"""
自定义模块注册 - 用于 MMDeploy ONNX 导出
处理 EVA-CLIP ViT 的特殊操作：
1. 禁用 xformers (不支持 ONNX)
2. 处理 RoPE 位置编码的动态形状
3. 不同 feature_mode (vanilla/csa) 的处理
"""

import torch
import torch.nn as nn
import torch.nn.functional as F
from typing import Tuple, List, Optional


def register_custom_rewriters():
    """注册自定义重写器到 MMDeploy"""
    try:
        from mmdeploy.core import FUNCTION_REWRITER, MODULE_REWRITER
    except ImportError:
        print("Warning: MMDeploy not installed. Skipping rewriter registration.")
        return
    
    # ============================================================
    # EVAVisionTransformer 相关重写器
    # ============================================================
    
    @FUNCTION_REWRITER.register_rewriter(
        func_name='src.open_clip.eva_clip.eva_vit_model.Attention.forward',
        backend='tensorrt'
    )
    def attention__forward__tensorrt(self, x, rel_pos_bias=None, attn_mask=None):
        """
        重写 Attention.forward 以禁用 xformers，使用标准 attention
        """
        B, N, C = x.shape
        
        if self.subln:
            q = F.linear(input=x, weight=self.q_proj.weight, bias=self.q_bias)
            k = F.linear(input=x, weight=self.k_proj.weight, bias=None)
            v = F.linear(input=x, weight=self.v_proj.weight, bias=self.v_bias)
            q = q.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
            k = k.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
            v = v.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
        else:
            qkv_bias = None
            if self.q_bias is not None:
                qkv_bias = torch.cat((
                    self.q_bias, 
                    torch.zeros_like(self.v_bias, requires_grad=False), 
                    self.v_bias
                ))
            qkv = F.linear(input=x, weight=self.qkv.weight, bias=qkv_bias)
            qkv = qkv.reshape(B, N, 3, self.num_heads, -1).permute(2, 0, 3, 1, 4)
            q, k, v = qkv[0], qkv[1], qkv[2]
        
        # RoPE 位置编码 (如果启用)
        if self.rope is not None:
            q_t = q[:, :, 1:, :]
            ro_q_t = self.rope(q_t)
            q = torch.cat((q[:, :, :1, :], ro_q_t), -2).type_as(v)
            
            k_t = k[:, :, 1:, :]
            ro_k_t = self.rope(k_t)
            k = torch.cat((k[:, :, :1, :], ro_k_t), -2).type_as(v)
        
        # 强制使用标准 attention (不使用 xformers)
        q = q * self.scale
        attn = (q @ k.transpose(-2, -1))
        
        if self.relative_position_bias_table is not None:
            relative_position_bias = \
                self.relative_position_bias_table[self.relative_position_index.view(-1)].view(
                    self.window_size[0] * self.window_size[1] + 1,
                    self.window_size[0] * self.window_size[1] + 1, -1)
            relative_position_bias = relative_position_bias.permute(2, 0, 1).contiguous()
            attn = attn + relative_position_bias.unsqueeze(0).type_as(attn)
        
        if rel_pos_bias is not None:
            attn = attn + rel_pos_bias.type_as(attn)
        
        if attn_mask is not None:
            attn_mask = attn_mask.bool()
            attn = attn.masked_fill(~attn_mask[:, None, None, :], float("-inf"))
        
        attn = attn.softmax(dim=-1)
        attn = self.attn_drop(attn)
        
        x = (attn @ v).transpose(1, 2).reshape(B, N, -1)
        x = self.inner_attn_ln(x)
        x = self.proj(x)
        x = self.proj_drop(x)
        
        return x
    
    @FUNCTION_REWRITER.register_rewriter(
        func_name='src.open_clip.eva_clip.eva_vit_model.Attention.ss_attn',
        backend='tensorrt'
    )
    def attention__ss_attn__tensorrt(self, x, mode, attn_mask=None):
        """
        重写 ss_attn (self-supervised attention) 用于 DeCLIP 的 csa 模式
        """
        B, N, C = x.shape
        
