/*Web Site Scraping, .NET. This sample demonstrates the PowerTCP WebASP Control in the .NET environment.
 */
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace Http
{
	/// <summary>
	/// Summary description for WebForm1.
	/// </summary>
	public class WebForm1 : System.Web.UI.Page
	{
		protected System.Web.UI.WebControls.Label lblUrl;
		protected System.Web.UI.WebControls.Label lblHeaders;
		protected System.Web.UI.WebControls.Label lblBody;
		protected System.Web.UI.WebControls.TextBox txtUrl;
		protected System.Web.UI.WebControls.Button cmdGetPage;
		protected System.Web.UI.WebControls.TextBox txtHeaders;
		protected System.Web.UI.WebControls.TextBox txtContent;
		protected System.Web.UI.WebControls.Label lblLinks;
		protected System.Web.UI.WebControls.Label lblImages;
		protected System.Web.UI.WebControls.Button cmdPrevImg;
		protected System.Web.UI.WebControls.Label lblImagesDisplay;
		protected System.Web.UI.WebControls.ListBox lstLinks;
		protected System.Web.UI.WebControls.Button cmdGetOtherPage;
		protected System.Web.UI.WebControls.Label lblTitle;
		protected System.Web.UI.WebControls.Button cmdNextImg;
		protected System.Web.UI.WebControls.Label lblImagesTitle;
		
		protected DartWebAspDotnet.WebASP WebAsp1 = new DartWebAspDotnet.WebASP(); // WebASP Control for HTTP communication
		protected DartWebAspDotnet.WebPage WebPage1 = new DartWebAspDotnet.WebPage(); // WebPage Object for parsing and resource collecting
		protected System.Collections.ArrayList ArrListImages = new System.Collections.ArrayList(); // holds list of images
		protected System.Collections.ArrayList ArrListLinks = new System.Collections.ArrayList(); // holds list of links


		public WebForm1()
		{
			Page.Init += new System.EventHandler(Page_Init);
		}

		private void Page_Load(object sender, System.EventArgs e)
		{
			// Put user code to initialize the page here
		}

		private void Page_Init(object sender, EventArgs e)
		{
			//
			// CODEGEN: This call is required by the ASP.NET Web Form Designer.
			//
			InitializeComponent();
		}

		#region Web Form Designer generated code
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{    
			this.cmdGetPage.Click += new System.EventHandler(this.cmdGetPage_Click);
			this.cmdGetOtherPage.Click += new System.EventHandler(this.cmdGetOtherPage_Click);
			this.cmdPrevImg.Click += new System.EventHandler(this.cmdPrevImg_Click);
			this.cmdNextImg.Click += new System.EventHandler(this.cmdNextImg_Click);
			this.Load += new System.EventHandler(this.Page_Load);

		}
		#endregion


		private void GetPage(string url)
		{
			bool success = false; // true if HEAD commannd is successful ... the page exists! 
			bool displayable = false; // true if content is presumed to be ascii

			ClearAll();

			// set url to textbox content
			if(url != "")
			{
				WebAsp1.Request.Url = url;
				WebAsp1.Timeout = 20000;
				success = CheckHeader(ref displayable);
			
				if(success)
				{
					success = false;
					try
					{
						WebAsp1.Get();
						success = true;
					}
					catch(Exception GetError)
					{
						txtHeaders.Text = "Get Error: " + GetError.Message;
					}
					if(success)
					{
						lblTitle.Text = "Page scrape for " + WebAsp1.Response.Url;
						txtUrl.Text = WebAsp1.Response.Url;
						if(!displayable)
						{
							// it must be binary
							txtHeaders.Text = "Not displayable, binary file";
						}
						else
						{
							// it is probably ascii so display
							txtHeaders.Text = WebAsp1.Response.Header.All;

							// read source of retrieved page into WebPage Object so we can parse and resource collect
							WebPage1.Source = WebAsp1.Response.Body.ReadString(0);
						
							if(WebPage1.Source == "")
							{
								// some links return a valid header but no content
								txtHeaders.Text = "Page " + WebAsp1.Response.Url + " cannot be retrieved.";
								txtContent.Text = "";
							}
							else
							{
	
								txtContent.Text = WebPage1.Source;
								// set UrlHost so relative links will be ok
								WebPage1.UrlHost = WebAsp1.Request.Url;
						
