//
// Mono.Tools.GacUtil
//
// Author(s):
//  Todd Berman <tberman@sevenl.net>
//  Jackson Harper <jackson@ximian.com>
//
// Copyright 2003, 2004 Todd Berman 
// Copyright 2004 Novell, Inc (http://www.novell.com)
//


using System;
using System.IO;
using System.Diagnostics;
using System.Text;
using System.Collections;
using System.Globalization;
using System.Runtime.InteropServices;
using System.Security.Cryptography;

using Mono.Security;
using Mono.Security.Cryptography;

using IKVM.Reflection;

namespace Mono.Tools {

	public class Driver {

		private enum Command {
			Unknown,
			Install,
			InstallFromList,
			Uninstall,
			UninstallFromList,
			UninstallSpecific,
			List,
			Help
		}

		private enum VerificationResult
		{
			StrongNamed,
			WeakNamed,
			DelaySigned,
			Skipped
		}

		private static bool silent;
		static bool in_bootstrap;
		private static Universe _universe;

		public static int Main (string [] args)
		{
			if (args.Length == 0)
				Usage ();

			Command command = Command.Unknown;
			string command_str = null;

			string libdir;
			string name, package, gacdir, root;
			name = package = root = gacdir = null;
			bool check_refs = false;

			// Check for silent arg first so we can suppress
			// warnings during command line parsing
			if (Array.IndexOf (args, "/silent") > -1 || Array.IndexOf (args, "-silent") > -1)
				silent = true;

			for (int i=0; i<args.Length; i++) {
				if (IsSwitch (args [i])) {

					// for cmd line compatibility with other gacutils
					// we always force it though
					if (args [i] == "-f" || args [i] == "/f")
						continue;

					// Ignore this option for now, although we might implement it someday
					if (args [i] == "/r") {
						WriteLine ("WARNING: gacutil does not support traced references." +
							"This option is being ignored.");
						i += 3;
						continue;
					}

					// This is already handled we just dont want to choke on it
					if (args [i] == "-silent" || args [i] == "/silent")
						continue; 

					if (args [i] == "-check_refs" || args [i] == "/check_refs") {
						check_refs = true;
						continue;
					}

					if (args [i] == "-bootstrap" || args [i] == "/bootstrap") {
						in_bootstrap = true;
						continue;
					}

					if (command == Command.Unknown) {
						command = GetCommand (args [i]);
						if (command != Command.Unknown) {
							command_str = args [i];
							continue;
						}
					}

					if (i + 1 >= args.Length) {
						Console.WriteLine ("Option " + args [i] + " takes 1 argument");
						return 1;
					}

					switch (args [i]) {
					case "-package":
					case "/package":
						package = args [++i];
						continue;
					case "-root":
					case "/root":
						root = args [++i];
						continue;
					case "-gacdir":
					case "/gacdir":
						gacdir = args [++i];
						continue;
					case "/nologo":
					case "-nologo":
						// we currently don't display a
						// logo banner, so ignore it
						// for command-line compatibility
						// with MS gacutil
						continue;
					}
				}
				if (name == null)
					name = args [i];
				else
					name += args [i];
			}

			if (command == Command.Unknown && IsSwitch (args [0])) {
				Console.WriteLine ("Unknown command: " + args [0]);
				return 1;
			} else if (command == Command.Unknown) {
				Usage ();
			} else if (command == Command.Help) {
				ShowHelp (true);
				return 1;
			}

			if (gacdir == null) {
				gacdir = GetGacDir ();
				libdir = GetLibDir ();
			} else {
				gacdir = EnsureLib (gacdir);
				libdir = Path.Combine (gacdir, "mono");
				gacdir = Path.Combine (libdir, "gac");
			}

			string link_gacdir = gacdir;
			string link_libdir = libdir;
			if (root != null) {
				libdir = Path.Combine (root, "mono");
				gacdir = Path.Combine (libdir, "gac");
			}

