/*
  KeePass Password Safe - The Open-Source Password Manager
  Copyright (C) 2003-2021 Dominik Reichl <dominik.reichl@t-online.de>

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
using System.Xml.XPath;

using KeePassLib.Delegates;
using KeePassLib.Interfaces;
using KeePassLib.Serialization;

namespace KeePassLib.Utility
{
	public static class XmlUtilEx
	{
		public static XmlDocument CreateXmlDocument()
		{
			XmlDocument d = new XmlDocument();

			// .NET 4.5.2 and newer do not resolve external XML resources
			// by default; for older .NET versions, we explicitly
			// prevent resolving
			d.XmlResolver = null; // Default in old .NET: XmlUrlResolver object

			return d;
		}

		public static XmlReaderSettings CreateXmlReaderSettings()
		{
			XmlReaderSettings xrs = new XmlReaderSettings();

			xrs.CloseInput = false;
			xrs.IgnoreComments = true;
			xrs.IgnoreProcessingInstructions = true;
			xrs.IgnoreWhitespace = true;

#if KeePassUAP
			xrs.DtdProcessing = DtdProcessing.Prohibit;
#else
			// Also see PrepMonoDev.sh script
			xrs.ProhibitDtd = true; // Obsolete in .NET 4, but still there
			// xrs.DtdProcessing = DtdProcessing.Prohibit; // .NET 4 only
#endif

			xrs.ValidationType = ValidationType.None;
			xrs.XmlResolver = null;

			return xrs;
		}

		public static XmlReader CreateXmlReader(Stream s)
		{
			if(s == null) { Debug.Assert(false); throw new ArgumentNullException("s"); }

			return XmlReader.Create(s, CreateXmlReaderSettings());
		}

		public static XmlWriterSettings CreateXmlWriterSettings()
		{
			XmlWriterSettings xws = new XmlWriterSettings();

			xws.CloseOutput = false;
			xws.Encoding = StrUtil.Utf8;
			xws.Indent = true;
			xws.IndentChars = "\t";
			xws.NewLineOnAttributes = false;

			return xws;
		}

		public static XmlWriter CreateXmlWriter(Stream s)
		{
			if(s == null) { Debug.Assert(false); throw new ArgumentNullException("s"); }

			return XmlWriter.Create(s, CreateXmlWriterSettings());
		}

		public static T Deserialize<T>(Stream s)
		{
			if(s == null) { Debug.Assert(false); throw new ArgumentNullException("s"); }

			XmlSerializer xs = new XmlSerializer(typeof(T));

			T t = default(T);
			using(XmlReader xr = CreateXmlReader(s))
			{
				t = (T)xs.Deserialize(xr);
			}

			return t;
		}

		public static void Serialize<T>(Stream s, T t)
		{
			if(s == null) { Debug.Assert(false); throw new ArgumentNullException("s"); }

			XmlSerializer xs = new XmlSerializer(typeof(T));
			using(XmlWriter xw = CreateXmlWriter(s))
			{
				xs.Serialize(xw, t);
			}
		}

		internal static void Serialize<T>(Stream s, T t, bool bRemoveXsdXsi)
		{
			// One way to remove the "xsd" and "xsi" namespace declarations
			// is to use an XmlSerializerNamespaces object containing only
			// a ""/"" pair; this seems to work, but Microsoft's
			// documentation explicitly states that it isn't supported:
			// https://docs.microsoft.com/en-us/dotnet/api/system.xml.serialization.xmlserializernamespaces
			// There are other, more complex ways, but these either rely on
			// undocumented details or require the type T to be modified.

			string str;
			using(MemoryStream ms = new MemoryStream())
			{
				Serialize<T>(ms, t);

				str = StrUtil.Utf8.GetString(ms.ToArray());
			}

			GFunc<string, string, bool> fFindPfx = delegate(string strText, string strSub)
			{
				int i = strText.IndexOf(strSub, StringComparison.Ordinal);
				if(i < 0) return false;
				if(i == 0) return true;
				return char.IsWhiteSpace(strText[i - 1]);
			};

			if(bRemoveXsdXsi)
			{
				if(!fFindPfx(str, "xsd:") && !fFindPfx(str, "xsi:"))
				{
					Debug.Assert(str.IndexOf("xmlns:xsd") > 0);
					str = str.Replace(" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"", string.Empty);
					Debug.Assert(str.IndexOf("xmlns:xsd") < 0);

