"""Implement application-layer logic for services."""

from __future__ import annotations

from typing import Generator

from app.domain.conversation import AnswerGenerator, AnswerResult, ConversationStore
from app.domain.retrieval import RetrievedChunk

from app.application.knowledge import KnowledgeRetrievalService
# Keep orchestration logic centralized so use-case flow stays easy to trace.



class AgentConversationService:
    """Provide the Agent Conversation Service service."""
    def __init__(
        self,
        *,
        retrieval_service: KnowledgeRetrievalService,
        answer_generator: AnswerGenerator,
        conversation_store: ConversationStore,
    ) -> None:
        """Initialize the Agent Conversation Service instance."""
        self.retrieval_service = retrieval_service
        self.answer_generator = answer_generator
        self.conversation_store = conversation_store

    def ask(
        self,
        *,
        query: str,
        filters: str | None = None,
        provider: str | None = None,
        model: str | None = None,
        top_k: int = 5,
        prompt_template: str | None = None,
        session_id: str | None = None,
    ) -> tuple[str | None, AnswerResult]:
        """Handle ask for the Agent Conversation Service instance."""
        history = None
        active_session_id = None
        if session_id:
            session = self.conversation_store.get_session(session_id)
            if not session:
                raise ValueError("会话不存在或已过期")
            history = [{"role": msg.role, "content": msg.content} for msg in session.messages[-10:]]
            active_session_id = session.session_id
            self.conversation_store.save_message(session_id, role="user", content=query)
        retrieved = self.retrieval_service.retrieve(query=query, top_k=top_k, filters=filters)
        result = self.answer_generator.generate(
            query=query,
            retrieved_chunks=retrieved,
            history=history,
            provider=provider,
            model=model,
            prompt_template=prompt_template,
        )
        if active_session_id:
            self.conversation_store.save_message(
                active_session_id,
                role="assistant",
                content=result.answer,
                sources=[source.__dict__ for source in result.sources],
            )
        return active_session_id, result

    def chat(
        self,
        *,
        query: str,
        session_id: str | None = None,
        filters: str | None = None,
        provider: str | None = None,
        model: str | None = None,
        top_k: int = 5,
    ) -> tuple[str, AnswerResult]:
        """Handle chat for the Agent Conversation Service instance."""
        session = self.conversation_store.get_session(session_id) if session_id else None
        if session is None:
            session = self.conversation_store.create_session()
        self.conversation_store.save_message(session.session_id, role="user", content=query)
        history = [{"role": msg.role, "content": msg.content} for msg in session.messages[-10:]]
        retrieved = self.retrieval_service.retrieve(query=query, top_k=top_k, filters=filters)
        result = self.answer_generator.generate(
            query=query,
            retrieved_chunks=retrieved,
            history=history,
            provider=provider,
            model=model,
        )
        self.conversation_store.save_message(
            session.session_id,
            role="assistant",
            content=result.answer,
            sources=[source.__dict__ for source in result.sources],
        )
        return session.session_id, result

    def stream_chat(
        self,
        *,
        query: str,
        session_id: str | None = None,
        filters: str | None = None,
        provider: str | None = None,
        model: str | None = None,
        top_k: int = 5,
        prompt_template: str | None = None,
    ) -> tuple[str, Generator[dict, None, None]]:
        """Stream chat for the Agent Conversation Service instance."""
        session = self.conversation_store.get_session(session_id) if session_id else None
        if session is None:
            session = self.conversation_store.create_session()
        self.conversation_store.save_message(session.session_id, role="user", content=query)
        history = [{"role": msg.role, "content": msg.content} for msg in session.messages[-10:]]
        retrieved = self.retrieval_service.retrieve(query=query, top_k=top_k, filters=filters)

        def event_stream() -> Generator[dict, None, None]:
            """Handle event stream for the Agent Conversation Service instance."""
            yield {"event": "status", "data": f"找到{len(retrieved)}条相关法规，正在生成回答..."}
            answer_parts: list[str] = []
            sources_payload: list[dict] = []
            for event in self.answer_generator.stream_generate(
                query=query,
                retrieved_chunks=retrieved,
                history=history,
                provider=provider,
                model=model,
                prompt_template=prompt_template,
            ):
                if event.get("event") == "sources":
                    sources_payload = event.get("data", [])
                if event.get("event") == "content":
                    answer_parts.append(str(event.get("data", "")))
                yield event
            full_answer = "".join(answer_parts)
            self.conversation_store.save_message(
                session.session_id,
                role="assistant",
                content=full_answer,
                sources=sources_payload,
            )

        return session.session_id, event_stream()