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# Copyright 2025 Deepseek AI and The HuggingFace Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import copy
from collections.abc import Callable
from dataclasses import dataclass

import torch
import torch.nn.functional as F
from torch import nn

from ... import initialization as init
from ...activations import ACT2FN
from ...cache_utils import Cache
from ...generation import ClassifierFreeGuidanceLogitsProcessor, GenerationMixin, GenerationMode, LogitsProcessorList
from ...generation.utils import GenerateDecoderOnlyOutput
from ...modeling_layers import GradientCheckpointingLayer
from ...modeling_outputs import BaseModelOutput, BaseModelOutputWithPooling, ModelOutput
from ...modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from ...processing_utils import Unpack
from ...utils import TransformersKwargs, auto_docstring, can_return_tuple, logging, torch_int
from ...utils.generic import check_model_inputs
from ..auto import AutoModel
from .configuration_janus import JanusConfig, JanusVisionConfig, JanusVQVAEConfig


logger = logging.get_logger(__name__)


@auto_docstring
class JanusPreTrainedModel(PreTrainedModel):
    config: JanusConfig
    base_model_prefix = "model"
    input_modalities = ("image", "text")
    supports_gradient_checkpointing = True
    _no_split_modules = ["LlamaDecoderLayer", "JanusVisionEncoderLayer"]
    _skip_keys_device_placement = ["past_key_values", "causal_mask"]
    _supports_flash_attn = True
    _supports_sdpa = True

    _can_compile_fullgraph = True

    def _init_weights(self, module):
        super()._init_weights(module)
        if isinstance(module, JanusVisionEmbeddings):
            init.copy_(module.position_ids, torch.arange(module.position_ids.shape[-1]).expand((1, -1)))


@dataclass
@auto_docstring(
    custom_intro="""
    Base class for Janus VQ-VAE mode model outputs.
    """
)
class JanusVQVAEOutput(ModelOutput):
    r"""
    decoded_pixel_values (`torch.FloatTensor` of shape `(batch_size, num_channels, image_size, image_size)`):
        Reconstructed pixel values after encoding and decoding the input.
    embedding_loss (`torch.FloatTensor`):
        Embedding loss.
    """

    decoded_pixel_values: torch.FloatTensor | None = None
    embedding_loss: torch.FloatTensor | None = None


@dataclass
@auto_docstring(
    custom_intro="""
    Base class for Janus model's outputs that may also contain a past key/values (to speed up sequential decoding).
    """
)
class JanusBaseModelOutputWithPast(ModelOutput):
    r"""
    last_hidden_state (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`):
        Sequence of hidden-states at the output of the last layer of the model.

        If `past_key_values` is used only the last hidden-state of the sequences of shape `(batch_size, 1,
        hidden_size)` is output.
    past_key_values (`Cache`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
        It is a [`~cache_utils.Cache`] instance. For more details, see our [kv cache guide](https://huggingface.co/docs/transformers/en/kv_cache).

        Contains pre-computed hidden-states (key and values in the self-attention blocks and optionally if
        `config.is_encoder_decoder=True` in the cross-attention blocks) that can be used (see `past_key_values`
        input) to speed up sequential decoding.
    image_hidden_states (`tuple(torch.FloatTensor)`, *optional*):
        Tuple of `torch.FloatTensor` (one for the output of the image embeddings, `(batch_size, num_images,
        sequence_length, hidden_size)`.

        image_hidden_states of the model produced by the vision encoder, and optionally by the perceiver
    """

    last_hidden_state: torch.FloatTensor | None = None
    past_key_values: Cache | None = None
    hidden_states: tuple[torch.FloatTensor] | None = None
    attentions: tuple[torch.FloatTensor] | None = None
    image_hidden_states: tuple[torch.FloatTensor] | None = None


@dataclass
@auto_docstring(
    custom_intro="""
    Base class for Janus causal language model (or autoregressive) outputs.
    """
)
class JanusCausalLMOutputWithPast(ModelOutput):
    r"""
    loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` is provided):
        Language modeling loss (for next-token prediction).
    logits (`torch.FloatTensor` of shape `(batch_size, sequence_length, config.vocab_size)`):
        Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax).
    past_key_values (`Cache`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
        It is a [`~cache_utils.Cache`] instance. For more details, see our [kv cache guide](https://huggingface.co/docs/transformers/en/kv_cache).

        Contains pre-computed hidden-states (key and values in the self-attention blocks) that can be used (see
        `past_key_values` input) to speed up sequential decoding.
    image_hidden_states (`tuple(torch.FloatTensor)`, *optional*):
        Tuple of `torch.FloatTensor` (one for the output of the image embeddings, `(batch_size, num_images,
        sequence_length, hidden_size)`.

        image_hidden_states of the model produced by the vision encoder, and optionally by the perceiver
    """

    loss: torch.FloatTensor | None = None
    logits: torch.FloatTensor | None = None
    past_key_values: Cache | None = None
    hidden_states: tuple[torch.FloatTensor] | None = None
    attentions: tuple[torch.FloatTensor] | None = None
    image_hidden_states: tuple[torch.FloatTensor] | None = None


class JanusVisionEmbeddings(nn.Module):
    def __init__(self, config: JanusVisionConfig):
        super().__init__()
        self.config = config
        self.embed_dim = config.hidden_size
        self.image_size = config.image_size
        self.patch_size = config.patch_size

        self.patch_embedding = nn.Conv2d(
            in_channels=config.num_channels,
            out_channels=self.embed_dim,
            kernel_size=self.patch_size,
            stride=self.patch_size,
            padding="valid",
        )

        self.num_patches = (self.image_size // self.patch_size) ** 2
        self.num_positions = self.num_patches
        self.position_embedding = nn.Embedding(self.num_positions, self.embed_dim)
        self.register_buffer("position_ids", torch.arange(self.num_positions).expand((1, -1)), persistent=False)

    def interpolate_pos_encoding(self, embeddings: torch.Tensor, height: int, width: int) -> torch.Tensor:
        """
        This method allows to interpolate the pre-trained position encodings, to be able to use the model on higher resolution
        images. This method is also adapted to support torch.jit tracing and no class embeddings.

