// System.Xml.XmlUrlResolver.cs
//
// Author: Duncan Mak (duncan@ximian.com)
//	   Atsushi Enomoto (ginga@kit.hi-ho.ne.jp)
//
// (C) Ximian, Inc.
//

using System.Net;
using System.IO;
using System.Text;
using Mono.Xml.Native;

namespace System.Xml
{
	public class XmlUrlResolver : XmlResolver
	{
		// Field
		ICredentials credential;
		WebClient webClientInternal;
		WebClient webClient {
			get {
				if (webClientInternal == null)
					webClientInternal = new WebClient ();
				return webClientInternal;
			}
		}

		// Constructor
		public XmlUrlResolver ()
			: base ()
		{
		}

		// Properties		
		public override ICredentials Credentials
		{
			set { credential = value; }
		}
		
		// Methods
		public override object GetEntity (Uri absoluteUri, string role, Type ofObjectToReturn)
		{
			if (ofObjectToReturn == null)
				ofObjectToReturn = typeof (Stream);
			if (ofObjectToReturn != typeof (Stream))
				throw new XmlException ("This object type is not supported.");

			if (absoluteUri.Scheme == "file") {
				if (absoluteUri.AbsolutePath == String.Empty)
					throw new ArgumentException ("uri must be absolute.", "absoluteUri");
				return new FileStream (UnescapeRelativeUriBody (absoluteUri.LocalPath), FileMode.Open, FileAccess.Read, FileShare.Read);
			}

			// (MS documentation says) parameter role isn't used yet.
			Stream s = null;
			using (s) {
				WebClient wc = new WebClient ();
				wc.Credentials = credential;
				byte [] data = wc.DownloadData (absoluteUri.ToString ());
				wc.Dispose ();
				return new MemoryStream (data, 0, data.Length);
			}
		}

		// see also XmlResolver.EscapeRelativeUriBody().
		private string UnescapeRelativeUriBody (string src)
		{
			return src.Replace ("%3C", "<")
				.Replace ("%3E", ">")
				.Replace ("%23", "#")
				.Replace ("%25", "%")
				.Replace ("%22", "\"");
		}
	}
}