from transformers.models.qwen2_vl.modeling_qwen2_vl import Qwen2VLCausalLMOutputWithPast
from transformers.models.qwen2_5_vl.modeling_qwen2_5_vl import Qwen2_5_VLCausalLMOutputWithPast
import torch
from typing import Optional, List, Union, Tuple
from torch.nn import CrossEntropyLoss
import numpy as np
import transformers.models.qwen2_vl.modeling_qwen2_vl
import transformers.models.qwen2_5_vl.modeling_qwen2_5_vl
from flash_attn.layers.rotary import apply_rotary_emb
from liger_kernel.transformers.fused_linear_cross_entropy import (
    LigerFusedLinearCrossEntropyLoss
)
from liger_kernel.transformers.swiglu import LigerSwiGLUMLP
from liger_kernel.transformers.rms_norm import LigerRMSNorm
from liger_kernel.transformers.qwen2vl_mrope import liger_multimodal_rotary_pos_emb


def replace_qwen_2_with_mixed_modality_forward():
    transformers.models.qwen2_vl.modeling_qwen2_vl.Qwen2VLForConditionalGeneration.forward = qwen_2_mixed_modality_forward

def replace_qwen2_5_with_mixed_modality_forward():
    # Apply LigerFusedLinearCrossEntropyLoss  to Qwen2_5_VL
    transformers.models.qwen2_5_vl.modeling_qwen2_5_vl.Qwen2_5_VLForConditionalGeneration.forward = qwen2_5_mixed_modality_forward
    # Apply LigerKernel to Qwen2_5_VL
    transformers.models.qwen2_5_vl.modeling_qwen2_5_vl.Qwen2MLP = LigerSwiGLUMLP
    transformers.models.qwen2_5_vl.modeling_qwen2_5_vl.Qwen2RMSNorm = LigerRMSNorm
    transformers.models.qwen2_5_vl.modeling_qwen2_5_vl.apply_multimodal_rotary_pos_emb = (liger_multimodal_rotary_pos_emb)
    
def qwen_2_mixed_modality_forward(
    self,
    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,
    pixel_values: Optional[torch.Tensor] = None,
    pixel_values_videos: Optional[torch.FloatTensor] = None,
    image_grid_thw: Optional[torch.LongTensor] = None,
    video_grid_thw: Optional[torch.LongTensor] = None,
    rope_deltas: Optional[torch.LongTensor] = None,
    cache_position: Optional[torch.LongTensor] = None,
    is_dummy: Optional[torch.BoolTensor] = None,  # Added for mixed-modality training
):
    
    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

    if inputs_embeds is None:
        inputs_embeds = self.model.embed_tokens(input_ids)
        if pixel_values is not None:
            pixel_values = pixel_values.type(self.visual.get_dtype())
            # This is a really nasty hack to avoid deepspeed error.
            # It it consumes a lot of time for taking this.
            # It need to be fixed in the future.
            if is_dummy.any():
                for i in range(is_dummy.shape[0]):
                    if is_dummy[i]:
                        # Setting dummy pixel_values for avoid deepspeed error.
                        self.visual(torch.zeros(14903, 1176), grid_thw=torch.Tensor([[1, 98, 146]]))
            image_embeds = self.visual(pixel_values, grid_thw=image_grid_thw)
            n_image_tokens = (input_ids == self.config.image_token_id).sum().item()
            n_image_features = image_embeds.shape[0]
            if n_image_tokens != n_image_features:
                raise ValueError(
                    f"Image features and image tokens do not match: tokens: {n_image_tokens}, features {n_image_features}"
                )
            image_mask = (
                (input_ids == self.config.image_token_id)
                .unsqueeze(-1)
                .expand_as(inputs_embeds)
                .to(inputs_embeds.device)
            )
            image_embeds = image_embeds.to(inputs_embeds.device, inputs_embeds.dtype)
            inputs_embeds = inputs_embeds.masked_scatter(image_mask, image_embeds)