        Adapted from:
        - https://github.com/facebookresearch/dino/blob/de9ee3df6cf39fac952ab558447af1fa1365362a/vision_transformer.py#L174-L194, and
        - https://github.com/facebookresearch/dinov2/blob/e1277af2ba9496fbadf7aec6eba56e8d882d1e35/dinov2/models/vision_transformer.py#L179-L211
        """

        num_patches = embeddings.shape[1]
        num_positions = self.position_embedding.weight.shape[0]

        # always interpolate when tracing to ensure the exported model works for dynamic input shapes
        if not torch.jit.is_tracing() and num_patches == num_positions and height == width:
            return self.position_embedding(self.position_ids)

        patch_pos_embed = self.position_embedding.weight.unsqueeze(0)

        dim = embeddings.shape[-1]

        new_height = height // self.patch_size
        new_width = width // self.patch_size

        sqrt_num_positions = torch_int(num_positions**0.5)
        patch_pos_embed = patch_pos_embed.reshape(1, sqrt_num_positions, sqrt_num_positions, dim)
        patch_pos_embed = patch_pos_embed.permute(0, 3, 1, 2)

        patch_pos_embed = nn.functional.interpolate(
            patch_pos_embed,
            size=(new_height, new_width),
            mode="bicubic",
            align_corners=False,
        )

        patch_pos_embed = patch_pos_embed.permute(0, 2, 3, 1).view(1, -1, dim)
        return patch_pos_embed

    def forward(self, pixel_values: torch.Tensor, interpolate_pos_encoding: bool = False) -> torch.Tensor:
        _, _, height, width = pixel_values.shape
        target_dtype = self.patch_embedding.weight.dtype
        patch_embeds = self.patch_embedding(pixel_values.to(dtype=target_dtype))  # shape = [*, width, grid, grid]
        embeddings = patch_embeds.flatten(2).transpose(1, 2)

        if interpolate_pos_encoding:
            pos_embeds = self.interpolate_pos_encoding(embeddings, height, width)
        else:
            pos_embeds = self.position_embedding(self.position_ids)

        embeddings = embeddings + pos_embeds

        return embeddings


def repeat_kv(hidden_states: torch.Tensor, n_rep: int) -> torch.Tensor:
    """
    This is the equivalent of torch.repeat_interleave(x, dim=1, repeats=n_rep). The hidden states go from (batch,
    num_key_value_heads, seqlen, head_dim) to (batch, num_attention_heads, seqlen, head_dim)
    """
    batch, num_key_value_heads, slen, head_dim = hidden_states.shape
    if n_rep == 1:
        return hidden_states
    hidden_states = hidden_states[:, :, None, :, :].expand(batch, num_key_value_heads, n_rep, slen, head_dim)
    return hidden_states.reshape(batch, num_key_value_heads * n_rep, slen, head_dim)


def eager_attention_forward(
    module: nn.Module,
    query: torch.Tensor,
    key: torch.Tensor,
    value: torch.Tensor,
    attention_mask: torch.Tensor | None,
    scaling: float,
    dropout: float = 0.0,
    **kwargs: Unpack[TransformersKwargs],
):
    key_states = repeat_kv(key, module.num_key_value_groups)
    value_states = repeat_kv(value, module.num_key_value_groups)

    attn_weights = torch.matmul(query, key_states.transpose(2, 3)) * 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.dtype)
    attn_weights = nn.functional.dropout(attn_weights, p=dropout, training=module.training)
    attn_output = torch.matmul(attn_weights, value_states)
    attn_output = attn_output.transpose(1, 2).contiguous()

    return attn_output, attn_weights


class JanusVisionAttention(nn.Module):
    """Attention Class for Janus Vision Encoder"""

    def __init__(self, config: JanusVisionConfig):
        super().__init__()
        self.config = config
        self.embed_dim = config.hidden_size
        self.num_heads = config.num_attention_heads
        self.head_dim = self.embed_dim // self.num_heads
        if self.head_dim * self.num_heads != self.embed_dim:
            raise ValueError(
                f"embed_dim must be divisible by num_heads (got `embed_dim`: {self.embed_dim} and `num_heads`:"
                f" {self.num_heads})."
            )
        self.scale = self.head_dim**-0.5
        self.attention_dropout = config.attention_dropout
        proj_dropout = config.projection_dropout
        qk_norm = config.use_qk_norm
        self.is_causal = False

        # Janus has no MHA, hence for `eager_attention_forward` call setting `num_key_value_groups` to 1.
        self.num_key_value_groups = 1

        self.q_proj = nn.Linear(self.embed_dim, self.num_heads * self.head_dim, bias=config.attention_bias)
        self.k_proj = nn.Linear(self.embed_dim, self.num_heads * self.head_dim, bias=config.attention_bias)
        self.v_proj = nn.Linear(self.embed_dim, self.num_heads * self.head_dim, bias=config.attention_bias)
        self.projection_layer = nn.Linear(self.embed_dim, self.embed_dim)
        self.projection_dropout = nn.Dropout(proj_dropout) if proj_dropout > 0 else nn.Identity()

        self.q_norm = nn.LayerNorm(self.embed_dim) if qk_norm else nn.Identity()
        self.k_norm = nn.LayerNorm(self.embed_dim) if qk_norm else nn.Identity()

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ):
        batch_size, seq_len, _ = hidden_states.size()

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

        query_states = query_states.reshape(-1, self.num_heads, self.head_dim)
        query_states = self.q_norm(query_states)

        key_states = key_states.reshape(-1, self.num_heads, self.head_dim)
        key_states = self.k_norm(key_states)

        query_states = query_states.reshape(batch_size, seq_len, self.num_heads, self.head_dim).transpose(1, 2)
        key_states = key_states.reshape(batch_size, seq_len, self.num_heads, self.head_dim).transpose(1, 2)
        value_states = value_states.view(batch_size, seq_len, self.num_heads, self.head_dim).transpose(1, 2)

        attention_interface: Callable = eager_attention_forward
        if self.config._attn_implementation != "eager":
            attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]

        attn_output, attn_weights = attention_interface(
            self,
            query_states,
            key_states,
            value_states,
            attention_mask,
            dropout=0.0 if not self.training else self.attention_dropout,
            scaling=self.scale,
            is_causal=self.is_causal,
            **kwargs,
        )
        attn_output = attn_output.reshape(batch_size, seq_len, self.embed_dim)

        output = self.projection_layer(attn_output)
        output = self.projection_dropout(output)
        return output, attn_weights


class JanusVisionMLP(nn.Module):
    def __init__(self, config: JanusVisionConfig):
        super().__init__()
        self.config = config
        self.intermediate_size = int(config.hidden_size * config.mlp_ratio)
        self.activation_fn = ACT2FN[config.hidden_act]  # Gelu act
        self.fc1 = nn.Linear(config.hidden_size, self.intermediate_size)
        self.fc2 = nn.Linear(self.intermediate_size, config.hidden_size)
        self.dropout1 = nn.Dropout(config.hidden_dropout_rate)
        self.dropout2 = nn.Dropout(config.hidden_dropout_rate)

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        hidden_states = self.fc1(hidden_states)
        hidden_states = self.activation_fn(hidden_states)
        hidden_states = self.dropout1(hidden_states)
        hidden_states = self.fc2(hidden_states)
        hidden_states = self.dropout2(hidden_states)
        return hidden_states


class JanusVisionEncoderLayer(GradientCheckpointingLayer):
    def __init__(self, config: JanusVisionConfig):
        super().__init__()
        self.embed_dim = config.hidden_size
        self.layer_norm1 = nn.LayerNorm(self.embed_dim, eps=config.layer_norm_eps)
        self.self_attn = JanusVisionAttention(config)
        self.layer_norm2 = nn.LayerNorm(self.embed_dim, eps=config.layer_norm_eps)
        self.mlp = JanusVisionMLP(config)
        self.config = config

