feat: main.py refresh token add

main.py

@@ -109,6 +109,33 @@ async def login(request: Request, form_data: OAuth2PasswordRequestForm = Depends
         logging.error(f"Login error: {str(e)}")
         raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="Internal server error")
 
+@app.post("/refresh", response_model=TokenResponse)
+async def refresh(refresh_request: RefreshTokenRequest):
+    try:
+        # Verify the refresh token
+        username = verify_token(refresh_request.refresh_token, REFRESH_SECRET_KEY)
+        
+        # Create new access token
+        access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+        access_token = create_token(
+            data={"sub": username},
+            expires_delta=access_token_expires,
+            secret_key=SECRET_KEY
+        )
+        
+        return {
+            "access_token": access_token,
+            "refresh_token": refresh_request.refresh_token,  # Return the same refresh token
+            "token_type": "bearer"
+        }
+        
+    except JWTError:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Could not validate credentials",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+        
 # Apply Rate Limiting on Generate API (Limit: 3 requests per 10 seconds)
 @app.post("/generate")
 @limiter.limit("3/10seconds")