			LoadConfig (silent);

			switch (command) {
			case Command.Install:
				if (name == null) {
					WriteLine ("Option " + command_str + " takes 1 argument");
					return 1;
				}
				if (!Install (check_refs, name, package, gacdir, link_gacdir, libdir, link_libdir))
					return 1;
				break;
			case Command.InstallFromList:
				if (name == null) {
					WriteLine ("Option " + command_str + " takes 1 argument");
					return 1;
				}
				if (!InstallFromList (check_refs, name, package, gacdir, link_gacdir, libdir, link_libdir))
					return 1;
				break;
			case Command.Uninstall:
				if (name == null) {
					WriteLine ("Option " + command_str + " takes 1 argument");
					return 1;
				}
				int uninstallCount = 0;
				int uninstallFailures = 0;
				Uninstall (name, package, gacdir, libdir, false,
					ref uninstallCount, ref uninstallFailures);
				WriteLine ("Assemblies uninstalled = {0}", uninstallCount);
				WriteLine ("Failures = {0}", uninstallFailures);
				if (uninstallFailures > 0)
					return 1;
				break;
			case Command.UninstallFromList:
				if (name == null) {
					WriteLine ("Option " + command_str + " takes 1 argument");
					return 1;
				}
				if (!UninstallFromList (name, package, gacdir, libdir))
					return 1;
				break;
			case Command.UninstallSpecific:
				if (name == null) {
					WriteLine ("Option " + command_str + " takes 1 argument");
					return 1;
				}
				if (!UninstallSpecific (name, package, gacdir, libdir))
					return 1;
				break;
			case Command.List:
				List (name, gacdir);
				break;
			}

			return 0;
		}

		static void Copy (string source, string target, bool v)
		{
			try {
				File.Delete (target);
			} catch {}
			File.Copy (source, target, v);
		}
		
		private static bool Install (bool check_refs, string name, string package,
				string gacdir, string link_gacdir, string libdir, string link_libdir)
		{
			string failure_msg = "Failure adding assembly {0} to the cache: ";
			ArrayList resources;

			if (!File.Exists (name)) {
				WriteLine (string.Format (failure_msg, name) + "The system cannot find the file specified.");
				return false;
			}

			Assembly assembly = null;
			AssemblyName an = null;

			try {
				assembly = ReflectionOnlyLoadFrom (name);
			} catch {
				WriteLine (string.Format (failure_msg, name) + "The file specified is not a valid assembly.");
				return false;
			}

			an = assembly.GetName ();

			switch (VerifyStrongName (an, name)) {
			case VerificationResult.StrongNamed:
			case VerificationResult.Skipped:
				break;
			case VerificationResult.WeakNamed:
				WriteLine (string.Format (failure_msg, name) + "Attempt to install an assembly without a strong name"
					+ (in_bootstrap ? "(continuing anyway)" : string.Empty));
				if (!in_bootstrap)
					return false;
				break;
			case VerificationResult.DelaySigned:
				WriteLine (string.Format (failure_msg, name) + "Strong name cannot be verified for delay-signed assembly"
					+ (in_bootstrap ? "(continuing anyway)" : string.Empty));
				if (!in_bootstrap)
					return false;
				break;
			}

			resources = new ArrayList ();
			foreach (string res_name in assembly.GetManifestResourceNames ()) {
				ManifestResourceInfo res_info = assembly.GetManifestResourceInfo (res_name);
				
				if ((res_info.ResourceLocation & ResourceLocation.Embedded) == 0) {
					if (!File.Exists (res_info.FileName)) {
						WriteLine (string.Format (failure_msg, name) + "The system cannot find resource " + res_info.FileName);
						return false;
					}

					resources.Add (res_info);
				}
			}

			if (check_refs && !CheckReferencedAssemblies (an)) {
				WriteLine (string.Format (failure_msg, name) +
					"Attempt to install an assembly that " +
					"references non strong named assemblies " +
					"with -check_refs enabled.");
				return false;
			}

			string [] siblings = { ".config", ".mdb" };
			string version_token = an.Version + "_" +
					       an.CultureInfo.Name.ToLower (CultureInfo.InvariantCulture) + "_" +
					       GetStringToken (an.GetPublicKeyToken ());
			string full_path = Path.Combine (Path.Combine (gacdir, an.Name), version_token);
			string asmb_file = Path.GetFileName (name);
			string asmb_path = Path.Combine (full_path, asmb_file);
			string asmb_name = assembly.GetName ().Name;
			
			if (Path.GetFileNameWithoutExtension (asmb_file) != asmb_name) {
				WriteLine (string.Format (failure_msg, name) +
				    string.Format ("the filename \"{0}\" doesn't match the assembly name \"{1}\"",
				    	asmb_file, asmb_name));
				return false;
			}

			try {
				if (Directory.Exists (full_path)) {
					// Wipe out the directory. This way we ensure old assemblies	
					// config files, and AOTd files are removed.
					Directory.Delete (full_path, true);
				}
				Directory.CreateDirectory (full_path);
			} catch {
				WriteLine (string.Format (failure_msg, name) +
					"gac directories could not be created, " +
					"possibly permission issues.");
				return false;
			}

