"""知识库 CRUD。前端助手编辑页的"知识库"下拉对接这里。

KB 自身引用一个 Embedding 模型资源。被助手引用时禁止删除
(DB 层 ON DELETE RESTRICT),这里把外键冲突翻译成 409。
"""

import uuid

from db.models import KnowledgeBase, ModelResource
from db.session import get_session
from fastapi import APIRouter, Depends, HTTPException
from schemas import KnowledgeBaseOut, KnowledgeBaseUpsert
from sqlalchemy import select
from sqlalchemy.exc import IntegrityError
from sqlalchemy.ext.asyncio import AsyncSession

router = APIRouter(prefix="/api/knowledge-bases", tags=["knowledge-bases"])


async def _validate_embedding_resource(
    session: AsyncSession, resource_id: str | None
) -> None:
    if not resource_id:
        return
    resource = await session.get(ModelResource, resource_id)
    if not resource or resource.capability != "Embedding":
        raise HTTPException(400, "知识库必须引用 Embedding 模型资源")


def _to_out(kb: KnowledgeBase) -> KnowledgeBaseOut:
    return KnowledgeBaseOut(
        id=kb.id,
        name=kb.name,
        description=kb.description,
        embedding_model_resource_id=kb.embedding_model_resource_id,
        status=kb.status,
        updated_at=kb.updated_at.isoformat() if kb.updated_at else None,
    )


@router.get("", response_model=list[KnowledgeBaseOut])
async def list_knowledge_bases(session: AsyncSession = Depends(get_session)):
    rows = (
        await session.execute(select(KnowledgeBase).order_by(KnowledgeBase.name))
    ).scalars().all()
    return [_to_out(kb) for kb in rows]


@router.post("", response_model=KnowledgeBaseOut)
async def create_knowledge_base(
    body: KnowledgeBaseUpsert, session: AsyncSession = Depends(get_session)
):
    await _validate_embedding_resource(session, body.embedding_model_resource_id)
    kb = KnowledgeBase(id=f"kb_{uuid.uuid4().hex[:12]}", **body.model_dump())
    session.add(kb)
    await session.commit()
    await session.refresh(kb)
    return _to_out(kb)


@router.get("/{kb_id}", response_model=KnowledgeBaseOut)
async def get_knowledge_base(
    kb_id: str, session: AsyncSession = Depends(get_session)
):
    kb = await session.get(KnowledgeBase, kb_id)
    if not kb:
        raise HTTPException(404, "知识库不存在")
    return _to_out(kb)


@router.put("/{kb_id}", response_model=KnowledgeBaseOut)
async def update_knowledge_base(
    kb_id: str,
    body: KnowledgeBaseUpsert,
    session: AsyncSession = Depends(get_session),
):
    kb = await session.get(KnowledgeBase, kb_id)
    if not kb:
        raise HTTPException(404, "知识库不存在")
    await _validate_embedding_resource(session, body.embedding_model_resource_id)
    for k, v in body.model_dump().items():
        setattr(kb, k, v)
    await session.commit()
    await session.refresh(kb)
    return _to_out(kb)


@router.delete("/{kb_id}")
async def delete_knowledge_base(
    kb_id: str, session: AsyncSession = Depends(get_session)
):
    kb = await session.get(KnowledgeBase, kb_id)
    if not kb:
        raise HTTPException(404, "知识库不存在")
    try:
        await session.delete(kb)
        await session.commit()
    except IntegrityError:
        # 被助手引用(ON DELETE RESTRICT):先解绑再删
        await session.rollback()
        raise HTTPException(409, "知识库正被助手引用,无法删除")
    return {"ok": True}