# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

from typing import TYPE_CHECKING, Optional, Union

import torch
import torch.nn as nn
from transformers import PretrainedConfig

from vllm.config.lora import LoRAConfig

if TYPE_CHECKING:
    from vllm.lora.punica_wrapper import PunicaWrapperBase


class BaseLayerWithLoRA(nn.Module):
    def slice_lora_a(
        self, lora_a: Union[torch.Tensor, list[Union[torch.Tensor, None]]]
    ) -> Union[torch.Tensor, list[Union[torch.Tensor, None]]]:
        """Slice lora a if splitting for tensor parallelism."""
        ...

    def slice_lora_b(
        self, lora_b: Union[torch.Tensor, list[Union[torch.Tensor, None]]]
    ) -> Union[torch.Tensor, list[Union[torch.Tensor, None]]]:
        """Slice lora b if splitting with tensor parallelism."""
        ...

    def create_lora_weights(
        self,
        max_loras: int,
        lora_config: LoRAConfig,
        model_config: Optional[PretrainedConfig] = None,
    ) -> None:
        """Initializes lora matrices."""
        ...

    def reset_lora(self, index: int):
        """Resets the lora weights at index back to 0."""
        ...

    def set_lora(
        self,
        index: int,
        lora_a: torch.Tensor,
        lora_b: torch.Tensor,
        embeddings_tensor: Optional[torch.Tensor],
        bias: Optional[torch.Tensor] = None,
    ):
        """Overwrites lora tensors at index."""
        ...

    def set_mapping(
        self,
        punica_wrapper,
    ):
        self.punica_wrapper: PunicaWrapperBase = punica_wrapper

    @classmethod
    def can_replace_layer(
        cls,
        source_layer: nn.Module,
        lora_config: LoRAConfig,
        packed_modules_list: list,
        model_config: Optional[PretrainedConfig],
    ) -> bool:
        """Returns True if the layer can be replaced by this LoRA layer."""
        raise NotImplementedError
