using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.IO;

namespace GridViewSample
{
	/// <summary>
	/// Converts ASP.Net 2.0 GridView to Excel files.
	/// 
	/// Written by Shay Friedman (http://www.IronShay.com).
	/// You can use this freely without any worries.
	/// </summary>    
	public class GridViewToExcel
	{
		#region Grid to CSV

		/// <summary>
		/// Converts a given GridView to a CSV file and sends it to the browser as the response stram
		/// </summary>
		/// <param name="grid">The filled GridView object to convert.</param>
		/// <param name="fileName">The filename that will appear to the user in the download dialog.</param>
		public static void ConvertGridToCSV(GridView grid, string fileName)
		{
			// Clear the response output stream before start
			HttpContext.Current.Response.Clear();

			// Set the response headers to fit our CSV file
			HttpContext.Current.Response.ContentType = "text/plain";
			HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);

			using (StreamWriter writer = new StreamWriter(HttpContext.Current.Response.OutputStream))
			{
				// Add header row
				writer.WriteLine(GetCSVLine(grid.HeaderRow.Cells));

				// Add all the data rows
				foreach (GridViewRow row in grid.Rows)
				{
					writer.WriteLine(GetCSVLine(row.Cells));
				}
			}

			// End the current response. Otherwise, excel will open with the whole page inside.
			HttpContext.Current.Response.End();
		}

		private static string GetCSVLine(TableCellCollection cellsToAdd)
		{
			string line = String.Empty;

			bool isFirst = true;
			foreach (TableCell cell in cellsToAdd)
			{
				if (!isFirst)
				{
					line += ",";
				}
				isFirst = false;

				line += cell.Text;
			}
			return line;
		}

		#endregion

		#region Grid to HTML

		/// <summary>
		/// Converts the given grid to HTML and sends it back to the browser as an Excel file.
		/// </summary>
		/// <param name="grid">The grid to convert.</param>
		public static void ConvertGridToHTML(GridView grid)
		{
			string gridHTML = String.Empty;

			using (StringWriter stringWriter = new StringWriter())
			{
				// Create a new page with a form element and the grid
				Page page = new Page();
				HtmlForm form = new HtmlForm();
				form.Controls.Add(grid);
				page.Controls.Add(form);

				// Get the HTML of the page
				HtmlTextWriter writer = new HtmlTextWriter(stringWriter);

				page.RenderControl(writer);

				writer.Flush();

				// Get the html
				gridHTML = stringWriter.ToString();
			}

			// Clear the response output stream before start
			HttpContext.Current.Response.Clear();

			// Set the response headers to fit our excel file
			HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";

			HttpContext.Current.Response.Write(gridHTML);

			// End the current response. Otherwise, excel will open with the whole page inside.
			HttpContext.Current.Response.End();
		}

		#endregion
	}
}