from datetime import datetime, timedelta, timezone

import bcrypt
import jwt
from fastapi import Depends, HTTPException, Request, status
from sqlalchemy.orm import Session

from .config import settings
from .db import get_db
from .models import User

COOKIE = "budget_session"
# Ordered by what each role may change. "management" (Upper Management) sits below editor: it only
# views, downloads and emails budgets and reports, in every department.
ROLES = ("viewer", "management", "editor", "approver", "admin")


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


def verify_password(password: str, hashed: str) -> bool:
    try:
        return bcrypt.checkpw(password.encode(), hashed.encode())
    except ValueError:
        return False


def make_token(user: User) -> str:
    exp = datetime.now(timezone.utc) + timedelta(hours=settings.session_hours)
    return jwt.encode({"sub": str(user.id), "exp": exp}, settings.secret_key, algorithm="HS256")


def current_user(request: Request, db: Session = Depends(get_db)) -> User:
    token = request.cookies.get(COOKIE)
    if not token:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "not_authenticated")
    try:
        payload = jwt.decode(token, settings.secret_key, algorithms=["HS256"])
    except jwt.PyJWTError:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "not_authenticated")
    user = db.get(User, int(payload["sub"]))
    if not user or not user.active:
        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "not_authenticated")
    return user


def require(min_role: str):
    def dep(user: User = Depends(current_user)) -> User:
        if ROLES.index(user.role) < ROLES.index(min_role):
            raise HTTPException(status.HTTP_403_FORBIDDEN, "forbidden")
        return user

    return dep