"""只读访问生产对话表，供内部浏览与快照。"""

from __future__ import annotations

from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import joinedload

from app.features.conversation.models import Conversation, ConversationMessage, Segment


class SessionCatalogRepo:
    def __init__(self, db: AsyncSession) -> None:
        self._db = db

    async def count_conversations(self, *, status: str | None = None) -> int:
        q = (
            select(func.count())
            .select_from(Conversation)
            .where(Conversation.deleted_at.is_(None))
        )
        if status:
            q = q.where(Conversation.status == status)
        r = await self._db.execute(q)
        return int(r.scalar() or 0)

    async def list_conversations(
        self,
        *,
        offset: int = 0,
        limit: int = 50,
        user_id: str | None = None,
        q_text: str | None = None,
        status: str | None = None,
    ) -> list[Conversation]:
        stmt = select(Conversation).where(Conversation.deleted_at.is_(None))
        if user_id:
            stmt = stmt.where(Conversation.user_id == user_id)
        if status:
            stmt = stmt.where(Conversation.status == status)
        if status == "active":
            stmt = stmt.order_by(
                Conversation.last_message_at.desc().nullslast(),
                Conversation.started_at.desc().nullslast(),
            )
        else:
            stmt = stmt.order_by(Conversation.started_at.desc().nullslast())
        stmt = stmt.offset(offset).limit(limit)
        # q_text: 简单按 topic 搜索（后续可扩展全文）
        if q_text:
            like = f"%{q_text.strip()}%"
            stmt = stmt.where(
                (Conversation.current_topic.isnot(None))
                & (Conversation.current_topic.ilike(like))
            )
        stmt = stmt.options(joinedload(Conversation.user))
        res = await self._db.execute(stmt)
        return list(res.scalars().unique().all())

    async def get_conversation(self, conversation_id: str) -> Conversation | None:
        return await self._db.get(Conversation, conversation_id)

    async def list_segments_for_conversation(
        self, conversation_id: str
    ) -> list[Segment]:
        stmt = (
            select(Segment)
            .where(Segment.conversation_id == conversation_id)
            .order_by(Segment.created_at.asc())
        )
        res = await self._db.execute(stmt)
        return list(res.scalars().all())

    async def list_messages_for_conversation(
        self, conversation_id: str
    ) -> list[ConversationMessage]:
        stmt = (
            select(ConversationMessage)
            .where(ConversationMessage.conversation_id == conversation_id)
            .order_by(ConversationMessage.created_at.asc())
        )
        res = await self._db.execute(stmt)
        return list(res.scalars().all())