using System;

using System.Runtime.Serialization;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

namespace SmartStore.Core

{

/// <summary>

/// A collection of objects that has been split into pages.

/// </summary>

public interface IPageable : IEnumerable

{

/// <summary>

/// The 0-based current page index

/// </summary>

[DataMember]

int PageIndex { get; set; }

/// <summary>

/// The number of items in each page.

/// </summary>

[DataMember]

int PageSize { get; set; }

/// <summary>

/// The total number of items.

/// </summary>

[DataMember]

int TotalCount { get; set; }

/// <summary>

/// The 1-based current page index

/// </summary>

[DataMember]

int PageNumber { get; set; }

/// <summary>

/// The total number of pages.

/// </summary>

[DataMember]

int TotalPages { get; }

/// <summary>

/// Whether there are pages before the current page.

/// </summary>

bool HasPreviousPage { get; }

/// <summary>

/// Whether there are pages after the current page.

/// </summary>

bool HasNextPage { get; }

/// <summary>

/// The 1-based index of the first item in the page.

/// </summary>

[DataMember]

int FirstItemIndex { get; }

/// <summary>

/// The 1-based index of the last item in the page.

/// </summary>

[DataMember]

int LastItemIndex { get; }

/// <summary>

/// Whether the page is the first page

/// </summary>

bool IsFirstPage { get; }

/// <summary>

/// Whether the page is the last page

/// </summary>

bool IsLastPage { get; }

}

/// <summary>

/// Paged list interface

/// </summary>

public interface IPagedList<T> : IPageable, IList<T>

{

/// <summary>

/// Gets underlying query without any paging applied

/// </summary>

IQueryable<T> SourceQuery { get; }

/// <summary>

/// Allows modification of the underlying query before it is executed.

/// </summary>

/// <param name="alterer">The alteration function. The underlying query is passed, the modified query should be returned.</param>

/// <returns>The current instance for chaining</returns>

IPagedList<T> AlterQuery(Func<IQueryable<T>, IQueryable<T>> alterer);

/// <summary>

/// Applies the initial paging arguments to the passed query

/// </summary>

/// <param name="query">The query</param>

/// <returns>A query with applied paging args</returns>

IQueryable<T> ApplyPaging(IQueryable<T> query);

/// <summary>

/// Loads the data synchronously.

/// </summary>

/// <param name="force">When <c>true</c>, always reloads data. When <c>false</c>, first checks to see whether data has been loaded already and skips if so.</param>

/// <returns>Returns itself for chaining.</returns>

IPagedList<T> Load(bool force = false);

/// <summary>

/// Loads the data asynchronously.

/// </summary>

/// <param name="force">When <c>true</c>, always reloads data. When <c>false</c>, first checks to see whether data has been loaded already and skips if so.</param>

/// <returns>Returns itself for chaining.</returns>

Task<IPagedList<T>> LoadAsync(bool force = false);

}

}