@using System.Net.Http.Json
@using System.Text.RegularExpressions
@using Telerik.Blazor.Extensions
@using WasmApp.Shared
@inject HttpClient Http

<TelerikGrid Data=@GridData
             Height="460px"
             RowHeight="60"
             PageSize="10"
             Pageable="true"
             Sortable="true"
             FilterMode="@GridFilterMode.FilterRow"
             SortMode="@SortMode.Multiple"
             OnRead=@ReadItems
             TotalCount=@Total>
    <GridColumns>
        <GridColumn Field="ProductID" />
        <GridColumn Field="ProductName" />
        <GridColumn Field="Discontinued" />
    </GridColumns>
</TelerikGrid>

@code{
    public List<ODataProduct> GridData { get; set; } = new List<ODataProduct>();
    public int Total { get; set; } = 0;

    protected async Task ReadItems(GridReadEventArgs args)
    {
        var baseUrl = "https://demos.telerik.com/kendo-ui/service-v4/odata/Products?";

        string OdataUrl = args.Request.ToODataString();

        // replace the original orederby clause with one that contains all the order rules
        Regex x = new Regex("(orderby=)(.*?)(&)", RegexOptions.IgnoreCase);
        string actualOrderByClause = "orderby=";

        for (int i = 0; i < args.Request.Sorts.Count; i++)
        {
            if (i > 0)
            {
                actualOrderByClause += ",";
            }
            string order = args.Request.Sorts[i].SortDirection == Telerik.DataSource.ListSortDirection.Ascending ? "" : "%20desc";
            actualOrderByClause += $"{args.Request.Sorts[i].Member}{order}";
        }

        actualOrderByClause += "&";

        string OdataQueryWithMultipleOrder = x.Replace(OdataUrl, actualOrderByClause);

        //do the request as usual
        var requestUrl = $"{baseUrl}{OdataQueryWithMultipleOrder}";

        ODataResponseOrders response = await Http.GetFromJsonAsync<ODataResponseOrders>(requestUrl);

        GridData = response.Products;
        Total = response.Total;
    }
}

<TelerikGrid Data=@MyData EditMode="@GridEditMode.Inline" Pageable="true" Height="500px" Navigable="true"
             OnUpdate="@UpdateHandler" OnDelete="@DeleteHandler" OnCreate="@CreateHandler" OnCancel="@CancelHandler">
    <GridToolBar>
        <GridCommandButton Command="Add" Icon="add">Add Employee</GridCommandButton>
    </GridToolBar>
    <GridColumns>
        <GridColumn Field=@nameof(SampleData.ID) Title="ID" Editable="false" />
        <GridColumn Field=@nameof(SampleData.Name) Title="Name" />
        <GridCommandColumn>
            <GridCommandButton Command="Save" Icon="save" ShowInEdit="true">Update</GridCommandButton>
            <GridCommandButton Command="Edit" Icon="edit">Edit</GridCommandButton>
            <GridCommandButton Command="Delete" Icon="delete">Delete</GridCommandButton>
            <GridCommandButton Command="Cancel" Icon="cancel" ShowInEdit="true">Cancel</GridCommandButton>
        </GridCommandColumn>
    </GridColumns>
</TelerikGrid>

@code {
        async Task UpdateHandler(GridCommandEventArgs args)
        {
            SampleData item = (SampleData)args.Item;

            if (item.ID == 0)
            {
                await CreateHandler(args);
            }
            else
            {
                // perform actual data source operations here through your service
                await MyService.Update(item);

                // update the local view-model data with the service data
                await GetGridData();

                Console.WriteLine("Update event is fired.");
            }
        }

        async Task DeleteHandler(GridCommandEventArgs args)
        {
            SampleData item = (SampleData)args.Item;

            // perform actual data source operation here through your service
            await MyService.Delete(item);

            // update the local view-model data with the service data
            await GetGridData();

            Console.WriteLine("Delete event is fired.");
        }

        async Task CreateHandler(GridCommandEventArgs args)
        {
            SampleData item = (SampleData)args.Item;

            // perform actual data source operation here through your service
            await MyService.Create(item);

            // update the local view-model data with the service data
            await GetGridData();

            Console.WriteLine("Create event is fired.");
        }

        async Task CancelHandler(GridCommandEventArgs args)
        {
            SampleData item = (SampleData)args.Item;

