// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

namespace CommunityToolkit.Common.Collections;

/// <summary>
/// This interface represents a data source whose items can be loaded incrementally.
/// </summary>
/// <typeparam name="TSource">Type of collection element.</typeparam>
public interface IIncrementalSource<TSource>
{
    /// <summary>
    /// This method is invoked every time the view need to show more items. Retrieves items based on <paramref name="pageIndex"/> and <paramref name="pageSize"/> arguments.
    /// </summary>
    /// <param name="pageIndex">
    /// The zero-based index of the page that corresponds to the items to retrieve.
    /// </param>
    /// <param name="pageSize">
    /// The number of <typeparamref name="TSource"/> items to retrieve for the specified <paramref name="pageIndex"/>.
    /// </param>
    /// <param name="cancellationToken">
    /// Used to propagate notification that operation should be canceled.
    /// </param>
    /// <returns>
    /// Returns a collection of <typeparamref name="TSource"/>.
    /// </returns>
    Task<IEnumerable<TSource>> GetPagedItemsAsync(int pageIndex, int pageSize, CancellationToken cancellationToken = default(CancellationToken));
}