    @auto_docstring
    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor,
        **kwargs: Unpack[TransformersKwargs],
    ) -> torch.FloatTensor:
        residual = hidden_states

        hidden_states = self.layer_norm1(hidden_states)
        hidden_states, _ = self.self_attn(
            hidden_states=hidden_states,
            attention_mask=attention_mask,
            **kwargs,
        )
        hidden_states = residual + hidden_states

        residual = hidden_states
        hidden_states = self.layer_norm2(hidden_states)
        hidden_states = self.mlp(hidden_states)
        hidden_states = residual + hidden_states

        return hidden_states


class JanusVisionEncoder(nn.Module):
    """
    Transformer encoder consisting of `config.num_hidden_layers` self attention layers. Each layer is a
    [`JanusVisionEncoderLayer`].

    Args:
        config: JanusVisionConfig
    """

    def __init__(self, config: JanusVisionConfig):
        super().__init__()
        self.config = config
        self.layers = nn.ModuleList([JanusVisionEncoderLayer(config) for _ in range(config.num_hidden_layers)])
        self.gradient_checkpointing = False

    # Ignore copy
    @auto_docstring
    def forward(
        self,
        inputs_embeds,
        attention_mask: torch.Tensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> BaseModelOutput:
        hidden_states = inputs_embeds
        for encoder_layer in self.layers:
            hidden_states = encoder_layer(
                hidden_states,
                attention_mask,
                **kwargs,
            )

        return BaseModelOutput(last_hidden_state=hidden_states)


class JanusAttention(nn.Module):
    """Multi-headed attention from 'Attention Is All You Need' paper"""

    def __init__(self, config):
        super().__init__()
        self.config = config
        self.embed_dim = config.hidden_size
        self.num_heads = config.num_attention_heads
        self.head_dim = self.embed_dim // self.num_heads
        if self.head_dim * self.num_heads != self.embed_dim:
            raise ValueError(
                f"embed_dim must be divisible by num_heads (got `embed_dim`: {self.embed_dim} and `num_heads`:"
                f" {self.num_heads})."
            )
        self.scale = self.head_dim**-0.5
        self.is_causal = False
        self.attention_dropout = config.attention_dropout

        # small tweak here compared to CLIP, no bias here
        self.qkv = nn.Linear(self.embed_dim, 3 * self.embed_dim, bias=False)

        if config.qkv_bias:
            q_bias = nn.Parameter(torch.zeros(self.embed_dim))
            v_bias = nn.Parameter(torch.zeros(self.embed_dim))
        else:
            q_bias = None
            v_bias = None

        if q_bias is not None:
            qkv_bias = torch.cat((q_bias, torch.zeros_like(v_bias, requires_grad=False), v_bias))
            self.qkv.bias = nn.Parameter(qkv_bias)

        self.projection = nn.Linear(self.embed_dim, self.embed_dim)

    def _shape(self, tensor: torch.Tensor, seq_len: int, bsz: int):
        return tensor.view(bsz, seq_len, self.num_heads, self.head_dim).transpose(1, 2).contiguous()

    def forward(
        self,
        hidden_states: torch.Tensor,
        **kwargs,
    ) -> tuple[torch.Tensor, torch.Tensor | None, tuple[torch.Tensor] | None]:
        """Input shape: Batch x Time x Channel"""

        bsz, tgt_len, embed_dim = hidden_states.size()

        mixed_qkv = self.qkv(hidden_states)

        mixed_qkv = mixed_qkv.reshape(bsz, tgt_len, 3, self.num_heads, embed_dim // self.num_heads).permute(
            2, 0, 3, 1, 4
        )
        query_states, key_states, value_states = mixed_qkv[0], mixed_qkv[1], mixed_qkv[2]

        attention_interface: Callable = eager_attention_forward

        if self.config._attn_implementation != "eager":
            attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]

        attn_output, attn_weights = attention_interface(
            self,
            query_states,
            key_states,
            value_states,
            attention_mask=None,
            dropout=0.0 if not self.training else self.attention_dropout,
            scaling=self.scale,
            **kwargs,
        )

        attn_output = attn_output.reshape(bsz, tgt_len, -1).contiguous()
        attn_output = self.projection(attn_output)

        return attn_output, attn_weights


class JanusMLP(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.config = config
        self.activation_fn = ACT2FN[config.hidden_act]
        self.fc1 = nn.Linear(config.hidden_size, config.intermediate_size)
        self.fc2 = nn.Linear(config.intermediate_size, config.hidden_size)

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        hidden_states = self.fc1(hidden_states)
        hidden_states = self.activation_fn(hidden_states)
        hidden_states = self.fc2(hidden_states)
        return hidden_states


class JanusEncoderLayer(GradientCheckpointingLayer):
    def __init__(self, config: JanusConfig):
        super().__init__()
        self.embed_dim = config.hidden_size
        self.self_attn = JanusAttention(config)
        self.layer_norm1 = nn.LayerNorm(self.embed_dim, eps=config.layer_norm_eps)
        self.mlp = JanusMLP(config)
        self.layer_norm2 = nn.LayerNorm(self.embed_dim, eps=config.layer_norm_eps)

    @auto_docstring
    def forward(
        self,
        hidden_states: torch.Tensor,
        **kwargs: Unpack[TransformersKwargs],
    ) -> torch.FloatTensor:
        residual = hidden_states

        hidden_states = self.layer_norm1(hidden_states)
        hidden_states, _ = self.self_attn(
            hidden_states=hidden_states,
            **kwargs,
        )
        hidden_states = hidden_states + residual
        residual = hidden_states
        hidden_states = self.layer_norm2(hidden_states)
        hidden_states = self.mlp(hidden_states)

        hidden_states = hidden_states + residual

        return hidden_states


@auto_docstring
class JanusVisionModel(JanusPreTrainedModel):
    main_input_name = "pixel_values"
    input_modalities = ("image",)
    config: JanusVisionConfig
    _can_record_outputs = {
        "hidden_states": JanusEncoderLayer,
        "attentions": JanusAttention,
    }

    def __init__(self, config: JanusVisionConfig):
        super().__init__(config)
        self.config = config
        embed_dim = config.hidden_size

        self.embeddings = JanusVisionEmbeddings(config)
        self.encoder = JanusVisionEncoder(config)
        self.post_layernorm = nn.LayerNorm(embed_dim, eps=config.layer_norm_eps)

        self.post_init()

