from typing import List, Optional, Tuple, Union

import torch
from torch import nn
from transformers.cache_utils import Cache, DynamicCache
from transformers.modeling_flash_attention_utils import FlashAttentionKwargs
from transformers.modeling_outputs import BaseModelOutputWithPast, CausalLMOutputWithPast
from transformers.models.cohere.modeling_cohere import (
    CohereAttention,
    CohereForCausalLM,
    CohereModel,
    StaticCache,
    apply_rotary_pos_emb,
    repeat_kv,
)
from transformers.processing_utils import Unpack
from transformers.utils import logging

from colossalai.pipeline.stage_manager import PipelineStageManager
from colossalai.shardformer.layer._operation import all_to_all_comm, split_forward_gather_backward
from colossalai.shardformer.shard import ShardConfig

from ..layer import ColoAttention, dist_cross_entropy
from ..layer._operation import gather_sp_output, is_share_sp_tp

_SUPPORTED_SP_MODE = ["all_to_all", "split_gather", "ring"]

_SUPPORTED_SP_MODE = ["all_to_all", "split_gather", "ring", "ring_attn"]

logger = logging.get_logger(__name__)


class CommandPipelineForwards:
    """
    This class serves as a micro library for forward function substitution of Command models
    under pipeline setting.
    """

    @staticmethod
    def command_model_forward(
        self: CohereModel,
        input_ids: Optional[torch.LongTensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.LongTensor] = None,
        past_key_values: Optional[Cache] = None,
        inputs_embeds: Optional[torch.FloatTensor] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        cache_position: Optional[torch.LongTensor] = None,
        stage_manager: Optional[PipelineStageManager] = None,
        hidden_states: Optional[torch.FloatTensor] = None,
        stage_index: Optional[List[int]] = None,
        shard_config: ShardConfig = None,
        force_sp_output_gather: bool = True,
        **flash_attn_kwargs: Unpack[FlashAttentionKwargs],
    ):

        logger = logging.get_logger(__name__)

        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        use_cache = use_cache if use_cache is not None else self.config.use_cache

        if use_cache:
            logger.warning_once(
                "`use_cache=True` is incompatible with pipeline parallelism. Setting `use_cache=False`..."
            )
            use_cache = False

        # retrieve input_ids and inputs_embeds
        if stage_manager.is_first_stage():
            if input_ids is not None and inputs_embeds is not None:
                raise ValueError("You cannot specify both input_ids and inputs_embeds at the same time")
            elif input_ids is not None:
                batch_size, seq_length = input_ids.shape[:2]
            elif inputs_embeds is not None:
                batch_size, seq_length, _ = inputs_embeds.shape[:2]
            else:
                raise ValueError("You have to specify either input_ids or inputs_embeds")
            device = input_ids.device if input_ids is not None else inputs_embeds.device
            if inputs_embeds is None:
                inputs_embeds = self.embed_tokens(input_ids)
            hidden_states = inputs_embeds
        else:
            input_shape = hidden_states.shape[:-1]
            batch_size, seq_length = input_shape
            device = hidden_states.device

        past_seen_tokens = 0
        if use_cache:  # kept for BC (cache positions)
            if not isinstance(past_key_values, StaticCache):
                past_key_values = DynamicCache.from_legacy_cache(past_key_values)
                past_seen_tokens = past_key_values.get_seq_length()

        # NOTE: For generating full positions ids
        # (the states will be gathered along the seq dim before attention fwd).
        if shard_config.sequence_parallelism_mode != "ring_attn" and not stage_manager.is_first_stage():
            seq_length *= shard_config.sequence_parallel_size

        if cache_position is None:
            if isinstance(past_key_values, StaticCache):
                raise ValueError("cache_position is a required argument when using StaticCache.")
            cache_position = torch.arange(past_seen_tokens, past_seen_tokens + seq_length, device=device)

        seq_length_with_past = seq_length + past_seen_tokens

        # TODO(jianghai): left the recording kv-value tensors as () or None type, this feature may be added in the future.
        if output_attentions:
            logger.warning_once("output_attentions=True is not supported for pipeline models at the moment.")
            output_attentions = False
        if output_hidden_states:
            logger.warning_once("output_hidden_states=True is not supported for pipeline models at the moment.")
            output_hidden_states = False
        if use_cache:
            logger.warning_once("use_cache=True is not supported for pipeline models at the moment.")
            use_cache = False

        if position_ids is None:
            position_ids = cache_position.unsqueeze(0)

