using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;
using System.Xml;

namespace PageStatus {
	public class PageStatusTester {
		string requestUrl, cachedHeaderList, cachedHeaderHtmlTable, cachedDefinitionList, contentType, content, server, responseUrl, error, userAgent;
		bool autoRedirect, deferTesting, isReady, xmlCacheIsStale;
		HttpStatusCode status;
		WebHeaderCollection headers;
		IPAddress ipAddress;
		Uri uri;
		XmlDocument xml;

		#region Class constructor
		public PageStatusTester() { }

		public PageStatusTester(string url) {
			Url = url;
		}

		public PageStatusTester(Uri uri) {
			Url = uri.ToString();
		}

		public PageStatusTester(string url, bool deferIO) {
			if (deferTesting = deferIO)
				requestUrl = url;
			else
				Url = url;
		}

		public PageStatusTester(Uri uri, bool deferIO) {
			if (deferTesting = deferIO)
				requestUrl = uri.ToString();
			else
				Url = uri.ToString();
		}
		#endregion
		#region Real work
		void Clear(string newRequestUrl) {
			requestUrl = newRequestUrl;
			cachedHeaderList = string.Empty;
			cachedHeaderHtmlTable = string.Empty;
			contentType = string.Empty;
			content = string.Empty;
			server = string.Empty;
			error = string.Empty;
			status = 0;
			headers = null;
			ipAddress = null;
			isReady = false;
			xmlCacheIsStale = true;
			xml = null;
		}

		public void TestStatus() {
			Clear(requestUrl);

			try {
				HttpWebRequest req = (HttpWebRequest)WebRequest.Create(requestUrl);

				req.AllowAutoRedirect = autoRedirect;
				if (!string.IsNullOrEmpty(userAgent))
					req.UserAgent = userAgent;

				HttpWebResponse resp = (HttpWebResponse)req.GetResponse();

				status = resp.StatusCode;
				headers = resp.Headers;

				for (int i = 0; i != resp.Headers.Count; i++) {
					cachedHeaderList += resp.Headers.AllKeys[i] + "\t=\t" + resp.Headers[i] + "\n";
					cachedHeaderHtmlTable += "<tr><td class='httpHeaderName'>" + resp.Headers.AllKeys[i] + "</td><td class='httpHeaderValue'>" + resp.Headers[i] + "</td></tr>";
					cachedDefinitionList += "<dt>" + resp.Headers.AllKeys[i] + "</dt><dd>" + resp.Headers[i] + "</dd>";
				}

				cachedHeaderHtmlTable = "<table><tr><td class='httpHeaderName'>Name</td><td>Value</td><td class='httpHeaderValue'>" + cachedHeaderHtmlTable + "</td></tr></table>";
				cachedDefinitionList = "<dl>" + cachedDefinitionList + "</dl>";
				server = resp.Server;
				responseUrl = resp.ResponseUri.ToString();
				IPAddress[] ips = System.Net.Dns.GetHostAddresses(resp.ResponseUri.DnsSafeHost);
				if (ips.Length > 0)
					ipAddress = ips[0];
				contentType = resp.ContentType;
				StreamReader tempReader = new StreamReader(resp.GetResponseStream());
				content = tempReader.ReadToEnd();
				tempReader.Dispose();
			} catch (WebException ex) {
				if (ex.Message.Contains("404"))
					status = System.Net.HttpStatusCode.NotFound;

				error = ex.Message;
			}
			isReady = true;
		}

		public string Url {
			get { return requestUrl; }
			set {
				requestUrl = value;
				uri = new Uri(value);
				isReady = false;

				if (!deferTesting)
					TestStatus();
			}
		}
		#endregion

		#region Properties - Set behavior
		/// <summary>
		/// Gets or sets a value indicating whether redirects will be honored. If you need to
		/// learn whether a page is using a 301/permenant vs a 302/temporary redirect, this
		/// must be set to false. If you want to see whether the page that’s redirected TO
		/// works properly, setting true will create and report on a new request against the
		/// Location header.
		/// </summary>
		public bool AutoRedirect { get { return autoRedirect; } set { autoRedirect = value; } }

		public string UserAgent { get { return userAgent; } set { userAgent = value; } }
		#endregion
		#region Properties - expose the collected data
		public bool IsReady { get { return isReady; } }

		public int HttpStatusCode { get { if (!IsReady) TestStatus(); return (int)status; } }

		public string HttpStatusDescription { get { if (!IsReady) TestStatus(); return status.ToString(); } }

		public WebHeaderCollection Headers { get { if (!IsReady) TestStatus(); return headers; } }

		public string HeaderText { get { if (!IsReady) TestStatus(); return cachedHeaderList; } }

		public string HeaderHtmlTable { get { if (!IsReady) TestStatus(); return cachedHeaderHtmlTable; } }

		public string ContentType { get { if (!IsReady) TestStatus(); return contentType; } }

		public string Content { get { if (!IsReady) TestStatus(); return content; } }

		public IPAddress IPAddress { get { if (!IsReady) TestStatus(); return ipAddress; } }

		public string Server { get { return server; } }
		#endregion
		#region Properties - calculate on the fly
		public string Domain { get { if (!IsReady) TestStatus(); return uri == null ? string.Empty : uri.Host; } }

		public string Page { get { if (!IsReady) TestStatus(); return uri == null ? string.Empty : uri.PathAndQuery; } }

		public XmlDocument Xml {
			get {
				if (!xmlCacheIsStale)
					return xml;

				if (IsValidXml)
					return xml;

				return null;
			}
		}

		public bool IsValidXml {
			get {
				try {
					if (!xmlCacheIsStale)
						return xml != null;

					if (!IsReady)
						TestStatus();

					xml = new XmlDocument();
					xml.LoadXml(content);
					xmlCacheIsStale = false;
				} catch (Exception ex) {
					return false;
				}
				return true;
			}
		}
		#endregion

	}
}