    @check_model_inputs(tie_last_hidden_states=False)
    @auto_docstring
    def forward(
        self,
        pixel_values: torch.FloatTensor | None = None,
        interpolate_pos_encoding: bool = False,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | BaseModelOutputWithPooling:
        if pixel_values is None:
            raise ValueError("You have to specify pixel_values")

        hidden_states = self.embeddings(pixel_values, interpolate_pos_encoding=interpolate_pos_encoding)

        encoder_outputs: BaseModelOutput = self.encoder(
            inputs_embeds=hidden_states,
            **kwargs,
        )

        last_hidden_state = encoder_outputs.last_hidden_state
        last_hidden_state = self.post_layernorm(last_hidden_state)

        pooled_output = last_hidden_state[:, 0, :]
        pooled_output = self.post_layernorm(pooled_output)

        return BaseModelOutputWithPooling(
            last_hidden_state=last_hidden_state,
            pooler_output=pooled_output,
        )

    def get_input_embeddings(self):
        return self.embeddings


class JanusVisionAlignerMLP(nn.Module):
    def __init__(self, config: JanusVisionConfig):
        super().__init__()

        self.fc1 = nn.Linear(config.hidden_size, config.projection_dim)
        self.hidden_layers = nn.ModuleList(
            [nn.Linear(config.projection_dim, config.projection_dim) for _ in range(1, config.depth)]
        )
        self.activation_fn = ACT2FN[config.hidden_act]

    def forward(self, hidden_states):
        hidden_states = self.fc1(hidden_states)
        for layer in self.hidden_layers:
            hidden_states = self.activation_fn(hidden_states)
            hidden_states = layer(hidden_states)
        return hidden_states


class JanusVQVAEVectorQuantizer(nn.Module):
    """
    A module for vector quantization using learned embedding vectors.

    This module implements the quantization process similar to te one described in
    the VQ-VAE (Vector Quantized Variational AutoEncoder) paper. It quantizes continuous
    input vectors into discrete codebook vectors, which are learned during training.
    Current implementation improves over previous ones by avoiding costly matrix multiplications
    and allowing for post-hoc remapping of indices.
    """

    def __init__(self, config: JanusVQVAEConfig):
        super().__init__()
        self.num_embeddings = config.num_embeddings
        self.embedding_dim = config.embed_dim
        self.beta = getattr(config, "beta", 0.25)

        self.embedding = nn.Embedding(self.num_embeddings, self.embedding_dim)
        self.quant_state_dims = [config.num_patches] * 2

    def forward(self, hidden_state: torch.Tensor):
        hidden_state = hidden_state.permute(0, 2, 3, 1).contiguous()
        hidden_state_flattened = hidden_state.view(-1, self.embedding_dim)

        # distances from z to embeddings e_j (z - e)^2 = z^2 + e^2 - 2 e * z
        distances = (
            torch.sum(hidden_state_flattened**2, dim=1, keepdim=True)
            + torch.sum(self.embedding.weight**2, dim=1)
            - 2 * torch.einsum("bd,dn->bn", hidden_state_flattened, self.embedding.weight.transpose(0, 1))
        )

        min_encoding_indices = torch.argmin(distances, dim=1)
        hidden_state_quant = self.embedding(min_encoding_indices).view(hidden_state.shape)

        # compute loss for embedding
        loss = torch.mean((hidden_state_quant.detach() - hidden_state) ** 2) + self.beta * torch.mean(
            (hidden_state_quant - hidden_state.detach()) ** 2
        )

        # preserve gradients
        hidden_state_quant = hidden_state + (hidden_state_quant - hidden_state).detach()

        # reshape back to match original input shape
        hidden_state_quant = hidden_state_quant.permute(0, 3, 1, 2).contiguous()

        return hidden_state_quant, loss, min_encoding_indices

    def get_codebook_entry(self, image_tokens: torch.LongTensor) -> torch.FloatTensor:
        batch_size = image_tokens.shape[0]
        emb_dim: int = self.embedding.weight.shape[-1]

        # get quantized latent vectors
        hidden_state_quant = self.embedding(image_tokens)
        # l2 normalization on the last dimension
        hidden_state_quant = F.normalize(hidden_state_quant, p=2, dim=-1)

        # reshape back to match original input shape
        hidden_state_quant = hidden_state_quant.view((batch_size, *self.quant_state_dims, emb_dim))
        hidden_state_quant = hidden_state_quant.permute(0, 3, 1, 2).contiguous()

        return hidden_state_quant


class JanusVQVAEResnetBlock(nn.Module):
    def __init__(
        self,
        config,
        in_channels,
        out_channels=None,
        conv_shortcut=False,
    ):
        super().__init__()
        self.in_channels = in_channels
        self.out_channels = in_channels if out_channels is None else out_channels
        self.use_conv_shortcut = conv_shortcut

        self.norm1 = torch.nn.GroupNorm(num_groups=32, num_channels=in_channels, eps=1e-6, affine=True)
        self.conv1 = torch.nn.Conv2d(in_channels, out_channels, kernel_size=3, stride=1, padding=1)
        self.norm2 = torch.nn.GroupNorm(num_groups=32, num_channels=out_channels, eps=1e-6, affine=True)
        self.dropout = torch.nn.Dropout(config.dropout)
        self.conv2 = torch.nn.Conv2d(out_channels, out_channels, kernel_size=3, stride=1, padding=1)
        if self.in_channels != self.out_channels:
            if self.use_conv_shortcut:
                self.conv_shortcut = torch.nn.Conv2d(in_channels, out_channels, kernel_size=3, stride=1, padding=1)
            else:
                self.nin_shortcut = torch.nn.Conv2d(in_channels, out_channels, kernel_size=1, stride=1, padding=0)

    def forward(self, hidden_states):
        residual = hidden_states
        hidden_states = self.norm1(hidden_states)
        hidden_states *= torch.sigmoid(hidden_states)
        hidden_states = self.conv1(hidden_states)

        hidden_states = self.norm2(hidden_states)
        hidden_states *= torch.sigmoid(hidden_states)
        hidden_states = self.dropout(hidden_states)
        hidden_states = self.conv2(hidden_states)

        if self.in_channels != self.out_channels:
            if self.use_conv_shortcut:
                residual = self.conv_shortcut(residual)
            else:
                residual = self.nin_shortcut(residual)

        return residual + hidden_states


class JanusVQVAEAttnBlock(nn.Module):
    def __init__(self, in_channels):
        super().__init__()
        self.in_channels = in_channels

        self.norm = torch.nn.GroupNorm(num_groups=32, num_channels=in_channels, eps=1e-6, affine=True)
        self.q = torch.nn.Conv2d(in_channels, in_channels, kernel_size=1, stride=1, padding=0)
        self.k = torch.nn.Conv2d(in_channels, in_channels, kernel_size=1, stride=1, padding=0)
        self.v = torch.nn.Conv2d(in_channels, in_channels, kernel_size=1, stride=1, padding=0)
        self.proj_out = torch.nn.Conv2d(in_channels, in_channels, kernel_size=1, stride=1, padding=0)

    def forward(self, hidden_states):
        residual = hidden_states
        hidden_states = self.norm(hidden_states)
        query_states = self.q(hidden_states)
        key_states = self.k(hidden_states)
        value_states = self.v(hidden_states)

