import os
import sys
import math
import time
import shutil
import numpy as np
import torch
import torch.nn as nn
from typing import Dict, Union, Any, Tuple
from packaging import version
from llava.utils import SpecialAccuracyMetric, dataset_encode_names

from transformers.integrations import hp_params

import torch.distributed as dist
from torch.nn import CrossEntropyLoss
from torch.utils.data import DataLoader, RandomSampler, Dataset, Sampler
from transformers.debug_utils import DebugOption, DebugUnderflowOverflow
from transformers.training_args import OptimizerNames, ParallelMode
from transformers.integrations.deepspeed import deepspeed_init, deepspeed_load_checkpoint, is_deepspeed_available
from transformers.trainer_callback import (
    ExportableState,
    TrainerState,
)

from transformers.trainer_pt_utils import (
    LengthGroupedSampler,
    get_model_param_count,
    get_parameter_names,
    find_batch_size,
    nested_detach,
    EvalLoopContainer,
    IterableDatasetShard,
)

from transformers import Trainer
from transformers.trainer import (
    is_sagemaker_mp_enabled,
    get_parameter_names,
    has_length,
    ALL_LAYERNORM_LAYERS,
    logger,
)

from transformers.trainer_utils import (
    HPSearchBackend,
    TrainOutput,
    has_length,
    speed_metrics,
    denumpify_detensorize,
    EvalLoopOutput,
    EvalPrediction,
)

from transformers.utils import is_peft_available, is_accelerate_available, is_apex_available, is_torch_xla_available
from transformers.integrations.tpu import tpu_spmd_dataloader

# Name of the files used for checkpointing
TRAINING_ARGS_NAME = "training_args.bin"
TRAINER_STATE_NAME = "trainer_state.json"
OPTIMIZER_NAME = "optimizer.pt"
OPTIMIZER_NAME_BIN = "optimizer.bin"
SCHEDULER_NAME = "scheduler.pt"
SCALER_NAME = "scaler.pt"
FSDP_MODEL_NAME = "pytorch_model_fsdp"

def is_debug():
    return int(os.environ.get('DEBUG', 0))

if is_apex_available():
    from apex import amp
    
if is_torch_xla_available():
    import torch_xla.core.xla_model as xm
    import torch_xla.debug.metrics as met
    from torch_xla import __version__ as XLA_VERSION

    IS_XLA_FSDPV2_POST_2_2 = version.parse(XLA_VERSION) >= version.parse(XLA_FSDPV2_MIN_VERSION)
    if IS_XLA_FSDPV2_POST_2_2:
        import torch_xla.distributed.spmd as xs
        import torch_xla.runtime as xr
else:
    IS_XLA_FSDPV2_POST_2_2 = False
    
if is_sagemaker_mp_enabled():
    import smdistributed.modelparallel.torch as smp
    from smdistributed.modelparallel import __version__ as SMP_VERSION

    IS_SAGEMAKER_MP_POST_1_10 = version.parse(SMP_VERSION) >= version.parse("1.10")

    from transformers.trainer_pt_utils import smp_forward_backward, smp_forward_only, smp_gather, smp_nested_concat
else:
    IS_SAGEMAKER_MP_POST_1_10 = False

if is_accelerate_available():
    from accelerate import skip_first_batches
    from accelerate import __version__ as accelerate_version
    from accelerate.utils import (
        DistributedType,
        is_mlu_available,
        is_mps_available,
        is_npu_available,
        is_torch_version,
        is_xpu_available,
    )

    DATA_SAMPLERS = [RandomSampler]
    if version.parse(accelerate_version) > version.parse("0.23.0"):
        from accelerate.data_loader import SeedableRandomSampler

        DATA_SAMPLERS += [SeedableRandomSampler]

    if is_deepspeed_available():
        from accelerate.utils import DeepSpeedSchedulerWrapper

from packaging import version
import importlib.metadata

def is_dist_avail_and_initialized():
    if not dist.is_available():
        return False
    if not dist.is_initialized():
        return False
    return True

def get_world_size():
    if not is_dist_avail_and_initialized():
        return 1
    return dist.get_world_size()

if is_peft_available():
    from peft import PeftModel

from typing import List, Optional

def _is_peft_model(model):
    if is_peft_available():
        classes_to_check = (PeftModel,) if is_peft_available() else ()
        # Here we also check if the model is an instance of `PeftMixedModel` introduced in peft>=0.7.0: https://github.com/huggingface/transformers/pull/28321
        if version.parse(importlib.metadata.version("peft")) >= version.parse("0.7.0"):
            from peft import PeftMixedModel

            classes_to_check = (*classes_to_check, PeftMixedModel)
        return isinstance(model, classes_to_check)
    return False

def calculate_loss_xe(labels, logits, vocab_size):
    # Shift so that tokens < n predict n
    shift_logits = logits[..., :-1, :].contiguous()
    shift_labels = labels[..., 1:].contiguous()
    # Flatten the tokens
    loss_fct = CrossEntropyLoss()
    shift_logits = shift_logits.view(-1, vocab_size)
    shift_labels = shift_labels.view(-1)
    # Enable model parallelism
    shift_labels = shift_labels.to(shift_logits.device)
    loss = loss_fct(shift_logits, shift_labels)
    return loss

def maybe_zero_3(param, ignore_status=False, name=None):
    from deepspeed import zero
    from deepspeed.runtime.zero.partition_parameters import ZeroParamStatus
    if hasattr(param, "ds_id"):
        if param.ds_status == ZeroParamStatus.NOT_AVAILABLE:
            if not ignore_status:
                print(name, 'no ignore status')
        with zero.GatheredParameters([param]):
            param = param.data.detach().cpu().clone()
    else:
        param = param.detach().cpu().clone()
    return param


def get_mm_adapter_state_maybe_zero_3(named_params, keys_to_match):
    to_return = {k: t for k, t in named_params if any(key_match in k for key_match in keys_to_match)}
    to_return = {k: maybe_zero_3(v, ignore_status=True, name=k).cpu() for k, v in to_return.items()}
    return to_return


def split_to_even_chunks(indices, lengths, num_chunks):
    """
    Split a list of indices into `chunks` chunks of roughly equal lengths.
    """

    if len(indices) % num_chunks != 0:
        return [indices[i::num_chunks] for i in range(num_chunks)]

    num_indices_per_chunk = len(indices) // num_chunks

    chunks = [[] for _ in range(num_chunks)]
    chunks_lengths = [0 for _ in range(num_chunks)]
    for index in indices:
        shortest_chunk = chunks_lengths.index(min(chunks_lengths))
        chunks[shortest_chunk].append(index)
        chunks_lengths[shortest_chunk] += lengths[index]
        if len(chunks[shortest_chunk]) == num_indices_per_chunk:
            chunks_lengths[shortest_chunk] = float("inf")

    return chunks


def get_modality_length_grouped_indices(lengths, batch_size, world_size, generator=None):
    # We need to use torch for the random part as a distributed sampler will set the random seed for torch.
    assert all(l != 0 for l in lengths), "Should not have zero length."
    if all(l > 0 for l in lengths) or all(l < 0 for l in lengths):
        # all samples are in the same modality
        return get_length_grouped_indices(lengths, batch_size, world_size, generator=generator)
    mm_indices, mm_lengths = zip(*[(i, l) for i, l in enumerate(lengths) if l > 0])
    lang_indices, lang_lengths = zip(*[(i, -l) for i, l in enumerate(lengths) if l < 0])

    mm_shuffle = [mm_indices[i] for i in get_length_grouped_indices(mm_lengths, batch_size, world_size, generator=None)]
    lang_shuffle = [lang_indices[i] for i in get_length_grouped_indices(lang_lengths, batch_size, world_size, generator=None)]
    megabatch_size = world_size * batch_size
    mm_megabatches = [mm_shuffle[i : i + megabatch_size] for i in range(0, len(mm_shuffle), megabatch_size)]
    lang_megabatches = [lang_shuffle[i : i + megabatch_size] for i in range(0, len(lang_shuffle), megabatch_size)]

