids"] for f in features], dtype=dtype)

    # Handling of all other possible keys.
    # Again, we will use the first element to figure out which key/values are not None for this model.
    for k, v in first.items():
        if k not in ("label", "label_ids") and v is not None and not isinstance(v, str):
            if isinstance(v, torch.Tensor):
                batch[k] = torch.stack([f[k] for f in features])
            elif isinstance(v, np.ndarray):
                batch[k] = torch.tensor(np.stack([f[k] for f in features]))
            else:
                batch[k] = torch.tensor([f[k] for f in features])

    return batch


def tf_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
    import tensorflow as tf

    if not isinstance(features[0], Mapping):
        features = [vars(f) for f in features]
    first = features[0]
    batch = {}

    # Special handling for labels.
    # Ensure that tensor is created with the correct type
    # (it should be automatically the case, but let's make sure of it.)
    if "label" in first and first["label"] is not None:
        label_col_name = "label"
    elif "label_ids" in first and first["label_ids"] is not None:
        label_col_name = "label_ids"
    elif "labels" in first and first["labels"] is not None:
        label_col_name = "labels"
    else:
        label_col_name = None
    if label_col_name is not None:
        if isinstance(first[label_col_name], tf.Tensor):
            dtype = tf.int64 if first[label_col_name].dtype.is_integer else tf.float32
        elif isinstance(first[label_col_name], np.ndarray) or isinstance(first[label_col_name], np.generic):
            dtype = tf.int64 if np.issubdtype(first[label_col_name].dtype, np.integer) else tf.float32
        elif isinstance(first[label_col_name], (tuple, list)):
            dtype = tf.int64 if isinstance(first[label_col_name][0], int) else tf.float32
        else:
            dtype = tf.int64 if isinstance(first[label_col_name], int) else tf.float32
        batch["labels"] = tf.convert_to_tensor([f[label_col_name] for f in features], dtype=dtype)
    # Handling of all other possible keys.
    # Again, we will use the first element to figure out which key/values are not None for this model.
    for k, v in first.items():
        if k not in ("label", "label_ids", "labels") and v is not None and not isinstance(v, str):
            if isinstance(v, (tf.Tensor, np.ndarray)):
                batch[k] = tf.stack([f[k] for f in features])
            else:
                batch[k] = tf.convert_to_tensor([f[k] for f in features])

    return batch


def numpy_default_data_collator(features: List[InputDataClass]) -> Dict[str, Any]:
    if not isinstance(features[0], Mapping):
        features = [vars(f) for f in features]
    first = features[0]
    batch = {}

    # Special handling for labels.
    # Ensure that tensor is created with the correct type
    # (it should be automatically the case, but let's make sure of it.)
    if "label" in first and first["label"] is not None:
        label = first["label"].item() if isinstance(first["label"], np.ndarray) else first["label"]
        dtype = np.int64 if isinstance(label, int) else np.float32
        batch["labels"] = np.array([f["label"] for f in features], dtype=dtype)
    elif "label_ids" in first and first["label_ids"] is not None:
        if isinstance(first["label_ids"], np.ndarray):
            batch["labels"] = np.stack([f["label_ids"] for f in features])
        else:
            dtype = np.int64 if type(first["label_ids"][0]) is int else np.float32
            batch["labels"] = np.array([f["label_ids"] for f in features], dtype=dtype)

    # Handling of all other possible keys.
    # Again, we will use the first element to figure out which key/values are not None for this model.
    for k, v in first.items():
        if k not in ("label", "label_ids") and v is not None and not isinstance(v, str):
            if isinstance(v, np.ndarray):
                batch[k] = np.stack([f[k] for f in features])
            else:
                batch[k] = np.array([f[k] for f in features])

    return batch


@dataclass
class DataCollatorWithPadding:
    """
    Data collator that will dynamically pad the inputs received.

    Args:
        tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
            The tokenizer used for encoding the data.
        padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
            Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
            among:

            - `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
              sequence is provided).
            - `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
              acceptable input length for the model if that argument is not provided.
            - `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
        max_length (`int`, *optional*):
            Maximum length of the returned list and optionally padding length (see above).
        pad_to_multiple_of (`int`, *optional*):
            If set will pad the sequence to a multiple of the provided value.

            This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
            7.5 (Volta).
        return_tensors (`str`):
            The type of Tensor to return. Allowable values are "np", "pt" and "tf".
    """

    tokenizer: PreTrainedTokenizerBase
    padding: Union[bool, str, PaddingStrategy] = True
    max_length: Optional[int] = None
    pad_to_multiple_of: Optional[int] = None
    return_tensors: str = "pt"

    def __call__(self, features: List[Dict[str, Any]]) -> Dict[str, Any]:
        batch = self.tokenizer.pad(
            features,
            padding=self.padding,
            max_length=self.max_length,
            pad_to_multiple_of=self.pad_to_multiple_of,
            return_tensors=self.return_tensors,
        )
        if "label" in batch:
            batch["labels"] = batch["label"]
            del batch["label"]
        if "label_ids" in batch:
            batch["labels"] = batch["label_ids"]
            del batch["label_ids"]
        return batch


@dataclass
class DataCollatorForTokenClassification(DataCollatorMixin):
    """
    Data collator that will dynamically pad the inputs received, as well as the labels.

    Args:
        tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
            The tokenizer used for encoding the data.
        padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
            Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
            among:

            - `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
              sequence is provided).
            - `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
              acceptable input length for the model if that argument is not provided.
            - `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
        max_length (`int`, *optional*):
            Maximum length of the returned list and optionally padding length (see above).
        pad_to_multiple_of (`int`, *optional*):
            If set will pad the sequence to a multiple of the provided value.

            This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
            7.5 (Volta).
        label_pad_token_id (`int`, *optional*, defaults to -100):
            The id to use when padding the labels (-100 will be automatically ignore by PyTorch loss functions).
        return_tensors (`str`):
            The type of Tensor to return. Allowable values are "np", "pt" and "tf".
    """

    tokenizer: PreTrainedTokenizerBase
    padding: Union[bool, str, PaddingStrategy] = True
    max_length: Optional[int] = None
    pad_to_multiple_of: Optional[int] = None
    label_pad_token_id: int = -100
    return_tensors: str = "pt"

    def torch_call(self, features):
        import torch

        label_name = "label" if "label" in features[0].keys() else "labels"
        labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None

        no_labels_features = [{k: v for k, v in feature.items() if k != label_name} for feature in features]

        batch = self.tokenizer.pad(
            no_labels_features,
            padding=self.padding,
            max_length=self.max_length,
            pad_to_multiple_of=self.pad_to_multiple_of,
            return_tensors="pt",
        )

        if labels is None:
            return batch

        sequence_length = batch["input_ids"].shape[1]
        padding_side = self.tokenizer.padding_side

        def to_list(tensor_or_iterable):
            if isinstance(tensor_or_iterable, torch.Tensor):
                return tensor_or_iterable.tolist()
            return list(tensor_or_iterable)

        if padding_side == "right":
            batch[label_name] = [
                to_list(label) + [self.label_pad_token_id] * (sequence_length - len(label)) for label in labels
            ]
        else:
            batch[label_name] = [
                [self.label_pad_token_id] * (sequence_length - len(label)) + to_list(label) for label in labels
            ]

