//
// ClientAccessPolicyParser.cs
//
// Authors:
//	Atsushi Enomoto <atsushi@ximian.com>
//	Moonlight List (moonlight-list@lists.ximian.com)
//
// Copyright (C) 2009-2010 Novell, Inc.  http://www.novell.com
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

#if MOBILE

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Xml;

/*
default namespace = ""

grammar {

start = access-policy

access-policy = element access-policy {
  element cross-domain-access {
    element policy { allow-from, grant-to }
  }
}

allow-from = element allow-from {
  attribute http-request-headers { text },
  element domain {
    attribute uri { text }
  }
}

grant-to = element grant-to {
  (resource | socket-resource)+
}

resource = element resource {
  attribute path { text },
  attribute include-subpaths { "true" | "false" }
}

socket-resource = element socket-resource {
  attribute port { text },
  attribute protocol { text }
}

}
*/

namespace System.Net.Policy {

	partial class ClientAccessPolicy {

		static bool IsNonElement (XmlReader reader)
		{
			return (reader.NodeType != XmlNodeType.Element);
		}

		static bool IsNonEmptyElement (XmlReader reader)
		{
			return (reader.IsEmptyElement || IsNonElement (reader));
		}

		static public ICrossDomainPolicy FromStream (Stream stream)
		{
			ClientAccessPolicy cap = new ClientAccessPolicy ();

			// Silverlight accepts whitespaces before the XML - which is invalid XML
			StreamReader sr = new StreamReader (stream);
			while (Char.IsWhiteSpace ((char) sr.Peek ()))
				sr.Read ();

			XmlReaderSettings policy_settings = new XmlReaderSettings ();
			policy_settings.DtdProcessing = DtdProcessing.Ignore;
			using (XmlReader reader = XmlReader.Create (sr, policy_settings)) {
				reader.MoveToContent ();
				if (reader.IsEmptyElement) {
					reader.Skip ();
					return null;
				}
				reader.ReadStartElement ("access-policy", String.Empty);
				for (reader.MoveToContent (); reader.NodeType != XmlNodeType.EndElement; reader.MoveToContent ()) {
					if (IsNonEmptyElement (reader) || (reader.LocalName != "cross-domain-access")) {
						reader.Skip ();
						continue;
					}

					reader.ReadStartElement ("cross-domain-access", String.Empty);
					for (reader.MoveToContent (); reader.NodeType != XmlNodeType.EndElement; reader.MoveToContent ()) {
						if (IsNonEmptyElement (reader) || (reader.Name != "policy")) {
							reader.Skip ();
							continue;
						}

						ReadPolicyElement (reader, cap);
					}
					reader.ReadEndElement ();
				}
				reader.ReadEndElement ();
			}
			return cap;
		}

		static void ReadPolicyElement (XmlReader reader, ClientAccessPolicy cap)
		{
			if (reader.HasAttributes || reader.IsEmptyElement) {
				reader.Skip ();
				return;
			}

			var policy = new AccessPolicy ();
			bool valid = true;

			reader.ReadStartElement ("policy", String.Empty);
			for (reader.MoveToContent (); reader.NodeType != XmlNodeType.EndElement; reader.MoveToContent ()) {
				if (IsNonElement (reader)) {
					reader.Skip ();
					continue;
				}

				switch (reader.LocalName) {
				case "allow-from":
					ReadAllowFromElement (reader, policy);
					break;
				case "grant-to":
					ReadGrantToElement (reader, policy);
					break;
				default:
					valid = false;
					reader.Skip ();
					break;
				}
			}

			if (valid)
				cap.AccessPolicyList.Add (policy);
			reader.ReadEndElement ();
		}

		static void ReadAllowFromElement (XmlReader reader, AccessPolicy policy)
		{
			if (IsNonEmptyElement (reader)) {
				reader.Skip ();
				return;
			}