            // if necessary, perform actual data source operation here through your service

            Console.WriteLine("Cancel event is fired.");
        }


    // in a real case, keep the models in dedicated locations, this is just an easy to copy and see example
    public class SampleData
    {
        public int ID { get; set; }
        public string Name { get; set; }
    }

    public List<SampleData> MyData { get; set; }

    async Task GetGridData()
    {
        MyData = await MyService.Read();
    }

    protected override async Task OnInitializedAsync()
    {
        await GetGridData();
    }

    // the following static class mimics an actual data service that handles the actual data source
    // replace it with your actual service through the DI, this only mimics how the API can look like and works for this standalone page
    public static class MyService
    {
        private static List<SampleData> _data { get; set; } = new List<SampleData>();

        public static async Task Create(SampleData itemToInsert)
        {
            itemToInsert.ID = _data.Count + 1;
            _data.Insert(0, itemToInsert);
        }

        public static async Task<List<SampleData>> Read()
        {
            if (_data.Count < 1)
            {
                for (int i = 1; i < 50; i++)
                {
                    _data.Add(new SampleData()
                    {
                        ID = i,
                        Name = "Name " + i.ToString()
                    });
                }
            }

            return await Task.FromResult(_data);
        }

        public static async Task Update(SampleData itemToUpdate)
        {
            var index = _data.FindIndex(i => i.ID == itemToUpdate.ID);
            if (index != -1)
            {
                _data[index] = itemToUpdate;
            }
        }

        public static async Task Delete(SampleData itemToDelete)
        {
            _data.Remove(itemToDelete);
        }
    }
}

@page "/"

<TelerikGrid Data=@GridData
             SelectionMode="GridSelectionMode.Multiple"
             SelectedItemsChanged="@((IEnumerable<Employee> employeeList) => OnSelect(employeeList))"
             SelectedItems="@PersistedSelectedItems"
             @bind-Page="@CurrentPage"
             PageSize="@PageSize"
             Pageable="true"
             FilterMode="GridFilterMode.FilterRow"
             OnStateChanged="@((GridStateEventArgs<Employee> args) => OnStateChangedHandler(args))">
    <GridColumns>
        <GridCheckboxColumn />
        <GridColumn Field=@nameof(Employee.EmployeeId) />
        <GridColumn Field=@nameof(Employee.Name) />
        <GridColumn Field=@nameof(Employee.Team) />
    </GridColumns>
</TelerikGrid>

@if (PersistedSelectedItems != null)
{
    <ul>
        @foreach (Employee employee in PersistedSelectedItems.OrderBy(e => e.EmployeeId))
        {
            <li>
                @employee.EmployeeId
            </li>
        }
    </ul>
}

@code {
    public List<Employee> PersistedSelectedItems { get; set; } = new List<Employee>();
    int CurrentPage { get; set; }
    int PageSize { get; set; } = 5;

    private async void OnStateChangedHandler(GridStateEventArgs<Employee> args)
    {
        await Task.Delay(5000);
    }

    protected void OnSelect(IEnumerable<Employee> employees)
    {
        IEnumerable<Employee> CurrentPageEmployees = GridData.Skip(PageSize * (CurrentPage - 1)).Take(PageSize);

        if (employees == null || employees.Count() == 0)
        {
            //the user de-selected all items with the header checkbox
            PersistedSelectedItems = PersistedSelectedItems.Except(CurrentPageEmployees).ToList();
        }
        else
        {
            //handle any deselected items
            var UnselectedEmployees = CurrentPageEmployees.Except(employees);
            PersistedSelectedItems = PersistedSelectedItems.Except(UnselectedEmployees).ToList();

            //add any new items if they were not selected already
            foreach (var item in employees)
            {
                if (!PersistedSelectedItems.Contains(item))
                {
                    PersistedSelectedItems.Add(item);
                }
            }
        }
    }

    //data binding and sample data
    public List<Employee> GridData { get; set; }

    protected override void OnInitialized()
    {
        GridData = new List<Employee>();
        for (int i = 0; i < 15; i++)
        {
            GridData.Add(new Employee()
            {
                EmployeeId = i,
                Name = "Employee " + i.ToString(),
                Team = "Team " + i % 3
            });
        }
    }

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
    }
}