        # compute attention
        batch_size, channels, height, width = query_states.shape
        query_states = query_states.reshape(batch_size, channels, height * width).permute(0, 2, 1)
        key_states = key_states.reshape(batch_size, channels, height * width)
        attn_weights = torch.bmm(query_states, key_states)
        attn_weights = attn_weights * (int(channels) ** (-0.5))
        attn_weights = F.softmax(attn_weights, dim=2)

        # attend to values
        value_states = value_states.reshape(batch_size, channels, height * width)
        attn_weights = attn_weights.permute(0, 2, 1)
        attn_output = torch.bmm(value_states, attn_weights).reshape(batch_size, channels, height, width)

        attn_output = self.proj_out(attn_output)
        return residual + attn_output


class JanusVQVAEConvDownsample(nn.Module):
    def __init__(self, in_channels):
        super().__init__()
        self.conv = nn.Conv2d(in_channels, in_channels, kernel_size=3, stride=2, padding=0)

    def forward(self, hidden_states):
        # no asymmetric padding in torch conv, must do it ourselves
        hidden_states = F.pad(hidden_states, pad=(0, 1, 0, 1), mode="constant", value=0)
        hidden_states = self.conv(hidden_states)
        return hidden_states


class JanusVQVAEConvUpsample(nn.Module):
    def __init__(self, in_channels):
        super().__init__()
        self.conv = torch.nn.Conv2d(in_channels, in_channels, kernel_size=3, stride=1, padding=1)

    def forward(self, hidden_states):
        hidden_states = F.interpolate(hidden_states, scale_factor=2.0, mode="nearest")
        hidden_states = self.conv(hidden_states)
        return hidden_states


class JanusVQVAEMidBlock(nn.Module):
    def __init__(self, config: JanusVQVAEConfig, channels: int):
        super().__init__()
        self.block_1 = JanusVQVAEResnetBlock(
            config=config,
            in_channels=channels,
            out_channels=channels,
        )
        self.attn_1 = JanusVQVAEAttnBlock(channels)
        self.block_2 = JanusVQVAEResnetBlock(
            config=config,
            in_channels=channels,
            out_channels=channels,
        )

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        hidden_states = self.block_1(hidden_states)
        hidden_states = self.attn_1(hidden_states)
        hidden_states = self.block_2(hidden_states)
        return hidden_states


class JanusVQVAEEncoder(nn.Module):
    def __init__(self, config):
        super().__init__()

        self.num_resolutions = len(config.channel_multiplier)
        self.num_res_blocks = config.num_res_blocks
        base_channels = config.base_channels
        in_channels = config.in_channels
        double_latent = config.double_latent
        latent_channels = config.latent_channels
        channel_multiplier = config.channel_multiplier

        self.conv_in = torch.nn.Conv2d(in_channels, base_channels, kernel_size=3, stride=1, padding=1)

        in_channel_multiplier = (1,) + tuple(channel_multiplier)
        self.in_channel_multiplier = in_channel_multiplier
        self.down = nn.ModuleList()
        for i_level in range(self.num_resolutions):
            block = nn.ModuleList()
            attn = nn.ModuleList()
            block_in = base_channels * in_channel_multiplier[i_level]
            block_out = base_channels * channel_multiplier[i_level]
            for i_block in range(self.num_res_blocks):
                block.append(
                    JanusVQVAEResnetBlock(
                        config=config,
                        in_channels=block_in,
                        out_channels=block_out,
                    )
                )
                block_in = block_out
                if i_level == self.num_resolutions - 1:
                    attn.append(JanusVQVAEAttnBlock(block_in))

            down = nn.Module()
            down.block = block
            down.attn = attn
            if i_level != self.num_resolutions - 1:
                down.downsample = JanusVQVAEConvDownsample(block_in)
            self.down.append(down)

        self.mid = JanusVQVAEMidBlock(config, block_in)

        self.norm_out = torch.nn.GroupNorm(num_groups=32, num_channels=block_in, eps=1e-6, affine=True)
        self.conv_out = torch.nn.Conv2d(
            block_in,
            2 * latent_channels if double_latent else latent_channels,
            kernel_size=3,
            stride=1,
            padding=1,
        )

    def forward(self, pixel_values: torch.LongTensor):
        # downsampling
        hidden_states = [self.conv_in(pixel_values)]
        for i_level in range(self.num_resolutions):
            for i_block in range(self.num_res_blocks):
                hidden_state = self.down[i_level].block[i_block](
                    hidden_states[-1],
                )
                if len(self.down[i_level].attn) > 0:
                    hidden_state = self.down[i_level].attn[i_block](hidden_state)
                hidden_states.append(hidden_state)
            if i_level != self.num_resolutions - 1:
                hidden_states.append(self.down[i_level].downsample(hidden_states[-1]))

        # middle
        last_hidden_state = hidden_states[-1]
        last_hidden_state = self.mid(last_hidden_state)

        # end
        last_hidden_state = self.norm_out(last_hidden_state)
        last_hidden_state *= torch.sigmoid(last_hidden_state)
        last_hidden_state = self.conv_out(last_hidden_state)
        return last_hidden_state


class JanusVQVAEDecoder(nn.Module):
    def __init__(self, config):
        super().__init__()

        self.num_resolutions = len(config.channel_multiplier)
        self.num_res_blocks = config.num_res_blocks
        base_channels = config.base_channels
        latent_channels = config.latent_channels
        out_channels = config.out_channels

        # compute in_ch_mult, block_in and curr_res at lowest res
        block_in = base_channels * config.channel_multiplier[self.num_resolutions - 1]

        # z to block_in
        self.conv_in = torch.nn.Conv2d(latent_channels, block_in, kernel_size=3, stride=1, padding=1)

        # middle
        self.mid = JanusVQVAEMidBlock(config, block_in)

        # upsampling
        self.up = nn.ModuleList()
        for i_level in reversed(range(self.num_resolutions)):
            block = nn.ModuleList()
            attn = nn.ModuleList()
            block_out = base_channels * config.channel_multiplier[i_level]
            for i_block in range(self.num_res_blocks + 1):
                block.append(
                    JanusVQVAEResnetBlock(
                        config=config,
                        in_channels=block_in,
                        out_channels=block_out,
                    )
                )
                block_in = block_out
                if i_level == self.num_resolutions - 1:
                    attn.append(JanusVQVAEAttnBlock(block_in))
            up = nn.Module()
            up.block = block
            up.attn = attn
            if i_level != 0:
                up.upsample = JanusVQVAEConvUpsample(block_in)
            self.up.append(up)

