import os
import secrets

from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from passlib.context import CryptContext
from sqlalchemy import select
from sqlalchemy.orm import Session

from database import get_db
from models import User

security = HTTPBasic()
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")


def hash_password(password: str) -> str:
    return pwd_context.hash(password)


def verify_password(password: str, password_hash: str) -> bool:
    return pwd_context.verify(password, password_hash)


def ensure_default_admin(db: Session) -> None:
    username = os.getenv("ADMIN_USERNAME", "admin")
    password = os.getenv("ADMIN_PASSWORD", "admin")
    existing = db.scalar(select(User).where(User.username == username))
    if existing:
        return
    db.add(User(username=username, password_hash=hash_password(password), role="admin"))
    db.commit()


def get_current_user(
    credentials: HTTPBasicCredentials = Depends(security),
    db: Session = Depends(get_db),
) -> User:
    user = db.scalar(select(User).where(User.username == credentials.username))
    if not user or not verify_password(credentials.password, user.password_hash):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid credentials",
            headers={"WWW-Authenticate": "Basic"},
        )
    if not secrets.compare_digest(user.username, credentials.username):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid credentials")
    return user


def require_manager(user: User = Depends(get_current_user)) -> User:
    if user.role not in {"admin", "manager"}:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Manager access required")
    return user


def require_admin(user: User = Depends(get_current_user)) -> User:
    if user.role != "admin":
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Admin access required")
    return user