        batch[label_name] = torch.tensor(batch[label_name], dtype=torch.int64)
        return batch

    def tf_call(self, features):
        import tensorflow as tf

        label_name = "label" if "label" in features[0].keys() else "labels"
        labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
        batch = self.tokenizer.pad(
            features,
            padding=self.padding,
            max_length=self.max_length,
            pad_to_multiple_of=self.pad_to_multiple_of,
            # Conversion to tensors will fail if we have labels as they are not of the same length yet.
            return_tensors="tf" if labels is None else None,
        )

        if labels is None:
            return batch

        sequence_length = tf.convert_to_tensor(batch["input_ids"]).shape[1]
        padding_side = self.tokenizer.padding_side
        if padding_side == "right":
            batch["labels"] = [
                list(label) + [self.label_pad_token_id] * (sequence_length - len(label)) for label in labels
            ]
        else:
            batch["labels"] = [
                [self.label_pad_token_id] * (sequence_length - len(label)) + list(label) for label in labels
            ]

        batch = {k: tf.convert_to_tensor(v, dtype=tf.int64) for k, v in batch.items()}
        return batch

    def numpy_call(self, features):
        label_name = "label" if "label" in features[0].keys() else "labels"
        labels = [feature[label_name] for feature in features] if label_name in features[0].keys() else None
        batch = self.tokenizer.pad(
            features,
            padding=self.padding,
            max_length=self.max_length,
            pad_to_multiple_of=self.pad_to_multiple_of,
            # Conversion to tensors will fail if we have labels as they are not of the same length yet.
            return_tensors="np" if labels is None else None,
        )

        if labels is None:
            return batch

        sequence_length = np.array(batch["input_ids"]).shape[1]
        padding_side = self.tokenizer.padding_side
        if padding_side == "right":
            batch["labels"] = [
                list(label) + [self.label_pad_token_id] * (sequence_length - len(label)) for label in labels
            ]
        else:
            batch["labels"] = [
                [self.label_pad_token_id] * (sequence_length - len(label)) + list(label) for label in labels
            ]

        batch = {k: np.array(v, dtype=np.int64) for k, v in batch.items()}
        return batch


def _torch_collate_batch(examples, tokenizer, pad_to_multiple_of: Optional[int] = None):
    """Collate `examples` into a batch, using the information in `tokenizer` for padding if necessary."""
    import torch

    # Tensorize if necessary.
    if isinstance(examples[0], (list, tuple, np.ndarray)):
        examples = [torch.tensor(e, dtype=torch.long) for e in examples]

    length_of_first = examples[0].size(0)

    # Check if padding is necessary.

    are_tensors_same_length = all(x.size(0) == length_of_first for x in examples)
    if are_tensors_same_length and (pad_to_multiple_of is None or length_of_first % pad_to_multiple_of == 0):
        return torch.stack(examples, dim=0)

    # If yes, check if we have a `pad_token`.
    if tokenizer._pad_token is None:
        raise ValueError(
            "You are attempting to pad samples but the tokenizer you are using"
            f" ({tokenizer.__class__.__name__}) does not have a pad token."
        )

    # Creating the full tensor and filling it with our data.
    max_length = max(x.size(0) for x in examples)
    if pad_to_multiple_of is not None and (max_length % pad_to_multiple_of != 0):
        max_length = ((max_length // pad_to_multiple_of) + 1) * pad_to_multiple_of
    result = examples[0].new_full([len(examples), max_length], tokenizer.pad_token_id)
    for i, example in enumerate(examples):
        if tokenizer.padding_side == "right":
            result[i, : example.shape[0]] = example
        else:
            result[i, -example.shape[0] :] = example
    return result


def _tf_collate_batch(examples, tokenizer, pad_to_multiple_of: Optional[int] = None):
    import tensorflow as tf

    """Collate `examples` into a batch, using the information in `tokenizer` for padding if necessary."""
    # Tensorize if necessary.
    if isinstance(examples[0], (list, tuple)):
        examples = [tf.convert_to_tensor(e, dtype=tf.int64) for e in examples]

    # Check if padding is necessary.
    length_of_first = len(examples[0])
    are_tensors_same_length = all(len(x) == length_of_first for x in examples)
    if are_tensors_same_length and (pad_to_multiple_of is None or length_of_first % pad_to_multiple_of == 0):
        return tf.stack(examples, axis=0)

    # If yes, check if we have a `pad_token`.
    if tokenizer._pad_token is None:
        raise ValueError(
            "You are attempting to pad samples but the tokenizer you are using"
            f" ({tokenizer.__class__.__name__}) does not have a pad token."
        )

    # Creating the full tensor and filling it with our data.
    max_length = max(len(x) for x in examples)
    if pad_to_multiple_of is not None and (max_length % pad_to_multiple_of != 0):
        max_length = ((max_length // pad_to_multiple_of) + 1) * pad_to_multiple_of
    # result = examples[0].new_full([len(examples), max_length], tokenizer.pad_token_id)
    result = []
    rank = tf.rank(examples[0])
    paddings = np.zeros((rank, 2), dtype=np.int32)
    for example in examples:
        if tokenizer.padding_side == "right":
            paddings[0, 1] = max_length - len(example)
        else:
            paddings[0, 0] = max_length - len(example)
        result.append(tf.pad(example, paddings, constant_values=tokenizer.pad_token_id))
    return tf.stack(result, axis=0)


def _numpy_collate_batch(examples, tokenizer, pad_to_multiple_of: Optional[int] = None):
    """Collate `examples` into a batch, using the information in `tokenizer` for padding if necessary."""
    # Tensorize if necessary.
    if isinstance(examples[0], (list, tuple)):
        examples = [np.array(e, dtype=np.int64) for e in examples]

    # Check if padding is necessary.
    length_of_first = len(examples[0])
    are_tensors_same_length = all(len(x) == length_of_first for x in examples)
    if are_tensors_same_length and (pad_to_multiple_of is None or length_of_first % pad_to_multiple_of == 0):
        return np.stack(examples, axis=0)

    # If yes, check if we have a `pad_token`.
    if tokenizer._pad_token is None:
        raise ValueError(
            "You are attempting to pad samples but the tokenizer you are using"
            f" ({tokenizer.__class__.__name__}) does not have a pad token."
        )

    # Creating the full tensor and filling it with our data.
    max_length = max(len(x) for x in examples)
    if pad_to_multiple_of is not None and (max_length % pad_to_multiple_of != 0):
        max_length = ((max_length // pad_to_multiple_of) + 1) * pad_to_multiple_of
    result = np.full(shape=(len(examples), max_length), fill_value=tokenizer.pad_token_id, dtype=examples[0].dtype)
    for i, example in enumerate(examples):
        if tokenizer.padding_side == "right":
            result[i, : example.shape[0]] = example
        else:
            result[i, -example.shape[0] :] = example
    return result


def tolist(x):
    if isinstance(x, list):
        return x
    elif hasattr(x, "numpy"):  # Checks for TF tensors without needing the import
        x = x.numpy()
    return x.tolist()


@dataclass
class DataCollatorForSeq2Seq:
    """
    Data collator that will dynamically pad the inputs received, as well as the labels.