        # embed positions, for the first stage, hidden_states is the input embeddings,
        # for the other stages, hidden_states is the output of the previous stage
        shard_config.enable_flash_attention = True
        if shard_config.enable_flash_attention:
            # in this case, attention_mask is a dict rather than a tensor
            mask_shape = (batch_size, 1, seq_length, seq_length_with_past)
            attention_mask = ColoAttention.prepare_attn_kwargs(
                mask_shape,
                hidden_states.dtype,
                hidden_states.device,
                q_padding_mask=attention_mask,
                is_causal=True,
            )
        else:
            # v4.51.3 transformers attention_mask calculation
            attention_mask = self._update_causal_mask(attention_mask, hidden_states, cache_position, past_key_values)

        if self.gradient_checkpointing and self.training and use_cache:
            if use_cache:
                logger.warning_once(
                    "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..."
                )
                use_cache = False

        if stage_manager.is_first_stage() and shard_config.enable_sequence_parallelism:
            if shard_config.sequence_parallelism_mode in ["split_gather", "ring"]:
                hidden_states = split_forward_gather_backward(
                    hidden_states,
                    dim=1,
                    process_group=shard_config.tensor_parallel_process_group,
                    fp8_communication=shard_config.fp8_communication,
                )
            elif shard_config.sequence_parallelism_mode == "all_to_all":
                hidden_states = split_forward_gather_backward(
                    hidden_states,
                    dim=1,
                    process_group=shard_config.sequence_parallel_process_group,
                    grad_scale=1 / shard_config.sequence_parallel_size,
                    fp8_communication=shard_config.fp8_communication,
                )

        # decoder layers
        all_hidden_states = () if output_hidden_states else None
        all_self_attns = () if output_attentions else None
        next_decoder_cache = None
        # v4.51.3 transformers position_embeddings calculation
        position_embeddings = self.rotary_emb(hidden_states, position_ids)

        start_idx, end_idx = stage_index[0], stage_index[1]
        num_ckpt_layers = 0
        if self.gradient_checkpointing and self.training:
            num_ckpt_layers = end_idx - start_idx
            # TODO: We can replace `gradient_checkpointing_enable` fn and initialize a gradient_checkpointing (List[bool]) for each layer
            if shard_config.gradient_checkpoint_config is not None:
                num_ckpt_layers = shard_config.gradient_checkpoint_config.get_num_ckpt_layers(
                    stage=stage_manager.stage,
                    num_stages=stage_manager.num_stages,
                    num_layers=end_idx - start_idx,
                    model_chunk_id=(stage_manager.model_chunk_id if stage_manager.is_interleave else 0),
                    num_model_chunks=stage_manager.num_model_chunks,
                )
            assert num_ckpt_layers <= end_idx - start_idx

        for idx, decoder_layer in enumerate(self.layers[start_idx:end_idx], start=start_idx):
            if output_hidden_states:
                all_hidden_states += (hidden_states,)

            if idx - start_idx < num_ckpt_layers:
                layer_outputs = self._gradient_checkpointing_func(
                    decoder_layer.__call__,
                    hidden_states,
                    attention_mask,
                    position_ids,
                    past_key_values,
                    output_attentions,
                    use_cache,
                    cache_position,
                    position_embeddings,
                )
            else:
                layer_outputs = decoder_layer(
                    hidden_states,
                    attention_mask=attention_mask,
                    position_ids=position_ids,
                    past_key_value=past_key_values,
                    output_attentions=output_attentions,
                    use_cache=use_cache,
                    cache_position=cache_position,
                    position_embeddings=position_embeddings,
                )

