"""Base RAG service interface."""

from abc import ABC, abstractmethod
from types import TracebackType
from typing import Self

from pydantic import BaseModel, Field


class Message(BaseModel):
    """OpenAI-style message format."""

    role: str = Field(..., description="Role: system, user, or assistant")
    content: str = Field(..., description="Message content")


class RAGRequest(BaseModel):
    """Request model for RAG endpoint."""

    messages: list[Message] = Field(..., description="Conversation history")


class RAGResponse(BaseModel):
    """Response model from RAG endpoint."""

    response: str = Field(..., description="Generated response from RAG")


class RAGServiceBase(ABC):
    """Abstract base class for RAG service implementations.

    Provides a common interface for different RAG service backends
    (HTTP, mock, echo, etc.).
    """

    @abstractmethod
    async def query(self, messages: list[dict[str, str]]) -> str:
        """Send conversation history to RAG endpoint and get response.

        Args:
            messages: OpenAI-style conversation history
                     e.g., [{"role": "user", "content": "Hello"}, ...]

        Returns:
            Response string from RAG endpoint

        Raises:
            Exception: Implementation-specific exceptions

        """
        ...

    @abstractmethod
    async def close(self) -> None:
        """Close the service and release resources."""
        ...

    async def __aenter__(self) -> Self:
        """Async context manager entry."""
        return self

    async def __aexit__(
        self,
        exc_type: type[BaseException] | None,
        exc_val: BaseException | None,
        exc_tb: TracebackType | None,
    ) -> None:
        """Async context manager exit."""
        await self.close()