import json
import secrets

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session

from app.config import settings
from app.database import get_db
from app.models import Mindmap
from app.schemas import MindmapCreateRequest, MindmapNode, MindmapResponse

router = APIRouter(prefix="/mindmaps", tags=["mindmaps"])


def generate_unique_id() -> str:
    return secrets.token_urlsafe(16)


def extract_title_from_json(mindmap_json: dict) -> str:
    label = mindmap_json.get("label", "")
    return label.strip() if label else "未命名思维导图"


def to_response(mindmap: Mindmap) -> MindmapResponse:
    tree_data = json.loads(mindmap.raw_json)
    tree = MindmapNode.model_validate(tree_data)
    url = f"{settings.frontend_base_url}/mindmap/{mindmap.unique_id}"

    return MindmapResponse(
        id=mindmap.id,
        unique_id=mindmap.unique_id,
        session_id=mindmap.session_id,
        title=mindmap.title,
        raw_json=mindmap.raw_json,
        tree=tree,
        url=url,
        created_at=mindmap.created_at,
        updated_at=mindmap.updated_at,
    )


@router.post("", response_model=MindmapResponse, status_code=status.HTTP_201_CREATED)
def create_mindmap(
    payload: MindmapCreateRequest,
    db: Session = Depends(get_db),
) -> MindmapResponse:
    title = extract_title_from_json(payload.mindmap_json)
    raw_json = json.dumps(payload.mindmap_json, ensure_ascii=False)
    unique_id = generate_unique_id()

    mindmap = Mindmap(
        unique_id=unique_id,
        session_id=payload.session_id,
        title=title,
        raw_json=raw_json,
    )
    db.add(mindmap)
    db.commit()
    db.refresh(mindmap)

    return to_response(mindmap)


@router.get("/{unique_id}", response_model=MindmapResponse)
def get_mindmap(
    unique_id: str,
    db: Session = Depends(get_db),
) -> MindmapResponse:
    mindmap = db.query(Mindmap).filter(Mindmap.unique_id == unique_id).first()

    if not mindmap:
        raise HTTPException(status_code=404, detail="脑图不存在")

    return to_response(mindmap)