        if self.subln:
            q = F.linear(input=x, weight=self.q_proj.weight, bias=self.q_bias)
            k = F.linear(input=x, weight=self.k_proj.weight, bias=None)
            v = F.linear(input=x, weight=self.v_proj.weight, bias=self.v_bias)
            q = q.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
            k = k.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
            v = v.reshape(B, N, self.num_heads, -1).permute(0, 2, 1, 3)
        else:
            qkv_bias = None
            if self.q_bias is not None:
                qkv_bias = torch.cat((
                    self.q_bias,
                    torch.zeros_like(self.v_bias, requires_grad=False),
                    self.v_bias
                ))
            qkv = F.linear(input=x, weight=self.qkv.weight, bias=qkv_bias)
            qkv = qkv.reshape(B, N, 3, self.num_heads, -1).permute(2, 0, 3, 1, 4)
            q, k, v = qkv[0], qkv[1], qkv[2]
        
        # RoPE 位置编码
        if self.rope is not None:
            q_t = q[:, :, 1:, :]
            ro_q_t = self.rope(q_t)
            q = torch.cat((q[:, :, :1, :], ro_q_t), -2).type_as(v)
            
            k_t = k[:, :, 1:, :]
            ro_k_t = self.rope(k_t)
            k = torch.cat((k[:, :, :1, :], ro_k_t), -2).type_as(v)
        
        q = q.contiguous().view(B * self.num_heads, N, -1)
        k = k.contiguous().view(B * self.num_heads, N, -1)
        v = v.contiguous().view(B * self.num_heads, N, -1)
        
        # CSA (Combined Self-Attention) 模式
        if 'csa' in mode:
            q_attn = torch.bmm(q, q.transpose(1, 2))
            k_attn = torch.bmm(k, k.transpose(1, 2))
            attn_weights = F.softmax(q_attn, dim=-1) + F.softmax(k_attn, dim=-1)
        elif 'qq' in mode:
            q_attn = torch.bmm(q, q.transpose(1, 2))
            attn_weights = F.softmax(q_attn, dim=-1)
        elif 'kk' in mode:
            k_attn = torch.bmm(k, k.transpose(1, 2))
            attn_weights = F.softmax(k_attn, dim=-1)
        elif 'vv' in mode:
            v_attn = torch.bmm(v, v.transpose(1, 2))
            attn_weights = F.softmax(v_attn, dim=-1)
        else:  # vanilla
            q_scaled = q * (q.shape[-1] ** -0.5)
            attn_weights = F.softmax(torch.bmm(q_scaled, k.transpose(1, 2)), dim=-1)
        
        attn_output = torch.bmm(attn_weights, v)
        attn_output = attn_output.transpose(0, 1).contiguous().view(N, B, C).transpose(0, 1)
        attn_output = self.inner_attn_ln(attn_output)
        attn_output = self.proj(attn_output)
        attn_output = self.proj_drop(attn_output)
        
        return attn_output
    
    @FUNCTION_REWRITER.register_rewriter(
        func_name='src.open_clip.eva_clip.eva_vit_model.EVAVisionTransformer.encode_dense',
        backend='tensorrt'
    )
    def eva_vit__encode_dense__tensorrt(
        self, x, keep_shape=True, mode="csa", get_intermediate_layer=None
    ):
        """
        重写 encode_dense 用于 ONNX 导出
        简化逻辑，移除不兼容 ONNX 的操作
        """
        if get_intermediate_layer is None:
            get_intermediate_layer = []
        get_intermediate_layer = set(get_intermediate_layer)
        
        bs, _, h, w = x.shape
        h = h // self.patch_embed.patch_size[0]
        w = w // self.patch_embed.patch_size[1]
        x = self.patch_embed(x)
        batch_size, seq_len, _ = x.size()
        
        cls_tokens = self.cls_token.expand(batch_size, -1, -1)
        x = torch.cat((cls_tokens, x), dim=1)
        
        if self.pos_embed is not None:
            x = x + self.rescale_positional_embedding(out_size=(h, w))
        x = self.pos_drop(x)
        
        # 跳过 patch_dropout (推理时不需要)
        rel_pos_bias = self.rel_pos_bias() if self.rel_pos_bias is not None else None
        
        for blk in self.blocks[:-1]:
            x = blk(x, rel_pos_bias=rel_pos_bias)
        