        if pixel_values_videos is not None:
            pixel_values_videos = pixel_values_videos.type(self.visual.get_dtype())
            if is_dummy.any():
                for i in range(is_dummy.shape[0]):
                    if is_dummy[i]:
                        # Setting dummy pixel_values for avoid deepspeed error.
                        self.visual(torch.zeros(14903, 1176), grid_thw=torch.Tensor([[1, 98, 146]]))
            video_embeds = self.visual(pixel_values_videos, grid_thw=video_grid_thw)
            n_video_tokens = (input_ids == self.config.video_token_id).sum().item()
            n_video_features = video_embeds.shape[0]
            if n_video_tokens != n_video_features:
                raise ValueError(
                    f"Video features and video tokens do not match: tokens: {n_video_tokens}, features {n_video_features}"
                )
            video_mask = (
                (input_ids == self.config.video_token_id)
                .unsqueeze(-1)
                .expand_as(inputs_embeds)
                .to(inputs_embeds.device)
            )
            video_embeds = video_embeds.to(inputs_embeds.device, inputs_embeds.dtype)
            inputs_embeds = inputs_embeds.masked_scatter(video_mask, video_embeds)

        if attention_mask is not None:
            attention_mask = attention_mask.to(inputs_embeds.device)

    # if we get 4D attention mask we cannot calculate rope deltas anymore. TODO @raushan fixme
    if position_ids is None and (attention_mask is None or attention_mask.ndim == 2):
        # calculate RoPE index once per generation in the pre-fill stage only
        if (cache_position is not None and cache_position[0] == 0) or self.rope_deltas is None:
            position_ids, rope_deltas = self.get_rope_index(
                input_ids, image_grid_thw, video_grid_thw, attention_mask
            )
            self.rope_deltas = rope_deltas
        # then use the prev pre-calculated rope-deltas to get the correct position ids
        else:
            batch_size, seq_length, _ = inputs_embeds.shape
            delta = cache_position[0] + self.rope_deltas if cache_position is not None else 0
            position_ids = torch.arange(seq_length, device=inputs_embeds.device)
            position_ids = position_ids.view(1, -1).expand(batch_size, -1)
            if cache_position is not None:  # otherwise `deltas` is an int `0`
                delta = delta.repeat_interleave(batch_size // delta.shape[0], dim=0)
            position_ids = position_ids.add(delta)
            position_ids = position_ids.unsqueeze(0).expand(3, -1, -1)

    outputs = self.model(
        input_ids=None,
        position_ids=position_ids,
        attention_mask=attention_mask,
        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,
    )

    hidden_states = outputs[0]

    loss = None
    logits = None

    if self.training and (labels is not None):
        shift_hidden_states = hidden_states[..., :-1, :].contiguous()
        shift_labels = labels[..., 1:].contiguous()

        # Flatten tokens
        shift_hidden_states = shift_hidden_states.view(-1, self.config.hidden_size)
        shift_labels = shift_labels.view(-1)

        lce = LigerFusedLinearCrossEntropyLoss()
        loss = lce(self.lm_head.weight, shift_hidden_states, shift_labels)
    else:
        logits = self.lm_head(hidden_states)
        if labels is not None:
            # Upcast to float if we need to compute the loss to avoid potential precision issues
            logits = logits.float()
            # 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, self.config.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)

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

    return Qwen2VLCausalLMOutputWithPast(
        loss=loss,
        logits=logits,
        past_key_values=outputs.past_key_values,
        hidden_states=outputs.hidden_states,
        attentions=outputs.attentions,
        rope_deltas=self.rope_deltas,
    )

def qwen2_5_mixed_modality_forward(
    self,
    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,
    pixel_values: Optional[torch.Tensor] = None,
    pixel_values_videos: Optional[torch.FloatTensor] = None,
    image_grid_thw: Optional[torch.LongTensor] = None,
    video_grid_thw: Optional[torch.LongTensor] = None,
    rope_deltas: Optional[torch.LongTensor] = None,
    cache_position: Optional[torch.LongTensor] = None,
    second_per_grid_ts: Optional[torch.Tensor] = None,
    is_dummy: Optional[torch.BoolTensor] = None,  # Added for mixed-modality training
) -> Union[Tuple, Qwen2_5_VLCausalLMOutputWithPast]:

