@using Telerik.DataSource

<p>Group by a third column, so that it should come last in the Group Panel:</p>

<TelerikGrid @ref="@GridRef"
             Data="@GridData"
             Pageable="true"
             Sortable="true"
             Groupable="true"
             FilterMode="GridFilterMode.FilterRow"
             OnStateInit="@( (GridStateEventArgs<Employee> args) => OnGridStateInit(args) )"
             OnStateChanged="@( (GridStateEventArgs<Employee> args) => OnGridStateChanged(args) )">
    <GridColumns>
        <GridColumn Field="@nameof(Employee.Name)" />
        <GridColumn Field="@nameof(Employee.Team)" />
        <GridColumn Field="@nameof(Employee.Salary)" />
        <GridColumn Field="@nameof(Employee.OnVacation)" />
    </GridColumns>
</TelerikGrid>

@code {
    private TelerikGrid<Employee>? GridRef { get; set; }

    private List<Employee> GridData { get; set; } = new();

    private void OnGridStateInit(GridStateEventArgs<Employee> args)
    {
        args.GridState.GroupDescriptors = new List<GroupDescriptor>();

        args.GridState.GroupDescriptors.Add(new GroupDescriptor()
        {
            Member = nameof(Employee.Team),
            MemberType = typeof(string)
        });

        args.GridState.GroupDescriptors.Add(new GroupDescriptor()
        {
            Member = nameof(Employee.OnVacation),
            MemberType = typeof(bool)
        });
    }

    private async Task OnGridStateChanged(GridStateEventArgs<Employee> args)
    {
        if (args.PropertyName == "GroupDescriptors" && args.GridState.GroupDescriptors.Count > 2 && GridRef != null)
        {
            var secondGroupDescriptor = args.GridState.GroupDescriptors.ElementAt(1);

            args.GridState.GroupDescriptors.Remove(secondGroupDescriptor);
            args.GridState.GroupDescriptors.Add(secondGroupDescriptor);

            await GridRef.SetStateAsync(args.GridState);
        }
    }

    protected override void OnInitialized()
    {
        var rnd = new Random();

        for (int i = 1; i <= 20; i++)
        {
            GridData.Add(new Employee()
            {
                Id = i,
                Name = "Name " + i,
                Team = "Team " + (i % 4 + 1),
                Salary = (decimal)rnd.Next(1000, 3000),
                OnVacation = i % 3 == 0
            });
        }
    }

    public class Employee
    {
        public int Id { get; set; }
        public string Name { get; set; } = string.Empty;
        public string Team { get; set; } = string.Empty;
        public decimal Salary { get; set; }
        public bool OnVacation { get; set; }
    }
}