            hidden_states = layer_outputs[0]

            if use_cache:
                next_decoder_cache = layer_outputs[2 if output_attentions else 1]
            if output_attentions:
                all_self_attns += (layer_outputs[1],)

        if stage_manager.is_last_stage():
            hidden_states = self.norm(hidden_states)
            sp_mode = shard_config.sequence_parallelism_mode
            if shard_config.enable_sequence_parallelism:
                if (not shard_config.parallel_output) or force_sp_output_gather or is_share_sp_tp(sp_mode):
                    hidden_states = gather_sp_output(hidden_states, shard_config)

        # add hidden states from the last decoder layer
        if output_hidden_states:
            all_hidden_states += (hidden_states,)
        next_cache = next_decoder_cache if use_cache else None
        if stage_manager.is_last_stage():
            return BaseModelOutputWithPast(
                last_hidden_state=hidden_states,
                past_key_values=next_cache,
                hidden_states=all_hidden_states,
                attentions=all_self_attns,
            )
        # always return dict for imediate stage
        return {"hidden_states": hidden_states}

    @staticmethod
    def command_for_causal_lm_forward(
        self: CohereForCausalLM,
        input_ids: torch.LongTensor = None,
        attention_mask: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.LongTensor] = None,
        past_key_values: Optional[List[torch.FloatTensor]] = None,
        inputs_embeds: Optional[torch.FloatTensor] = None,
        labels: Optional[torch.LongTensor] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
        cache_position: Optional[torch.LongTensor] = None,
        stage_manager: Optional[PipelineStageManager] = None,
        hidden_states: Optional[torch.FloatTensor] = None,
        stage_index: Optional[List[int]] = None,
        shard_config: ShardConfig = None,
    ):
        r"""
        Args:
            labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
                Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
                config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
                (masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.

        Returns:

        Example:

        ```python
        >>> from transformers import AutoTokenizer, CohereForCausalLM

        >>> model = CohereForCausalLM.from_pretrained(PATH_TO_CONVERTED_WEIGHTS)
        >>> tokenizer = AutoTokenizer.from_pretrained(PATH_TO_CONVERTED_TOKENIZER)

        >>> prompt = "Hey, are you conscious? Can you talk to me?"
        >>> inputs = tokenizer(prompt, return_tensors="pt")

        >>> # Generate
        >>> generate_ids = model.generate(inputs.input_ids, max_length=30)
        >>> tokenizer.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
        "Hey, are you conscious? Can you talk to me?\nI'm not conscious, but I can talk to you."
        ```"""
        logger = logging.get_logger(__name__)
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        # TODO(jianghai): left the recording kv-value tensors as () or None type, this feature may be added in the future.
        if output_attentions:
            logger.warning_once("output_attentions=True is not supported for pipeline models at the moment.")
            output_attentions = False
        if output_hidden_states:
            logger.warning_once("output_hidden_states=True is not supported for pipeline models at the moment.")
            output_hidden_states = False

        # decoder outputs consists of (dec_features, layer_state, dec_hidden, dec_attn)
        outputs = CommandPipelineForwards.command_model_forward(
            self.model,
            input_ids=input_ids,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
            cache_position=cache_position,
            stage_manager=stage_manager,
            hidden_states=hidden_states,
            stage_index=stage_index,
            shard_config=shard_config,
            force_sp_output_gather=False,
        )
        past_key_values = None

        if stage_manager.is_last_stage():
            hidden_states = outputs[0]
            logits = self.lm_head(hidden_states)
            logits = logits * self.logit_scale
            logits = logits.float()

            loss = None
            if labels is not None:
                loss = dist_cross_entropy(labels, logits, shard_config, self.lm_head.out_features, self.model.dtype)

