"""
Domain Layer - LLM Interface

Defines contract for LLM implementations.
"""
from abc import ABC, abstractmethod
from dataclasses import dataclass
from typing import AsyncIterator, List, Optional


@dataclass
class LLMMessage:
    """Chat message"""

    role: str  # system, user, assistant
    content: str


@dataclass
class LLMResponse:
    """LLM generation response"""

    content: str
    model: str
    tokens_used: int
    finish_reason: str


class ILLM(ABC):
    """Interface for LLM implementations"""

    @abstractmethod
    async def generate(
        self,
        messages: List[LLMMessage],
        temperature: float = 0.7,
        max_tokens: int = 2048,
        stream: bool = False,
    ) -> LLMResponse:
        """Generate response from LLM"""
        pass

    @abstractmethod
    async def generate_stream(
        self,
        messages: List[LLMMessage],
        temperature: float = 0.7,
        max_tokens: int = 2048,
    ) -> AsyncIterator[str]:
        """Generate streaming response from LLM"""
        pass

    @abstractmethod
    def get_model_name(self) -> str:
        """Get model name"""
        pass


class IPromptBuilder(ABC):
    """Interface for prompt building"""

    @abstractmethod
    def build_rag_prompt(
        self, query: str, context: List[str], system_prompt: Optional[str] = None
    ) -> List[LLMMessage]:
        """Build RAG prompt with query and context"""
        pass

    @abstractmethod
    def build_query_expansion_prompt(self, query: str) -> List[LLMMessage]:
        """Build prompt for query expansion"""
        pass