			Copy (name, asmb_path, true);

			var name_pdb = Path.ChangeExtension (name, ".pdb");
			if (File.Exists (name_pdb)) {
				Copy (name_pdb, Path.ChangeExtension (asmb_path, ".pdb"), true);
			}

			foreach (string ext in siblings) {
				string sibling = String.Concat (name, ext);
				if (File.Exists (sibling))
					Copy (sibling, String.Concat (asmb_path, ext), true);
			}

			foreach (ManifestResourceInfo resource_info in resources) {
				try {
					Copy (resource_info.FileName, Path.Combine (full_path, Path.GetFileName (resource_info.FileName)), true);
				} catch {
					WriteLine ("ERROR: Could not install resource file " + resource_info.FileName);
					Environment.Exit (1);
				}
			}

			if (package != null) {
				string ref_dir = Path.Combine (libdir, package);
				string ref_path = Path.Combine (ref_dir, asmb_file);

				if (File.Exists (ref_path))
					File.Delete (ref_path);
				try {
					Directory.CreateDirectory (ref_dir);
				} catch {
					WriteLine ("ERROR: Could not create package dir file.");
					Environment.Exit (1);
				}
 				if (Path.DirectorySeparatorChar == '/') {
					string pkg_path_abs = Path.Combine (gacdir, Path.Combine (an.Name, Path.Combine (version_token, asmb_file)));
					string pkg_path = AbsoluteToRelativePath (ref_dir, pkg_path_abs);
 					symlink (pkg_path, ref_path);

 					var pdb_pkg_path = Path.ChangeExtension (pkg_path, ".pdb");
 					var pdb_ref_path = Path.ChangeExtension (ref_path, ".pdb");

 					if (File.Exists (pdb_pkg_path)) {
 						symlink (pdb_pkg_path, pdb_ref_path);
 					} else {
						try {
							File.Delete (pdb_ref_path);
						} catch {
							// Ignore error, just delete files that should not be there.
						}
 					}

					foreach (string ext in siblings) {
						string sibling = String.Concat (pkg_path, ext);
						string sref = String.Concat (ref_path, ext);

						if (File.Exists (sibling))
							symlink (sibling, sref);
						else {
							try {
								File.Delete (sref);
							} catch {
								// Ignore error, just delete files that should not be there.
							}
						}
					}
					WriteLine ("Package exported to: {0} -> {1}", ref_path, pkg_path);
				} else {
					// string link_path = Path.Combine (Path.Combine (link_gacdir, an.Name), version_token);
					//
					// We can't use 'link_path' here, since it need not be a valid path at the time 'gacutil'
					// is run, esp. when invoked in a DESTDIR install.
 					Copy (name, ref_path, true);
					WriteLine ("Package exported to: " + ref_path);
 				}
			}

			WriteLine ("Installed {0} into the gac ({1})", name,
				gacdir);

			return true;
		}

		//from MonoDevelop.Core.FileService
		unsafe static string AbsoluteToRelativePath (string baseDirectoryPath, string absPath)
		{
			if (!Path.IsPathRooted (absPath) || string.IsNullOrEmpty (baseDirectoryPath))
				return absPath;

			absPath = Path.GetFullPath (absPath);
			baseDirectoryPath = Path.GetFullPath (baseDirectoryPath).TrimEnd (Path.DirectorySeparatorChar);

			fixed (char* bPtr = baseDirectoryPath, aPtr = absPath) {
				var bEnd = bPtr + baseDirectoryPath.Length;
				var aEnd = aPtr + absPath.Length;
				char* lastStartA = aEnd;
				char* lastStartB = bEnd;

				int indx = 0;
				// search common base path
				var a = aPtr;
				var b = bPtr;
				while (a < aEnd) {
					if (*a != *b)
						break;
					if (IsSeparator (*a)) {
						indx++;
						lastStartA = a + 1;
						lastStartB = b;
					}
					a++;
					b++;
					if (b >= bEnd) {
						if (a >= aEnd || IsSeparator (*a)) {
							indx++;
							lastStartA = a + 1;
							lastStartB = b;
						}
						break;
					}
				}
				if (indx == 0)
					return absPath;

				if (lastStartA >= aEnd)
					return ".";

