// Created by Windward Studios - no copyright is claimed. This code can be used in
// any manner by anyone for any reason. There is no copyright of any kind on it. You may
// use it in commercial products. You may change it without sharing those changes.
// We ask that you keep the "created by Windward Studios" in a comment at the top.

using System;
using System.IO;
using System.Net;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Xml;

namespace net.windward.utils.xml
{
	/// <summary>
	/// Provides the capability to open and test an xml file regardless of it's filename/url and the
	/// security mechanism. This includes most combinations where the calling program is on a domain
	/// or workgroup and the xml file is on a domain (same or different), workgroup, http, ftp, or a
	/// system with no uname/password required.
	/// It does not handle every combination because Windows does not provide the capabilities to do so
	/// in an API (even though "net use" can do so).
	/// bugbug - need to add schema support for open and test; return an XPathDocument also.
	/// </summary>
	public class XmlFileOpen
	{
		[DllImport("advapi32.dll", SetLastError = true)]
		private static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken);

		[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
		private extern static bool CloseHandle(IntPtr handle);

		/*
		[DllImport("NetApi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		private static extern UInt32 NetUseAdd(string UncServerName, int Level, ref USE_INFO_2 Buf, out uint ParmError);

		[DllImport("NetApi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
		private static extern uint NetUseDel(string UncServerName, string UseName, uint ForceCond);
		*/

		[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
		private struct USE_INFO_2
		{
			public string ui2_local;
			public string ui2_remote;
			public string ui2_password;
			public uint ui2_status;
			public uint ui2_asg_type;
			public uint ui2_refcount;
			public uint ui2_usecount;
			public string ui2_username;
			public string ui2_domainname;
		}

		const int LOGON32_PROVIDER_DEFAULT = 0;
		const int LOGON32_LOGON_NEW_CREDENTIALS = 9;

		/// <summary>
		/// Open the XML document using the passed in credentials.
		/// </summary>
		/// <param name="filename">The name of the file. Can be http(s) or ftp as well as a share or plain old filename.</param>
		/// <param name="username">Username to open under. If null then anonymous user.</param>
		/// <param name="password">Password to open under.</param>
		/// <returns>the loaded XML document.</returns>
		public static XmlDocument OpenXmlDocument(string filename, string username, string password)
		{

			// handle http(s) and ftp using credentials
			string lcName = filename.ToLower();
			if (lcName.StartsWith("http:") || lcName.StartsWith("https:") || lcName.StartsWith("ftp:"))
			{
				XmlDocument xmlDoc = new XmlDocument();
				if (username != null)
				{
					XmlUrlResolver resolver = new XmlUrlResolver();
					resolver.Credentials = new NetworkCredential(username, password);
					xmlDoc.XmlResolver = resolver;
				}
				xmlDoc.Load(filename);
				return xmlDoc;
			}

			// if anon - try it
			if (username == null)
			{
				// can't do this -- return OpenWithIdentity(filename, WindowsIdentity.GetAnonymous());
				XmlDocument xmlDoc = new XmlDocument();
				xmlDoc.Load(filename);
				return xmlDoc;
			}

			// get the username & domain
			string domain, user;
			int pos = username.IndexOf('\\');
			if (pos == -1)
				pos = username.IndexOf('/');
			bool onlyDomain;
			if (pos != -1)
			{
				onlyDomain = true;
				domain = username.Substring(0, pos);
				user = username.Substring(pos + 1);
			}
			else
			{
				onlyDomain = false;
				WindowsIdentity ident = WindowsIdentity.GetCurrent();
				if (ident == null)
					domain = null;
				else
				{
					domain = ident.Name;
					pos = domain.IndexOf('\\');
					if (pos != -1)
						domain = domain.Substring(0, pos);
				}
				user = username;
			}

			// first we try a domain set of credentials
			if (domain != null)
			{
				try
				{
					XmlDocument doc = OpenAsDomainUser(filename, domain, user, password);
					if (doc != null)
						return doc;
				}
				catch (Exception)
				{
					if (onlyDomain)
						throw;
				}
			}
			if (onlyDomain)
				throw new IOException("Could not open: " + filename + " as user: " + domain + "\\" + user);

			// get the share name (may not be one) - we don't handle z:\file.xml using local user on Z: system
			/* only needed if we have remote local user access
			string share = null;
			if (filename.StartsWith("\\\\"))
			{
				pos = filename.IndexOf('\\', 3);
				if (pos != -1)
				{
					pos = filename.IndexOf('\\', pos + 2);
					if (pos != -1)
						share = filename.Substring(0, pos);
				}
			}
			*/

			// second we try as a local user on this system
			return OpenAsDomainUser(filename, ".", user, password);

			/* No good way to open as a local user on a remote machine
			try
			{
				XmlDocument doc = OpenAsDomainUser(filename, ".", user, password);
				if (doc != null)
					return doc;
			}
			catch (Exception)
			{
				// if not a share - we're done
				if (share == null)
					throw;
			}

			// if no share, we're done
			if (share == null)
				throw new ApplicationException("bugbug");

			// third try local user on remote system
			return OpenAsRemoteUser(share, filename, username, password);
			*/
		}

		/// <summary>
		/// Open the XML document using the passed in credentials.
		/// </summary>
		/// <param name="filename">The name of the file. Can be http(s) or ftp as well as a share or plain old filename.</param>
		/// <param name="username">Username to open under. If null then anonymous user.</param>
		/// <param name="password">Password to open under.</param>
		public static void TestXmlFile(string filename, string username, string password)
		{

