from datetime import datetime, timedelta
from typing import Optional
from fastapi import Request, Depends, HTTPException, status
from jose import JWTError, jwt
import bcrypt
from sqlalchemy.orm import Session
import database

# JWT Configuration (for security, in a real environment this should come from environment variables)
SECRET_KEY = "wake_on_lan_secret_key_2026_dev_mode"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 1440  # 24 hours

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) -> str:
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

# Dependency to get db session
def get_db():
    db = database.SessionLocal()
    try:
        yield db
    finally:
        db.close()

def get_current_user(request: Request, db: Session = Depends(get_db)) -> database.User:
    # We retrieve the token from the "access_token" HTTP-only cookie
    token = request.cookies.get("access_token")
    
    # Optional authorization header fallback for API clients
    if not token:
        authorization = request.headers.get("Authorization")
        if authorization and authorization.startswith("Bearer "):
            token = authorization.split(" ")[1]
            
    if not token:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="No autenticado. Por favor inicie sesión.",
            headers={"WWW-Authenticate": "Bearer"},
        )
        
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Credenciales inválidas.",
            )
    except JWTError:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Token inválido o expirado.",
        )
        
    user = db.query(database.User).filter(database.User.username == username).first()
    if user is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Usuario no encontrado.",
        )
    return user

def get_current_admin(current_user: database.User = Depends(get_current_user)) -> database.User:
    if not current_user.is_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Acceso denegado. Se requieren permisos de administrador.",
        )
    return current_user