    last_mm = mm_megabatches[-1]
    last_lang = lang_megabatches[-1]
    additional_batch = last_mm + last_lang
    megabatches = mm_megabatches[:-1] + lang_megabatches[:-1]
    megabatch_indices = torch.randperm(len(megabatches), generator=generator)
    megabatches = [megabatches[i] for i in megabatch_indices]

    if len(additional_batch) > 0:
        megabatches.append(sorted(additional_batch))

    return [i for megabatch in megabatches for i in megabatch]


def get_length_grouped_indices(lengths, batch_size, world_size, generator=None, merge=True):
    # We need to use torch for the random part as a distributed sampler will set the random seed for torch.
    indices = torch.randperm(len(lengths), generator=generator)
    megabatch_size = world_size * batch_size
    megabatches = [indices[i : i + megabatch_size].tolist() for i in range(0, len(lengths), megabatch_size)]
    megabatches = [sorted(megabatch, key=lambda i: lengths[i], reverse=True) for megabatch in megabatches]
    megabatches = [split_to_even_chunks(megabatch, lengths, world_size) for megabatch in megabatches]

    return [i for megabatch in megabatches for batch in megabatch for i in batch]


class LengthGroupedSampler(Sampler):
    r"""
    Sampler that samples indices in a way that groups together features of the dataset of roughly the same length while
    keeping a bit of randomness.
    """

    def __init__(
        self,
        batch_size: int,
        world_size: int,
        lengths: Optional[List[int]] = None,
        generator=None,
        group_by_modality: bool = False,
    ):
        if lengths is None:
            raise ValueError("Lengths must be provided.")

        self.batch_size = batch_size
        self.world_size = world_size
        self.lengths = lengths
        self.generator = generator
        self.group_by_modality = group_by_modality

    def __len__(self):
        return len(self.lengths)

    def __iter__(self):
        if self.group_by_modality:
            indices = get_modality_length_grouped_indices(self.lengths, self.batch_size, self.world_size, generator=self.generator)
        else:
            indices = get_length_grouped_indices(self.lengths, self.batch_size, self.world_size, generator=self.generator)
        return iter(indices)


class LLaVATrainer(Trainer):

    def _get_train_sampler(self) -> Optional[torch.utils.data.Sampler]:
        if self.train_dataset is None or not has_length(self.train_dataset):
            return None

        if self.args.group_by_modality_length:
            lengths = self.train_dataset.modality_lengths
            return LengthGroupedSampler(
                self.args.train_batch_size,
                world_size=self.args.world_size * self.args.gradient_accumulation_steps,
                lengths=lengths,
                group_by_modality=True,
            )
        else:
            return super()._get_train_sampler()

    def create_optimizer(self):
        """
        Setup the optimizer.

        We provide a reasonable default that works well. If you want to use something else, you can pass a tuple in the
        Trainer's init through `optimizers`, or subclass and override this method in a subclass.
        """
        if is_sagemaker_mp_enabled():
            return super().create_optimizer()

        opt_model = self.model

        if self.optimizer is None:
            decay_parameters = get_parameter_names(opt_model, ALL_LAYERNORM_LAYERS)
            decay_parameters = [name for name in decay_parameters if "bias" not in name]
            if self.args.mm_projector_lr is not None:
                projector_parameters = [name for name, _ in opt_model.named_parameters() if "mm_projector" in name]
                optimizer_grouped_parameters = [
                    {
                        "params": [
                            p for n, p in opt_model.named_parameters() if (n in decay_parameters and n not in projector_parameters and p.requires_grad)
                        ],
                        "weight_decay": self.args.weight_decay,
                    },
                    {
                        "params": [
                            p for n, p in opt_model.named_parameters() if (n not in decay_parameters and n not in projector_parameters and p.requires_grad)
                        ],
                        "weight_decay": 0.0,
                    },
                    {
                        "params": [
                            p for n, p in opt_model.named_parameters() if (n in decay_parameters and n in projector_parameters and p.requires_grad)
                        ],
                        "weight_decay": self.args.weight_decay,
                        "lr": self.args.mm_projector_lr,
                    },
                    {
                        "params": [
                            p for n, p in opt_model.named_parameters() if (n not in decay_parameters and n in projector_parameters and p.requires_grad)
                        ],
                        "weight_decay": 0.0,
                        "lr": self.args.mm_projector_lr,
                    },
                ]
            else:
                optimizer_grouped_parameters = [
                    {
                        "params": [
                            p for n, p in opt_model.named_parameters() if (n in decay_parameters and p.requires_grad)
                        ],
                        "weight_decay": self.args.weight_decay,
                    },
                    {
                        "params": [
                            p for n, p in opt_model.named_parameters() if (n not in decay_parameters and p.requires_grad)
                        ],
                        "weight_decay": 0.0,
                    },
                ]

            optimizer_cls, optimizer_kwargs = Trainer.get_optimizer_cls_and_kwargs(self.args)

            self.optimizer = optimizer_cls(optimizer_grouped_parameters, **optimizer_kwargs)
            if optimizer_cls.__name__ == "Adam8bit":
                import bitsandbytes

                manager = bitsandbytes.optim.GlobalOptimManager.get_instance()

                skipped = 0
                for module in opt_model.modules():
                    if isinstance(module, nn.Embedding):
                        skipped += sum({p.data_ptr(): p.numel() for p in module.parameters()}.values())
                        logger.info(f"skipped {module}: {skipped/2**20}M params")
                        manager.register_module_override(module, "weight", {"optim_bits": 32})
                        logger.debug(f"bitsandbytes: will optimize {module} in fp32")
                logger.info(f"skipped: {skipped/2**20}M params")

        return self.optimizer

    def _save_checkpoint(self, model, trial, metrics=None):
        if getattr(self.args, 'tune_mm_mlp_adapter', False):
            from transformers.trainer_utils import PREFIX_CHECKPOINT_DIR
            checkpoint_folder = f"{PREFIX_CHECKPOINT_DIR}-{self.state.global_step}"

            run_dir = self._get_output_dir(trial=trial)
            output_dir = os.path.join(run_dir, checkpoint_folder)

            # Only save Adapter
            keys_to_match = ['mm_projector', 'vision_resampler']
            if getattr(self.args, "use_im_start_end", False):
                keys_to_match.extend(['embed_tokens', 'embed_in'])

            weight_to_save = get_mm_adapter_state_maybe_zero_3(self.model.named_parameters(), keys_to_match)

            if self.args.local_rank == 0 or self.args.local_rank == -1:
                self.model.config.save_pretrained(output_dir)
                torch.save(weight_to_save, os.path.join(output_dir, f'mm_projector.bin'))
        else:
            super(LLaVATrainer, self)._save_checkpoint(model, trial, metrics)

    def _save(self, output_dir: Optional[str] = None, state_dict=None):
        if getattr(self.args, 'tune_mm_mlp_adapter', False):
            pass
        else:
            super(LLaVATrainer, self)._save(output_dir, state_dict)
            
    def training_step(self, model: nn.Module, inputs: Dict[str, Union[torch.Tensor, Any]]) -> torch.Tensor:
        """
        Perform a training step on a batch of inputs.

        Subclass and override to inject custom behavior.

        Args:
            model (`nn.Module`):
                The model to train.
            inputs (`Dict[str, Union[torch.Tensor, Any]]`):
                The inputs and targets of the model.

                The dictionary will be unpacked before being fed to the model. Most models expect the targets under the
                argument `labels`. Check your model's documentation for all accepted arguments.

