"""知识库服务：CRUD + Token 管理。"""

from app.core.errors import NotFoundError, PermissionDeniedError
from app.models.knowledge_base import KnowledgeBase
from app.models.user import User
from app.repositories.kb_repo import KnowledgeBaseRepository
from app.services.token_service import TokenService
from sqlalchemy.orm import Session


class KnowledgeBaseService:
    def __init__(self, session: Session) -> None:
        self._session = session
        self._kb_repo = KnowledgeBaseRepository(session)
        self._token_svc = TokenService()

    def create(self, user: User, name: str, description: str | None) -> tuple[KnowledgeBase, str]:
        """创建知识库。返回 (kb, full_token)。

        full_token 仅此一次返回，用于构建完整 AI URL。
        """
        token, token_hash, token_encrypted, token_hint = self._token_svc.create_token_pair()
        kb = self._kb_repo.create(
            user_id=user.id,
            name=name,
            description=description,
            token_hash=token_hash,
            token_encrypted=token_encrypted,
            token_hint=token_hint,
        )
        self._session.commit()
        return kb, token

    def get_or_404(self, kb_id: str, user: User) -> KnowledgeBase:
        """获取知识库，校验所有权。不存在或无权 → 404。"""
        kb = self._kb_repo.get_by_id(kb_id)
        if kb is None or kb.user_id != user.id or kb.status == "DELETED":
            raise NotFoundError("知识库不存在。")
        return kb

    def list_by_user(self, user: User, *, page: int = 1, page_size: int = 20):
        """分页列表。"""
        return self._kb_repo.list_by_user(user.id, page=page, page_size=page_size)

    def update(self, kb_id: str, user: User, name: str | None, description: str | None) -> KnowledgeBase:
        kb = self.get_or_404(kb_id, user)
        update_fields = {}
        if name is not None:
            update_fields["name"] = name
        if description is not None:
            update_fields["description"] = description
        if update_fields:
            self._kb_repo.update(kb, **update_fields)
            self._session.commit()
        return kb

    def delete(self, kb_id: str, user: User) -> None:
        kb = self.get_or_404(kb_id, user)
        self._kb_repo.delete(kb)
        self._session.commit()

    def regenerate_token(self, kb_id: str, user: User) -> tuple[KnowledgeBase, str]:
        """重新生成 Token。旧链接立即失效。"""
        kb = self.get_or_404(kb_id, user)
        token, token_hash, token_encrypted, token_hint = self._token_svc.create_token_pair()
        self._kb_repo.update(
            kb,
            token_hash=token_hash,
            token_encrypted=token_encrypted,
            token_hint=token_hint,
        )
        self._session.commit()
        return kb, token

    def set_enabled(self, kb_id: str, user: User, enabled: bool) -> KnowledgeBase:
        kb = self.get_or_404(kb_id, user)
        self._kb_repo.update(kb, enabled=enabled)
        self._session.commit()
        return kb

    def get_full_token(self, kb: KnowledgeBase) -> str | None:
        """解密 token 原文（供后台显示完整链接）。"""
        if kb.token_encrypted:
            return self._token_svc.decrypt_token(kb.token_encrypted)
        return None