				// handle case a: some/path b: some/path/deeper...
				if (a >= aEnd) {
					if (IsSeparator (*b)) {
						lastStartA = a + 1;
						lastStartB = b;
					}
				}

				// look how many levels to go up into the base path
				int goUpCount = 0;
				while (lastStartB < bEnd) {
					if (IsSeparator (*lastStartB))
						goUpCount++;
					lastStartB++;
				}
				var size = goUpCount * 2 + goUpCount + aEnd - lastStartA;
				var result = new char [size];
				fixed (char* rPtr = result) {
					// go paths up
					var r = rPtr;
					for (int i = 0; i < goUpCount; i++) {
						*(r++) = '.';
						*(r++) = '.';
						*(r++) = Path.DirectorySeparatorChar;
					}
					// copy the remaining absulute path
					while (lastStartA < aEnd)
						*(r++) = *(lastStartA++);
				}
				return new string (result);
			}
		}

		static bool IsSeparator (char ch)
		{
			return ch == Path.DirectorySeparatorChar || ch == Path.AltDirectorySeparatorChar || ch == Path.VolumeSeparatorChar;
		}

		private static void Uninstall (string name, string package, string gacdir, string libdir, bool listMode, ref int uninstalled, ref int failures)
		{
			string [] assembly_pieces = name.Split (new char[] { ',' });
			Hashtable asm_info = new Hashtable ();

			foreach (string item in assembly_pieces) {
				if (item == String.Empty) continue;
				string[] pieces = item.Trim ().Split (new char[] { '=' }, 2);
				if(pieces.Length == 1)
					asm_info ["assembly"] = pieces [0];
				else
					asm_info [pieces[0].Trim ().ToLower (CultureInfo.InvariantCulture)] = pieces [1];
			}

			string assembly_name = (string) asm_info ["assembly"];
			string asmdir = Path.Combine (gacdir, assembly_name);
			if (!Directory.Exists (asmdir)) {
				if (listMode) {
					failures++;
					WriteLine ("Assembly: " + name);
				}
				WriteLine ("No assemblies found that match: " + name);
				return;
			}

			string searchString = GetSearchString (asm_info);
			string [] directories = Directory.GetDirectories (asmdir, searchString);

			if (directories.Length == 0) {
				if (listMode) {
					failures++;
					WriteLine ("Assembly: " + name);
					WriteLine ("No assemblies found that match: " + name);
				}
				return;
			}

			for (int i = 0; i < directories.Length; i++) {
				if (listMode && i > 0)
					break;

				string dir = directories [i];
				string extension = null;

				if (File.Exists (Path.Combine (dir, assembly_name + ".dll"))) {
					extension = ".dll";
				} else if (File.Exists (Path.Combine (dir, assembly_name + ".exe"))) {
					extension = ".exe";
				} else {
					failures++;
					WriteLine("Cannot find the assembly: " + assembly_name);
					continue;
				}

				string assembly_filename = assembly_name + extension;

				AssemblyName an = AssemblyName.GetAssemblyName (
					Path.Combine (dir, assembly_filename));
				WriteLine ("Assembly: " + an.FullName);

				Directory.Delete (dir, true);
				if (package != null) {
					string link_dir = Path.Combine (libdir, package);
					string link = Path.Combine (link_dir, assembly_filename);

					try { 
						File.Delete (link);
					} catch {
						// The file might not exist, happens with
						// the debugger on make uninstall
					}
					
					if (Directory.GetFiles (link_dir).Length == 0) {
						WriteLine ("Cleaning package directory, it is empty.");
						try {
							Directory.Delete (link_dir);
						} catch {
							// Workaround: GetFiles does not list Symlinks
						}
					}
				}

				uninstalled++;
				WriteLine ("Uninstalled: " + an.FullName);
			}

			if (Directory.GetDirectories (asmdir).Length == 0) {
				WriteLine ("Cleaning assembly dir, it is empty");
				try {
					Directory.Delete (asmdir);
				} catch {
					// Workaround: GetFiles does not list Symlinks
				}
			}
		}

		private static bool UninstallSpecific (string name, string package,
				string gacdir, string libdir)
		{
			string failure_msg = "Failure to remove assembly from the cache: ";

			if (!File.Exists (name)) {
				WriteLine (failure_msg + "The system cannot find the file specified.");
				return false;
			}