        Return:
            `torch.Tensor`: The tensor with training loss on this batch.
        """
        model.train()
        inputs = self._prepare_inputs(inputs)
        # if is_sagemaker_mp_enabled():
        #     loss_mb = smp_forward_backward(model, inputs, self.args.gradient_accumulation_steps)
        #     return loss_mb.reduce_mean().detach().to(self.args.device)

        with self.compute_loss_context_manager():
            dict_loss = self.compute_loss(model, inputs)
            loss= dict_loss['loss']

        del inputs
        if (
            self.args.torch_empty_cache_steps is not None
            and self.state.global_step % self.args.torch_empty_cache_steps == 0
        ):
            if is_xpu_available():
                torch.xpu.empty_cache()
            elif is_mlu_available():
                torch.mlu.empty_cache()
            elif is_npu_available():
                torch.npu.empty_cache()
            elif is_torch_version(">=", "2.0") and is_mps_available():
                torch.mps.empty_cache()
            else:
                torch.cuda.empty_cache()

        kwargs = {}

        # For LOMO optimizers you need to explicitly use the learnign rate
        if self.args.optim in [OptimizerNames.LOMO, OptimizerNames.ADALOMO]:
            kwargs["learning_rate"] = self._get_learning_rate()

        if self.args.n_gpu > 1:
            loss = loss.mean()  # mean() to average on multi-gpu parallel training

        if self.use_apex:
            with amp.scale_loss(loss, self.optimizer) as scaled_loss:
                scaled_loss.backward()
        else:
            self.accelerator.backward(loss, **kwargs)

        return (loss.detach() / self.args.gradient_accumulation_steps), dict_loss

    def compute_loss(self, model, inputs):
        """
        How the loss is computed by Trainer. By default, all models return the loss in the first element.

        Subclass and override for custom behavior.
        """
        if 'dataset_name' in inputs:
            inputs.pop('dataset_name')
        if 'original_question' in inputs:
            inputs.pop('original_question')
        if 'original_image' in inputs:
            inputs.pop('original_image')
        meta_dict= model.prepare_input_loss_computation(**inputs)
        outputs = model(**inputs)
        
        if self.args.visual_rag:
            if not self.args.standard_loss:
                # special losses
                # Mask special labels
                ret_token= self.args.special_token_retrieval
                no_ret_token= self.args.special_token_no_retrieval
                
                answer_labels= meta_dict['labels'].clone()
                answer_labels = torch.where(answer_labels == no_ret_token, -100, answer_labels)
                answer_labels = torch.where(answer_labels == ret_token, -100, answer_labels)
                
                # TODO: VERIFY IF IT IS OK --> Mask answer labels
                special_labels= meta_dict['labels'].clone()
                mask = (special_labels == ret_token) | (special_labels == no_ret_token)
                special_labels[~mask] = -100
                
                logits= outputs.logits
                loss_special_xe= calculate_loss_xe(special_labels, logits, self.model.vocab_size)
                loss_answer_xe= calculate_loss_xe(answer_labels, logits, self.model.vocab_size)

                loss = self.args.weight_loss_special*loss_special_xe + loss_answer_xe
            else:
                standard_labels= meta_dict['labels'].clone()
                logits= outputs.logits
                loss= calculate_loss_xe(standard_labels, logits, self.model.vocab_size)
        else:
            standard_labels= meta_dict['labels'].clone()
            logits= outputs.logits
            loss= calculate_loss_xe(standard_labels, logits, self.model.vocab_size)
            
        # add log
        loss_dict={
            'loss': loss,
            "outputs": outputs,
            "labels": meta_dict['labels'].clone(),
        }
        
        if self.args.visual_rag and (not self.args.standard_loss):
            loss_dict['loss_special_xe'] = loss_special_xe
            loss_dict['loss_answer_xe'] = loss_answer_xe
            loss_dict['weight_loss_special'] = self.args.weight_loss_special

        return loss_dict

    def _maybe_log_save_evaluate(self, tr_loss, grad_norm, model, trial, epoch, ignore_keys_for_eval, dict_loss):
        if self.control.should_log and self.state.global_step > self._globalstep_last_logged:
            if is_torch_xla_available():
                xm.mark_step()

            logs: Dict[str, float] = {}

            # all_gather + mean() to get average loss over all processes
            tr_loss_scalar = self._nested_gather(tr_loss).mean().item()

            # reset tr_loss to zero
            tr_loss -= tr_loss

            logs["loss"] = round(tr_loss_scalar / (self.state.global_step - self._globalstep_last_logged), 4)
            if grad_norm is not None:
                logs["grad_norm"] = grad_norm.detach().item() if isinstance(grad_norm, torch.Tensor) else grad_norm
            logs["learning_rate"] = self._get_learning_rate()
            if 'loss_answer_xe' in dict_loss:
                logs["loss_answer_xe"] = round(dict_loss['loss_answer_xe'].detach().item(), 4)
                logs["loss_special_xe"] = round(dict_loss['loss_special_xe'].detach().item(), 4)
                logs["weight_loss_special"] = dict_loss['weight_loss_special']

            self._total_loss_scalar += tr_loss_scalar
            self._globalstep_last_logged = self.state.global_step
            self.store_flos()

            self.log(logs)

        metrics = None
        if self.control.should_evaluate:
            metrics = self._evaluate(trial, ignore_keys_for_eval)

        if self.control.should_save:
            self._save_checkpoint(model, trial, metrics=metrics)
            self.control = self.callback_handler.on_save(self.args, self.state, self.control)

    def _inner_training_loop(
        self, batch_size=None, args=None, resume_from_checkpoint=None, trial=None, ignore_keys_for_eval=None
    ):
        self.accelerator.free_memory()
        self._train_batch_size = batch_size
        if self.args.auto_find_batch_size:
            if self.state.train_batch_size != self._train_batch_size:
                from accelerate.utils import release_memory

                (self.model_wrapped,) = release_memory(self.model_wrapped)
                self.model_wrapped = self.model

                # Check for DeepSpeed *after* the intial pass and modify the config
                if self.is_deepspeed_enabled:
                    # Temporarily unset `self.args.train_batch_size`
                    original_bs = self.args.per_device_train_batch_size
                    self.args.per_device_train_batch_size = self._train_batch_size // max(1, self.args.n_gpu)
                    self.propagate_args_to_deepspeed(True)
                    self.args.per_device_train_batch_size = original_bs
            self.state.train_batch_size = self._train_batch_size
        logger.debug(f"Currently training with a batch size of: {self._train_batch_size}")
        # Data loader and number of training steps
        train_dataloader = self.get_train_dataloader()
        if self.is_fsdp_xla_v2_enabled:
            train_dataloader = tpu_spmd_dataloader(train_dataloader)

        # Setting up training control variables:
        # number of training epochs: num_train_epochs
        # number of training steps per epoch: num_update_steps_per_epoch
        # total number of training steps to execute: max_steps
        total_train_batch_size = self._train_batch_size * args.gradient_accumulation_steps * args.world_size

        len_dataloader = None
        num_train_tokens = None
        if has_length(train_dataloader):
            len_dataloader = len(train_dataloader)
            num_update_steps_per_epoch = len_dataloader // args.gradient_accumulation_steps
            num_update_steps_per_epoch = max(num_update_steps_per_epoch, 1)
            num_examples = self.num_examples(train_dataloader)
            if args.max_steps > 0:
                max_steps = args.max_steps
                num_train_epochs = args.max_steps // num_update_steps_per_epoch + int(
                    args.max_steps % num_update_steps_per_epoch > 0
                )
                # May be slightly incorrect if the last batch in the training dataloader has a smaller size but it's
                # the best we can do.
                num_train_samples = args.max_steps * total_train_batch_size
                if args.include_tokens_per_second:
                    num_train_tokens = (
                        self.num_tokens(train_dataloader, args.max_steps) * args.gradient_accumulation_steps
                    )
            else:
                max_steps = math.ceil(args.num_train_epochs * num_update_steps_per_epoch)
                num_train_epochs = math.ceil(args.num_train_epochs)
                num_train_samples = self.num_examples(train_dataloader) * args.num_train_epochs
                if args.include_tokens_per_second:
                    num_train_tokens = self.num_tokens(train_dataloader) * args.num_train_epochs
        elif args.max_steps > 0:  # Rely on max_steps when dataloader does not have a working size
            max_steps = args.max_steps
            # Setting a very large number of epochs so we go as many times as necessary over the iterator.
            num_train_epochs = sys.maxsize
            num_update_steps_per_epoch = max_steps
            num_examples = total_train_batch_size * args.max_steps
            num_train_samples = args.max_steps * total_train_batch_size
            if args.include_tokens_per_second:
                num_train_tokens = self.num_tokens(train_dataloader, args.max_steps) * args.gradient_accumulation_steps
        else:
            raise ValueError(
                "args.max_steps must be set to a positive value if dataloader does not have a length, was"
                f" {args.max_steps}"
            )

