using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

​

namespace SmartVideoLibrary

{

​

    public class PageHelper

    {

​

        public static int stc_displayPageButtonCount = 6; //寫死6個，可以改

        public delegate string PageButtonUrlStringFormatMethod(int pageIndex);

​

        /// <summary>

        /// 建構式

        /// </summary>

        /// <param name="currentPageIndx">目前所在的pageIndex, 1based</param>

        /// <param name="pageSize">每一頁的row個數</param>

        /// <param name="totalRowCount">資料總row個數</param>

        public PageHelper(

            int currentPageIndx, 

            int pageSize, 

            int totalRowCount,

            PageButtonUrlStringFormatMethod func

        )

        {

            _currentPageIndx = currentPageIndx;

            _pageSize = pageSize;            

            _totalRowCount= totalRowCount;

            _func = func;

​

            //calc

            _maxPageIndex = totalRowCount / _pageSize + 1;

            _lastPageBlockIndex = totalRowCount / (stc_displayPageButtonCount * _pageSize) + 1;

            _pageBlockIndex = ((_currentPageIndx -1) / stc_displayPageButtonCount) + 1;

            _startPageIndex = (_pageBlockIndex - 1) * stc_displayPageButtonCount + 1;

            _endPageIndex = (_startPageIndex + stc_displayPageButtonCount -1) < _maxPageIndex ? (_startPageIndex + stc_displayPageButtonCount - 1) : _maxPageIndex;

​

            _isDisplayPrevBtn = _pageBlockIndex != 1;

            _isDisplayNextBtn = _pageBlockIndex != _lastPageBlockIndex;

        }

​

        public string Render()

        {

            string html = string.Empty;

            html += "<nav class=\"clearfix text-center\"><ul class=\"pagination\">";

​

            if (_isDisplayPrevBtn)

            {

                html += string.Format("<li><a href=\"{0}\"><<</a></li>", _func(_startPageIndex-1), _startPageIndex -1);

            }

​

​

            for(int i = _startPageIndex; i <= _endPageIndex; i++)

            {

                //i從目前activePageIndex到最大按鈕數

                if(i != _currentPageIndx)

                {

                    html += string.Format("<li><a href=\"{0}\">{1}</a></li>", _func(i), i);

                }

                else

                {

                    html += string.Format("<li><a class=\"active\" href =\"{0}\">{1}</a></li>", _func(i), i);

                }

            }

​

            if (_isDisplayNextBtn)

            {

                html += string.Format("<li><a href=\"{0}\">>></a></li>", _func(_endPageIndex+1), _endPageIndex+1);

            }

​

            html += "</ul></nav>";

​

            return html;

        }

​

        int _currentPageIndx;

        int _pageSize;

        int _totalRowCount;

        private int _maxPageIndex; //最大maxPageIndex

        private int _pageBlockIndex; //頁面段index

​

        PageButtonUrlStringFormatMethod _func;

        private int _startPageIndex; //開始頁面index

        private int _endPageIndex; //結束頁面index

        private bool _isDisplayPrevBtn;

        private bool _isDisplayNextBtn;

        private int _lastPageBlockIndex;

    }

}

​