			bool valid = true;
			string headers = null;
			string methods = null;		// new in SL3
			if (reader.HasAttributes) {
				int n = reader.AttributeCount;
				headers = reader.GetAttribute ("http-request-headers");
				if (headers != null)
					n--;
				methods = reader.GetAttribute ("http-methods");
				if (methods != null)
					n--;
				valid = (n == 0);
			}

			var v = new AllowFrom ();
			v.HttpRequestHeaders.SetHeaders (headers);
			v.AllowAnyMethod = (methods == "*"); // only legal value defined, otherwise restricted to GET and POST
			reader.ReadStartElement ("allow-from", String.Empty);
			for (reader.MoveToContent (); reader.NodeType != XmlNodeType.EndElement; reader.MoveToContent ()) {
				if (IsNonElement (reader) || !String.IsNullOrEmpty (reader.NamespaceURI)) {
					reader.Skip ();
					continue;
				}
				switch (reader.LocalName) {
				case "domain":
					var d = reader.GetAttribute ("uri");
					if (d == "*")
						v.AllowAnyDomain = true;
					else
						v.Domains.Add (d);
					reader.Skip ();
					break;
				default:
					valid = false;
					reader.Skip ();
					continue;
				}
			}
			if (valid)
				policy.AllowedServices.Add (v);
			reader.ReadEndElement ();
		}

		// only "path" and "include-subpaths" attributes are allowed - anything else is not considered
		static Resource CreateResource (XmlReader reader)
		{
			int n = reader.AttributeCount;
			string path = reader.GetAttribute ("path");
			if (path != null)
				n--;
			string subpaths = reader.GetAttribute ("include-subpaths");
			if (subpaths != null)
				n--;
			if ((n != 0) || !reader.IsEmptyElement)
				return null;

			return new Resource () { 
				Path = path,
				IncludeSubpaths = subpaths == null ? false : XmlConvert.ToBoolean (subpaths)
			};
		}

		static void ReadGrantToElement (XmlReader reader, AccessPolicy policy)
		{
			var v = new GrantTo ();
			bool valid = true;

			if (reader.HasAttributes || reader.IsEmptyElement) {
				reader.Skip ();
				return;
			}

			reader.ReadStartElement ("grant-to", String.Empty);
			for (reader.MoveToContent (); reader.NodeType != XmlNodeType.EndElement; reader.MoveToContent ()) {
				if (IsNonElement (reader) || !String.IsNullOrEmpty (reader.NamespaceURI)) {
					reader.Skip ();
					continue;
				}

				switch (reader.LocalName) {
				case "resource":
					var r = CreateResource (reader);
					if (r == null)
						valid = false;
					else
						v.Resources.Add (r);
					break;
				case "socket-resource":
					// ignore everything that is not TCP
					if (reader.GetAttribute ("protocol") != "tcp")
						break;
					// we can merge them all together inside a policy
					policy.PortMask |= ParsePorts (reader.GetAttribute ("port"));
					break;
				default:
					valid = false;
					break;
				}
				reader.Skip ();
			}
			if (valid)
				policy.GrantedResources.Add (v);
			reader.ReadEndElement ();
		}

		// e.g. reserved ? 4534-4502
		static long ParsePorts (string ports)
		{
			long mask = 0;
			int sep = ports.IndexOf ('-');
			if (sep >= 0) {
				// range
				ushort from = ParsePort (ports.Substring (0, sep));
				ushort to = ParsePort (ports.Substring (sep + 1));
				for (int port = from; port <= to; port++)
					mask |= (long) (1ul << (port - AccessPolicy.MinPort));
			} else {
				// single
				ushort port = ParsePort (ports);
				mask |= (long) (1ul << (port - AccessPolicy.MinPort));
			}
			return mask;
		}

		static ushort ParsePort (string s)
		{
			ushort port;
			if (!UInt16.TryParse (s, out port) || (port < AccessPolicy.MinPort) || (port > AccessPolicy.MaxPort))
				throw new XmlException ("Invalid port");
			return port;
		}
	}
}

#endif