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#           This file was automatically generated from src/transformers/models/pp_ocrv5_server_rec/modular_pp_ocrv5_server_rec.py.
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#                          modular_pp_ocrv5_server_rec.py file directly. One of our CI enforces this.
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# Copyright 2026 The PaddlePaddle Team and The HuggingFace Inc. 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.

from collections.abc import Callable
from dataclasses import dataclass

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

from ...activations import ACT2FN
from ...backbone_utils import load_backbone
from ...modeling_layers import GradientCheckpointingLayer
from ...modeling_outputs import BaseModelOutputWithNoAttention
from ...modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from ...processing_utils import Unpack
from ...utils import TransformersKwargs, auto_docstring, can_return_tuple
from ...utils.generic import merge_with_config_defaults
from ...utils.output_capturing import capture_outputs
from .configuration_pp_ocrv5_server_rec import PPOCRV5ServerRecConfig


class PPOCRV5ServerRecBlock(GradientCheckpointingLayer):
    def __init__(self, config):
        super().__init__()
        self.embed_dim = config.hidden_size
        self.self_attn = PPOCRV5ServerRecAttention(config)
        self.layer_norm1 = nn.LayerNorm(self.embed_dim, eps=config.layer_norm_eps)
        self.mlp = PPOCRV5ServerRecMLP(
            config=config,
            in_features=self.embed_dim,
            hidden_features=int(self.embed_dim * config.mlp_ratio),
        )
        self.layer_norm2 = nn.LayerNorm(self.embed_dim, eps=config.layer_norm_eps)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor | None = None,
        **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


# Adapted from transformers.models.siglip.modeling_siglip.eager_attention_forward -> BLIP doesn't cast attn weights to fp32
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,
):
    attn_weights = torch.matmul(query, key.transpose(-1, -2)) * scaling
    if attention_mask is not None:
        attn_weights = attn_weights + attention_mask

    attn_weights = nn.functional.softmax(attn_weights, dim=-1)
    attn_weights = nn.functional.dropout(attn_weights, p=dropout, training=module.training)

    attn_output = torch.matmul(attn_weights, value)
    attn_output = attn_output.transpose(1, 2).contiguous()

    return attn_output, attn_weights


class PPOCRV5ServerRecAttention(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,
        attention_mask: torch.Tensor | None = None,  # Not used but kept for signature matching in downstream modules
        **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 = ALL_ATTENTION_FUNCTIONS.get_interface(
            self.config._attn_implementation, eager_attention_forward
        )

        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 PPOCRV5ServerRecConvLayer(nn.Module):
    def __init__(
        self,
        in_channels: int,
        out_channels: int,
        kernel_size: tuple[int, int] = (3, 3),
        stride: int = 1,
        activation: str = "silu",
    ):
        super().__init__()
        self.convolution = nn.Conv2d(
            in_channels,
            out_channels,
            kernel_size=kernel_size,
            stride=stride,
            padding=(kernel_size[0] // 2, kernel_size[1] // 2),
            bias=False,
        )
        self.normalization = nn.BatchNorm2d(out_channels)
        self.activation = ACT2FN[activation] if activation is not None else nn.Identity()

    def forward(self, input: Tensor) -> Tensor:
        hidden_state = self.convolution(input)
        hidden_state = self.normalization(hidden_state)
        hidden_state = self.activation(hidden_state)
        return hidden_state


@auto_docstring
class PPOCRV5ServerRecPreTrainedModel(PreTrainedModel):
    config: PPOCRV5ServerRecConfig
    base_model_prefix = "model"
    supports_gradient_checkpointing = True
    _no_split_modules = ["PPOCRV5ServerRecBlock"]
    _skip_keys_device_placement = ["past_key_values"]
    _supports_flash_attn = True
    _supports_sdpa = True
    _supports_flex_attn = True

    _can_compile_fullgraph = True
    _supports_attention_backend = True
    _can_record_outputs = {
        "hidden_states": PPOCRV5ServerRecBlock,
    }
    main_input_name = "pixel_values"
    input_modalities = ("image",)


class PPOCRV5ServerRecHead(nn.Module):
    def __init__(self, config):
        super().__init__()

        self.encoder = PPOCRV5ServerRecEncoderWithSVTR(config)
        self.head = nn.Linear(config.hidden_size, config.head_out_channels)

    def forward(self, hidden_states: torch.FloatTensor, **kwargs: Unpack[TransformersKwargs]):
        outputs = self.encoder(hidden_states, **kwargs)
        hidden_states = self.head(outputs.last_hidden_state)
        hidden_states = F.softmax(hidden_states, dim=2, dtype=torch.float32).to(hidden_states.dtype)

        return BaseModelOutputWithNoAttention(last_hidden_state=hidden_states, hidden_states=outputs.hidden_states)


class PPOCRV5ServerRecMLP(nn.Module):
    def __init__(self, config, in_features, hidden_features=None, out_features=None, drop=0.0):
        super().__init__()
        out_features = out_features or in_features
        hidden_features = hidden_features or in_features
        self.fc1 = nn.Linear(in_features, hidden_features)
        self.activation = ACT2FN[config.hidden_act]
        self.fc2 = nn.Linear(hidden_features, out_features)
        self.drop = nn.Dropout(drop)