			// handle http(s) and ftp using credentials
			string lcName = filename.ToLower();
			if (lcName.StartsWith("http:") || lcName.StartsWith("https:") || lcName.StartsWith("ftp:"))
			{
				XmlReaderSettings readerSettings = new XmlReaderSettings();
				readerSettings.ProhibitDtd = false;
				readerSettings.ValidationType = ValidationType.DTD;
				if (username != null)
				{
					XmlUrlResolver resolver = new XmlUrlResolver();
					resolver.Credentials = new NetworkCredential(username, password);
					readerSettings.XmlResolver = resolver;
				}
				XmlReader xmlReader = XmlReader.Create(filename, readerSettings);
				while (xmlReader.Read())
					// nothing - just make sure can read all
					;
				return;
			}

			// if anon - try it
			if (username == null)
			{
				XmlReaderSettings readerSettings = new XmlReaderSettings();
				readerSettings.ProhibitDtd = false;
				readerSettings.ValidationType = ValidationType.DTD;
				XmlReader xmlReader = XmlReader.Create(filename, readerSettings);
				while (xmlReader.Read())
					// nothing - just make sure can read all
					;
				return;
			}

			// get the username & domain
			string domain, user;
			int pos = username.IndexOf('\\');
			if (pos == -1)
				pos = username.IndexOf('/');
			bool onlyDomain;
			if (pos != -1)
			{
				onlyDomain = true;
				domain = username.Substring(0, pos);
				user = username.Substring(pos + 1);
			}
			else
			{
				onlyDomain = false;
				WindowsIdentity ident = WindowsIdentity.GetCurrent();
				Trap.trap(ident == null);
				if (ident == null)
					domain = null;
				else
				{
					domain = ident.Name;
					pos = domain.IndexOf('\\');
					if (pos != -1)
						domain = domain.Substring(0, pos);
				}
				user = username;
			}

			// first we try a domain set of credentials
			if (domain != null)
			{
				try
				{
					TestAsDomainUser(filename, domain, user, password);
					return;
				}
				catch (Exception)
				{
					if (onlyDomain)
						throw;
				}
			}
			if (onlyDomain)
				throw new IOException("Could not test: " + filename + " as user: " + domain + "\\" + user);

			// second we try as a local user on this system
			TestAsDomainUser(filename, ".", user, password);
		}

		private static XmlDocument OpenWithIdentity(string filename, WindowsIdentity identity)
		{
			WindowsImpersonationContext impersonationContext = identity.Impersonate();
			try
			{
				XmlDocument xmlDoc = new XmlDocument();
				xmlDoc.Load(filename);
				return xmlDoc;
			}
			finally
			{
				impersonationContext.Undo();
				impersonationContext.Dispose();
			}
		}

		private static XmlDocument OpenAsDomainUser(string filename, string domain, string username, string password)
		{
			IntPtr tokenHandle = new IntPtr(0);
			bool returnValue = LogonUser(username, domain, password, LOGON32_LOGON_NEW_CREDENTIALS, LOGON32_PROVIDER_DEFAULT, ref tokenHandle);
			if (returnValue == false)
				return null;
			try
			{
				WindowsIdentity identity = new WindowsIdentity(tokenHandle);
				return OpenWithIdentity(filename, identity);
			}
			finally
			{
				CloseHandle(tokenHandle);
			}
		}

		private static void TestAsDomainUser(string filename, string domain, string username, string password)
		{

			IntPtr tokenHandle = new IntPtr(0);
			bool returnValue = LogonUser(username, domain, password, LOGON32_LOGON_NEW_CREDENTIALS, LOGON32_PROVIDER_DEFAULT, ref tokenHandle);
			if (returnValue == false)
				throw new IOException("Could not login as user: " + domain + "\\" + username);
			try
			{
				WindowsIdentity identity = new WindowsIdentity(tokenHandle);
				WindowsImpersonationContext impersonationContext = identity.Impersonate();
				try
				{
					XmlReaderSettings readerSettings = new XmlReaderSettings();
					readerSettings.ProhibitDtd = false;
					readerSettings.ValidationType = ValidationType.DTD;
					XmlReader xmlReader = XmlReader.Create(filename, readerSettings);
					while (xmlReader.Read())
						// nothing - just make sure can read all
						;
				}
				finally
				{
					impersonationContext.Undo();
					impersonationContext.Dispose();
				}
			}
			finally
			{
				CloseHandle(tokenHandle);
			}
		}

		/*
		private static XmlDocument OpenAsRemoteUser(string share, string filename, string username, string password)
		{

			USE_INFO_2 useInfo = new USE_INFO_2();
			useInfo.ui2_remote = share;
			useInfo.ui2_password = password;
			useInfo.ui2_asg_type = 0;    //disk drive
			useInfo.ui2_usecount = 1;
			useInfo.ui2_username = username;
			useInfo.ui2_domainname = ".";

			uint paramErrorIndex;
			uint returnCode = NetUseAdd(String.Empty, 2, ref useInfo, out paramErrorIndex);
			if (returnCode != 0)
				throw new Win32Exception((int)returnCode);

			XmlDocument xmlDoc = new XmlDocument();
			xmlDoc.Load(filename);

			//			NetUseDel()

			return xmlDoc;
		}
		*/
	}
}