using System;

using System.Collections.Generic;

using System.Globalization;

using System.Linq;



namespace Foundation

{

    /// <summary>

    /// Adds pagination information to a collection.

    /// </summary>

    /// <typeparam name="T"></typeparam>

    public class PaginatedCollection<T> : List<T>, IPaginatedCollection<T>

    {

        const int defaultPageSize = 25;



        protected readonly IList<string> pages;



        /// <summary>

        /// Gets or sets the current page number.

        /// </summary>

        /// <value>The page.</value>

        public int Page { get; private set; }



        /// <summary>

        /// Gets or sets the number of records to return per page.

        /// </summary>

        /// <value>The size of the page.</value>

        public int PageSize { get; private set; }



        /// <summary>

        /// Gets the total number of records.

        /// </summary>

        /// <value>The record count.</value>

        public int RecordCount { get; private set; }



        /// <summary>

        /// Gets the total number of pages.

        /// </summary>

        /// <value>The page count.</value>

        public int PageCount { get; private set; }

        

        /// <summary>

        /// Initializes a new instance of the <see cref="PaginatedCollection&lt;T&gt;"/> class.

        /// </summary>

        public PaginatedCollection()

        {

            Page = 1;

            PageSize = defaultPageSize;

            RecordCount = 0;

            PageCount = 1;

        }



        /// <summary>

        /// Initializes a new instance of the <see cref="PaginatedCollection&lt;T&gt;"/> class.

        /// </summary>

        /// <param name="source">The source.</param>

        /// <param name="page">The page.</param>

        /// <param name="pageSize">Size of the page.</param>

        public PaginatedCollection(IEnumerable<T> source, int page, int pageSize) : this(source, page, pageSize, source.Count()){}



        /// <summary>

        /// Initializes a new instance of the <see cref="PaginatedCollection&lt;T&gt;"/> class.

        /// </summary>

        /// <param name="source">The source.</param>

        /// <param name="page">The page.</param>

        /// <param name="pageSize">Size of the page.</param>

        /// <param name="recordCount">The record count.</param>

        public PaginatedCollection(IEnumerable<T> source, int page, int pageSize, int recordCount)

        {

            Page = page;

            PageSize = pageSize;

            RecordCount = recordCount;

            PageCount = (int)Math.Ceiling(RecordCount / (double)PageSize);



            // Don't skip if there's not enough records. This can happen if we've already been passed

            // the page data rather than the whole list

            var skip = source.Count() <= pageSize ? 0 : (Page - 1) * PageSize;



            // Default page names

            pages = Enumerable.Range(1, PageCount).ToList().ConvertAll(input => input.ToString(CultureInfo.CurrentCulture));



            AddRange(source.Skip(skip).Take(pageSize));

        }



        /// <summary>

        /// Gets a value indicating whether there is a page of results preceding this one.

        /// </summary>

        /// <value>

        /// 	<c>true</c> if this instance has a previous page; otherwise, <c>false</c>.

        /// </value>

        public bool HasPreviousPage { get { return Page > 1; } }



        /// <summary>

        /// Gets a value indicating whether there is another page of results following this one.

        /// </summary>

        /// <value>

        /// 	<c>true</c> if this instance has a next page; otherwise, <c>false</c>.

        /// </value>

        public bool HasNextPage { get { return (Page < PageCount); } }

        

        /// <summary>

        /// A collection of names for the pages. Usually this defaults to the page numbers but can

        /// be changed depending on the pagination strategy, i.e. alphabetical names for alphabetical pagination

        /// </summary>

        public IEnumerable<string> PageNames

        {

            get { return pages; }

        }

    }

}