        if DebugOption.UNDERFLOW_OVERFLOW in self.args.debug:
            if self.args.n_gpu > 1:
                # nn.DataParallel(model) replicates the model, creating new variables and module
                # references registered here no longer work on other gpus, breaking the module
                raise ValueError(
                    "Currently --debug underflow_overflow is not supported under DP. Please use DDP"
                    " (torchrun or torch.distributed.launch (deprecated))."
                )
            else:
                debug_overflow = DebugUnderflowOverflow(self.model)  # noqa

        delay_optimizer_creation = is_sagemaker_mp_enabled() or self.is_fsdp_xla_enabled or self.is_fsdp_enabled

        # We need to reset the scheduler, as its parameters may be different on subsequent calls
        if self._created_lr_scheduler:
            self.lr_scheduler = None
            self._created_lr_scheduler = False

        if self.is_deepspeed_enabled:
            self.optimizer, self.lr_scheduler = deepspeed_init(self, num_training_steps=max_steps)

        if not delay_optimizer_creation:
            self.create_optimizer_and_scheduler(num_training_steps=max_steps)

        self.state = TrainerState(
            stateful_callbacks=[
                cb for cb in self.callback_handler.callbacks + [self.control] if isinstance(cb, ExportableState)
            ]
        )
        self.state.is_hyper_param_search = trial is not None
        self.state.train_batch_size = self._train_batch_size

        # Compute absolute values for logging, eval, and save if given as ratio
        if args.logging_steps is not None:
            if args.logging_steps < 1:
                self.state.logging_steps = math.ceil(max_steps * args.logging_steps)
            else:
                self.state.logging_steps = args.logging_steps
        if args.eval_steps is not None:
            if args.eval_steps < 1:
                self.state.eval_steps = math.ceil(max_steps * args.eval_steps)
            else:
                self.state.eval_steps = args.eval_steps
        if args.save_steps is not None:
            if args.save_steps < 1:
                self.state.save_steps = math.ceil(max_steps * args.save_steps)
            else:
                self.state.save_steps = args.save_steps

        # Activate gradient checkpointing if needed
        if args.gradient_checkpointing:
            if args.gradient_checkpointing_kwargs is None:
                gradient_checkpointing_kwargs = {}
            else:
                gradient_checkpointing_kwargs = args.gradient_checkpointing_kwargs

            self.model.gradient_checkpointing_enable(gradient_checkpointing_kwargs=gradient_checkpointing_kwargs)

        model = self._wrap_model(self.model_wrapped)

        # as the model is wrapped, don't use `accelerator.prepare`
        # this is for unhandled cases such as
        # FSDP-XLA, SageMaker MP/DP, DataParallel, IPEX
        use_accelerator_prepare = True if model is self.model else False

        if delay_optimizer_creation:
            if use_accelerator_prepare:
                self._fsdp_qlora_plugin_updates()
                self.model = self.accelerator.prepare(self.model)
            self.create_optimizer_and_scheduler(num_training_steps=max_steps)

        # prepare using `accelerator` prepare
        if use_accelerator_prepare:
            self.model.train()
            if hasattr(self.lr_scheduler, "step"):
                if self.use_apex:
                    model = self.accelerator.prepare(self.model)
                else:
                    model, self.optimizer = self.accelerator.prepare(self.model, self.optimizer)
            else:
                # to handle cases wherein we pass "DummyScheduler" such as when it is specified in DeepSpeed config.
                model, self.optimizer, self.lr_scheduler = self.accelerator.prepare(
                    self.model, self.optimizer, self.lr_scheduler
                )
        elif self.args.optim in [OptimizerNames.LOMO, OptimizerNames.ADALOMO]:
            # In this case we are in DDP + LOMO, which should be supported
            self.optimizer = self.accelerator.prepare(self.optimizer)

        if self.is_fsdp_enabled:
            self.model = self.model_wrapped = model

        # for the rest of this function `model` is the outside model, whether it was wrapped or not
        if model is not self.model:
            self.model_wrapped = model

        # backward compatibility
        if self.is_deepspeed_enabled:
            self.deepspeed = self.model_wrapped

        # ckpt loading
        if resume_from_checkpoint is not None:
            if self.is_deepspeed_enabled:
                deepspeed_load_checkpoint(
                    self.model_wrapped, resume_from_checkpoint, load_module_strict=not _is_peft_model(self.model)
                )
            elif is_sagemaker_mp_enabled() or self.is_fsdp_enabled:
                self._load_from_checkpoint(resume_from_checkpoint, self.model_wrapped)

        # Check if saved optimizer or scheduler states exist
        self._load_optimizer_and_scheduler(resume_from_checkpoint)

        # important: at this point:
        # self.model         is the Transformers Model
        # self.model_wrapped is DDP(Transformers Model), Deepspeed(Transformers Model),
        # FSDP(Transformers Model), Dynamo Optimized Module(Transformers Model) etc.

        # Train!
        logger.info("***** Running training *****")
        logger.info(f"  Num examples = {num_examples:,}")
        logger.info(f"  Num Epochs = {num_train_epochs:,}")
        logger.info(f"  Instantaneous batch size per device = {self.args.per_device_train_batch_size:,}")
        if self.args.per_device_train_batch_size != self._train_batch_size:
            logger.info(f"  Training with DataParallel so batch size has been adjusted to: {self._train_batch_size:,}")
        logger.info(f"  Total train batch size (w. parallel, distributed & accumulation) = {total_train_batch_size:,}")
        logger.info(f"  Gradient Accumulation steps = {args.gradient_accumulation_steps}")
        logger.info(f"  Total optimization steps = {max_steps:,}")
        logger.info(f"  Number of trainable parameters = {get_model_param_count(model, trainable_only=True):,}")

        self.state.epoch = 0
        start_time = time.time()
        epochs_trained = 0
        steps_trained_in_current_epoch = 0
        steps_trained_progress_bar = None

        # Check if continuing training from a checkpoint
        if resume_from_checkpoint is not None and os.path.isfile(
            os.path.join(resume_from_checkpoint, TRAINER_STATE_NAME)
        ):
            self.state = TrainerState.load_from_json(os.path.join(resume_from_checkpoint, TRAINER_STATE_NAME))
            self.compare_trainer_and_checkpoint_args(self.args, self.state)
            self._load_callback_state()
            epochs_trained = self.state.global_step // num_update_steps_per_epoch
            if not args.ignore_data_skip:
                steps_trained_in_current_epoch = self.state.global_step % (num_update_steps_per_epoch)
                steps_trained_in_current_epoch *= args.gradient_accumulation_steps
            else:
                steps_trained_in_current_epoch = 0

            logger.info("  Continuing training from checkpoint, will skip to saved global_step")
            logger.info(f"  Continuing training from epoch {epochs_trained}")
            logger.info(f"  Continuing training from global step {self.state.global_step}")
            if not args.ignore_data_skip:
                logger.info(
                    f"  Will skip the first {epochs_trained} epochs then the first"
                    f" {steps_trained_in_current_epoch} batches in the first epoch."
                )