    def forward(self, hidden_state):
        hidden_state = self.fc1(hidden_state)
        hidden_state = self.activation(hidden_state)
        hidden_state = self.drop(hidden_state)
        hidden_state = self.fc2(hidden_state)
        hidden_state = self.drop(hidden_state)
        return hidden_state


class PPOCRV5ServerRecEncoderWithSVTR(PPOCRV5ServerRecPreTrainedModel):
    """
    SVTR: Scene Text Recognition with a Single Visual Model
    https://www.paddleocr.ai/v2.10.0/en/algorithm/text_recognition/algorithm_rec_svtr.html
    """

    def __init__(
        self,
        config,
    ):
        super().__init__(config)
        in_channels = config.backbone_config.stage_out_channels[-1]
        hidden_size = config.hidden_size

        self.conv_block = nn.ModuleList(
            [
                PPOCRV5ServerRecConvLayer(
                    in_channels=in_channels,
                    out_channels=in_channels // 8,
                    kernel_size=config.conv_kernel_size,
                ),
                PPOCRV5ServerRecConvLayer(in_channels=in_channels // 8, out_channels=hidden_size, kernel_size=(1, 1)),
                PPOCRV5ServerRecConvLayer(in_channels=hidden_size, out_channels=in_channels, kernel_size=(1, 1)),
                PPOCRV5ServerRecConvLayer(
                    in_channels=2 * in_channels,
                    out_channels=in_channels // 8,
                    kernel_size=config.conv_kernel_size,
                ),
                PPOCRV5ServerRecConvLayer(in_channels=in_channels // 8, out_channels=hidden_size, kernel_size=(1, 1)),
            ]
        )
        self.svtr_block = nn.ModuleList()
        for _ in range(config.depth):
            self.svtr_block.append(PPOCRV5ServerRecBlock(config=config))

        self.norm = nn.LayerNorm(hidden_size, eps=config.layer_norm_eps)
        self.post_init()

    @merge_with_config_defaults
    @capture_outputs
    def forward(self, hidden_states: torch.FloatTensor, **kwargs: Unpack[TransformersKwargs]):
        residual = hidden_states

        hidden_states = self.conv_block[0](hidden_states)
        hidden_states = self.conv_block[1](hidden_states)

        batch_size, channels, height, width = hidden_states.shape
        hidden_states = hidden_states.flatten(2).transpose(1, 2)
        for block in self.svtr_block:
            hidden_states = block(hidden_states)

        hidden_states = self.norm(hidden_states)
        hidden_states = hidden_states.view(batch_size, height, width, channels).permute(0, 3, 1, 2)
        hidden_states = self.conv_block[2](hidden_states)
        hidden_states = self.conv_block[3](torch.cat((residual, hidden_states), dim=1))
        hidden_states = self.conv_block[4](hidden_states)
        hidden_states = hidden_states.squeeze(2).transpose(1, 2)

        return BaseModelOutputWithNoAttention(last_hidden_state=hidden_states)


@auto_docstring(custom_intro="PPOCRV5ServerRec model, consisting of Backbone and Head networks.")
class PPOCRV5ServerRecModel(PPOCRV5ServerRecPreTrainedModel):
    def __init__(self, config: PPOCRV5ServerRecConfig):
        super().__init__(config)
        self.backbone = load_backbone(config)

        self.gradient_checkpointing = False
        self.post_init()

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        pixel_values: torch.FloatTensor,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple[torch.FloatTensor] | BaseModelOutputWithNoAttention:
        outputs = self.backbone(pixel_values, **kwargs)
        hidden_state = outputs.feature_maps[-1]
        hidden_state = F.avg_pool2d(hidden_state, (3, 2))

        return BaseModelOutputWithNoAttention(
            last_hidden_state=hidden_state,
            hidden_states=outputs.hidden_states,
        )


@dataclass
@auto_docstring
class PPOCRV5ServerRecForTextRecognitionOutput(BaseModelOutputWithNoAttention):
    r"""
    head_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
        Hidden-states of the PPOCRV5ServerRecHead at the output of each layer plus the optional initial embedding outputs.
    """

    head_hidden_states: torch.FloatTensor | None = None


@auto_docstring(custom_intro="PPOCRV5ServerRec model for text recognition tasks.")
class PPOCRV5ServerRecForTextRecognition(PPOCRV5ServerRecPreTrainedModel):
    _keys_to_ignore_on_load_missing = ["num_batches_tracked"]

    def __init__(self, config: PPOCRV5ServerRecConfig):
        super().__init__(config)
        self.model = PPOCRV5ServerRecModel(config)
        self.head = PPOCRV5ServerRecHead(config)

        self.post_init()

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        pixel_values: torch.FloatTensor,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple[torch.FloatTensor] | BaseModelOutputWithNoAttention:
        outputs = self.model(pixel_values, **kwargs)
        head_outputs = self.head(outputs.last_hidden_state, **kwargs)

        return PPOCRV5ServerRecForTextRecognitionOutput(
            last_hidden_state=head_outputs.last_hidden_state,
            hidden_states=outputs.hidden_states,
            head_hidden_states=head_outputs.hidden_states,
        )


__all__ = [
    "PPOCRV5ServerRecForTextRecognition",
    "PPOCRV5ServerRecModel",
    "PPOCRV5ServerRecPreTrainedModel",
    "PPOCRV5ServerRecEncoderWithSVTR",
]