			AssemblyName an = null;

			try {
				an = AssemblyName.GetAssemblyName (name);
			} catch {
				WriteLine (failure_msg + "The file specified is not a valid assembly.");
				return false;
			}

			int uninstallCount = 0;
			int uninstallFailures = 0;
			Uninstall (an.FullName.Replace (" ", String.Empty),
				package, gacdir, libdir, true, ref uninstallCount,
				ref uninstallFailures);
			WriteLine ("Assemblies uninstalled = {0}", uninstallCount);
			WriteLine ("Failures = {0}", uninstallFailures);
			return (uninstallFailures == 0);
		}

		private static void List (string name, string gacdir)
		{
			WriteLine ("The following assemblies are installed into the GAC:");

			if (name != null) {
				FilteredList (name, gacdir);
				return;
			}

			int count = 0;
			DirectoryInfo gacinfo = new DirectoryInfo (gacdir);
			foreach (DirectoryInfo parent in gacinfo.GetDirectories ()) {
				foreach (DirectoryInfo dir in parent.GetDirectories ()) {
					string asmb = Path.Combine (Path.Combine (parent.FullName, dir.Name), parent.Name) + ".dll";
					if (File.Exists (asmb)) {
						WriteLine (AsmbNameFromVersionString (parent.Name, dir.Name));
						count++;
					}
				}
			}
			WriteLine ("Number of items = " + count);
		}

		private static void FilteredList (string name, string gacdir)
		{
			string [] assembly_pieces = name.Split (new char[] { ',' });
			Hashtable asm_info = new Hashtable ();

			foreach (string item in assembly_pieces) {
				string[] pieces = item.Trim ().Split (new char[] { '=' }, 2);
				if(pieces.Length == 1)
					asm_info ["assembly"] = pieces [0];
				else
					asm_info [pieces[0].Trim ().ToLower (CultureInfo.InvariantCulture)] = pieces [1];
			}
			
			string asmdir = Path.Combine (gacdir, (string) asm_info ["assembly"]);
			if (!Directory.Exists (asmdir)) {
				WriteLine ("Number of items = 0");
				return;
			}
			string search = GetSearchString (asm_info);
			string [] dir_list = Directory.GetDirectories (asmdir, search);

			int count = 0;
			foreach (string dir in dir_list) {
				string asmb = Path.Combine (dir, (string) asm_info ["assembly"]) + ".dll";
				if (File.Exists (asmb)) {
					WriteLine (AsmbNameFromVersionString ((string) asm_info ["assembly"],
								   new DirectoryInfo (dir).Name));
					count++;
				}
			}
			WriteLine ("Number of items = " + count);
		}

		private static bool InstallFromList (bool check_refs, string list_file, string package,
				string gacdir, string link_gacdir, string libdir, string link_libdir)
		{
			StreamReader s = null;
			int processed, failed;
			string listdir = Path.GetDirectoryName (
				Path.GetFullPath (list_file));

			processed = failed = 0;

			try {
				s = new StreamReader (list_file);

				string line;
				while ((line = s.ReadLine ()) != null) {
					string file = line.Trim ();
					if (file.Length == 0)
						continue;

					string assemblyPath = Path.Combine (listdir,
						file);

					if (!Install (check_refs, assemblyPath, package, gacdir,
						     link_gacdir, libdir, link_libdir))
						failed++;
					processed++;
				}

				WriteLine ("Assemblies processed = {0}", processed);
				WriteLine ("Assemblies installed = {0}", processed - failed);
				WriteLine ("Failures = {0}", failed);

				return (failed == 0);
			} catch (IOException) {
				WriteLine ("Failed to open assemblies list file " + list_file + ".");
				return false;
			} finally {
				if (s != null)
					s.Close ();
			}
		}

		private static bool UninstallFromList (string list_file, string package,
				string gacdir, string libdir)
		{
			StreamReader s = null;
			int failed, uninstalled;

			failed = uninstalled = 0;

			try {
				s = new StreamReader (list_file);

				string line;
				while ((line = s.ReadLine ()) != null) {
					string name = line.Trim ();
					if (name.Length == 0)
						continue;
					Uninstall (line, package, gacdir, libdir,
						true, ref uninstalled, ref failed);
				}