        # end
        self.norm_out = torch.nn.GroupNorm(num_groups=32, num_channels=block_in, eps=1e-6, affine=True)
        self.conv_out = torch.nn.Conv2d(block_in, out_channels, kernel_size=3, stride=1, padding=1)

    def forward(self, hidden_state: torch.FloatTensor) -> torch.FloatTensor:
        hidden_state = self.conv_in(hidden_state)

        # middle
        hidden_state = self.mid(hidden_state)

        # upsampling
        for i_level in range(self.num_resolutions):
            for i_block in range(self.num_res_blocks + 1):
                hidden_state = self.up[i_level].block[i_block](hidden_state)
                if len(self.up[i_level].attn) > 0:
                    hidden_state = self.up[i_level].attn[i_block](hidden_state)
            if i_level != self.num_resolutions - 1:
                hidden_state = self.up[i_level].upsample(hidden_state)

        hidden_state = self.norm_out(hidden_state)
        hidden_state *= torch.sigmoid(hidden_state)
        hidden_state = self.conv_out(hidden_state)
        return hidden_state


@auto_docstring(
    custom_intro="""
    The VQ-VAE model used in Janus for encoding/decoding images into discrete tokens.
    This model follows the "Make-a-scene: Scene-based text-to-image generation with human priors" paper from
    [ Oran Gafni, Adam Polyak, Oron Ashual, Shelly Sheynin, Devi Parikh, and Yaniv
    Taigman](https://huggingface.co/papers/2203.13131).
    """
)
class JanusVQVAE(JanusPreTrainedModel):
    config: JanusVQVAEConfig
    _no_split_modules = [
        "JanusVQVAEAttnBlock",
        "JanusVQVAEResnetBlock",
        "JanusVQVAEVectorQuantizer",
    ]
    main_input_name = "pixel_values"

    def __init__(self, config: JanusVQVAEConfig):
        super().__init__(config)

        self.encoder = JanusVQVAEEncoder(config)
        self.quantize = JanusVQVAEVectorQuantizer(config)
        self.quant_conv = torch.nn.Conv2d(config.latent_channels, config.embed_dim, 1)
        self.post_quant_conv = torch.nn.Conv2d(config.embed_dim, config.latent_channels, 1)
        self.eval()  # Janus's VQ model is frozen
        self.decoder = JanusVQVAEDecoder(config)
        self.gradient_checkpointing = False
        self.post_init()

    def encode(self, pixel_values: torch.LongTensor):
        hidden_states = self.encoder(pixel_values)
        hidden_states = self.quant_conv(hidden_states)
        quant, emb_loss, indices = self.quantize(hidden_states)
        return quant, emb_loss, indices

    def decode(self, image_tokens: torch.LongTensor) -> torch.FloatTensor:
        """
        Decodes quantized token IDs into pixel values.
        Args:
            image_tokens (torch.LongTensor): Batch of token IDs.
        Returns:
            pixel_values (`torch.FloatTensor` of shape `(batch_size, num_channels, image_size, image_size)`):
                Pixel values decoded from the token IDs.
        """
        if image_tokens.shape[1] != self.quantize.quant_state_dims[0] * self.quantize.quant_state_dims[1]:
            raise ValueError(
                f"Expected `image_tokens` to have shape `(batch_size, {self.quantize.quant_state_dims[0] * self.quantize.quant_state_dims[1]})`, "
                f"but got shape `{image_tokens.shape}`."
            )
        codebook_entry = self.quantize.get_codebook_entry(image_tokens)
        hidden_states = self.post_quant_conv(codebook_entry)
        pixel_values = self.decoder(hidden_states)
        return pixel_values

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        pixel_values: torch.FloatTensor,
        **kwargs,
    ) -> tuple[torch.FloatTensor, torch.FloatTensor]:
        batch_size = pixel_values.shape[0]
        quant, embedding_loss, indices = self.encode(pixel_values)
        decoded_pixel_values = self.decode(indices.view(batch_size, -1))

        return JanusVQVAEOutput(decoded_pixel_values, embedding_loss)


class JanusVQVAEAlignerMLP(nn.Module):
    def __init__(self, config: JanusVQVAEConfig):
        super().__init__()

        self.fc1 = nn.Linear(config.embed_dim, config.projection_dim)
        self.hidden_layers = nn.ModuleList(
            [nn.Linear(config.projection_dim, config.projection_dim) for _ in range(1, config.num_hidden_layers)]
        )
        self.activation_fn = ACT2FN[config.hidden_act]

    def forward(self, hidden_states):
        hidden_states = self.fc1(hidden_states)
        for layer in self.hidden_layers:
            hidden_states = self.activation_fn(hidden_states)
            hidden_states = layer(hidden_states)
        return hidden_states


class JanusVQVAEHead(nn.Module):
    """Head used for sampling tokens in image generation, replacing the usual lm head."""

    def __init__(self, config: JanusVQVAEConfig):
        super().__init__()
        self.proj_out = nn.Linear(config.image_token_embed_dim, config.projection_dim)
        self.activation_fn = ACT2FN[config.hidden_act]
        self.vision_head = nn.Linear(config.projection_dim, config.num_embeddings)

    def forward(self, hidden_states: torch.Tensor) -> torch.tensor:
        hidden_states = self.proj_out(hidden_states)
        hidden_states = self.activation_fn(hidden_states)
        hidden_states = self.vision_head(hidden_states)
        return hidden_states


@auto_docstring(
    custom_intro="""
    The Janus model which consists of a siglip vision backbone, a Llama language model and a VQ model.
    """
)
class JanusModel(JanusPreTrainedModel):
    def __init__(self, config: JanusConfig):
        super().__init__(config)
        self.config = config
        # This is necessary for backward compatibility, see SiglipModel initialization
        self.vision_model = JanusVisionModel._from_config(config.vision_config)
        self.aligner = JanusVisionAlignerMLP(self.vision_model.config)

        self.vqmodel = JanusVQVAE._from_config(config.vq_config)