            if not return_dict:
                output = (logits,) + outputs[1:]
                return (loss,) + output if loss is not None else output

            return CausalLMOutputWithPast(
                loss=loss,
                logits=logits,
                past_key_values=outputs.past_key_values,
                hidden_states=outputs.hidden_states,
                attentions=outputs.attentions,
            )
        else:
            hidden_states = outputs.get("hidden_states")
            return {"hidden_states": hidden_states}


def get_command_flash_attention_forward(shard_config: ShardConfig, sp_mode=None, sp_size=None, sp_group=None):
    def forward(
        self: CohereAttention,
        hidden_states: torch.Tensor,
        position_embeddings: Tuple[torch.Tensor, torch.Tensor],
        attention_mask: Optional[torch.Tensor] = None,
        past_key_value: Optional[Cache] = None,
        cache_position: Optional[torch.LongTensor] = None,
        **kwargs: Unpack[FlashAttentionKwargs],
    ) -> Tuple[torch.Tensor, Optional[torch.Tensor], Optional[Tuple[torch.Tensor]]]:
        if sp_mode is not None:
            assert sp_mode in _SUPPORTED_SP_MODE, f"SP mode {sp_mode} is not supported by {type(self)} yet"
            assert (sp_size is not None) and (
                sp_group is not None
            ), "Must specify sp_size and sp_group for sequence parallel"

        bsz, q_len, _ = hidden_states.size()

        # sp: modify sp_len when sequence parallel mode is ring
        if sp_mode in ["split_gather", "ring"]:
            q_len *= sp_size

        query_states = self.q_proj(hidden_states)
        key_states = self.k_proj(hidden_states)
        value_states = self.v_proj(hidden_states)

        # sp: all-to-all comminucation when introducing sequence parallel
        if sp_mode == "all_to_all":
            query_states = all_to_all_comm(query_states, sp_group, fp8_communication=shard_config.fp8_communication)
            key_states = all_to_all_comm(key_states, sp_group, fp8_communication=shard_config.fp8_communication)
            value_states = all_to_all_comm(value_states, sp_group, fp8_communication=shard_config.fp8_communication)
            bsz, q_len, _ = query_states.size()

        query_states = query_states.view(bsz, q_len, -1, self.head_dim).transpose(1, 2)
        key_states = key_states.view(bsz, q_len, -1, self.head_dim).transpose(1, 2)
        value_states = value_states.view(bsz, q_len, -1, self.head_dim).transpose(1, 2)

        cos, sin = position_embeddings

        query_states, key_states = apply_rotary_pos_emb(query_states, key_states, cos, sin)

        # repeat k/v heads if n_kv_heads < n_heads
        key_states = repeat_kv(key_states, self.num_key_value_groups)
        value_states = repeat_kv(value_states, self.num_key_value_groups)
        attn_weights = None

        shard_config.enable_flash_attention = True

        if shard_config.enable_flash_attention:
            assert isinstance(attention_mask, dict), "Flash Attention Error: attention_mask should be a dict."
            attn_output = ColoAttention.attention(query_states, key_states, value_states, **attention_mask)
        else:
            # attn_weights and attn_output calculation is modified on the v4.51.3 of transformers.models.cohere.modeling_cohere.CohereAttention.forward.
            attn_weights = torch.matmul(query_states, key_states.transpose(2, 3)) * self.scaling
            if attention_mask is not None:
                causal_mask = attention_mask[:, :, :, : key_states.shape[-2]]
                attn_weights = attn_weights + causal_mask

            attn_weights = nn.functional.softmax(attn_weights, dim=-1, dtype=torch.float32).to(query_states.dtype)
            dropout = 0.0 if not self.training else self.attention_dropout
            attn_weights = nn.functional.dropout(attn_weights, p=dropout, training=self.training)
            attn_output = torch.matmul(attn_weights, value_states)
            attn_output = attn_output.transpose(1, 2).contiguous()

