from datetime import datetime, timedelta, timezone

import bcrypt
import jwt
from sqlalchemy import or_, 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 | None) -> bool:
    if not hashed:
        return False
    try:
        return bcrypt.checkpw(plain.encode(), hashed.encode())
    except Exception:
        return False


def create_access_token(user_id: str, remember_me: bool = False, token_version: int = 0) -> 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, "ver": token_version}
    return jwt.encode(payload, settings.SECRET_KEY, algorithm=settings.JWT_ALGORITHM)


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


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

    result = await db.execute(
        select(User)
        .where(or_(User.username == value, User.phone == value))
        .limit(1)
    )
    return result.scalar_one_or_none()


async def get_user_by_phone(db: AsyncSession, phone: str) -> User | None:
    result = await db.execute(select(User).where(User.phone == phone).limit(1))
    return result.scalar_one_or_none()


async def authenticate_user(
    db: AsyncSession, username: str, password: str
) -> User | None:
    user = await get_user_by_username_or_phone(db, username)
    if not user or not verify_password(password, user.hashed_password):
        return None
    if not user.is_active:
        return None
    return user


def user_must_set_password(user: User | None) -> bool:
    return bool(user and user.user_type == "frontend" and not user.hashed_password)