        # Update the references
        self.callback_handler.model = self.model
        self.callback_handler.optimizer = self.optimizer
        self.callback_handler.lr_scheduler = self.lr_scheduler
        self.callback_handler.train_dataloader = train_dataloader
        if self.hp_name is not None and self._trial is not None:
            # use self._trial because the SigOpt/Optuna hpo only call `_hp_search_setup(trial)` instead of passing trial
            # parameter to Train when using DDP.
            self.state.trial_name = self.hp_name(self._trial)
        if trial is not None:
            assignments = trial.assignments if self.hp_search_backend == HPSearchBackend.SIGOPT else trial
            self.state.trial_params = hp_params(assignments)
        else:
            self.state.trial_params = None
        # This should be the same if the state has been saved but in case the training arguments changed, it's safer
        # to set this after the load.
        self.state.max_steps = max_steps
        self.state.num_train_epochs = num_train_epochs
        self.state.is_local_process_zero = self.is_local_process_zero()
        self.state.is_world_process_zero = self.is_world_process_zero()

        # tr_loss is a tensor to avoid synchronization of TPUs through .item()
        tr_loss = torch.tensor(0.0).to(args.device)
        # _total_loss_scalar is updated everytime .item() has to be called on tr_loss and stores the sum of all losses
        self._total_loss_scalar = 0.0
        self._globalstep_last_logged = self.state.global_step
        model.zero_grad()
        grad_norm: Optional[float] = None
        self.control = self.callback_handler.on_train_begin(args, self.state, self.control)

        if args.eval_on_start:
            self._evaluate(trial, ignore_keys_for_eval, skip_scheduler=True)

        total_batched_samples = 0
        for epoch in range(epochs_trained, num_train_epochs):
            epoch_iterator = train_dataloader
            if hasattr(epoch_iterator, "set_epoch"):
                epoch_iterator.set_epoch(epoch)

            # Reset the past mems state at the beginning of each epoch if necessary.
            if args.past_index >= 0:
                self._past = None

            steps_in_epoch = (
                len(epoch_iterator)
                if len_dataloader is not None
                else args.max_steps * args.gradient_accumulation_steps
            )
            self.control = self.callback_handler.on_epoch_begin(args, self.state, self.control)

            if epoch == epochs_trained and resume_from_checkpoint is not None and steps_trained_in_current_epoch == 0:
                self._load_rng_state(resume_from_checkpoint)

            rng_to_sync = False
            steps_skipped = 0
            if steps_trained_in_current_epoch > 0:
                epoch_iterator = skip_first_batches(epoch_iterator, steps_trained_in_current_epoch)
                steps_skipped = steps_trained_in_current_epoch
                steps_trained_in_current_epoch = 0
                rng_to_sync = True

            step = -1
            for step, inputs in enumerate(epoch_iterator):
                if is_debug() and step > 100:
                    logger.info("Debug Mode detected... exit from the training loop!")
                    break
                
                total_batched_samples += 1
                if self.args.include_num_input_tokens_seen:
                    main_input_name = getattr(self.model, "main_input_name", "input_ids")
                    if main_input_name not in inputs:
                        logger.warning(
                            "Tried to track the number of tokens seen, however the current model is "
                            "not configured properly to know what item is the input. To fix this, add "
                            "a `main_input_name` attribute to the model class you are using."
                        )
                    else:
                        self.state.num_input_tokens_seen += (
                            torch.sum(
                                self.accelerator.gather(
                                    torch.tensor(
                                        inputs[main_input_name].numel(), device=self.args.device, dtype=torch.int64
                                    )
                                )
                            )
                            .cpu()
                            .item()
                        )
                if rng_to_sync:
                    self._load_rng_state(resume_from_checkpoint)
                    rng_to_sync = False

                # Skip past any already trained steps if resuming training
                if steps_trained_in_current_epoch > 0:
                    steps_trained_in_current_epoch -= 1
                    if steps_trained_progress_bar is not None:
                        steps_trained_progress_bar.update(1)
                    if steps_trained_in_current_epoch == 0:
                        self._load_rng_state(resume_from_checkpoint)
                    continue
                elif steps_trained_progress_bar is not None:
                    steps_trained_progress_bar.close()
                    steps_trained_progress_bar = None

                if step % args.gradient_accumulation_steps == 0:
                    self.control = self.callback_handler.on_step_begin(args, self.state, self.control)

                with self.accelerator.accumulate(model):
                    tr_loss_step, dict_loss = self.training_step(model, inputs)

                if (
                    args.logging_nan_inf_filter
                    and not is_torch_xla_available()
                    and (torch.isnan(tr_loss_step) or torch.isinf(tr_loss_step))
                ):
                    # if loss is nan or inf simply add the average of previous logged losses
                    tr_loss += tr_loss / (1 + self.state.global_step - self._globalstep_last_logged)
                else:
                    if tr_loss.device != tr_loss_step.device:
                        raise ValueError(
                            f"Calculated loss must be on the original device: {tr_loss.device} but device in use is {tr_loss_step.device}"
                        )
                    tr_loss += tr_loss_step

                self.current_flos += float(self.floating_point_ops(inputs))

                is_last_step_and_steps_less_than_grad_acc = (
                    steps_in_epoch <= args.gradient_accumulation_steps and (step + 1) == steps_in_epoch
                )

                if (
                    total_batched_samples % args.gradient_accumulation_steps == 0
                    or
                    # last step in epoch but step is always smaller than gradient_accumulation_steps
                    is_last_step_and_steps_less_than_grad_acc
                ):
                    # the `or` condition of `is_last_step_and_steps_less_than_grad_acc` is not covered
                    # in accelerate. So, explicitly enable sync gradients to True in that case.
                    if is_last_step_and_steps_less_than_grad_acc:
                        self.accelerator.gradient_state._set_sync_gradients(True)

                    # Gradient clipping
                    if args.max_grad_norm is not None and args.max_grad_norm > 0:
                        # deepspeed does its own clipping

                        if is_sagemaker_mp_enabled() and args.fp16:
                            _grad_norm = self.optimizer.clip_master_grads(args.max_grad_norm)
                        elif self.use_apex:
                            # Revert to normal clipping otherwise, handling Apex or full precision
                            _grad_norm = nn.utils.clip_grad_norm_(
                                amp.master_params(self.optimizer),
                                args.max_grad_norm,
                            )
                        else:
                            _grad_norm = self.accelerator.clip_grad_norm_(
                                model.parameters(),
                                args.max_grad_norm,
                            )

                        if (
                            is_accelerate_available()
                            and self.accelerator.distributed_type == DistributedType.DEEPSPEED
                        ):
                            grad_norm = model.get_global_grad_norm()
                            # In some cases the grad norm may not return a float
                            if hasattr(grad_norm, "item"):
                                grad_norm = grad_norm.item()
                        else:
                            grad_norm = _grad_norm

                    self.optimizer.step()

                    self.control = self.callback_handler.on_optimizer_step(args, self.state, self.control)

                    optimizer_was_run = not self.accelerator.optimizer_step_was_skipped
                    if optimizer_was_run:
                        # Delay optimizer scheduling until metrics are generated
                        if not isinstance(self.lr_scheduler, torch.optim.lr_scheduler.ReduceLROnPlateau):
                            self.lr_scheduler.step()

                    model.zero_grad()
                    self.state.global_step += 1
                    self.state.epoch = epoch + (step + 1 + steps_skipped) / steps_in_epoch
                    self.control = self.callback_handler.on_step_end(args, self.state, self.control)

                    self._maybe_log_save_evaluate(tr_loss, grad_norm, model, trial, epoch, ignore_keys_for_eval, dict_loss)
                else:
                    self.control = self.callback_handler.on_substep_end(args, self.state, self.control)

