using System;
using System.IO;
using System.Text;
using System.Xml;
using HtmlAgilityPack;

namespace Endpoint
{
	public class HtmlEndpoint : HttpEndpoint
	{
		/// <summary>
		/// Returns the HTML parsed into a standard XmlDocument.
		/// Uses the HtmlAgilityPack library for "out of the web" (poorly formatted) html file support.
		/// </summary>
		/// <param name="html">The HTML</param>
		/// <returns>An XmlDocument from the HTML</returns>
		private static XmlDocument GetHtmlXml(string html)
		{
			var htmlDocument = new HtmlDocument();
			htmlDocument.LoadHtml(html);

			var xmlDocument = new XmlDocument();
			using (Stream stream = new MemoryStream())
			{
				XmlWriter xmlTextWriter = new XmlTextWriter(stream, Encoding.UTF8);

				htmlDocument.Save(xmlTextWriter);

				stream.Seek(0, SeekOrigin.Begin);

				using (var sr = new StreamReader(stream))
					xmlDocument.Load(sr);

				xmlTextWriter.Close();
			}
			return xmlDocument;
		}

		/// <summary>
		/// Returns the HTML grabbed from the passed in URL parsed into a standard XmlDocument.
		/// Uses the HtmlAgilityPack library for "out of the web" html file support.
		/// </summary>
		/// <param name="url">The URL.</param>
		/// <param name="requestContent">The post data.</param>
		/// <returns>An XmlDocument from the HTML</returns>
		private static XmlDocument GetHtmlXml(Uri url, string requestContent)
		{
			return GetHtmlXml(GetUrlContent(url, "application/x-www-form-urlencoded", requestContent, null));
		}


		/// <summary>
		/// Gets the HTTP endpoint configuration.
		/// </summary>
		/// <value>The HTTP endpoint configuration.</value>
		public HtmlEndpointConfiguration HtmlEndpointConfiguration
		{
			get { return (HtmlEndpointConfiguration)_httpEndpointConfiguration; }
		}

		/// <summary>
		/// Initializes a new instance of the <see cref="HttpEndpoint"/> class.
		/// </summary>
		/// <param name="config">The HttpEndpointConfiguration.</param>
		public HtmlEndpoint(HtmlEndpointConfiguration config)
			: base(config)
		{
		}

		/// <summary>
		/// Gets the current status result of the endpoint
		/// </summary>
		/// <returns>Status</returns>
		public override Status GetStatus()
		{
			Status baseStatus = base.GetStatus();
			if (baseStatus != Status.Up)
				return baseStatus;

			try
			{
				XmlDocument xml = GetHtmlXml(HttpEndpointConfiguration.Uri, HtmlEndpointConfiguration.RequestContent);

				// xml.Save(@"c:\test.xml");

				XmlNodeList nodes = xml.SelectNodes(HtmlEndpointConfiguration.XpathQuery);
				
				// verify html has expected value
				if (nodes == null || nodes.Count == 0)
				{
					StatusDescription = "Couldn't find expected value in html";
					return Status.Error;
				}
				string value = nodes[0].Value.Trim();
				if (value != HtmlEndpointConfiguration.ExpectedXpathResult)
				{
					StatusDescription = String.Format("Result was: '{0}', was expecting '{1}'", value,
								  HtmlEndpointConfiguration.ExpectedXpathResult);
					return Status.Error;
				}
			}
			catch (Exception ex)
			{
				StatusDescription = ex.Message;
				return Status.Error;
			}
			return Status.Up;
		}
	}
}