					Debug.Assert(str.IndexOf("xmlns:xsi") > 0);
					str = str.Replace(" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"", string.Empty);
					Debug.Assert(str.IndexOf("xmlns:xsi") < 0);
				}
				else { Debug.Assert(false); } // "xsd"/"xsi" decl. may be required
			}

			MemUtil.Write(s, StrUtil.Utf8.GetBytes(str));
		}

#if DEBUG
		internal static void ValidateXml(string strXml, bool bReplaceStdEntities)
		{
			if(strXml == null) throw new ArgumentNullException("strXml");
			if(strXml.Length == 0) { Debug.Assert(false); return; }

			string str = strXml;

			if(bReplaceStdEntities)
				str = str.Replace("&nbsp;", "&#160;");

			XmlDocument d = new XmlDocument();
			d.LoadXml(str);
		}
#endif

		internal static XPathNodeIterator FindNodes(PwDatabase pd, string strXPath,
			IStatusLogger sl, out XmlDocument xd)
		{
			if(pd == null) throw new ArgumentNullException("pd");
			if(strXPath == null) { Debug.Assert(false); strXPath = string.Empty; }

			KdbxFile kdbx = new KdbxFile(pd);

			byte[] pbXml;
			using(MemoryStream ms = new MemoryStream())
			{
				kdbx.Save(ms, null, KdbxFormat.PlainXml, sl);
				pbXml = ms.ToArray();
			}
			string strXml = StrUtil.Utf8.GetString(pbXml);

			xd = CreateXmlDocument();
			xd.LoadXml(strXml);

			XPathNavigator xpNav = xd.CreateNavigator();
			return xpNav.Select(strXPath);
			// XPathExpression xpExpr = xpNav.Compile(strXPath);
			// xpExpr.SetContext(new XuXsltContext());
			// return xpNav.Select(xpExpr);
		}

		/* private sealed class XuFnMatches : IXsltContextFunction
		{
			private readonly XPathResultType[] m_vArgTypes = new XPathResultType[] {
				XPathResultType.String, XPathResultType.String, XPathResultType.String
			};
			public XPathResultType[] ArgTypes { get { return m_vArgTypes; } }

			public int Maxargs { get { return 3; } }
			public int Minargs { get { return 2; } }

			public XPathResultType ReturnType { get { return XPathResultType.Boolean; } }

			private static string GetArgString(object[] args, int i, string strDefault)
			{
				if(args == null) { Debug.Assert(false); return strDefault; }
				if(i >= args.Length) return strDefault;

				object o = args[i];
				if(o == null) return strDefault;

				XPathNodeIterator it = (o as XPathNodeIterator);
				if(it != null) o = it.Current.Value;

				return (o.ToString() ?? strDefault);
			}

			public object Invoke(XsltContext xsltContext, object[] args,
				XPathNavigator docContext)
			{
				string strInput = GetArgString(args, 0, string.Empty);
				string strPattern = GetArgString(args, 1, string.Empty);
				string strFlags = GetArgString(args, 2, null);

				RegexOptions ro = RegexOptions.None;
				if(!string.IsNullOrEmpty(strFlags))
				{
					if(strFlags.IndexOf('s') >= 0) ro |= RegexOptions.Singleline;
					if(strFlags.IndexOf('m') >= 0) ro |= RegexOptions.Multiline;
					if(strFlags.IndexOf('i') >= 0) ro |= RegexOptions.IgnoreCase;
					if(strFlags.IndexOf('x') >= 0) ro |= RegexOptions.IgnorePatternWhitespace;
				}

				return Regex.IsMatch(strInput, strPattern, ro);
			}
		}

		private sealed class XuXsltContext : XsltContext
		{
			public override bool Whitespace { get { return false; } }

			public override int CompareDocument(string baseUri, string nextbaseUri)
			{
				return string.CompareOrdinal(baseUri, nextbaseUri);
			}

			public override bool PreserveWhitespace(XPathNavigator node)
			{
				return false;
			}

			public override IXsltContextFunction ResolveFunction(string prefix,
				string name, XPathResultType[] ArgTypes)
			{
				if(prefix != "kp") { Debug.Assert(false); return null; }

				if(name == "matches") return new XuFnMatches();

				Debug.Assert(false);
				return null;
			}

			public override IXsltContextVariable ResolveVariable(string prefix,
				string name)
			{
				Debug.Assert(false);
				return null;
			}
		} */
	}
}
