app/auth.py

import jwt
import os
import time
from fastapi import HTTPException, Security
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from passlib.context import CryptContext
from pydantic import BaseModel

# Secret key for JWT signing. In production, this must be a secure random string loaded from .env
# For this deployment, we use a fallback to ensure it works out of the box if missing.
SECRET_KEY = os.getenv("JWT_SECRET", "kia_shqiperia_2026_super_secret_key_12345")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 60 * 24 * 7  # 7 days

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

# Hardcoded Access Codes mapping to roles (for the C4ISR prototype)
# In a real deployed system, these would be in a DB mapped to user emails.
ROLE_CREDENTIALS = {
    "visitor": "",              # no password required for unclassified
    "officer": "oficer2025",
    "commander": "komanda2025",
    "general": "kia_gjeneral"
}

class LoginRequest(BaseModel):
    role: str
    access_code: str = ""

def verify_password(plain_password, target_password):
    # Standard string comparison for demo. In production, use pwd_context.verify
    return plain_password == target_password

def create_access_token(data: dict, expires_delta: int = ACCESS_TOKEN_EXPIRE_MINUTES):
    to_encode = data.copy()
    expire = time.time() + (expires_delta * 60)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def authenticate_role(role: str, access_code: str):
    if role not in ROLE_CREDENTIALS:
        return False
        
    expected_code = ROLE_CREDENTIALS[role]
    if expected_code == "" or verify_password(access_code, expected_code):
        return True
    return False

def verify_token(credentials: HTTPAuthorizationCredentials = Security(security)):
    """FastAPI Depends function that extracts and validates the JWT, returning the role."""
    token = credentials.credentials
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        role: str = payload.get("role")
        if role is None:
            raise HTTPException(status_code=401, detail="Token i pavlefshëm (Rol nuk gjendet)")
        
        # Check expiration manually since pyjwt does it too, but just to be safe
        exp = payload.get("exp")
        if exp and time.time() > exp:
            raise HTTPException(status_code=401, detail="Sesioni ka skaduar")
            
        return role
    except jwt.ExpiredSignatureError:
        raise HTTPException(status_code=401, detail="Sesioni ka skaduar. Ju lutem mbyllni dhe hyni përsëri.")
    except jwt.PyJWTError:
        raise HTTPException(status_code=401, detail="Lidhje e paautorizuar. Kërkohet verifikim kredencialesh.")