        # Below generation_* modules are used for Image generation.
        # Embeddings used for image generation, instead of Janus vision embeddings.
        self.generation_embeddings = nn.Embedding(self.vqmodel.config.num_embeddings, self.vqmodel.config.embed_dim)
        self.generation_aligner = JanusVQVAEAlignerMLP(self.vqmodel.config)
        self.generation_head = JanusVQVAEHead(self.vqmodel.config)

        self.language_model = AutoModel.from_config(config=config.text_config)

        self.gradient_checkpointing = False
        # Initialize weights and apply final processing.
        self.post_init()

    def get_input_embeddings(self):
        return self.language_model.get_input_embeddings()

    def set_input_embeddings(self, value):
        self.language_model.set_input_embeddings(value)

    def get_image_features(self, pixel_values):
        image_embeds = self.vision_model(pixel_values)
        image_embeds = self.aligner(image_embeds.last_hidden_state)
        return image_embeds

    def get_placeholder_mask(
        self, input_ids: torch.LongTensor, inputs_embeds: torch.FloatTensor, image_features: torch.FloatTensor
    ):
        """
        Obtains multimodal placeholder mask from `input_ids` or `inputs_embeds`, and checks that the placeholder token count is
        equal to the length of multimodal features. If the lengths are different, an error is raised.
        """
        if input_ids is None:
            special_image_mask = inputs_embeds == self.get_input_embeddings()(
                torch.tensor(self.config.image_token_id, dtype=torch.long, device=inputs_embeds.device)
            )
            special_image_mask = special_image_mask.all(-1)
        else:
            special_image_mask = input_ids == self.config.image_token_id

        n_image_tokens = special_image_mask.sum()
        special_image_mask = special_image_mask.unsqueeze(-1).expand_as(inputs_embeds).to(inputs_embeds.device)
        if inputs_embeds[special_image_mask].numel() != image_features.numel():
            n_image_features = image_features.shape[0] * image_features.shape[1]
            raise ValueError(
                f"Image features and image tokens do not match: tokens: {n_image_tokens}, features {n_image_features}"
            )
        return special_image_mask

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        pixel_values: torch.FloatTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        cache_position: torch.LongTensor | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        use_cache: bool | None = None,
        logits_to_keep: int | torch.Tensor = 0,
        **kwargs,
    ) -> JanusBaseModelOutputWithPast:
        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 inputs_embeds is None:
            inputs_embeds = self.get_input_embeddings()(input_ids)

        if pixel_values is not None:
            image_embeds = self.get_image_features(pixel_values)
            image_features = image_embeds.reshape(-1, inputs_embeds.shape[-1])
            image_features = image_features.to(inputs_embeds.device, inputs_embeds.dtype)
            image_attention_mask = self.get_placeholder_mask(
                input_ids, inputs_embeds=inputs_embeds, image_features=image_features
            )
            inputs_embeds = inputs_embeds.masked_scatter(image_attention_mask, image_features)

        lm_output = self.language_model(
            inputs_embeds=inputs_embeds,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            use_cache=use_cache,
            cache_position=cache_position,
            logits_to_keep=logits_to_keep,
            **kwargs,
        )

        return JanusBaseModelOutputWithPast(
            last_hidden_state=lm_output.last_hidden_state,
            past_key_values=lm_output.past_key_values,
            hidden_states=lm_output.hidden_states,
            attentions=lm_output.attentions,
            image_hidden_states=image_embeds if pixel_values is not None else None,
        )


class JanusForConditionalGeneration(JanusPreTrainedModel, GenerationMixin):
    _tied_weights_keys = {"lm_head.weight": "model.language_model.embed_tokens.weight"}
    output_modalities = ("image", "text")
    _can_compile_fullgraph = True

    def __init__(self, config: JanusConfig):
        super().__init__(config)
        self.config = config
        self.model = JanusModel(config)
        self.lm_head = nn.Linear(config.text_config.hidden_size, config.text_config.vocab_size, bias=False)

        # Initialize weights and apply final processing.
        self.post_init()

    def get_input_embeddings(self):
        return self.model.language_model.get_input_embeddings()

    def set_input_embeddings(self, value):
        self.model.language_model.set_input_embeddings(value)

    def prepare_embeddings_for_image_generation(self, inputs: torch.Tensor) -> torch.Tensor:
        hidden_state = self.model.generation_embeddings(inputs)
        hidden_state = self.model.generation_aligner(hidden_state)
        return hidden_state

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        pixel_values: torch.FloatTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        cache_position: torch.LongTensor | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        labels: torch.LongTensor | None = None,
        use_cache: bool | None = None,
        logits_to_keep: int | torch.Tensor = 0,
        **kwargs: Unpack[TransformersKwargs],
    ) -> JanusCausalLMOutputWithPast:
        r"""
        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]`.
        """
        outputs = self.model(
            input_ids=input_ids,
            pixel_values=pixel_values,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            cache_position=cache_position,
            **kwargs,
        )
        hidden_states = outputs.last_hidden_state
        # Only compute necessary logits, and do not upcast them to float if we are not computing the loss
        slice_indices = slice(-logits_to_keep, None) if isinstance(logits_to_keep, int) else logits_to_keep
        logits = self.lm_head(hidden_states[:, slice_indices, :])

        loss = None
        if labels is not None:
            loss = self.loss_function(
                logits=logits, labels=labels, vocab_size=self.config.text_config.vocab_size, **kwargs
            )

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

    def prepare_inputs_for_generation(
        self,
        input_ids,
        pixel_values=None,
        past_key_values=None,
        attention_mask=None,
        inputs_embeds=None,
        cache_position=None,
        logits_to_keep=None,
        is_first_iteration=False,
        **kwargs,
    ):
        # Overwritten -- extra custom processing

        model_inputs = super().prepare_inputs_for_generation(
            input_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            attention_mask=attention_mask,
            cache_position=cache_position,
            logits_to_keep=logits_to_keep,
            is_first_iteration=is_first_iteration,
            **kwargs,
        )

        # Pixel values are used only in the first iteration if available
        # In subsquent iterations, they are already merged with text and cached
        # NOTE: first iteration doesn't have to be prefill, it can be the first
        # iteration with a question and cached system prompt (continue generate from cache)
        if is_first_iteration or not kwargs.get("use_cache", True):
            model_inputs["pixel_values"] = pixel_values

        return model_inputs

    def decode_image_tokens(self, image_tokens: torch.Tensor):
        """
        Decodes generated image tokens from language model to continuous pixel values
        with VQGAN module via upsampling.
        Args:
            image_tokens (`torch.LongTensor` of shape `(batch_size, num_of_tokens)`):
                The tensors corresponding to the input images.
        """
        decoded_image = self.model.vqmodel.decode(image_tokens)
        decoded_image = decoded_image.permute(0, 2, 3, 1)
        return decoded_image

    @torch.no_grad()
    def generate(
        self,
        inputs: torch.Tensor | None = None,
        attention_mask: torch.LongTensor | None = None,
        logits_processor: LogitsProcessorList | None = None,
        **kwargs,
    ):
        # 1. Handle generation config and model kwargs
        generation_config = kwargs.pop("generation_config", self.generation_config)
        generation_config = copy.deepcopy(generation_config)

        # Default to "text" generation if mode isn't provided
        generation_mode = kwargs.pop("generation_mode", "text")
        if generation_mode == "text":
            # Set guidance_scale=None to prevent running UnbatchedCFG processor.
            return super().generate(
                inputs=inputs,
                attention_mask=attention_mask,
                generation_config=generation_config,
                guidance_scale=None,
                **kwargs,
            )

        model_kwargs = generation_config.update(**kwargs)  # All unused kwargs must be model kwargs

