Как получить сумму заказов у каждого пользователя. Объединение объектов списка по критерию

modelBuilder.Entity<User>().HasData(
    new User[]
    {
        new User { Id=1, Email="user1@gmail.com", Status=UserStatus.Active},
        new User { Id=2, Email="user2@gmail.com", Status=UserStatus.Active},
        new User { Id=3, Email="user3@gmail.com", Status=UserStatus.Inactive},
        new User { Id=4, Email="user4@gmail.com", Status=UserStatus.Active},
        new User { Id=5, Email="user5@gmail.com", Status=UserStatus.Active},
        new User { Id=6, Email="user6@gmail.com", Status=UserStatus.Inactive},
        new User { Id=7, Email="user7@gmail.com", Status=UserStatus.Active},
    });
 
modelBuilder.Entity<Order>().HasData(
    new Order[]
    {
        new Order {Id=1, ProductName="Apple", Price=10, Quantity=130, UserId=1, CreatedAt=new DateTime(2003, 7, 28, 12, 0, 0), Status=OrderStatus.Created},
        new Order {Id=2, ProductName="Lemon", Price=30, Quantity=2, UserId=1, CreatedAt=new DateTime(2004, 5, 31, 12, 0, 0), Status=OrderStatus.Delivered},
        new Order {Id=3, ProductName="Cucumber", Price=5, Quantity=10, UserId=1, CreatedAt=new DateTime(2010, 6, 1, 12, 0, 0), Status=OrderStatus.Paid},
        new Order {Id=4, ProductName="Cabbage", Price=7, Quantity=2, UserId=2, CreatedAt=new DateTime(2023, 8, 8, 12, 0, 0), Status=OrderStatus.Delivered},
        new Order {Id=5, ProductName="Onion", Price=8, Quantity=6, UserId=2, CreatedAt=new DateTime(2019, 1, 1, 12, 0, 0), Status=OrderStatus.PaymentFailed},
        new Order {Id=6, ProductName="Carrot", Price=9, Quantity=5, UserId=2, CreatedAt=new DateTime(2020, 9, 10, 12, 0, 0), Status=OrderStatus.Delivered},
        new Order {Id=7, ProductName="Mango", Price=40, Quantity=2, UserId=3, CreatedAt=new DateTime(2010, 11, 13, 12, 0, 0), Status=OrderStatus.PaymentFailed},
        new Order {Id=8, ProductName="Orange", Price=45, Quantity=5, UserId=4, CreatedAt=new DateTime(2003, 3, 3, 12, 0, 0), Status=OrderStatus.Delivered},
        new Order {Id=9, ProductName="Watermelon", Price=100, Quantity=1, UserId=4, CreatedAt=new DateTime(2024, 3, 8, 12, 0, 0), Status=OrderStatus.Delivered},
        new Order {Id=10, ProductName="Garlic", Price=8, Quantity=12, UserId=4, CreatedAt=new DateTime(2019, 5, 14, 12, 0, 0), Status=OrderStatus.Delivered},
        new Order {Id=11, ProductName="Potato", Price=3, Quantity=100, UserId=7, CreatedAt=new DateTime(2010, 1, 1, 12, 0, 0), Status=OrderStatus.Paid},
        new Order {Id=12, ProductName="Carrot", Price=9, Quantity=15, UserId=7, CreatedAt=new DateTime(2006, 9, 1, 12, 0, 0), Status=OrderStatus.PaymentFailed},
        new Order {Id=13, ProductName="Onion", Price=8, Quantity=15, UserId=7, CreatedAt=new DateTime(2003, 5, 30, 12, 0, 0), Status=OrderStatus.Delivered},
        new Order {Id=14, ProductName="Pumpkin", Price=50, Quantity=1, UserId=7, CreatedAt=new DateTime(2021, 6, 11, 12, 0, 0), Status=OrderStatus.Paid},
        new Order {Id=15, ProductName="Watermelon", Price=100, Quantity=12, UserId=7, CreatedAt=new DateTime(2003, 12, 21, 12, 0, 0), Status=OrderStatus.Delivered},
    });

public class UserService : IUserService 
{
 
  private readonly ApplicationDbContext? _context;
 
  public UserService(ApplicationDbContext? context) => _context = context;
 
  async Task<User> IUserService.GetUser()         //return a User with max total sum of orders
  {
      List<(int, int)> pricesSumByUsers = new();
  
      DateTime date = new DateTime(2003, 1, 1, 0, 0, 0);
  
      if (_context != null)
      {
          await foreach (User user in _context.Users)
          {
              int pricesSumByUser = 0;                   
              await foreach (Order order in _context.Orders)
              {
                  if (order.UserId == user.Id
                      && order.Status == OrderStatus.Delivered
                      && order.CreatedAt >= date)
                  {
                      pricesSumByUser += order.Price;
                  }
                  pricesSumByUsers.Add((pricesSumByUser, user.Id));
              }
          }
      }
 
      User userMax = new User();                  //stub
      return userMax;
}

async Task<User?> IUserService.GetUser()
{
    DateTime date = new DateTime(2003, 1, 1, 0, 0, 0);
    return await _context.Users.Select(u => new {
        User = u,
        Total = u.Orders.Where(o => o.Status == OrderStatus.Delivered && o.CreatedAt >= date).Sum(o => o.Price)
    })
    .OrderByDescending(_ => _.Total)
    .Select(_ => _.User)
    .FirstOrDefaultAsync();
}