    Args:
        tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
            The tokenizer used for encoding the data.
        model ([`PreTrainedModel`]):
            The model that is being trained. If set and has the *prepare_decoder_input_ids_from_labels*, use it to
            prepare the *decoder_input_ids*

            This is useful when using *label_smoothing* to avoid calculating loss twice.
        padding (`bool`, `str` or [`~utils.PaddingStrategy`], *optional*, defaults to `True`):
            Select a strategy to pad the returned sequences (according to the model's padding side and padding index)
            among:

            - `True` or `'longest'` (default): Pad to the longest sequence in the batch (or no padding if only a single
              sequence is provided).
            - `'max_length'`: Pad to a maximum length specified with the argument `max_length` or to the maximum
              acceptable input length for the model if that argument is not provided.
            - `False` or `'do_not_pad'`: No padding (i.e., can output a batch with sequences of different lengths).
        max_length (`int`, *optional*):
            Maximum length of the returned list and optionally padding length (see above).
        pad_to_multiple_of (`int`, *optional*):
            If set will pad the sequence to a multiple of the provided value.

            This is especially useful to enable the use of Tensor Cores on NVIDIA hardware with compute capability >=
            7.5 (Volta).
        label_pad_token_id (`int`, *optional*, defaults to -100):
            The id to use when padding the labels (-100 will be automatically ignored by PyTorch loss functions).
        return_tensors (`str`):
            The type of Tensor to return. Allowable values are "np", "pt" and "tf".
    """

    tokenizer: PreTrainedTokenizerBase
    model: Optional[Any] = None
    padding: Union[bool, str, PaddingStrategy] = True
    max_length: Optional[int] = None
    pad_to_multiple_of: Optional[int] = None
    label_pad_token_id: int = -100
    return_tensors: str = "pt"

    def __call__(self, features, return_tensors=None):
        if return_tensors is None:
            return_tensors = self.return_tensors
        labels = [feature["labels"] for feature in features] if "labels" in features[0].keys() else None
        # We have to pad the labels before calling `tokenizer.pad` as this method won't pad them and needs them of the
        # same length to return tensors.
        if labels is not None:
            max_label_length = max(len(l) for l in labels)
            if self.pad_to_multiple_of is not None:
                max_label_length = (
                    (max_label_length + self.pad_to_multiple_of - 1)
                    // self.pad_to_multiple_of
                    * self.pad_to_multiple_of
                )

            padding_side = self.tokenizer.padding_side
            for feature in features:
                remainder = [self.label_pad_token_id] * (max_label_length - len(feature["labels"]))
                if isinstance(feature["labels"], list):
                    feature["labels"] = (
                        feature["labels"] + remainder if padding_side == "right" else remainder + feature["labels"]
                    )
                elif padding_side == "right":
                    feature["labels"] = np.concatenate([feature["labels"], remainder]).astype(np.int64)
                else:
                    feature["labels"] = np.concatenate([remainder, feature["labels"]]).astype(np.int64)

        features = self.tokenizer.pad(
            features,
            padding=self.padding,
            max_length=self.max_length,
            pad_to_multiple_of=self.pad_to_multiple_of,
            return_tensors=return_tensors,
        )

        # prepare decoder_input_ids
        if (
            labels is not None
            and self.model is not None
            and hasattr(self.model, "prepare_decoder_input_ids_from_labels")
        ):
            decoder_input_ids = self.model.prepare_decoder_input_ids_from_labels(labels=features["labels"])
            features["decoder_input_ids"] = decoder_input_ids

        return features


@dataclass
class DataCollatorForLanguageModeling(DataCollatorMixin):
    """
    Data collator used for language modeling. Inputs are dynamically padded to the maximum length of a batch if they
    are not all of the same length.

    Args:
        tokenizer ([`PreTrainedTokenizer`] or [`PreTrainedTokenizerFast`]):
            The tokenizer used for encoding the data.
        mlm (`bool`, *optional*, defaults to `True`):
            Whether or not to use masked language modeling. If set to `False`, the labels are the same as the inputs
            with the padding tokens ignored (by setting them to -100). Otherwise, the labels are -100 for non-masked
            tokens and the value to predict for the masked token.
        mlm_probability (`float`, *optional*, defaults to 0.15):
            The probability with which to (randomly) mask tokens in the input, when `mlm` is set to `True`.
        pad_to_multiple_of (`int`, *optional*):
            If set will pad the sequence to a multiple of the provided value.
        return_tensors (`str`):
            The type of Tensor to return. Allowable values are "np", "pt" and "tf".

    <Tip>

    For best performance, this data collator should be used with a dataset having items that are dictionaries or
    BatchEncoding, with the `"special_tokens_mask"` key, as returned by a [`PreTrainedTokenizer`] or a
    [`PreTrainedTokenizerFast`] with the argument `return_special_tokens_mask=True`.

    </Tip>"""

    tokenizer: PreTrainedTokenizerBase
    mlm: bool = True
    mlm_probability: float = 0.15
    pad_to_multiple_of: Optional[int] = None
    tf_experimental_compile: bool = False
    return_tensors: str = "pt"

    def __post_init__(self):
        if self.mlm and self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for masked language modeling. "
                "You should pass `mlm=False` to train on causal language modeling instead."
            )
        if self.tf_experimental_compile:
            import tensorflow as tf

            self.tf_mask_tokens = tf.function(self.tf_mask_tokens, jit_compile=True)

    @staticmethod
    def tf_bernoulli(shape, probability):
        import tensorflow as tf

        prob_matrix = tf.fill(shape, probability)
        return tf.cast(prob_matrix - tf.random.uniform(shape, 0, 1) >= 0, tf.bool)

    def tf_mask_tokens(
        self, inputs: Any, vocab_size, mask_token_id, special_tokens_mask: Optional[Any] = None
    ) -> Tuple[Any, Any]:
        """
        Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original.
        """
        import tensorflow as tf

        mask_token_id = tf.cast(mask_token_id, inputs.dtype)

        input_shape = tf.shape(inputs)
        # 1 for a special token, 0 for a normal token in the special tokens mask
        # We sample a few tokens in each sequence for MLM training (with probability `self.mlm_probability`)
        masked_indices = self.tf_bernoulli(input_shape, self.mlm_probability) & ~special_tokens_mask
        # Replace unmasked indices with -100 in the labels since we only compute loss on masked tokens
        labels = tf.where(masked_indices, inputs, -100)

        # 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
        indices_replaced = self.tf_bernoulli(input_shape, 0.8) & masked_indices

        inputs = tf.where(indices_replaced, mask_token_id, inputs)

        # 10% of the time, we replace masked input tokens with random word
        indices_random = self.tf_bernoulli(input_shape, 0.1) & masked_indices & ~indices_replaced
        random_words = tf.random.uniform(input_shape, maxval=vocab_size, dtype=inputs.dtype)

        inputs = tf.where(indices_random, random_words, inputs)

        # The rest of the time (10% of the time) we keep the masked input tokens unchanged
        return inputs, labels

    def tf_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        import tensorflow as tf

