refactor: improve code structure and optimize key functions

backend/app/core/security.py

@@ -0,0 +1,30 @@
+from datetime import datetime, timedelta, timezone
+from typing import Any, Dict, Optional
+
+from fastapi import HTTPException, status
+from fastapi.security import OAuth2PasswordBearer
+from jose import JWTError, jwt
+
+from app.core.config import settings
+
+
+ALGORITHM = "HS256"
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login", scheme_name="Bearer")
+
+
+def create_access_token(*, subject: str, role: str, expires_delta: Optional[timedelta] = None) -> str:
+    expire = datetime.now(timezone.utc) + (expires_delta or timedelta(minutes=settings.JWT_EXPIRE_MINUTES))
+    to_encode: Dict[str, Any] = {"sub": subject, "role": role, "exp": expire}
+    return jwt.encode(to_encode, settings.JWT_SECRET_KEY, algorithm=ALGORITHM)
+
+
+def decode_access_token(token: str) -> Dict[str, Any]:
+    try:
+        payload = jwt.decode(token, settings.JWT_SECRET_KEY, algorithms=[ALGORITHM])
+    except JWTError as exc:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Could not validate credentials",
+            headers={"WWW-Authenticate": "Bearer"},
+        ) from exc
+    return payload