        attn_output = attn_output.transpose(1, 2).contiguous()
        # sp: all-to-all comminucation when introducing sequence parallel
        if sp_mode == "all_to_all":
            attn_output = attn_output.reshape(bsz, q_len, self.num_heads * self.head_dim)
            attn_output = all_to_all_comm(
                attn_output, sp_group, scatter_dim=1, gather_dim=2, fp8_communication=shard_config.fp8_communication
            )
        else:
            attn_output = attn_output.reshape(bsz, q_len, -1).contiguous()

        attn_output = self.o_proj(attn_output)

        return attn_output, attn_weights

    return forward


def get_command_flash_attention_model_forward(shard_config: ShardConfig, sp_mode=None, sp_size=None, sp_group=None):
    logger = logging.get_logger(__name__)

    def forward(
        self,
        input_ids: Optional[torch.LongTensor] = None,
        attention_mask: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.LongTensor] = None,
        past_key_values: Optional[Cache] = None,
        inputs_embeds: Optional[torch.FloatTensor] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        cache_position: Optional[torch.LongTensor] = None,
        force_sp_output_gather: bool = True,
        **flash_attn_kwargs: Unpack[FlashAttentionKwargs],
    ) -> BaseModelOutputWithPast:
        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        use_cache = use_cache if use_cache is not None else self.config.use_cache

        # retrieve input_ids and inputs_embeds
        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError(
                "You cannot specify both input_ids and inputs_embeds at the same time, and must specify either one"
            )

        if (self.gradient_checkpointing or sp_mode in ["ring", "all_to_all"]) and self.training:
            if use_cache:
                logger.warning_once(
                    "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..."
                )
                use_cache = False

        if inputs_embeds is None:
            inputs_embeds = self.embed_tokens(input_ids)

        past_seen_tokens = 0
        seq_len = inputs_embeds.shape[1]
        if use_cache:  # kept for BC (cache positions)
            if not isinstance(past_key_values, StaticCache):
                past_key_values = DynamicCache.from_legacy_cache(past_key_values)
                past_seen_tokens = past_key_values.get_seq_length()
        if cache_position is None:
            if isinstance(past_key_values, StaticCache):
                raise ValueError("cache_position is a required argument when using StaticCache.")
            cache_position = torch.arange(past_seen_tokens, past_seen_tokens + seq_len, device=inputs_embeds.device)

        if position_ids is None:
            position_ids = cache_position.unsqueeze(0)

        shard_config.enable_flash_attention = True

        # in this case, attention_mask is a dict rather than a tensor
        if shard_config.enable_flash_attention:
            mask_shape = (inputs_embeds.shape[0], 1, past_seen_tokens + seq_len, past_seen_tokens + seq_len)
            attention_mask = ColoAttention.prepare_attn_kwargs(
                mask_shape,
                inputs_embeds.dtype,
                inputs_embeds.device,
                q_padding_mask=attention_mask,
                is_causal=True,
            )
        else:
            # v4.51.3 transformers attention_mask calculation
            attention_mask = self._update_causal_mask(attention_mask, inputs_embeds, cache_position, past_key_values)

        if sp_mode in ["ring", "split_gather"]:
            inputs_embeds = split_forward_gather_backward(
                inputs_embeds, 1, sp_group, fp8_communication=shard_config.fp8_communication
            )
        elif sp_mode == "all_to_all":
            inputs_embeds = split_forward_gather_backward(
                inputs_embeds, 1, sp_group, 1 / sp_size, fp8_communication=shard_config.fp8_communication
            )
        hidden_states = inputs_embeds

        # decoder layers
        all_hidden_states = () if output_hidden_states else None
        all_self_attns = () if output_attentions else None
        next_decoder_cache = None

