using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Pagination : WebBlockUserControl
{
    public int MaxResults
    {
        get { return (ViewState["MaxResults"] == null ? -1 : (int)ViewState["MaxResults"]); }
        set { ViewState["MaxResults"] = value; }
    }

    private int _PageSize = -1;
    public int PageSize
    {
        get
        {
            if (_PageSize == -1)
            {
                string ps = Configuration.Get("BrowsePageSize");
                if (ps == null || ps.Length == 0)
                    _PageSize = 15;
                else
                    _PageSize = Int32.Parse(ps);
            }
            return _PageSize;
        }
    }

    private int _PageIndex = 1;
    public int PageIndex
    {
        get
        {
            if (Request["Page"] != null)
            {
                if (!Int32.TryParse(Request["Page"], out _PageIndex))
                    throw new Exception("Please specify an integer page index.");
            }
            else
                _PageIndex = 1;

            return _PageIndex;
        }
    }

    private int _LowRow = 0;
    public int LowRow
    {
        get
        {
            if (_LowRow == 0)
                _LowRow = ((PageIndex-1) * PageSize) +1;

            return _LowRow;
        }
    }

    private int _HighRow = 0;
    public int HighRow
    {
        get
        {
            if (_HighRow == 0)
                _HighRow = (PageIndex * PageSize) + 1;

            return _HighRow;
        }
    }

    protected override void Render(HtmlTextWriter writer)
    {
        int TotalPages = Math.Max(1, (int)Math.Ceiling((double)MaxResults / PageSize));

        if(PageIndex == -1)
        {
            TotalPages = 1;
        }

        if (TotalPages > 1) // build out paging
        {
            writer.Write("<div class=\"pagination\">");

            string cleanQueryString = GetCleanQueryString(Request.QueryString.ToString());

            if (cleanQueryString.Length > 0)
                cleanQueryString += "&";

            cleanQueryString = "?" + cleanQueryString;

            // may not be needed, but ill put it in just in case
            cleanQueryString = Request.Path + cleanQueryString;

            writer.Write("<a href='");
            writer.Write(cleanQueryString);
            writer.Write("Page=-1'>View All</a>&nbsp;&nbsp;");
            writer.Write("<a href='");
            writer.Write(cleanQueryString);
            writer.Write("Page=1'><<</a>&nbsp;&nbsp;<a href='");
            writer.Write(cleanQueryString);
            writer.Write("Page=");
            writer.Write(Math.Max(PageIndex - 1, 1));
            writer.Write("'><</a>&nbsp;&nbsp;");

            int startPageIndex;
            int endPageIndex;

            if (PageIndex + 2 >= TotalPages)
            {
                endPageIndex = Math.Min(TotalPages, PageIndex + 2);
                startPageIndex = Math.Max(endPageIndex - 4, 1);
            }
            else
            {
                startPageIndex = Math.Max(1, PageIndex - 2);
                endPageIndex = Math.Min(startPageIndex + 4, TotalPages);
            }


            for (int i = startPageIndex; i <= endPageIndex; i++)
            {
                writer.Write("<a href='");
                writer.Write(cleanQueryString);
                writer.Write("Page=");
                writer.Write(i);
                writer.Write("'>");
                if (i == PageIndex)
                {
                    writer.Write("<b>");
                    writer.Write(i);
                    writer.Write("</b>");
                }
                else
                {
                    writer.Write(i);
                }
                writer.Write("</a>&nbsp;&nbsp;");
            }

            writer.Write("<a href='");
            writer.Write(cleanQueryString);
            writer.Write("Page=");
            writer.Write(Math.Min(PageIndex + 1, TotalPages));
            writer.Write("'>></a>&nbsp;&nbsp;<a href='");
            writer.Write(cleanQueryString);
            writer.Write("Page=");
            writer.Write(TotalPages);
            writer.Write("'>>></a>");

            writer.Write("</div>");
        }
    }

    private string GetCleanQueryString(string q)
    {
        // the first step is that we need to remove any pagination info from the query string
        // example query strings:
        // Case 1: 
        // Case 2: Search=stuff
        // Case 3: Search=stuff&Page=10
        // Case 4: Search=stuff&Page=10&Color=red
        // Case 5: Page=10&Search=stuff
        // Case 6: Page=10
        int startIndex = q.IndexOf("Page=");

        if (startIndex == -1)
        {
            // case 1 and 2
            // do nothing
        }
        else
        {
            int endIndex = q.IndexOf('&', startIndex);

            if (endIndex == -1)
            {
                if (startIndex == 0) // case 3
                    q = q.Remove(startIndex);
                else // case 6
                    q = q.Remove(startIndex - 1);
            }
            else
            {
                if (startIndex == 0) // case 5
                    q = q.Remove(startIndex, endIndex);
                else // case 4
                    q = q.Remove(startIndex - 1, endIndex - startIndex + 1);
            }
        }

        return q;
    }
}