import logging

import bcrypt
from sqlalchemy import func, select, update

from fabledassistant.models import async_session
from fabledassistant.models.conversation import Conversation
from fabledassistant.models.note import Note
from fabledassistant.models.setting import Setting
from fabledassistant.models.user import User

logger = logging.getLogger(__name__)


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


def verify_password(password: str, password_hash: str) -> bool:
    return bcrypt.checkpw(password.encode(), password_hash.encode())


async def get_user_count() -> int:
    async with async_session() as session:
        return await session.scalar(select(func.count(User.id))) or 0


async def create_user(
    username: str, password: str, email: str | None = None
) -> User:
    user_count = await get_user_count()
    role = "admin" if user_count == 0 else "user"

    async with async_session() as session:
        user = User(
            username=username,
            email=email,
            password_hash=hash_password(password),
            role=role,
        )
        session.add(user)
        await session.commit()
        await session.refresh(user)

        # First user claims all pre-existing data (migration assigns user_id=1,
        # which matches SERIAL first insert; also handles any NULLs)
        if role == "admin":
            await session.execute(
                update(Note)
                .where((Note.user_id.is_(None)) | (Note.user_id == user.id))
                .values(user_id=user.id)
            )
            await session.execute(
                update(Conversation)
                .where(
                    (Conversation.user_id.is_(None))
                    | (Conversation.user_id == user.id)
                )
                .values(user_id=user.id)
            )
            await session.execute(
                update(Setting)
                .where(Setting.user_id == user.id)
                .values(user_id=user.id)
            )
            # Auto-close registration after first user setup
            session.add(Setting(user_id=user.id, key="registration_open", value="false"))
            await session.commit()
            logger.info("First user '%s' created as admin, claimed orphaned data", username)

        return user


async def authenticate(username: str, password: str) -> User | None:
    async with async_session() as session:
        result = await session.execute(
            select(User).where(User.username == username)
        )
        user = result.scalars().first()
        if user and verify_password(password, user.password_hash):
            return user
        return None


async def get_user_by_id(user_id: int) -> User | None:
    async with async_session() as session:
        return await session.get(User, user_id)


async def change_password(user_id: int, current_password: str, new_password: str) -> bool:
    """Change a user's password. Returns True on success, False if current password is wrong."""
    async with async_session() as session:
        user = await session.get(User, user_id)
        if not user:
            return False
        if not verify_password(current_password, user.password_hash):
            return False
        user.password_hash = hash_password(new_password)
        await session.commit()
        logger.info("Password changed for user %d (%s)", user_id, user.username)
        return True


async def is_registration_open() -> bool:
    """Check if new user registration is allowed.

    Always open when no users exist (first-user setup).
    Otherwise reads the admin's 'registration_open' setting (default closed).
    """
    user_count = await get_user_count()
    if user_count == 0:
        return True

    async with async_session() as session:
        # Find the admin user's registration_open setting
        result = await session.execute(
            select(Setting)
            .join(User, Setting.user_id == User.id)
            .where(User.role == "admin", Setting.key == "registration_open")
        )
        setting = result.scalar_one_or_none()
        return setting.value == "true" if setting else False


async def list_users() -> list[User]:
    async with async_session() as session:
        result = await session.execute(select(User).order_by(User.created_at))
        return list(result.scalars().all())


async def delete_user(user_id: int) -> bool:
    async with async_session() as session:
        user = await session.get(User, user_id)
        if not user:
            return False
        await session.delete(user)
        await session.commit()
        logger.info("Deleted user %d (%s)", user_id, user.username)
        return True


async def set_registration_open(admin_user_id: int, open: bool) -> None:
    from fabledassistant.services.settings import set_setting
    await set_setting(admin_user_id, "registration_open", "true" if open else "false")