    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

    if inputs_embeds is None:
        inputs_embeds = self.model.embed_tokens(input_ids)
        if pixel_values is not None:
            pixel_values = pixel_values.type(self.visual.dtype)
            if is_dummy.any():
                for i in range(is_dummy.shape[0]):
                    if is_dummy[i]:
                        # Setting dummy pixel_values for avoid deepspeed error.
                        self.visual(torch.zeros(14903, 1176), grid_thw=torch.Tensor([[1, 98, 146]]))
            image_embeds = self.visual(pixel_values, grid_thw=image_grid_thw)
            n_image_tokens = (input_ids == self.config.image_token_id).sum().item()
            n_image_features = image_embeds.shape[0]
            if n_image_tokens != n_image_features:
                raise ValueError(
                    f"Image features and image tokens do not match: tokens: {n_image_tokens}, features {n_image_features}"
                )

            mask = input_ids == self.config.image_token_id
            mask_unsqueezed = mask.unsqueeze(-1)
            mask_expanded = mask_unsqueezed.expand_as(inputs_embeds)
            image_mask = mask_expanded.to(inputs_embeds.device)

            image_embeds = image_embeds.to(inputs_embeds.device, inputs_embeds.dtype)
            inputs_embeds = inputs_embeds.masked_scatter(image_mask, image_embeds)

        if pixel_values_videos is not None:
            pixel_values_videos = pixel_values_videos.type(self.visual.dtype)
            if is_dummy.any():
                for i in range(is_dummy.shape[0]):
                    if is_dummy[i]:
                        # Setting dummy pixel_values for avoid deepspeed error.
                        self.visual(torch.zeros(14903, 1176), grid_thw=torch.Tensor([[1, 98, 146]]))
            video_embeds = self.visual(pixel_values_videos, grid_thw=video_grid_thw)
            n_video_tokens = (input_ids == self.config.video_token_id).sum().item()
            n_video_features = video_embeds.shape[0]
            if n_video_tokens != n_video_features:
                raise ValueError(
                    f"Video features and video tokens do not match: tokens: {n_video_tokens}, features {n_video_features}"
                )

            mask = input_ids == self.config.video_token_id
            mask_unsqueezed = mask.unsqueeze(-1)
            mask_expanded = mask_unsqueezed.expand_as(inputs_embeds)
            video_mask = mask_expanded.to(inputs_embeds.device)

            video_embeds = video_embeds.to(inputs_embeds.device, inputs_embeds.dtype)
            inputs_embeds = inputs_embeds.masked_scatter(video_mask, video_embeds)

        if attention_mask is not None:
            attention_mask = attention_mask.to(inputs_embeds.device)

    # if we get 4D attention mask we cannot calculate rope deltas anymore. TODO @raushan fixme
    if position_ids is None and (attention_mask is None or attention_mask.ndim == 2):
        # calculate RoPE index once per generation in the pre-fill stage only
        if (cache_position is not None and cache_position[0] == 0) or self.rope_deltas is None:
            position_ids, rope_deltas = self.get_rope_index(
                input_ids,
                image_grid_thw,
                video_grid_thw,
                second_per_grid_ts,
                attention_mask,
            )
            self.rope_deltas = rope_deltas
        # then use the prev pre-calculated rope-deltas to get the correct position ids
        else:
            batch_size, seq_length, _ = inputs_embeds.shape
            delta = (
                (cache_position[0] + self.rope_deltas).to(inputs_embeds.device)
                if cache_position is not None
                else 0
            )
            position_ids = torch.arange(seq_length, device=inputs_embeds.device)
            position_ids = position_ids.view(1, -1).expand(batch_size, -1)
            if cache_position is not None:  # otherwise `deltas` is an int `0`
                delta = delta.repeat_interleave(batch_size // delta.shape[0], dim=0)
            position_ids = position_ids.add(delta)
            position_ids = position_ids.unsqueeze(0).expand(3, -1, -1)

    outputs = self.model(
        input_ids=None,
        position_ids=position_ids,
        attention_mask=attention_mask,
        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,
    )

    hidden_states = outputs[0]
    
    loss = None
    logits = None

    if self.training and (labels is not None):
        shift_hidden_states = hidden_states[..., :-1, :].contiguous()
        shift_labels = labels[..., 1:].contiguous()

        # Flatten tokens
        shift_hidden_states = shift_hidden_states.view(-1, self.config.hidden_size)
        shift_labels = shift_labels.view(-1)

        lce = LigerFusedLinearCrossEntropyLoss()
        loss = lce(self.lm_head.weight, shift_hidden_states, shift_labels)
    else:
        logits = self.lm_head(hidden_states)
        if labels is not None:
            # Upcast to float if we need to compute the loss to avoid potential precision issues
            logits = logits.float()
            # 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, self.config.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)

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

    return Qwen2_5_VLCausalLMOutputWithPast(
        loss=loss,
        logits=logits,
        past_key_values=outputs.past_key_values,
        hidden_states=outputs.hidden_states,
        attentions=outputs.attentions,
        rope_deltas=self.rope_deltas,
    )