"""密码重置令牌创建与校验。"""

from __future__ import annotations

import secrets
from datetime import datetime, timedelta

from sqlalchemy import delete, select
from sqlalchemy.ext.asyncio import AsyncSession

from models.models import PasswordResetToken, User


def _token_expires_at(hours: int) -> datetime:
    return datetime.utcnow() + timedelta(hours=max(1, min(168, int(hours or 24))))


async def invalidate_user_reset_tokens(db: AsyncSession, user_id: int) -> None:
    await db.execute(
        delete(PasswordResetToken).where(PasswordResetToken.user_id == user_id)
    )


async def create_password_reset_token(
    db: AsyncSession,
    user: User,
    expire_hours: int = 24,
) -> str:
    await invalidate_user_reset_tokens(db, user.id)
    token = secrets.token_urlsafe(32)
    db.add(
        PasswordResetToken(
            user_id=user.id,
            token=token,
            expires_at=_token_expires_at(expire_hours),
        )
    )
    await db.flush()
    return token


async def verify_password_reset_token(db: AsyncSession, token: str) -> User | None:
    value = (token or "").strip()
    if not value:
        return None

    result = await db.execute(
        select(PasswordResetToken, User)
        .join(User, User.id == PasswordResetToken.user_id)
        .where(PasswordResetToken.token == value)
    )
    row = result.first()
    if not row:
        return None

    record, user = row
    if record.expires_at < datetime.utcnow():
        await db.delete(record)
        await db.flush()
        return None

    await db.delete(record)
    await db.flush()
    return user