        # Handle dict or lists with proper padding and conversion to tensor.
        if isinstance(examples[0], Mapping):
            batch = self.tokenizer.pad(examples, return_tensors="tf", pad_to_multiple_of=self.pad_to_multiple_of)
        else:
            batch = {
                "input_ids": _tf_collate_batch(examples, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
            }

        # If special token mask has been preprocessed, pop it from the dict.
        special_tokens_mask = batch.pop("special_tokens_mask", None)
        if self.mlm:
            if special_tokens_mask is None:
                special_tokens_mask = [
                    self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True)
                    for val in batch["input_ids"].numpy().tolist()
                ]
                # Cannot directly create as bool
                special_tokens_mask = tf.cast(tf.convert_to_tensor(special_tokens_mask, dtype=tf.int64), tf.bool)
            else:
                special_tokens_mask = tf.cast(special_tokens_mask, tf.bool)
            batch["input_ids"], batch["labels"] = self.tf_mask_tokens(
                tf.cast(batch["input_ids"], tf.int64),
                special_tokens_mask=special_tokens_mask,
                mask_token_id=self.tokenizer.mask_token_id,
                vocab_size=len(self.tokenizer),
            )
        else:
            labels = batch["input_ids"]
            if self.tokenizer.pad_token_id is not None:
                # Replace self.tokenizer.pad_token_id with -100
                labels = tf.where(labels == self.tokenizer.pad_token_id, -100, labels)
            else:
                labels = tf.identity(labels)  # Makes a copy, just in case
            batch["labels"] = labels
        return batch

    def torch_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        # Handle dict or lists with proper padding and conversion to tensor.
        if isinstance(examples[0], Mapping):
            batch = self.tokenizer.pad(examples, return_tensors="pt", pad_to_multiple_of=self.pad_to_multiple_of)
        else:
            batch = {
                "input_ids": _torch_collate_batch(examples, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
            }

        # If special token mask has been preprocessed, pop it from the dict.
        special_tokens_mask = batch.pop("special_tokens_mask", None)
        if self.mlm:
            batch["input_ids"], batch["labels"] = self.torch_mask_tokens(
                batch["input_ids"], special_tokens_mask=special_tokens_mask
            )
        else:
            labels = batch["input_ids"].clone()
            if self.tokenizer.pad_token_id is not None:
                labels[labels == self.tokenizer.pad_token_id] = -100
            batch["labels"] = labels
        return batch

    def torch_mask_tokens(self, inputs: Any, special_tokens_mask: Optional[Any] = None) -> Tuple[Any, Any]:
        """
        Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original.
        """
        import torch

        labels = inputs.clone()
        # We sample a few tokens in each sequence for MLM training (with probability `self.mlm_probability`)
        probability_matrix = torch.full(labels.shape, self.mlm_probability)
        if special_tokens_mask is None:
            special_tokens_mask = [
                self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
            ]
            special_tokens_mask = torch.tensor(special_tokens_mask, dtype=torch.bool)
        else:
            special_tokens_mask = special_tokens_mask.bool()

        probability_matrix.masked_fill_(special_tokens_mask, value=0.0)
        masked_indices = torch.bernoulli(probability_matrix).bool()
        labels[~masked_indices] = -100  # We only compute loss on masked tokens

        # 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
        indices_replaced = torch.bernoulli(torch.full(labels.shape, 0.8)).bool() & masked_indices
        inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)

        # 10% of the time, we replace masked input tokens with random word
        indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
        random_words = torch.randint(len(self.tokenizer), labels.shape, dtype=torch.long)
        inputs[indices_random] = random_words[indices_random]

        # The rest of the time (10% of the time) we keep the masked input tokens unchanged
        return inputs, labels

    def numpy_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        # Handle dict or lists with proper padding and conversion to tensor.
        if isinstance(examples[0], Mapping):
            batch = self.tokenizer.pad(examples, return_tensors="np", pad_to_multiple_of=self.pad_to_multiple_of)
        else:
            batch = {
                "input_ids": _numpy_collate_batch(examples, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
            }

        # If special token mask has been preprocessed, pop it from the dict.
        special_tokens_mask = batch.pop("special_tokens_mask", None)
        if self.mlm:
            batch["input_ids"], batch["labels"] = self.numpy_mask_tokens(
                batch["input_ids"], special_tokens_mask=special_tokens_mask
            )
        else:
            labels = np.copy(batch["input_ids"])
            if self.tokenizer.pad_token_id is not None:
                labels[labels == self.tokenizer.pad_token_id] = -100
            batch["labels"] = labels
        return batch

    def numpy_mask_tokens(self, inputs: Any, special_tokens_mask: Optional[Any] = None) -> Tuple[Any, Any]:
        """
        Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original.
        """
        labels = np.copy(inputs)
        # We sample a few tokens in each sequence for MLM training (with probability `self.mlm_probability`)
        probability_matrix = np.full(labels.shape, self.mlm_probability)
        if special_tokens_mask is None:
            special_tokens_mask = [
                self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
            ]
            special_tokens_mask = np.array(special_tokens_mask, dtype=bool)
        else:
            special_tokens_mask = special_tokens_mask.astype(bool)

        probability_matrix[special_tokens_mask] = 0
        # Numpy doesn't have bernoulli, so we use a binomial with 1 trial
        masked_indices = np.random.binomial(1, probability_matrix, size=probability_matrix.shape).astype(bool)
        labels[~masked_indices] = -100  # We only compute loss on masked tokens

        # 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
        indices_replaced = np.random.binomial(1, 0.8, size=labels.shape).astype(bool) & masked_indices
        inputs[indices_replaced] = self.tokenizer.mask_token_id

        # 10% of the time, we replace masked input tokens with random word
        # indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
        indices_random = (
            np.random.binomial(1, 0.5, size=labels.shape).astype(bool) & masked_indices & ~indices_replaced
        )
        random_words = np.random.randint(
            low=0, high=len(self.tokenizer), size=np.count_nonzero(indices_random), dtype=np.int64
        )
        inputs[indices_random] = random_words

        # The rest of the time (10% of the time) we keep the masked input tokens unchanged
        return inputs, labels


@dataclass
class DataCollatorForWholeWordMask(DataCollatorForLanguageModeling):
    """
    Data collator used for language modeling that masks entire words.

    - collates batches of tensors, honoring their tokenizer's pad_token
    - preprocesses batches for masked language modeling

    <Tip>

    This collator relies on details of the implementation of subword tokenization by [`BertTokenizer`], specifically
    that subword tokens are prefixed with *##*. For tokenizers that do not adhere to this scheme, this collator will
    produce an output that is roughly equivalent to [`.DataCollatorForLanguageModeling`].

