using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Web;
namespace CP.Common
{
    /// <summary>
    /// 通用分页方法
    /// 支持UrlRewrite
    /// </summary>
    public class ShowPageList
    {

        /// <summary>
        /// 通用分页方法
        /// </summary>
        /// <param name="pagesize">每页条数</param>
        /// <param name="page">页码</param>
        /// <param name="recordcount">记录总数</param>
        /// <param name="rewriter">重写规则</param>
        /// <returns></returns>
        public static string PageList(int pagesize, int page, int recordcount, string rewriter = null, bool first = true)
        {

            System.Text.StringBuilder sb = new System.Text.StringBuilder();

            if (recordcount == 0)
                return "";

            int pagecount = 0;
            if (recordcount % pagesize == 0)
                pagecount = recordcount / pagesize;
            else
                pagecount = recordcount / pagesize + 1;
            if (first)
                sb.Append("<a href=\"" + GetLink(1, rewriter) + "\" class=\"next\">第一页</a>");
            if (page > 1)
                sb.Append("<a href=\"" + GetLink((page - 1), rewriter) + "\" class=\"next\">上一页</a>");
            else
                sb.Append("<a href=\"" + GetLink(1, rewriter) + "\" class=\"next\">上一页</a>");


            ///显示1,2,3,4,5的链接
            if (pagecount < 5)
            {
                for (int i = 1; i <= pagecount; i++)
                {
                    if (i != page)
                        sb.Append("<a href=\"" + GetLink(i, rewriter) + "\">" + i + "</a>");
                    else
                        sb.Append("<a class=\"tab\">" + i + "</a>");
                }
            }
            else
            {
                if (page < 5)
                {
                    for (int i = 1; i <= 5; i++)
                    {
                        if (i != page)
                            sb.Append("<a href=\"" + GetLink(i, rewriter) + "\">" + i + "</a>");
                        else
                            sb.Append("<a class=\"tab\">" + i + "</a>");
                    }
                }
                else
                {
                    if (page + 3 <= pagecount)
                    {
                        for (int i = page - 2; i < page + 2; i++)
                        {
                            if (i != page)
                                sb.Append("<a href=\"" + GetLink(i, rewriter) + "\">" + i + "</a>");
                            else
                                sb.Append("<a class=\"tab\">" + i + "</a>");
                        }
                    }
                    else
                    {
                        for (int i = pagecount - 2; i <= pagecount; i++)
                        {
                            if (i != page)
                                sb.Append("<a href=\"" + GetLink(i, rewriter) + "\">" + i + "</a>");
                            else
                                sb.Append("<a class=\"tab\">" + i + "</a>");
                        }
                    }
                }
            }

            if (page < pagecount)
                sb.Append("<a href=\"" + GetLink((page + 1), rewriter) + "\" class=\"next\">下一页</a>");
            else
                sb.Append("<a href=\"" + GetLink(pagecount, rewriter) + "\" class=\"next\">下一页</a>");

            if (first)
            {
                if (pagecount == 0)
                    sb.Append("<a href=\"" + GetLink(1, rewriter) + "\">末尾页</a>");
                else
                    sb.Append("<a href=\"" + GetLink(pagecount, rewriter) + " \" class=\"next\">末尾页</a>");
            }
            sb.Append("<a class=\"next\">"+page+"/" + pagecount + "</a>");

            return sb.ToString();
        }

        private static string GetLink(int page, string rewriter)
        {
            //目前只支持如：rewriter="topic-xxxx-{0}.html"的重写
            string link = string.Empty;
            string url = string.Empty;
            if (!string.IsNullOrEmpty(rewriter))  //url重写时
            {
                if (page == 1)
                    url = rewriter.Replace("-{0}", "");
                else
                    url = string.Format(rewriter, page);
                link = url;
            }
            else
            {
                url = HttpContext.Current.Request.RawUrl;
                if (url.IndexOf('?') != -1)
                {
                    if (page == 1)
                    {
                        link = Regex.Replace(url, @"[\&,\?]p=\d+", "");
                    }
                    else
                    {
                        if (url.IndexOf("p=") != -1)
                            link = Regex.Replace(url, @"p=\d+", "p=" + page);
                        else
                            link = url + "&p=" + page;
                    }
                }
                else
                {
                    link = url + "?p=" + page;
                }
            }
            return link;
        }
    }
}