from datetime import UTC, datetime
from uuid import uuid4

from sqlalchemy.ext.asyncio import AsyncSession

from app.core.contracts import RequestContext
from app.core.errors import (
    FeedbackAlreadyExistsError,
    GenericResourceNotFoundError,
)
from app.model.audit import InteractionAudit
from app.model.conversation import ConversationFeedback
from app.repository.conversation_repository import ConversationRepository
from app.service.authorization_service import AuthorizationService


class ConversationService:
    def __init__(self, session: AsyncSession) -> None:
        self.session = session
        self.repository = ConversationRepository(session)

    async def messages(
        self, session_id: str, context: RequestContext, limit: int, before: int | None = None
    ) -> dict[str, object]:
        """消息列表投影；`before` 是文档 §3.8 的游标（记录 ID 边界），已由入口校验。

        取 `limit + 1` 行来判断"还有没有更旧的"：只看"取满没取满"会把恰好等于 limit 的
        最后一页说成还有下一页。`next_cursor` 就是本页最后一条的 `message_id` ——
        游标语义是"取更旧的一页"，所以它天然可续（集成测试正是这么翻页的）。

        返回的是内部结构 `{items, next_cursor, has_more}`，由 Controller 用
        `list_envelope` 拆成 `docs/05` §3.3 要求的 `{data, meta}`；此前这里直接返回
        `{"data": [...]}`，成功响应因此**完全没有 `meta.trace_id`**。
        """
        rows = await self.repository.messages(
            session_id, int(context.user_id), limit + 1, before=before
        )
        has_more = len(rows) > limit
        page_rows = rows[:limit]
        return {
            "items": [
                {
                    "message_id": str(row.id),
                    "role": row.role,
                    "content": row.content,
                    "created_at": row.created_at.isoformat() + "Z",
                }
                for row in page_rows
            ],
            "next_cursor": str(page_rows[-1].id) if has_more and page_rows else None,
            "has_more": has_more,
        }

    async def feedback(
        self, message_id: int, context: RequestContext, rating: int,
        feedback_type: str | None, feedback_content: str | None,
    ) -> dict[str, object]:
        await AuthorizationService.require(context, "conversation:feedback")
        async with self.session.begin():
            message = await self.repository.message(message_id, int(context.user_id))
            if message is None:
                raise GenericResourceNotFoundError("消息不存在")
            if await self.repository.feedback(message_id, int(context.user_id)) is not None:
                raise FeedbackAlreadyExistsError("消息已反馈")
            now = datetime.now(UTC).replace(tzinfo=None)
            feedback = ConversationFeedback(
                feedback_no=f"fb-{uuid4().hex[:24]}", session_id=message.session_id,
                message_id=message_id, customer_id=int(context.user_id), rating=rating,
                feedback_type=feedback_type, feedback_content=feedback_content, status="open",
                created_at=now, updated_at=now,
            )
            self.session.add(feedback)
            self._audit(context, message.session_id, "conversation.feedback_created",
                        {"feedback_no": feedback.feedback_no})
            # 只返回业务数据；§3.3 的信封由 Controller 套（此前这里自带 {"data": ...}，
            # 于是成功响应没有 meta.trace_id）。
            return {"feedback_no": feedback.feedback_no, "status": feedback.status}

    # 转人工申请（POST /api/v1/conversations/{id}/handover-requests）的唯一实现
    # 在 PublicPlatformService.write("handover", ...)：它同一事务写工单 + Outbox
    # 事件 + 审计。此处曾经的第二实现只写审计，会让转人工异步链路断掉，已删除。

    def _audit(
        self, context: RequestContext, session_id: str, action: str, detail: dict[str, object]
    ) -> None:
        self.session.add(InteractionAudit(
            actor_type="user", actor_id=int(context.user_id), session_id=session_id,
            portal=context.portal, action_type=action,
            detail={**detail, "trace_id": context.trace_id},
            created_at=datetime.now(UTC).replace(tzinfo=None),
        ))