    </Tip>"""

    def torch_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        if isinstance(examples[0], Mapping):
            input_ids = [e["input_ids"] for e in examples]
        else:
            input_ids = examples
            examples = [{"input_ids": e} for e in examples]

        batch_input = _torch_collate_batch(input_ids, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)

        mask_labels = []
        for e in examples:
            ref_tokens = []
            for id in tolist(e["input_ids"]):
                token = self.tokenizer._convert_id_to_token(id)
                ref_tokens.append(token)

            # For Chinese tokens, we need extra inf to mark sub-word, e.g [喜,欢]-> [喜，##欢]
            if "chinese_ref" in e:
                ref_pos = tolist(e["chinese_ref"])
                len_seq = len(e["input_ids"])
                for i in range(len_seq):
                    if i in ref_pos:
                        ref_tokens[i] = "##" + ref_tokens[i]
            mask_labels.append(self._whole_word_mask(ref_tokens))
        batch_mask = _torch_collate_batch(mask_labels, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
        inputs, labels = self.torch_mask_tokens(batch_input, batch_mask)
        return {"input_ids": inputs, "labels": labels}

    def tf_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        import tensorflow as tf

        if isinstance(examples[0], Mapping):
            input_ids = [e["input_ids"] for e in examples]
        else:
            input_ids = examples
            examples = [{"input_ids": e} for e in examples]

        batch_input = _tf_collate_batch(input_ids, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)

        mask_labels = []
        for e in examples:
            ref_tokens = []
            for id in tolist(e["input_ids"]):
                token = self.tokenizer._convert_id_to_token(id)
                ref_tokens.append(token)

            # For Chinese tokens, we need extra inf to mark sub-word, e.g [喜,欢]-> [喜，##欢]
            if "chinese_ref" in e:
                ref_pos = tolist(e["chinese_ref"])
                len_seq = len(e["input_ids"])
                for i in range(len_seq):
                    if i in ref_pos:
                        ref_tokens[i] = "##" + ref_tokens[i]
            mask_labels.append(self._whole_word_mask(ref_tokens))
        batch_mask = _tf_collate_batch(mask_labels, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
        inputs, labels = self.tf_mask_tokens(tf.cast(batch_input, tf.int64), batch_mask)
        return {"input_ids": inputs, "labels": labels}

    def numpy_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        if isinstance(examples[0], Mapping):
            input_ids = [e["input_ids"] for e in examples]
        else:
            input_ids = examples
            examples = [{"input_ids": e} for e in examples]

        batch_input = _numpy_collate_batch(input_ids, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)

        mask_labels = []
        for e in examples:
            ref_tokens = []
            for id in tolist(e["input_ids"]):
                token = self.tokenizer._convert_id_to_token(id)
                ref_tokens.append(token)

            # For Chinese tokens, we need extra inf to mark sub-word, e.g [喜,欢]-> [喜，##欢]
            if "chinese_ref" in e:
                ref_pos = tolist(e["chinese_ref"])
                len_seq = len(e["input_ids"])
                for i in range(len_seq):
                    if i in ref_pos:
                        ref_tokens[i] = "##" + ref_tokens[i]
            mask_labels.append(self._whole_word_mask(ref_tokens))
        batch_mask = _numpy_collate_batch(mask_labels, self.tokenizer, pad_to_multiple_of=self.pad_to_multiple_of)
        inputs, labels = self.numpy_mask_tokens(batch_input, batch_mask)
        return {"input_ids": inputs, "labels": labels}

    def _whole_word_mask(self, input_tokens: List[str], max_predictions=512):
        """
        Get 0/1 labels for masked tokens with whole word mask proxy
        """
        if not isinstance(self.tokenizer, (BertTokenizer, BertTokenizerFast)):
            warnings.warn(
                "DataCollatorForWholeWordMask is only suitable for BertTokenizer-like tokenizers. "
                "Please refer to the documentation for more information."
            )

        cand_indexes = []
        for i, token in enumerate(input_tokens):
            if token == "[CLS]" or token == "[SEP]":
                continue

            if len(cand_indexes) >= 1 and token.startswith("##"):
                cand_indexes[-1].append(i)
            else:
                cand_indexes.append([i])

        random.shuffle(cand_indexes)
        num_to_predict = min(max_predictions, max(1, int(round(len(input_tokens) * self.mlm_probability))))
        masked_lms = []
        covered_indexes = set()
        for index_set in cand_indexes:
            if len(masked_lms) >= num_to_predict:
                break
            # If adding a whole-word mask would exceed the maximum number of
            # predictions, then just skip this candidate.
            if len(masked_lms) + len(index_set) > num_to_predict:
                continue
            is_any_index_covered = False
            for index in index_set:
                if index in covered_indexes:
                    is_any_index_covered = True
                    break
            if is_any_index_covered:
                continue
            for index in index_set:
                covered_indexes.add(index)
                masked_lms.append(index)

        if len(covered_indexes) != len(masked_lms):
            raise ValueError("Length of covered_indexes is not equal to length of masked_lms.")
        mask_labels = [1 if i in covered_indexes else 0 for i in range(len(input_tokens))]
        return mask_labels

    def torch_mask_tokens(self, inputs: Any, mask_labels: Any) -> Tuple[Any, Any]:
        """
        Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original. Set
        'mask_labels' means we use whole word mask (wwm), we directly mask idxs according to it's ref.
        """
        import torch

        if self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
                " --mlm flag if you want to use this tokenizer."
            )
        labels = inputs.clone()
        # We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)

        probability_matrix = mask_labels

        special_tokens_mask = [
            self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
        ]
        probability_matrix.masked_fill_(torch.tensor(special_tokens_mask, dtype=torch.bool), value=0.0)
        if self.tokenizer._pad_token is not None:
            padding_mask = labels.eq(self.tokenizer.pad_token_id)
            probability_matrix.masked_fill_(padding_mask, value=0.0)

        masked_indices = probability_matrix.bool()
        labels[~masked_indices] = -100  # We only compute loss on masked tokens

        # 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
        indices_replaced = torch.bernoulli(torch.full(labels.shape, 0.8)).bool() & masked_indices
        inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)

        # 10% of the time, we replace masked input tokens with random word
        indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
        random_words = torch.randint(len(self.tokenizer), labels.shape, dtype=torch.long)
        inputs[indices_random] = random_words[indices_random]

        # The rest of the time (10% of the time) we keep the masked input tokens unchanged
        return inputs, labels

    def tf_mask_tokens(self, inputs: Any, mask_labels: Any) -> Tuple[Any, Any]:
        """
        Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original. Set
        'mask_labels' means we use whole word mask (wwm), we directly mask idxs according to it's ref.
        """
        import tensorflow as tf

        input_shape = tf.shape(inputs)
        if self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
                " --mlm flag if you want to use this tokenizer."
            )
        labels = tf.identity(inputs)
        # We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)

        masked_indices = tf.cast(mask_labels, tf.bool)

        special_tokens_mask = [
            self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels
        ]
        masked_indices = masked_indices & ~tf.cast(special_tokens_mask, dtype=tf.bool)
        if self.tokenizer._pad_token is not None:
            padding_mask = inputs == self.tokenizer.pad_token_id
            masked_indices = masked_indices & ~padding_mask

        # Replace unmasked indices with -100 in the labels since we only compute loss on masked tokens
        labels = tf.where(masked_indices, inputs, -100)

        # 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
        indices_replaced = self.tf_bernoulli(input_shape, 0.8) & masked_indices

        inputs = tf.where(indices_replaced, self.tokenizer.mask_token_id, inputs)

