import os
from datetime import datetime, timedelta
from typing import Optional
import jwt
import bcrypt
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.orm import Session
from app.db.database import get_db
from app.models import models

# Password hashing setup
# We use bcrypt directly to bypass a known incompatibility between passlib and bcrypt >= 4.0.0

# JWT Setup
SECRET_KEY = os.environ.get("SECRET_KEY", "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24 * 7 # 7 days

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")

def verify_password(plain_password: str, hashed_password: str) -> bool:
    try:
        return bcrypt.checkpw(plain_password.encode('utf-8'), hashed_password.encode('utf-8'))
    except Exception:
        return False

def get_password_hash(password: str) -> str:
    salt = bcrypt.gensalt()
    return bcrypt.hashpw(password.encode('utf-8'), salt).decode('utf-8')

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        email: str = payload.get("sub")
        if email is None:
            raise credentials_exception
    except jwt.PyJWTError:
        raise credentials_exception
        
    user = db.query(models.User).filter(models.User.email == email).first()
    if user is None:
        raise credentials_exception
    return user