"""Assistant chat thread management.

The conversation itself is persisted by the AG-UI snapshot store
(app/agent/snapshot_store.py) under a single ("default", "main") thread;
this router only exposes the reset used by "Nueva conversación".
"""

from fastapi import APIRouter, Depends
from pydantic import BaseModel
from sqlmodel import Session, select

from app.auth import get_current_user
from app.db import get_session
from app.models.models import ChatThreadSnapshot

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

CHAT_SCOPE = "default"
CHAT_THREAD_ID = "main"


class ClearThreadResponse(BaseModel):
    cleared: bool


@router.delete("/thread", response_model=ClearThreadResponse)
def clear_thread(
    session: Session = Depends(get_session),
    _user: str = Depends(get_current_user),
):
    row = session.exec(
        select(ChatThreadSnapshot).where(
            ChatThreadSnapshot.scope == CHAT_SCOPE,
            ChatThreadSnapshot.thread_id == CHAT_THREAD_ID,
        )
    ).first()
    if row is None:
        return {"cleared": False}
    session.delete(row)
    session.commit()
    return {"cleared": True}