        # v4.51.3 transformers position_embeddings calculation
        position_embeddings = self.rotary_emb(hidden_states, position_ids)

        for decoder_layer in self.layers:
            if output_hidden_states:
                all_hidden_states += (hidden_states,)
            if self.gradient_checkpointing and self.training:
                layer_outputs = self._gradient_checkpointing_func(
                    decoder_layer.__call__,
                    hidden_states,
                    attention_mask,
                    position_ids,
                    past_key_values,
                    output_attentions,
                    use_cache,
                    cache_position,
                    position_embeddings,
                )
            else:
                layer_outputs = decoder_layer(
                    hidden_states,
                    attention_mask=attention_mask,
                    position_ids=position_ids,
                    past_key_value=past_key_values,
                    output_attentions=output_attentions,
                    use_cache=use_cache,
                    cache_position=cache_position,
                    position_embeddings=position_embeddings,
                )

            hidden_states = layer_outputs[0]

        hidden_states = self.norm(hidden_states)

        # Cases that don't support parallelizing cross entropy computation along sequence
        if shard_config.enable_sequence_parallelism:
            if (not shard_config.parallel_output) or is_share_sp_tp(sp_mode) or force_sp_output_gather:
                hidden_states = gather_sp_output(hidden_states, shard_config)

        # add hidden states from the last decoder layer
        if output_hidden_states:
            all_hidden_states += (hidden_states,)

        next_cache = None
        if use_cache:
            next_cache = (
                next_decoder_cache.to_legacy_cache() if isinstance(next_decoder_cache, Cache) else next_decoder_cache
            )

        return BaseModelOutputWithPast(
            last_hidden_state=hidden_states,
            past_key_values=next_cache,
            hidden_states=all_hidden_states,
            attentions=all_self_attns,
        )

    return forward


def get_lm_forward_with_dist_cross_entropy(shard_config: ShardConfig):
    from transformers import CohereForCausalLM

    def forward(
        self: CohereForCausalLM,
        input_ids: torch.LongTensor = None,
        attention_mask: Optional[torch.Tensor] = None,
        position_ids: Optional[torch.LongTensor] = None,
        past_key_values: Optional[List[torch.FloatTensor]] = None,
        inputs_embeds: Optional[torch.FloatTensor] = None,
        labels: Optional[torch.LongTensor] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        return_dict: Optional[bool] = None,
        cache_position: Optional[torch.LongTensor] = None,
    ) -> Union[Tuple, CausalLMOutputWithPast]:
        r"""
        Args:
            labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
                Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
                config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
                (masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.

        Returns:

        Example:

        ```python
        >>> from transformers import AutoTokenizer, CohereForCausalLM

        >>> model = CohereForCausalLM.from_pretrained(PATH_TO_CONVERTED_WEIGHTS)
        >>> tokenizer = AutoTokenizer.from_pretrained(PATH_TO_CONVERTED_TOKENIZER)

        >>> prompt = "Hey, are you conscious? Can you talk to me?"
        >>> inputs = tokenizer(prompt, return_tensors="pt")

        >>> # Generate
        >>> generate_ids = model.generate(inputs.input_ids, max_length=30)
        >>> tokenizer.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
        "Hey, are you conscious? Can you talk to me?\nI'm not conscious, but I can talk to you."
        ```"""

        output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
        output_hidden_states = (
            output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
        )
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        # decoder outputs consists of (dec_features, layer_state, dec_hidden, dec_attn)
        outputs = self.model(
            input_ids=input_ids,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            output_attentions=output_attentions,
            output_hidden_states=output_hidden_states,
            return_dict=return_dict,
            cache_position=cache_position,
            force_sp_output_gather=False,
        )

        hidden_states = outputs[0]

        logits = self.lm_head(hidden_states)
        logits = logits * self.logit_scale
        logits = logits.float()

        loss = None
        if labels is not None:
            loss = dist_cross_entropy(
                labels,
                logits,
                shard_config,
                self.lm_head.out_features,
                self.model.dtype,
            )

        if not return_dict:
            output = (logits,) + outputs[1:]
            return (loss,) + output if loss is not None else output

        return CausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
        )

    return forward