								// iterate through the resources, adding link and image urls to the appropriate array
								for(int i = 1; i < WebPage1.Resources.Count-1; i++)
								{
									Trace.Write("i: " + i.ToString());
									Trace.Write("UrlType: " + WebPage1.Resources.Item(i).UrlType);
									Trace.Write("Url: " + WebPage1.Resources.Item(i).Url);

									if(WebPage1.Resources.Item(i).UrlType == DartWebAspDotnet.ResourceConstants.resA)
										if(WebPage1.Resources.Item(i).Url != null)
											ArrListLinks.Add(WebPage1.Resources.Item(i).Url);
							
									if(WebPage1.Resources.Item(i).UrlType == DartWebAspDotnet.ResourceConstants.resImg)
										if(WebPage1.Resources.Item(i).Url != "")
											ArrListImages.Add(WebPage1.Resources.Item(i).Url);
								}
								// check for any links
								if(ArrListLinks.Count == 0)
									ArrListLinks.Add("No links to display on this page");
								// check for any images
								if(ArrListImages.Count == 0)
								{
									lblImages.Text = "No images to display";
									cmdPrevImg.Enabled = false;
									cmdNextImg.Enabled = false;
								}
								else
								{
									// save current image and array of images to session, this will allow us to access after the postback
									Page.Session["CurrentImg"] = 0;
									Page.Session["ArrListImages"] = ArrListImages;
									ChangeImage("none");
								}
								lstLinks.DataSource = ArrListLinks;
								lstLinks.DataBind();
							}
						}
					}
				}
			}
			else
			{
				txtHeaders.Text = "Null URL. Unable to GET";
				lstLinks.DataSource = "";
				lstLinks.DataBind();
				lblImagesDisplay.Text = "";
			}
		}
		private void ClearAll()
		{
			ArrListLinks.Clear();
			ArrListImages.Clear();
			txtHeaders.Text = "";
			txtContent.Text = "";
			WebAsp1.Request.Header.Clear();
			WebAsp1.Response.Header.Clear();
		}

		private bool CheckHeader(ref bool displayable)
		{ 
			string temp;
			bool okHead = false;
			try
			{
				WebAsp1.Head();
				okHead = true;

			}
			catch(Exception HeadError)
			{
				okHead = false;
				txtHeaders.Text = "Head Error: " + HeadError.Message;
			}
			int tempint;
			tempint = 0;
			temp = WebAsp1.Response.Header.Find(DartWebAspDotnet.HttpLabelConstants.httpContentType, "", ref tempint);
			temp = temp.ToLower();

			// check for binary file
			if(temp.IndexOf("application") != -1 )
				displayable = false;
			else if(temp.IndexOf("image") != -1)
				displayable = false;
			else if(temp.IndexOf("audio") != -1)
				displayable = false;
			else
				displayable = true;
			return okHead;
		}
		
		private void ChangeImage(string change)
		{
			/*change will either be "none" meaning display the same image,
			 * "next" meaning display the next image, or "prev" meaning display the previous image
			 */
		 
			System.Collections.ArrayList temparray = new System.Collections.ArrayList();
			int tempint;
			int addto;

			// unload system var into temp array for easier handling
			temparray = (System.Collections.ArrayList)Session["ArrListImages"];
			// same goes for current image
			tempint = (int)Session["CurrentImg"];
			
			// check to see if we are at the first image and want to go to the previous...
			if(change == "prev" && tempint == 0)
			{
				tempint = temparray.Count - 1;
				addto = 0;
			}
			// ...or if we are at the last image and want to go next
			else if(change == "next" && tempint == (temparray.Count - 1))
			{
				tempint = 0;
				addto = 0;
			}
			// otherwise process as normal
			else
			{
				switch(change)
				{
					case "none":
						addto = 0;
						break;
					case "prev":
						addto = -1;
						break;
					case "next":
						addto = 1;
						break;
					default:
						addto = 0;
						break;
				}
				
			}
			Session["CurrentImg"] = tempint + addto;
			lblImagesTitle.Text = "Image " + (((int)tempint+addto) + 1) + " of " + temparray.Count.ToString();
			lblImagesDisplay.Text = "<img src = '" + temparray[tempint + addto] + "'>";
		}

		private void cmdGetOtherPage_Click(object sender, System.EventArgs e)
		{
			GetPage(lstLinks.SelectedItem.ToString());
		}

		private void cmdPrevImg_Click(object sender, System.EventArgs e)
		{
			ChangeImage("prev");
		}

		private void cmdNextImg_Click(object sender, System.EventArgs e)
		{
			ChangeImage("next");
		}

		private void cmdGetPage_Click(object sender, System.EventArgs e)
		{
			GetPage(txtUrl.Text);
		}
	}
}