from __future__ import annotations

from abc import ABC, abstractmethod
from collections.abc import AsyncIterator
from typing import Any

from ..config import ModelConfig, RuntimeConfig
from ..types import BackendError, ChatChunk, ChatParams


class BaseBackend(ABC):
    def __init__(self, model: ModelConfig, runtime: RuntimeConfig) -> None:
        self.model = model
        self.runtime = runtime
        self.loaded = False

    @abstractmethod
    async def load(self) -> None:
        raise NotImplementedError

    @abstractmethod
    async def unload(self) -> None:
        raise NotImplementedError

    @abstractmethod
    async def chat(
        self,
        messages: list[dict[str, Any]],
        params: ChatParams,
        stream: bool = False,
    ) -> AsyncIterator[ChatChunk]:
        raise NotImplementedError

    @abstractmethod
    def info(self) -> dict[str, Any]:
        raise NotImplementedError

    async def embed(self, inputs: list[str]) -> list[list[float]]:
        raise BackendError(f"后端 {self.model.id} 不支持 embeddings")