import uuid
from typing import Sequence

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

from app.core.security import hash_password
from app.models.user import User
from app.schemas.user import UserCreate, UserUpdate


async def get_by_username(db: AsyncSession, username: str) -> User | None:
    result = await db.execute(select(User).where(User.username == username))
    return result.scalar_one_or_none()


async def get_by_id(db: AsyncSession, user_id: uuid.UUID) -> User | None:
    result = await db.execute(select(User).where(User.id == user_id))
    return result.scalar_one_or_none()


async def create_user(db: AsyncSession, user_in: UserCreate) -> User:
    user = User(
        username=user_in.username,
        hashed_password=hash_password(user_in.password),
        role=user_in.role,
        is_active=True,
    )
    db.add(user)
    await db.commit()
    await db.refresh(user)
    return user


async def update_user(db: AsyncSession, user: User, user_in: UserUpdate) -> User:
    update_data = {}
    if user_in.role is not None:
        update_data["role"] = user_in.role
    if user_in.is_active is not None:
        update_data["is_active"] = user_in.is_active
    if user_in.password:
        update_data["hashed_password"] = hash_password(user_in.password)

    if update_data:
        await db.execute(
            update(User)
            .where(User.id == user.id)
            .values(**update_data)
        )
        await db.commit()
    await db.refresh(user)
    return user


async def list_users(db: AsyncSession, skip: int = 0, limit: int = 100) -> Sequence[User]:
    result = await db.execute(select(User).offset(skip).limit(limit))
    return result.scalars().all()


async def ensure_admin_exists(db: AsyncSession, *, default_password: str = "admin123") -> None:
    result = await db.execute(select(User).where(User.username == "admin"))
    admin = result.scalar_one_or_none()
    if admin:
        return
    new_admin = User(
        username="admin",
        hashed_password=hash_password(default_password),
        role="ADMIN",
        is_active=True,
    )
    db.add(new_admin)
    await db.commit()