                if self.control.should_epoch_stop or self.control.should_training_stop:
                    # PyTorch/XLA relies on the data loader to insert the mark_step for
                    # each step. Since we are breaking the loop early, we need to manually
                    # insert the mark_step here.
                    if is_torch_xla_available():
                        xm.mark_step()
                    break
            if step < 0:
                logger.warning(
                    "There seems to be not a single sample in your epoch_iterator, stopping training at step"
                    f" {self.state.global_step}! This is expected if you're using an IterableDataset and set"
                    f" num_steps ({max_steps}) higher than the number of available samples."
                )
                self.control.should_training_stop = True

            self.control = self.callback_handler.on_epoch_end(args, self.state, self.control)
            self._maybe_log_save_evaluate(tr_loss, grad_norm, model, trial, epoch, ignore_keys_for_eval, dict_loss)

            if DebugOption.TPU_METRICS_DEBUG in self.args.debug:
                if is_torch_xla_available():
                    # tpu-comment: Logging debug metrics for PyTorch/XLA (compile, execute times, ops, etc.)
                    xm.master_print(met.metrics_report())
                else:
                    logger.warning(
                        "You enabled PyTorch/XLA debug metrics but you don't have a TPU "
                        "configured. Check your training configuration if this is unexpected."
                    )
            if self.control.should_training_stop:
                break

        if args.past_index and hasattr(self, "_past"):
            # Clean the state at the end of training
            delattr(self, "_past")

        logger.info("\n\nTraining completed. Do not forget to share your model on huggingface.co/models =)\n\n")
        if args.load_best_model_at_end and self.state.best_model_checkpoint is not None:
            # Wait for everyone to get here so we are sure the model has been saved by process 0.
            if is_torch_xla_available():
                xm.rendezvous("load_best_model_at_end")
            elif args.parallel_mode == ParallelMode.DISTRIBUTED:
                dist.barrier()
            elif is_sagemaker_mp_enabled():
                smp.barrier()

            self._load_best_model()

        # add remaining tr_loss
        self._total_loss_scalar += tr_loss.item()
        effective_global_step = max(self.state.global_step, 0.001)  # Avoid ZeroDivisionError
        train_loss = self._total_loss_scalar / effective_global_step

        metrics = speed_metrics(
            "train",
            start_time,
            num_samples=num_train_samples,
            num_steps=self.state.max_steps,
            num_tokens=num_train_tokens,
        )
        self.store_flos()
        metrics["total_flos"] = self.state.total_flos
        metrics["train_loss"] = train_loss

        self.is_in_train = False

        self._memory_tracker.stop_and_update_metrics(metrics)

        self.log(metrics)

        run_dir = self._get_output_dir(trial)
        checkpoints_sorted = self._sorted_checkpoints(use_mtime=False, output_dir=run_dir)

        # Delete the last checkpoint when save_total_limit=1 if it's different from the best checkpoint and process allowed to save.
        if self.args.should_save and self.state.best_model_checkpoint is not None and self.args.save_total_limit == 1:
            for checkpoint in checkpoints_sorted:
                if not os.path.samefile(checkpoint, self.state.best_model_checkpoint):
                    logger.info(f"Deleting older checkpoint [{checkpoint}] due to args.save_total_limit")
                    shutil.rmtree(checkpoint, ignore_errors=True)

        self.control = self.callback_handler.on_train_end(args, self.state, self.control)

        # Wait for the checkpoint to be uploaded.
        self._finish_current_push()

        # After training we make sure to retrieve back the original forward pass method
        # for the embedding layer by removing the forward post hook.
        if self.neftune_noise_alpha is not None:
            self._deactivate_neftune(self.model)

        return TrainOutput(self.state.global_step, train_loss, metrics)


    def evaluate_special_token(
        self,
        eval_dataset: Optional[Union[Dataset, Dict[str, Dataset]]] = None,
        ignore_keys: Optional[List[str]] = None,
        metric_key_prefix: str = "eval",
    ) -> Dict[str, float]:
        """
        Run evaluation and returns metrics.

        The calling script will be responsible for providing a method to compute metrics, as they are task-dependent
        (pass it to the init `compute_metrics` argument).

        You can also subclass and override this method to inject custom behavior.

        Args:
            eval_dataset (Union[`Dataset`, Dict[str, `Dataset`]), *optional*):
                Pass a dataset if you wish to override `self.eval_dataset`. If it is a [`~datasets.Dataset`], columns
                not accepted by the `model.forward()` method are automatically removed. If it is a dictionary, it will
                evaluate on each dataset, prepending the dictionary key to the metric name. Datasets must implement the
                `__len__` method.

                <Tip>

                If you pass a dictionary with names of datasets as keys and datasets as values, evaluate will run
                separate evaluations on each dataset. This can be useful to monitor how training affects other
                datasets or simply to get a more fine-grained evaluation.
                When used with `load_best_model_at_end`, make sure `metric_for_best_model` references exactly one
                of the datasets. If you, for example, pass in `{"data1": data1, "data2": data2}` for two datasets
                `data1` and `data2`, you could specify `metric_for_best_model="eval_data1_loss"` for using the
                loss on `data1` and `metric_for_best_model="eval_data2_loss"` for the loss on `data2`.

                </Tip>

            ignore_keys (`List[str]`, *optional*):
                A list of keys in the output of your model (if it is a dictionary) that should be ignored when
                gathering predictions.
            metric_key_prefix (`str`, *optional*, defaults to `"eval"`):
                An optional prefix to be used as the metrics key prefix. For example the metrics "bleu" will be named
                "eval_bleu" if the prefix is "eval" (default)

        Returns:
            A dictionary containing the evaluation loss and the potential metrics computed from the predictions. The
            dictionary also contains the epoch number which comes from the training state.
        """
        # handle multipe eval datasets
        override = eval_dataset is not None
        eval_dataset = eval_dataset if override else self.eval_dataset
        if isinstance(eval_dataset, dict):
            metrics = {}
            for eval_dataset_name, _eval_dataset in eval_dataset.items():
                dataset_metrics = self.evaluate_special_token(
                    eval_dataset=_eval_dataset if override else eval_dataset_name,
                    ignore_keys=ignore_keys,
                    metric_key_prefix=f"{metric_key_prefix}_{eval_dataset_name}",
                )
                metrics.update(dataset_metrics)
            return metrics

        # memory metrics - must set up as early as possible
        self._memory_tracker.start()

        eval_dataloader = self.get_eval_dataloader(eval_dataset)
        if self.is_fsdp_xla_v2_enabled:
            eval_dataloader = tpu_spmd_dataloader(eval_dataloader)

        start_time = time.time()

        eval_loop = self.prediction_loop if self.args.use_legacy_prediction_loop else self.evaluation_loop_special
        output = eval_loop(
            eval_dataloader,
            description="Evaluation",
            # No point gathering the predictions if there are no metrics, otherwise we defer to
            # self.args.prediction_loss_only
            prediction_loss_only=True if self.compute_metrics is None else None,
            ignore_keys=ignore_keys,
            metric_key_prefix=metric_key_prefix,
        )

        total_batch_size = self.args.eval_batch_size * self.args.world_size
        if f"{metric_key_prefix}_jit_compilation_time" in output.metrics:
            start_time += output.metrics[f"{metric_key_prefix}_jit_compilation_time"]
        if f"{metric_key_prefix}_model_preparation_time" in output.metrics:
            start_time += output.metrics[f"{metric_key_prefix}_model_preparation_time"]
        output.metrics.update(
            speed_metrics(
                metric_key_prefix,
                start_time,
                num_samples=output.num_samples,
                num_steps=math.ceil(output.num_samples / total_batch_size),
            )
        )

        self.log(output.metrics)

        if DebugOption.TPU_METRICS_DEBUG in self.args.debug:
            # tpu-comment: Logging debug metrics for PyTorch/XLA (compile, execute times, ops, etc.)
            xm.master_print(met.metrics_report())

        self.control = self.callback_handler.on_evaluate(self.args, self.state, self.control, output.metrics)

        self._memory_tracker.stop_and_update_metrics(output.metrics)

        return output.metrics
    
    
    def evaluation_loop_special(
        self,
        dataloader: DataLoader,
        description: str,
        prediction_loss_only: Optional[bool] = None,
        ignore_keys: Optional[List[str]] = None,
        metric_key_prefix: str = "eval",
    ) -> EvalLoopOutput:
        """
        Prediction/evaluation loop, shared by `Trainer.evaluate()` and `Trainer.predict()`.