        # Validate generation mode
        if generation_config.get_generation_mode() not in (GenerationMode.SAMPLE, GenerationMode.GREEDY_SEARCH):
            raise ValueError(
                "Got incompatible mode for Image Generation, should be one of greedy or sampling. "
                "Ensure that beam search is de-activated by setting `num_beams=1`."
            )

        # Validate the configuration and model kwargs
        generation_config.validate()
        self._validate_model_kwargs(model_kwargs.copy())

        # 2. Initialize logit processors
        logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()

        # Set `use_cache=True` as we will be using input embeds for generation.
        model_kwargs["use_cache"] = True

        if generation_config.guidance_scale is None:
            logger.warning("`guidance_scale` is required for CFG but not provided. Setting to default value of 5.")
            generation_config.guidance_scale = 5
        model_kwargs["guidance_scale"] = generation_config.guidance_scale

        # 3. Prepare model inputs
        input_ids, model_input_name, model_kwargs = self._prepare_model_inputs(
            inputs, generation_config.bos_token_id, model_kwargs
        )
        dtype, device = input_ids.dtype, input_ids.device

        if len(input_ids.shape) != 2:
            raise ValueError(
                f"Expected input ids of shape (batch_size, seq_len), but got {input_ids.shape}"
                "Passing `inputs embeds` is not supported currently."
            )

        # Prepare special tokens which will be used generate internally.
        kwargs_has_attention_mask = attention_mask is not None
        self._prepare_special_tokens(generation_config, kwargs_has_attention_mask, device=input_ids.device)

        # 4. Add CFG processor along with user passed logit processor.
        if generation_config.guidance_scale and generation_config.guidance_scale > 1:
            logits_processor.append(ClassifierFreeGuidanceLogitsProcessor(generation_config.guidance_scale))
            generation_config.guidance_scale = None  # Reset to prevent processor duplication.

        # 5. Prepare logits processor
        logits_processor = self._get_logits_processor(
            generation_config=generation_config,
            input_ids_seq_length=input_ids.shape[1],
            encoder_input_ids=input_ids,
            prefix_allowed_tokens_fn=None,
            logits_processor=logits_processor,
            device=device,
        )

        # 6. Expand inputs for multiple image generations per prompt.
        input_ids, model_kwargs = self._expand_inputs_for_generation(
            input_ids=input_ids,
            attention_mask=attention_mask,
            expand_size=generation_config.num_return_sequences,
            **model_kwargs,
        )

        # 7. Prepare input and model caches
        num_image_tokens = self.model.vision_model.config.num_image_tokens
        batch_size, seq_len = input_ids.shape

        input_tokens = input_ids.repeat(2, 1)  # Double batch size for conditional/unconditional logits
        attention_mask = model_kwargs.pop("attention_mask", None)
        attention_mask = attention_mask.repeat(2, 1)
        model_kwargs["attention_mask"] = attention_mask

        # Mask all the tokens that are neither BOS nor BOI with pad token in the unconditional logits.
        mask = (input_tokens[batch_size:, :] != generation_config.bos_token_id) & (
            input_tokens[batch_size:, :] != generation_config.generation_kwargs["boi_token_id"]
        )
        input_tokens[batch_size:, :].masked_fill_(mask, generation_config.pad_token_id)

        inputs_embeds = self.get_input_embeddings()(input_tokens)

        model_kwargs = self._get_initial_cache_position(seq_len, device, model_kwargs)

        if model_kwargs.get("past_key_values", None) is None:
            # Prepare cache if not provided.
            model_kwargs["past_key_values"] = self._get_cache(
                cache_implementation=generation_config.cache_implementation or "static",
                # batch_size should account for both conditional/unconditional input; hence multiplied by 2.
                batch_size=batch_size * 2,
                # we should have at least a cache len of seq_len + num_image_tokens.
                max_cache_len=max(generation_config.max_length, num_image_tokens + seq_len),
                model_kwargs=model_kwargs,
            )

        # Placeholder for generated tokens.
        generated_tokens = torch.zeros((batch_size, num_image_tokens), dtype=dtype, device=device)

        # 8. init attention / hidden states / scores tuples
        output_attentions = generation_config.output_attentions
        output_hidden_states = generation_config.output_hidden_states
        output_scores = generation_config.output_scores
        output_logits = generation_config.output_logits
        return_dict_in_generate = generation_config.return_dict_in_generate

        raw_scores = () if (return_dict_in_generate and output_scores) else None
        raw_logits = () if (return_dict_in_generate and output_logits) else None
        decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None
        decoder_attentions = () if (return_dict_in_generate and output_attentions) else None

        for i in range(num_image_tokens):
            model_inputs = self.prepare_inputs_for_generation(
                inputs_embeds=inputs_embeds, input_ids=input_tokens, **model_kwargs
            )
            if "attention_mask" in model_inputs:
                model_inputs["attention_mask"] = model_inputs["attention_mask"].to(inputs_embeds.device)
            model_inputs["cache_position"] = model_inputs["cache_position"].to(inputs_embeds.device)

            outputs = self.model.language_model(
                **model_inputs,
                output_attentions=output_attentions,
                output_hidden_states=output_hidden_states,
            )

            # Update model_kwargs like cache_position for next generation.
            model_kwargs = self._update_model_kwargs_for_generation(outputs, model_kwargs)
            hidden_state = outputs.last_hidden_state[:, -1, :].clone()

            # Generate scores using the generation head (Not using above defined LM Head)
            scores = self.model.generation_head(hidden_state)
            next_token_scores = logits_processor(input_ids, scores)

            # Sample next token.
            if generation_config.do_sample:
                probs = torch.softmax(next_token_scores, dim=-1)
                next_token = torch.multinomial(probs, num_samples=1).squeeze(-1)
            else:
                next_token = torch.argmax(next_token_scores, dim=-1)

            generated_tokens[:, i] = next_token

            # Prepare embeddings for the next step.
            next_token = torch.cat([next_token, next_token])
            next_token = next_token.unsqueeze(-1)

            inputs_embeds = self.prepare_embeddings_for_image_generation(next_token)

        if return_dict_in_generate:
            if output_scores:
                raw_scores += (scores,)
            if output_logits:
                raw_logits += (hidden_state.float(),)
            if output_attentions:
                decoder_attentions += outputs.attentions
            if output_hidden_states:
                decoder_hidden_states += outputs.hidden_states

        if return_dict_in_generate:
            return GenerateDecoderOnlyOutput(
                sequences=generated_tokens,
                scores=scores,
                logits=raw_logits,
                attentions=decoder_attentions,
                hidden_states=decoder_hidden_states,
                past_key_values=outputs.past_key_values,
            )
        else:
            return generated_tokens


__all__ = ["JanusPreTrainedModel", "JanusForConditionalGeneration", "JanusModel", "JanusVQVAE", "JanusVisionModel"]
