from datetime import datetime, timedelta
from typing import Annotated

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from passlib.context import CryptContext
from sqlalchemy.orm import Session

from app.config import settings
from app.database import get_db
from app.models.user import User, UserRole
from app.schemas import TokenData

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


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


def create_access_token(data: dict, expires_delta: timedelta | None = None) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + (
        expires_delta or timedelta(minutes=settings.access_token_expire_minutes)
    )
    to_encode.update({"exp": expire})
    return jwt.encode(to_encode, settings.secret_key, algorithm=settings.algorithm)


def get_user_by_username(db: Session, username: str) -> User | None:
    return db.query(User).filter(User.username == username).first()


def get_user_by_email(db: Session, email: str) -> User | None:
    return db.query(User).filter(User.email == email).first()


def authenticate_user(db: Session, username: str, password: str) -> User | None:
    user = get_user_by_username(db, username)
    if not user or not verify_password(password, user.hashed_password):
        return None
    return user


async def get_current_user(
    token: Annotated[str, Depends(oauth2_scheme)],
    db: Annotated[Session, Depends(get_db)],
) -> User:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(
            token, settings.secret_key, algorithms=[settings.algorithm]
        )
        username: str | None = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except JWTError:
        raise credentials_exception

    user = get_user_by_username(db, username=token_data.username)
    if user is None:
        raise credentials_exception
    if not user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return user


async def get_current_admin(
    current_user: Annotated[User, Depends(get_current_user)],
) -> User:
    if current_user.role != UserRole.admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Admin privileges required",
        )
    return current_user