        Works both with or without labels.
        """
        args = self.args

        prediction_loss_only = prediction_loss_only if prediction_loss_only is not None else args.prediction_loss_only

        # if eval is called w/o train, handle model prep here
        if self.is_deepspeed_enabled and self.deepspeed is None:
            _, _ = deepspeed_init(self, num_training_steps=0, inference=True)

        model = self._wrap_model(self.model, training=False, dataloader=dataloader)

        if len(self.accelerator._models) == 0 and model is self.model:
            start_time = time.time()
            model = (
                self.accelerator.prepare(model)
                if self.is_deepspeed_enabled
                else self.accelerator.prepare_model(model, evaluation_mode=True)
            )
            self.model_preparation_time = round(time.time() - start_time, 4)

            if self.is_fsdp_enabled:
                self.model = model

            # for the rest of this function `model` is the outside model, whether it was wrapped or not
            if model is not self.model:
                self.model_wrapped = model

            # backward compatibility
            if self.is_deepspeed_enabled:
                self.deepspeed = self.model_wrapped

        # if full fp16 or bf16 eval is wanted and this ``evaluation`` or ``predict`` isn't called
        # while ``train`` is running, cast it to the right dtype first and then put on device
        if not self.is_in_train:
            if args.fp16_full_eval:
                model = model.to(dtype=torch.float16, device=args.device)
            elif args.bf16_full_eval:
                model = model.to(dtype=torch.bfloat16, device=args.device)

        batch_size = self.args.eval_batch_size

        logger.info(f"\n***** Running {description} *****")
        if has_length(dataloader):
            logger.info(f"  Num examples = {self.num_examples(dataloader)}")
        else:
            logger.info("  Num examples: Unknown")
        logger.info(f"  Batch size = {batch_size}")

        model.eval()

        self.callback_handler.eval_dataloader = dataloader
        # Do this before wrapping.
        eval_dataset = getattr(dataloader, "dataset", None)

        if args.past_index >= 0:
            self._past = None

        # Initialize containers, also extended for different losses 
        all_losses = EvalLoopContainer(self.args.eval_do_concat_batches, padding_index=-100)
        all_preds = EvalLoopContainer(self.args.eval_do_concat_batches, padding_index=-100)
        all_labels = EvalLoopContainer(self.args.eval_do_concat_batches, padding_index=-100)
        all_inputs = EvalLoopContainer(self.args.eval_do_concat_batches, padding_index=-100)        
        all_datasets = []

        if not self.args.standard_loss:
            all_losses_special = EvalLoopContainer(self.args.eval_do_concat_batches, padding_index=-100)
            all_losses_answer = EvalLoopContainer(self.args.eval_do_concat_batches, padding_index=-100)

        metrics = None
        if self.args.compute_metrics_special_tokens == 'retrieval':
            special_tokens = self.args.special_token_retrieval, self.args.special_token_no_retrieval
            special_accuracy_metric = SpecialAccuracyMetric(special_tokens=special_tokens, file_to_save_wrong_predictions=os.path.join(self.args.model_name_or_path, 'wrong_encyclopedic_predictions.json'))
        elif self.args.compute_metrics_special_tokens == 'relevant':
            special_tokens = self.args.special_token_relevant, self.args.special_token_no_relevant
            special_accuracy_metric = SpecialAccuracyMetric(special_tokens=special_tokens)

        # Will be useful when we have an iterable dataset so don't know its length.
        observed_num_examples = 0
            
        # Main evaluation loop
        for step, inputs in enumerate(dataloader):
            # if is_debug() and step > 10:
            #     break
            dataset_name = inputs.pop('dataset_name')
            original_question = inputs.pop('original_question')
            original_image = inputs.pop('original_image')
            dataset_name_ids= dataset_encode_names(dataset_name).to(inputs['input_ids'].device)
            
            # Update the observed num examples
            observed_batch_size = find_batch_size(inputs)
            if observed_batch_size is not None:
                observed_num_examples += observed_batch_size
                # For batch samplers, batch_size is not known by the dataloader in advance.
                if batch_size is None:
                    batch_size = observed_batch_size

            # Prediction step
            dict_loss = self.prediction_step(model, inputs, prediction_loss_only, ignore_keys=ignore_keys)
            losses, logits, labels = dict_loss["loss"], dict_loss.get("outputs"), dict_loss.get("labels")
            
            main_input_name = getattr(self.model, "main_input_name", "input_ids")
            inputs_decode = self._prepare_input(inputs[main_input_name]) if args.include_inputs_for_metrics else None

            if is_torch_xla_available():
                xm.mark_step()

            # Update containers
            if losses is not None:
                losses = self.gather_function((losses.repeat(batch_size)))
                all_losses.add(losses)
                if not self.args.standard_loss:
                    all_losses_special.add(dict_loss['loss_special_xe'])
                    all_losses_answer.add(dict_loss['loss_answer_xe'])
            if inputs_decode is not None:
                inputs_decode = self.accelerator.pad_across_processes(inputs_decode, dim=1, pad_index=-100)
                inputs_decode = self.gather_function((inputs_decode))
                if not self.args.batch_eval_metrics or description == "Prediction":
                    all_inputs.add(inputs_decode)
            if labels is not None:
                # Pad labels here, preparing for preprocess_logits_for_metrics in next logits block.
                labels = self.accelerator.pad_across_processes(labels, dim=1, pad_index=-100)
            if logits is not None:
                logits = self.accelerator.pad_across_processes(logits, dim=1, pad_index=-100)
                if self.preprocess_logits_for_metrics is not None:
                    logits = self.preprocess_logits_for_metrics(logits, labels)
                logits = self.gather_function((logits))
                if not self.args.batch_eval_metrics or description == "Prediction":
                    all_preds.add(logits)
            if labels is not None:
                labels = self.gather_function((labels))
                if not self.args.batch_eval_metrics or description == "Prediction":
                    all_labels.add(labels)
            if dataset_name is not None:
                dataset_name_ids = self.gather_function((dataset_name_ids))
                # all_datasets.append(dataset_name)

            self.control = self.callback_handler.on_prediction_step(args, self.state, self.control)

            # if we are doing batch eval metrics, we need to update the self.compute_metrics
            if self.args.batch_eval_metrics:
                if self.compute_metrics is not None and logits is not None and labels is not None:
                    is_last_step = self.accelerator.gradient_state.end_of_dataloader
                    if args.include_inputs_for_metrics:
                        metrics = self.compute_metrics(
                            EvalPrediction(predictions=logits, label_ids=labels, inputs=inputs),
                            compute_result=is_last_step,
                        )
                    else:
                        metrics = self.compute_metrics(EvalPrediction(predictions=logits, label_ids=labels),
                                                       custom_metric= special_accuracy_metric,
                                                       dataset_name=dataset_name_ids,
                                                       compute_result=is_last_step, original_question=original_question, original_image=original_image)

                del losses, logits, labels, inputs
                torch.cuda.empty_cache()