        # 10% of the time, we replace masked input tokens with random word
        indices_random = self.tf_bernoulli(input_shape, 0.5) & masked_indices & ~indices_replaced
        random_words = tf.random.uniform(input_shape, maxval=len(self.tokenizer), dtype=tf.int64)
        inputs = tf.where(indices_random, random_words, inputs)

        # The rest of the time (10% of the time) we keep the masked input tokens unchanged
        return inputs, labels

    def numpy_mask_tokens(self, inputs: Any, mask_labels: Any) -> Tuple[Any, Any]:
        """
        Prepare masked tokens inputs/labels for masked language modeling: 80% MASK, 10% random, 10% original. Set
        'mask_labels' means we use whole word mask (wwm), we directly mask idxs according to it's ref.
        """
        if self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
                " --mlm flag if you want to use this tokenizer."
            )
        labels = np.copy(inputs)
        # We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)

        masked_indices = mask_labels.astype(bool)

        special_tokens_mask = [
            self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
        ]
        masked_indices[np.array(special_tokens_mask, dtype=bool)] = 0
        if self.tokenizer._pad_token is not None:
            padding_mask = labels == self.tokenizer.pad_token_id
            masked_indices[padding_mask] = 0

        labels[~masked_indices] = -100  # We only compute loss on masked tokens

        # 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
        indices_replaced = np.random.binomial(1, 0.8, size=labels.shape).astype(bool) & masked_indices
        inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)

        # 10% of the time, we replace masked input tokens with random word
        # indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
        indices_random = (
            np.random.binomial(1, 0.5, size=labels.shape).astype(bool) & masked_indices & ~indices_replaced
        )
        random_words = np.random.randint(low=0, high=len(self.tokenizer), size=labels.shape, dtype=np.int64)
        inputs[indices_random] = random_words[indices_random]

        # The rest of the time (10% of the time) we keep the masked input tokens unchanged
        return inputs, labels


@dataclass
class DataCollatorForSOP(DataCollatorForLanguageModeling):
    """
    Data collator used for sentence order prediction task.

    - collates batches of tensors, honoring their tokenizer's pad_token
    - preprocesses batches for both masked language modeling and sentence order prediction
    """

    def __init__(self, *args, **kwargs):
        warnings.warn(
            "DataCollatorForSOP is deprecated and will be removed in a future version, you can now use "
            "DataCollatorForLanguageModeling instead.",
            FutureWarning,
        )

    def __call__(self, examples: List[Dict[str, Any]]) -> Dict[str, Any]:
        import torch
        from torch.nn.utils.rnn import pad_sequence

        input_ids = [example["input_ids"] for example in examples]
        input_ids = _torch_collate_batch(input_ids, self.tokenizer)
        input_ids, labels, attention_mask = self.mask_tokens(input_ids)

        token_type_ids = [example["token_type_ids"] for example in examples]
        # size of segment_ids varied because randomness, padding zero to the end as the original implementation
        token_type_ids = pad_sequence(token_type_ids, batch_first=True, padding_value=self.tokenizer.pad_token_id)

        sop_label_list = [example["sentence_order_label"] for example in examples]
        sentence_order_label = torch.stack(sop_label_list)

        return {
            "input_ids": input_ids,
            "labels": labels,
            "attention_mask": attention_mask,
            "token_type_ids": token_type_ids,
            "sentence_order_label": sentence_order_label,
        }

    def mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any]:
        """
        Prepare masked tokens inputs/labels/attention_mask for masked language modeling: 80% MASK, 10% random, 10%
        original. N-gram not applied yet.
        """
        import torch

        if self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for masked language modeling. Remove the"
                " --mlm flag if you want to use this tokenizer."
            )

        labels = inputs.clone()
        # We sample a few tokens in each sequence for masked-LM training (with probability args.mlm_probability defaults to 0.15 in Bert/RoBERTa)
        probability_matrix = torch.full(labels.shape, self.mlm_probability)
        special_tokens_mask = [
            self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()
        ]
        probability_matrix.masked_fill_(torch.tensor(special_tokens_mask, dtype=torch.bool), value=0.0)
        if self.tokenizer._pad_token is not None:
            padding_mask = labels.eq(self.tokenizer.pad_token_id)
            probability_matrix.masked_fill_(padding_mask, value=0.0)
        masked_indices = torch.bernoulli(probability_matrix).bool()
        # probability be `1` (masked), however in albert model attention mask `0` means masked, revert the value
        attention_mask = (~masked_indices).float()
        if self.tokenizer._pad_token is not None:
            attention_padding_mask = labels.eq(self.tokenizer.pad_token_id)
            attention_mask.masked_fill_(attention_padding_mask, value=1.0)
        labels[~masked_indices] = -100  # We only compute loss on masked tokens, -100 is default for CE compute

        # 80% of the time, we replace masked input tokens with tokenizer.mask_token ([MASK])
        indices_replaced = torch.bernoulli(torch.full(labels.shape, 0.8)).bool() & masked_indices
        inputs[indices_replaced] = self.tokenizer.convert_tokens_to_ids(self.tokenizer.mask_token)

        # 10% of the time, we replace masked input tokens with random word
        indices_random = torch.bernoulli(torch.full(labels.shape, 0.5)).bool() & masked_indices & ~indices_replaced
        random_words = torch.randint(len(self.tokenizer), labels.shape, dtype=torch.long)
        inputs[indices_random] = random_words[indices_random]

        # The rest of the time (10% of the time) we keep the masked input tokens unchanged
        return inputs, labels, attention_mask


@dataclass
class DataCollatorForPermutationLanguageModeling(DataCollatorMixin):
    """
    Data collator used for permutation language modeling.

    - collates batches of tensors, honoring their tokenizer's pad_token
    - preprocesses batches for permutation language modeling with procedures specific to XLNet
    """

    tokenizer: PreTrainedTokenizerBase
    plm_probability: float = 1 / 6
    max_span_length: int = 5  # maximum length of a span of masked tokens
    return_tensors: str = "pt"

    def torch_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        if isinstance(examples[0], Mapping):
            examples = [e["input_ids"] for e in examples]
        batch = _torch_collate_batch(examples, self.tokenizer)
        inputs, perm_mask, target_mapping, labels = self.torch_mask_tokens(batch)
        return {"input_ids": inputs, "perm_mask": perm_mask, "target_mapping": target_mapping, "labels": labels}

    def tf_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        if isinstance(examples[0], Mapping):
            examples = [e["input_ids"] for e in examples]
        batch = _tf_collate_batch(examples, self.tokenizer)
        inputs, perm_mask, target_mapping, labels = self.tf_mask_tokens(batch)
        return {"input_ids": inputs, "perm_mask": perm_mask, "target_mapping": target_mapping, "labels": labels}

    def numpy_call(self, examples: List[Union[List[int], Any, Dict[str, Any]]]) -> Dict[str, Any]:
        if isinstance(examples[0], Mapping):
            examples = [e["input_ids"] for e in examples]
        batch = _numpy_collate_batch(examples, self.tokenizer)
        inputs, perm_mask, target_mapping, labels = self.numpy_mask_tokens(batch)
        return {"input_ids": inputs, "perm_mask": perm_mask, "target_mapping": target_mapping, "labels": labels}

    def torch_mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any, Any]:
        """
        The masked tokens to be predicted for a particular sequence are determined by the following algorithm:

