from datetime import datetime, timedelta, timezone

import bcrypt
import jwt
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import settings
from app.models.user import User


def hash_password(plain: str) -> str:
    return bcrypt.hashpw(plain.encode(), bcrypt.gensalt()).decode()


def verify_password(plain: str, hashed: str) -> bool:
    return bcrypt.checkpw(plain.encode(), hashed.encode())


def create_access_token(user_id: str, remember_me: bool = False) -> str:
    minutes = settings.JWT_EXPIRE_REMEMBER_MINUTES if remember_me else settings.JWT_EXPIRE_MINUTES
    expire = datetime.now(timezone.utc) + timedelta(minutes=minutes)
    payload = {"sub": user_id, "exp": expire}
    return jwt.encode(payload, settings.SECRET_KEY, algorithm=settings.JWT_ALGORITHM)


def decode_access_token(token: str) -> str | None:
    """Decode JWT and return user_id, or None if invalid."""
    try:
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=[settings.JWT_ALGORITHM]
        )
        return payload.get("sub")
    except jwt.PyJWTError:
        return None


async def authenticate_user(
    db: AsyncSession, username: str, password: str
) -> User | None:
    result = await db.execute(select(User).where(User.username == username))
    user = result.scalar_one_or_none()
    if not user:
        # Try phone number lookup for frontend users
        result = await db.execute(select(User).where(User.phone == username))
        user = result.scalar_one_or_none()
    if not user or not verify_password(password, user.hashed_password):
        return None
    if not user.is_active:
        return None
    return user