import os
from datetime import datetime, timedelta
from typing import Optional
from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from jose import JWTError, jwt
from passlib.context import CryptContext
from sqlalchemy.orm import Session
from backend.database import get_db, User

SECRET_KEY = os.environ.get("SECRET_KEY", "platform-secret-key-change-in-production-2024")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60
REFRESH_TOKEN_EXPIRE_DAYS = 30

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


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: Optional[timedelta] = None) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + (expires_delta or timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES))
    to_encode.update({"exp": expire, "type": "access"})
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)


def create_refresh_token(data: dict) -> str:
    to_encode = data.copy()
    expire = datetime.utcnow() + timedelta(days=REFRESH_TOKEN_EXPIRE_DAYS)
    to_encode.update({"exp": expire, "type": "refresh"})
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)


def decode_token(token: str) -> dict:
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        return payload
    except JWTError:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")


async def get_current_user(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db)
) -> User:
    token = credentials.credentials
    payload = decode_token(token)
    user_id = payload.get("sub")
    if not user_id:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token payload")
    user = db.query(User).filter(User.id == user_id).first()
    if not user or not user.is_active:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found or inactive")
    return user