				WriteLine ("Assemblies processed = {0}", uninstalled+failed);
				WriteLine ("Assemblies uninstalled = {0}", uninstalled);
				WriteLine ("Failures = {0}", failed);

				return (failed == 0);
			} catch (IOException) {
				WriteLine ("Failed to open assemblies list file " + list_file + ".");
				return false;
			} finally {
				if (s != null)
					s.Close ();
			}
		}

		private static Universe GetUniverse () {
			if (_universe == null) {
				_universe = new Universe (UniverseOptions.MetadataOnly);
			}
			return _universe;
		}

		private static Assembly ReflectionOnlyLoadFrom (string fileName)
		{
			return GetUniverse ().LoadFile (fileName);
		}
		private static AssemblyName GetCorlibName ()
		{
			return GetUniverse ().Mscorlib.GetName ();
		}

		private static bool CheckReferencedAssemblies (AssemblyName an)
		{
			try {
				Assembly a = ReflectionOnlyLoadFrom (an.CodeBase);
				AssemblyName corlib = GetCorlibName ();

				foreach (AssemblyName ref_an in a.GetReferencedAssemblies ()) {
					if (ref_an.Name == corlib.Name) // Just do a string compare so we can install on diff versions
						continue;
					byte [] pt = ref_an.GetPublicKeyToken ();
					if (pt == null || pt.Length == 0) {
						WriteLine ("Assembly " + ref_an.Name + " is not strong named.");
						return false;
					}
				}
			} catch (Exception e) {
				WriteLine (e.ToString ()); // This should be removed pre beta3
				return false;
			}

			return true;
		}

		private static string GetSearchString (Hashtable asm_info)
		{
			if (asm_info.Keys.Count == 1)
				return "*";
			string version, culture, token;

			version = asm_info ["version"] as string;
			version = (version == null ? "*" : version + "*");
			culture = asm_info ["culture"] as string;
			culture = (culture == null ? "*" : (culture == "neutral") ? String.Empty : culture.ToLower (CultureInfo.InvariantCulture));
			token = asm_info ["publickeytoken"] as string;
			token = (token == null ? "*" : token.ToLower (CultureInfo.InvariantCulture));
			
			return String.Format ("{0}_{1}_{2}", version, culture, token);
		}

		private static string AsmbNameFromVersionString (string name, string str)
		{
			string [] pieces = str.Split ('_');
			return String.Format ("{0}, Version={1}, Culture={2}, PublicKeyToken={3}",
					name, pieces [0], (pieces [1] == String.Empty ? "neutral" : pieces [1]),
					pieces [2]);
		}

		static bool LoadConfig (bool quiet)
		{
			System.Reflection.MethodInfo config = typeof (System.Environment).GetMethod ("GetMachineConfigPath",
				System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);

			if (config != null) {
				string path = (string) config.Invoke (null, null);

				bool exist = File.Exists (path);
				if (!quiet && !exist)
					Console.WriteLine ("Couldn't find machine.config");

				StrongNameManager.LoadConfig (path);
				return exist;
			} else if (!quiet)
				Console.WriteLine ("Couldn't resolve machine.config location (corlib issue)");

			// default CSP
			return false;
		}

		// modified copy from sn
		private static VerificationResult VerifyStrongName (AssemblyName an, string assemblyFile)
		{
			byte [] publicKey = StrongNameManager.GetMappedPublicKey (an.GetPublicKeyToken ());
			if ((publicKey == null) || (publicKey.Length < 12)) {
				// no mapping
				publicKey = an.GetPublicKey ();
				if ((publicKey == null) || (publicKey.Length < 12))
					return VerificationResult.WeakNamed;
			}

			// Note: MustVerify is based on the original token (by design). Public key
			// remapping won't affect if the assembly is verified or not.
			if (StrongNameManager.MustVerify (new System.Reflection.AssemblyName (an.FullName))) {
				RSA rsa = CryptoConvert.FromCapiPublicKeyBlob (publicKey, 12);
				StrongName sn = new StrongName (rsa);
				if (sn.Verify (assemblyFile)) {
					return VerificationResult.StrongNamed;
				} else {
					return VerificationResult.DelaySigned;
				}
			} else {
				return VerificationResult.Skipped;
			}
		}

		private static bool IsSwitch (string arg)
		{
			return (arg [0] == '-' || (arg [0] == '/' && !arg.EndsWith (".dll") && !arg.EndsWith (".exe") && arg.IndexOf ('/', 1) < 0 ) );
		}

		private static Command GetCommand (string arg)
		{
			Command c = Command.Unknown;