            # Gather all tensors and put them back on the CPU if we have done enough accumulation steps.
            elif args.eval_accumulation_steps is not None and (step + 1) % args.eval_accumulation_steps == 0:
                all_losses.to_cpu_and_numpy()
                all_preds.to_cpu_and_numpy()
                all_labels.to_cpu_and_numpy()
                all_inputs.to_cpu_and_numpy()
                if not self.args.standard_loss:
                    all_losses_special.to_cpu_and_numpy()
                    all_losses_answer.to_cpu_and_numpy()

                del losses, logits, labels, inputs
                torch.cuda.empty_cache()
            
        # After all calls to `.gather_function`, reset to `gather_for_metrics`:
        self.gather_function = self.accelerator.gather_for_metrics
        if args.past_index and hasattr(self, "_past"):
            # Clean the state at the end of the evaluation loop
            delattr(self, "_past")

        # Gather all remaining tensors and put them back on the CPU
        all_losses = all_losses.get_arrays()
        all_preds = all_preds.get_arrays()
        all_labels = all_labels.get_arrays()
        all_inputs = all_inputs.get_arrays()
        if not self.args.standard_loss:
            all_losses_special = all_losses_special.get_arrays()
            all_losses_answer = all_losses_answer.get_arrays()

        # Number of samples
        if has_length(eval_dataset):
            num_samples = len(eval_dataset)
        # The instance check is weird and does not actually check for the type, but whether the dataset has the right
        # methods. Therefore we need to make sure it also has the attribute.
        elif isinstance(eval_dataset, IterableDatasetShard) and getattr(eval_dataset, "num_examples", 0) > 0:
            num_samples = eval_dataset.num_examples
        else:
            if has_length(dataloader):
                num_samples = self.num_examples(dataloader)
            else:  # both len(dataloader.dataset) and len(dataloader) fail
                num_samples = observed_num_examples
        if num_samples == 0 and observed_num_examples > 0:
            num_samples = observed_num_examples

        # Metrics!
        if (
            self.compute_metrics is not None
            and all_preds is not None
            and all_labels is not None
            and not self.args.batch_eval_metrics
        ):
            if args.include_inputs_for_metrics:
                metrics = self.compute_metrics(
                    EvalPrediction(predictions=all_preds, label_ids=all_labels, inputs=all_inputs)
                )
            else:
                metrics = self.compute_metrics(EvalPrediction(predictions=all_preds, label_ids=all_labels), 
                                               dataset_name=all_datasets)
        elif metrics is None:
            metrics = {}

        # To be JSON-serializable, we need to remove numpy types or zero-d tensors
        metrics = denumpify_detensorize(metrics)

        if isinstance(all_losses, list) and all_losses:
            metrics[f"{metric_key_prefix}_loss"] = np.concatenate(all_losses).mean().item()
        elif isinstance(all_losses, np.ndarray):
            metrics[f"{metric_key_prefix}_loss"] = all_losses.mean().item()
        
        if hasattr(self, "jit_compilation_time"):
            metrics[f"{metric_key_prefix}_jit_compilation_time"] = self.jit_compilation_time
        if hasattr(self, "model_preparation_time"):
            metrics[f"{metric_key_prefix}_model_preparation_time"] = self.model_preparation_time
            
        if not self.args.standard_loss and isinstance(all_losses_special, np.ndarray):
            metrics[f"{metric_key_prefix}_loss_special_xe"] = all_losses_special.mean().item()
        if not self.args.standard_loss and isinstance(all_losses_answer, np.ndarray):
            metrics[f"{metric_key_prefix}_loss_answer_xe"] = all_losses_answer.mean().item()

        # Prefix all keys with metric_key_prefix + '_'
        for key in list(metrics.keys()):
            if not key.startswith(f"{metric_key_prefix}_"):
                metrics[f"{metric_key_prefix}_{key}"] = metrics.pop(key)

        return EvalLoopOutput(predictions=all_preds, label_ids=all_labels, metrics=metrics, num_samples=num_samples)
    
    def prediction_step(
        self,
        model: nn.Module,
        inputs: Dict[str, Union[torch.Tensor, Any]],
        prediction_loss_only: bool,
        ignore_keys: Optional[List[str]] = None,
    ) -> Tuple[Optional[torch.Tensor], Optional[torch.Tensor], Optional[torch.Tensor]]:
        """
        Perform an evaluation step on `model` using `inputs`.

        Subclass and override to inject custom behavior.

        Args:
            model (`nn.Module`):
                The model to evaluate.
            inputs (`Dict[str, Union[torch.Tensor, Any]]`):
                The inputs and targets of the model.

                The dictionary will be unpacked before being fed to the model. Most models expect the targets under the
                argument `labels`. Check your model's documentation for all accepted arguments.
            prediction_loss_only (`bool`):
                Whether or not to return the loss only.
            ignore_keys (`List[str]`, *optional*):
                A list of keys in the output of your model (if it is a dictionary) that should be ignored when
                gathering predictions.

        Return:
            Tuple[Optional[torch.Tensor], Optional[torch.Tensor], Optional[torch.Tensor]]: A tuple with the loss,
            logits and labels (each being optional).
        """
        has_labels = False if len(self.label_names) == 0 else all(inputs.get(k) is not None for k in self.label_names)
        # For CLIP-like models capable of returning loss values.
        # If `return_loss` is not specified or being `None` in `inputs`, we check if the default value of `return_loss`
        # is `True` in `model.forward`.
        return_loss = inputs.get("return_loss", None)
        if return_loss is None:
            return_loss = self.can_return_loss
        loss_without_labels = True if len(self.label_names) == 0 and return_loss else False

        inputs = self._prepare_inputs(inputs)
        if ignore_keys is None:
            if hasattr(self.model, "config"):
                ignore_keys = getattr(self.model.config, "keys_to_ignore_at_inference", [])
            else:
                ignore_keys = []

        # labels may be popped when computing the loss (label smoothing for instance) so we grab them first.
        if has_labels or loss_without_labels:
            labels = nested_detach(tuple(inputs.get(name) for name in self.label_names))
            if len(labels) == 1:
                labels = labels[0]
        else:
            labels = None

        with torch.no_grad():
            if is_sagemaker_mp_enabled():
                raw_outputs = smp_forward_only(model, inputs)
                if has_labels or loss_without_labels:
                    if isinstance(raw_outputs, dict):
                        loss_mb = raw_outputs["loss"]
                        logits_mb = tuple(v for k, v in raw_outputs.items() if k not in ignore_keys + ["loss"])
                    else:
                        loss_mb = raw_outputs[0]
                        logits_mb = raw_outputs[1:]

                    loss = loss_mb.reduce_mean().detach().cpu()
                    logits = smp_nested_concat(logits_mb)
                else:
                    loss = None
                    if isinstance(raw_outputs, dict):
                        logits_mb = tuple(v for k, v in raw_outputs.items() if k not in ignore_keys)
                    else:
                        logits_mb = raw_outputs
                    logits = smp_nested_concat(logits_mb)
            else:
                if has_labels or loss_without_labels:
                    with self.compute_loss_context_manager():
                        dict_loss = self.compute_loss(model, inputs)
                        loss= dict_loss['loss']
                        outputs = dict_loss['outputs']
                        
                    loss = loss.mean().detach()

                    if isinstance(outputs, dict):
                        logits = tuple(v for k, v in outputs.items() if k not in ignore_keys + ["loss"])
                    else:
                        logits = outputs[1:]
                else:
                    loss = None
                    with self.compute_loss_context_manager():
                        outputs = model(**inputs)
                    if isinstance(outputs, dict):
                        logits = tuple(v for k, v in outputs.items() if k not in ignore_keys)
                    else:
                        logits = outputs
                    # TODO: this needs to be fixed and made cleaner later.
                    if self.args.past_index >= 0:
                        self._past = outputs[self.args.past_index - 1]

        if prediction_loss_only:
            return (loss, None, None)

        logits = nested_detach(logits)
        if len(logits) == 1:
            logits = logits[0]

        dict_loss['outputs'] = logits
        return dict_loss