            0. Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
            1. Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
            2. Reserve a context of length `context_length = span_length / plm_probability` to surround span to be
               masked
            3. Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length -
               span_length]` and mask tokens `start_index:start_index + span_length`
            4. Set `cur_len = cur_len + context_length`. If `cur_len < max_len` (i.e. there are tokens remaining in the
               sequence to be processed), repeat from Step 1.
        """
        import torch

        if self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for permutation language modeling."
                " Please add a mask token if you want to use this tokenizer."
            )

        if inputs.size(1) % 2 != 0:
            raise ValueError(
                "This collator requires that sequence lengths be even to create a leakage-free perm_mask. Please see"
                " relevant comments in source code for details."
            )

        labels = inputs.clone()
        # Creating the mask and target_mapping tensors
        masked_indices = torch.full(labels.shape, 0, dtype=torch.bool)
        target_mapping = torch.zeros((labels.size(0), labels.size(1), labels.size(1)), dtype=torch.float32)

        for i in range(labels.size(0)):
            # Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
            cur_len = 0
            max_len = labels.size(1)

            while cur_len < max_len:
                # Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
                span_length = torch.randint(1, self.max_span_length + 1, (1,)).item()
                # Reserve a context of length `context_length = span_length / plm_probability` to surround the span to be masked
                context_length = int(span_length / self.plm_probability)
                # Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length - span_length]` and mask tokens `start_index:start_index + span_length`
                start_index = cur_len + torch.randint(context_length - span_length + 1, (1,)).item()
                masked_indices[i, start_index : start_index + span_length] = 1
                # Set `cur_len = cur_len + context_length`
                cur_len += context_length

            # Since we're replacing non-masked tokens with -100 in the labels tensor instead of skipping them altogether,
            # the i-th predict corresponds to the i-th token.
            target_mapping[i] = torch.eye(labels.size(1))

        special_tokens_mask = torch.tensor(
            [self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()],
            dtype=torch.bool,
        )
        masked_indices.masked_fill_(special_tokens_mask, value=0.0)
        if self.tokenizer._pad_token is not None:
            padding_mask = labels.eq(self.tokenizer.pad_token_id)
            masked_indices.masked_fill_(padding_mask, value=0.0)

        # Mask indicating non-functional tokens, where functional tokens are [SEP], [CLS], padding, etc.
        non_func_mask = ~(padding_mask | special_tokens_mask)

        inputs[masked_indices] = self.tokenizer.mask_token_id
        labels[~masked_indices] = -100  # We only compute loss on masked tokens

        perm_mask = torch.zeros((labels.size(0), labels.size(1), labels.size(1)), dtype=torch.float32)

        for i in range(labels.size(0)):
            # Generate permutation indices i.e. sample a random factorisation order for the sequence. This will
            # determine which tokens a given token can attend to (encoded in `perm_mask`).
            # Note: Length of token sequence being permuted has to be less than or equal to reused sequence length
            # (see documentation for `mems`), otherwise information may leak through due to reuse. In this implementation,
            # we assume that reused length is half of sequence length and permutation length is equal to reused length.
            # This requires that the sequence length be even.

            # Create a linear factorisation order
            perm_index = torch.arange(labels.size(1))
            # Split this into two halves, assuming that half the sequence is reused each time
            perm_index = perm_index.reshape((-1, labels.size(1) // 2)).transpose(0, 1)
            # Permute the two halves such that they do not cross over
            perm_index = perm_index[torch.randperm(labels.size(1) // 2)]
            # Flatten this out into the desired permuted factorisation order
            perm_index = torch.flatten(perm_index.transpose(0, 1))
            # Set the permutation indices of non-masked (non-functional) tokens to the
            # smallest index (-1) so that:
            # (1) They can be seen by all other positions
            # (2) They cannot see masked positions, so there won't be information leak
            perm_index.masked_fill_(~masked_indices[i] & non_func_mask[i], -1)
            # The logic for whether the i-th token can attend on the j-th token based on the factorisation order:
            # 0 (can attend): If perm_index[i] > perm_index[j] or j is neither masked nor a functional token
            # 1 (cannot attend): If perm_index[i] <= perm_index[j] and j is either masked or a functional token
            perm_mask[i] = (
                perm_index.reshape((labels.size(1), 1)) <= perm_index.reshape((1, labels.size(1)))
            ) & masked_indices[i]

        return inputs.long(), perm_mask, target_mapping, labels.long()

    def tf_mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any, Any]:
        """
        The masked tokens to be predicted for a particular sequence are determined by the following algorithm:

            0. Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
            1. Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
            2. Reserve a context of length `context_length = span_length / plm_probability` to surround span to be
               masked
            3. Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length -
               span_length]` and mask tokens `start_index:start_index + span_length`
            4. Set `cur_len = cur_len + context_length`. If `cur_len < max_len` (i.e. there are tokens remaining in the
               sequence to be processed), repeat from Step 1.
        """
        import tensorflow as tf

        if self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for permutation language modeling."
                " Please add a mask token if you want to use this tokenizer."
            )

        if tf.shape(inputs)[1] % 2 != 0:
            raise ValueError(
                "This collator requires that sequence lengths be even to create a leakage-free perm_mask. Please see"
                " relevant comments in source code for details."
            )

        labels = tf.identity(inputs)
        # Creating the mask and target_mapping tensors
        masked_indices = np.full(labels.shape.as_list(), 0, dtype=bool)
        labels_shape = tf.shape(labels)
        target_mapping = np.zeros((labels_shape[0], labels_shape[1], labels_shape[1]), dtype=np.float32)

        for i in range(len(labels)):
            # Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
            cur_len = 0
            max_len = tf.shape(labels)[1]

            while cur_len < max_len:
                # Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
                span_length = randint(1, self.max_span_length + 1)
                # Reserve a context of length `context_length = span_length / plm_probability` to surround the span to be masked
                context_length = int(span_length / self.plm_probability)
                # Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length - span_length]` and mask tokens `start_index:start_index + span_length`
                start_index = cur_len + randint(0, context_length - span_length + 1)
                masked_indices[i, start_index : start_index + span_length] = 1
                # Set `cur_len = cur_len + context_length`
                cur_len += context_length

            # Since we're replacing non-masked tokens with -100 in the labels tensor instead of skipping them altogether,
            # the i-th predict corresponds to the i-th token.
            target_mapping[i] = np.eye(labels_shape[1])
        masked_indices = tf.cast(tf.convert_to_tensor(masked_indices), dtype=tf.bool)
        target_mapping = tf.convert_to_tensor(target_mapping)
        special_tokens_mask = tf.convert_to_tensor(
            [
                self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True)
                for val in labels.numpy().tolist()
            ],
        )
        special_tokens_mask = tf.cast(special_tokens_mask, dtype=tf.bool)
        masked_indices = masked_indices & ~special_tokens_mask
        if self.tokenizer._pad_token is not None:
            padding_mask = labels == self.tokenizer.pad_token_id
            masked_indices = masked_indices & ~padding_mask

        # Mask indicating non-functional tokens, where functional tokens are [SEP], [CLS], padding, etc.
        non_func_mask = ~(padding_mask | special_tokens_mask)

        inputs = tf.where(masked_indices, self.tokenizer.mask_token_id, inputs)
        labels = tf.where(masked_indices, labels, -100)  # We only compute loss on masked tokens

        perm_mask = []

        for i in range(len(labels)):
            # Generate permutation indices i.e. sample a random factorisation order for the sequence. This will
            # determine which tokens a given token can attend to (encoded in `perm_mask`).
            # Note: Length of token sequence being permuted has to be less than or equal to reused sequence length
            # (see documentation for `mems`), otherwise information may leak through due to reuse. In this implementation,
            # we assume that reused length is half of sequence length and permutation length is equal to reused length.
            # This requires that the sequence length be even.