        # 最后一个 block 根据 mode 处理
        if mode == "vanilla":
            x = self.blocks[-1](x, rel_pos_bias=rel_pos_bias)
        else:
            x = self.blocks[-1].forward_without_rcffn(x, mode)
        
        x = x[:, 1:]  # 移除 CLS token
        x = self.norm(x)
        x = self.head(x)
        
        if keep_shape:
            x = x.view(bs, h, w, -1).permute(0, 3, 1, 2)
        
        return x
    
    print("Custom rewriters registered successfully.")


class EVACLIPWrapper(nn.Module):
    """
    EVA-CLIP 模型包装器，用于 ONNX 导出
    将复杂的模型接口简化为单一的 forward 方法
    """
    
    def __init__(self, model, mode='csa'):
        """
        Args:
            model: EVA-CLIP 模型实例
            mode: 特征提取模式 ('vanilla' 或 'csa')
        """
        super().__init__()
        self.model = model
        self.mode = mode
        self.visual = model.visual if hasattr(model, 'visual') else model
    
    def forward(self, x: torch.Tensor) -> torch.Tensor:
        """
        简化的 forward 方法
        
        Args:
            x: 输入图像 [B, C, H, W]
            
        Returns:
            dense_features: 密集特征图 [B, D, H', W']
        """
        return self.visual.encode_dense(x, keep_shape=True, mode=self.mode)
    
    def extract_roi_features(
        self, 
        x: torch.Tensor, 
        boxes: List[torch.Tensor]
    ) -> torch.Tensor:
        """
        提取 RoI 特征
        
        Args:
            x: 输入图像 [B, C, H, W]
            boxes: 归一化边界框列表，每个元素 [N, 4]
            
        Returns:
            roi_features: RoI 特征 [total_boxes, D]
        """
        return self.visual.extract_roi_features(
            x, boxes, mode=self.mode
        )


class TRTInferenceWrapper:
    """
    TensorRT 推理包装器
    处理 TRT Engine 的加载和推理
    """
    
    def __init__(self, engine_path: str, device: str = 'cuda:0'):
        """
        Args:
            engine_path: TRT 引擎文件路径
            device: 设备
        """
        self.engine_path = engine_path
        self.device = torch.device(device)
        self.engine = None
        self.context = None
        
    def load(self):
        """加载 TRT 引擎"""
        try:
            import tensorrt as trt
            
            logger = trt.Logger(trt.Logger.WARNING)
            runtime = trt.Runtime(logger)
            
            with open(self.engine_path, 'rb') as f:
                engine_data = f.read()
            
            self.engine = runtime.deserialize_cuda_engine(engine_data)
            self.context = self.engine.create_execution_context()
            
            print(f"Loaded TRT engine from {self.engine_path}")
            
        except ImportError:
            raise ImportError("TensorRT is not installed")
    
    def __call__(self, input_tensor: torch.Tensor) -> torch.Tensor:
        """
        运行推理
        
        Args:
            input_tensor: 输入张量 [B, C, H, W]
            
        Returns:
            output_tensor: 输出特征
        """
        if self.engine is None:
            self.load()
        
        # 实际推理逻辑需要根据具体引擎绑定实现
        # 这里只是一个框架
        raise NotImplementedError("TRT inference not fully implemented")


def disable_xformers_for_export(model):
    """
    禁用模型中的 xformers 以支持 ONNX 导出
    
    Args:
        model: EVA-CLIP 模型
    """
    def _disable_xattn(module):
        if hasattr(module, 'xattn'):
            module.xattn = False
    
    model.apply(_disable_xattn)
    print("Disabled xformers for ONNX export")
    
    return model


def prepare_model_for_export(model, mode='csa'):
    """
    准备模型用于 ONNX 导出
    
    Args:
        model: 原始模型
        mode: 特征模式
        
    Returns:
        wrapped_model: 包装后的模型
    """
    # 禁用 xformers
    model = disable_xformers_for_export(model)
    
    # 设置为评估模式
    model.eval()
    
    # 包装模型
    wrapped = EVACLIPWrapper(model, mode=mode)
    
    return wrapped


if __name__ == '__main__':
    # 测试注册
    register_custom_rewriters()