            # Create a linear factorisation order
            # tf.range is the equivalent of torch.arange
            perm_index = tf.range(labels_shape[1])
            # Split this into two halves, assuming that half the sequence is reused each time
            perm_index = tf.transpose(tf.reshape(perm_index, (-1, labels_shape[1] // 2)))
            # Permute the two halves such that they do not cross over
            perm_index = tf.random.shuffle(perm_index)  # Shuffles along the first dimension
            # Flatten this out into the desired permuted factorisation order
            perm_index = tf.reshape(tf.transpose(perm_index), (-1,))
            # Set the permutation indices of non-masked (non-functional) tokens to the
            # smallest index (-1) so that:
            # (1) They can be seen by all other positions
            # (2) They cannot see masked positions, so there won't be information leak
            perm_index = tf.where(~masked_indices[i] & non_func_mask[i], -1, perm_index)
            # The logic for whether the i-th token can attend on the j-th token based on the factorisation order:
            # 0 (can attend): If perm_index[i] > perm_index[j] or j is neither masked nor a functional token
            # 1 (cannot attend): If perm_index[i] <= perm_index[j] and j is either masked or a functional token
            perm_mask.append(
                (tf.reshape(perm_index, (labels_shape[1], 1)) <= tf.reshape(perm_index, (1, labels_shape[1])))
                & masked_indices[i]
            )
        perm_mask = tf.stack(perm_mask, axis=0)

        return tf.cast(inputs, tf.int64), tf.cast(perm_mask, tf.float32), target_mapping, tf.cast(labels, tf.int64)

    def numpy_mask_tokens(self, inputs: Any) -> Tuple[Any, Any, Any, Any]:
        """
        The masked tokens to be predicted for a particular sequence are determined by the following algorithm:

            0. Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
            1. Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
            2. Reserve a context of length `context_length = span_length / plm_probability` to surround span to be
               masked
            3. Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length -
               span_length]` and mask tokens `start_index:start_index + span_length`
            4. Set `cur_len = cur_len + context_length`. If `cur_len < max_len` (i.e. there are tokens remaining in the
               sequence to be processed), repeat from Step 1.
        """
        if self.tokenizer.mask_token is None:
            raise ValueError(
                "This tokenizer does not have a mask token which is necessary for permutation language modeling."
                " Please add a mask token if you want to use this tokenizer."
            )

        if inputs.shape[1] % 2 != 0:
            raise ValueError(
                "This collator requires that sequence lengths be even to create a leakage-free perm_mask. Please see"
                " relevant comments in source code for details."
            )

        labels = np.copy(inputs)
        # Creating the mask and target_mapping tensors
        masked_indices = np.full(labels.shape, 0, dtype=bool)
        target_mapping = np.zeros((labels.shape[0], labels.shape[1], labels.shape[1]), dtype=np.float32)

        for i in range(labels.shape[0]):
            # Start from the beginning of the sequence by setting `cur_len = 0` (number of tokens processed so far).
            cur_len = 0
            max_len = labels.shape[1]

            while cur_len < max_len:
                # Sample a `span_length` from the interval `[1, max_span_length]` (length of span of tokens to be masked)
                span_length = randint(1, self.max_span_length + 1)
                # Reserve a context of length `context_length = span_length / plm_probability` to surround the span to be masked
                context_length = int(span_length / self.plm_probability)
                # Sample a starting point `start_index` from the interval `[cur_len, cur_len + context_length - span_length]` and mask tokens `start_index:start_index + span_length`
                start_index = cur_len + randint(0, context_length - span_length + 1)
                masked_indices[i, start_index : start_index + span_length] = 1
                # Set `cur_len = cur_len + context_length`
                cur_len += context_length

            # Since we're replacing non-masked tokens with -100 in the labels tensor instead of skipping them altogether,
            # the i-th predict corresponds to the i-th token.
            target_mapping[i] = np.eye(labels.shape[1])

        special_tokens_mask = np.array(
            [self.tokenizer.get_special_tokens_mask(val, already_has_special_tokens=True) for val in labels.tolist()],
            dtype=bool,
        )
        masked_indices[special_tokens_mask] = 0
        if self.tokenizer._pad_token is not None:
            padding_mask = labels == self.tokenizer.pad_token_id
            masked_indices[padding_mask] = 0.0

        # Mask indicating non-functional tokens, where functional tokens are [SEP], [CLS], padding, etc.
        non_func_mask = ~(padding_mask | special_tokens_mask)

        inputs[masked_indices] = self.tokenizer.mask_token_id
        labels[~masked_indices] = -100  # We only compute loss on masked tokens

        perm_mask = np.zeros((labels.shape[0], labels.shape[1], labels.shape[1]), dtype=np.float32)

        for i in range(labels.shape[0]):
            # Generate permutation indices i.e. sample a random factorisation order for the sequence. This will
            # determine which tokens a given token can attend to (encoded in `perm_mask`).
            # Note: Length of token sequence being permuted has to be less than or equal to reused sequence length
            # (see documentation for `mems`), otherwise information may leak through due to reuse. In this implementation,
            # we assume that reused length is half of sequence length and permutation length is equal to reused length.
            # This requires that the sequence length be even.

            # Create a linear factorisation order
            perm_index = np.arange(labels.shape[1])
            # Split this into two halves, assuming that half the sequence is reused each time
            perm_index = perm_index.reshape((-1, labels.shape[1] // 2)).T
            # Permute the two halves such that they do not cross over
            np.random.shuffle(perm_index)
            # Flatten this out into the desired permuted factorisation order
            perm_index = perm_index.T.flatten()
            # Set the permutation indices of non-masked (non-functional) tokens to the
            # smallest index (-1) so that:
            # (1) They can be seen by all other positions
            # (2) They cannot see masked positions, so there won't be information leak
            perm_index[~masked_indices[i] & non_func_mask[i]] = -1
            # The logic for whether the i-th token can attend on the j-th token based on the factorisation order:
            # 0 (can attend): If perm_index[i] > perm_index[j] or j is neither masked nor a functional token
            # 1 (cannot attend): If perm_index[i] <= perm_index[j] and j is either masked or a functional token
            perm_mask[i] = (
                perm_index.reshape((labels.shape[1], 1)) <= perm_index.reshape((1, labels.shape[1]))
            ) & masked_indices[i]

        return inputs.astype(np.int64), perm_mask, target_mapping, labels.astype(np.int64)