			switch (arg) {
			case "-i":
			case "/i":
			case "--install":
				c = Command.Install;
				break;
			case "-il":
			case "/il":
			case "--install-from-list":
				c = Command.InstallFromList;
				break;
			case "-u":
			case "/u":
			case "/uf":
			case "--uninstall":
				c = Command.Uninstall;
				break;
			case "-ul":
			case "/ul":
			case "--uninstall-from-list":
				c = Command.UninstallFromList;
				break;
			case "-us":
			case "/us":
			case "--uninstall-specific":
				c = Command.UninstallSpecific;
				break;
			case "-l":
			case "/l":
			case "--list":
				c = Command.List;
				break;
			case "-?":
			case "/?":
			case "--help":
				c = Command.Help;
				break;
			}
			return c;	 
		}

		[DllImport ("libc", SetLastError=true)]
		public static extern int symlink (string oldpath, string newpath);

		private static string GetGacDir () {
			System.Reflection.PropertyInfo gac = typeof (System.Environment).GetProperty ("GacPath",
					System.Reflection.BindingFlags.Static|System.Reflection.BindingFlags.NonPublic);
			if (gac == null) {
				WriteLine ("ERROR: Mono runtime not detected, please use " +
						"the mono runtime for gacutil.exe");
				Environment.Exit (1);
			}
			System.Reflection.MethodInfo get_gac = gac.GetGetMethod (true);
			return (string) get_gac.Invoke (null, null);
		}

		private static string GetLibDir () {
			System.Reflection.MethodInfo libdir = typeof (System.Environment).GetMethod ("internalGetGacPath",
					System.Reflection.BindingFlags.Static|System.Reflection.BindingFlags.NonPublic);
			if (libdir == null) {
				WriteLine ("ERROR: Mono runtime not detected, please use " +
						"the mono runtime for gacutil.exe");
				Environment.Exit (1);
			}
			return Path.Combine ((string)libdir.Invoke (null, null), "mono");
		}

		private static string GetStringToken (byte[] tok)
		{
			StringBuilder sb = new StringBuilder ();
			for (int i = 0; i < tok.Length ; i++)
				sb.Append (tok[i].ToString ("x2"));
			return sb.ToString ();
		}

		private static string EnsureLib (string dir)
		{
			DirectoryInfo d = new DirectoryInfo (dir);
			if (d.Name == "lib")
				return dir;
			return Path.Combine (dir, "lib");
		}

		private static void WriteLine ()
		{
			if (silent)
				return;
			Console.WriteLine ();
		}

		private static void WriteLine (string line)
		{
			if (silent)
				return;
			Console.WriteLine (line);
		}

		private static void WriteLine (string line, params object [] p)
		{
			if (silent)
				return; 
			Console.WriteLine (line, p);
		}

		private static void Usage ()
		{
			ShowHelp (false);
			Environment.Exit (1);
		}

		private static void ShowHelp (bool detailed)
		{
			WriteLine ("Usage: gacutil.exe <commands> [ <options> ]");
			WriteLine ("Commands:");

			WriteLine ("-i <assembly_path> [-check_refs] [-package NAME] [-root ROOTDIR] [-gacdir GACDIR]");
			WriteLine ("\tInstalls an assembly into the global assembly cache.");
			if (detailed) {
				WriteLine ("\t<assembly_path> is the name of the file that contains the " +
						"\tassembly manifest\n" +
						"\tExample: -i myDll.dll");
			}
			WriteLine ();

			WriteLine ("-il <assembly_list_file> [-check_refs] [-package NAME] [-root ROOTDIR] [-gacdir GACDIR]");
			WriteLine ("\tInstalls one or more assemblies into the global assembly cache.");
			if (detailed) {
				WriteLine ("\t<assembly_list_file> is the path to a test file containing a list of\n" +
						"\tassembly file paths on separate lines.\n" +
						"\tExample -il assembly_list.txt\n" +
						"\t\tassembly_list.txt contents:\n" +
						"\t\tassembly1.dll\n" +
						"\t\tassembly2.dll");
			}
			WriteLine ();
			
			WriteLine ("-u <assembly_display_name> [-package NAME] [-root ROOTDIR] [-gacdir GACDIR]");
			WriteLine ("\tUninstalls an assembly from the global assembly cache.");
			if (detailed) {
				WriteLine ("\t<assembly_display_name> is the name of the assembly (partial or\n" +
						"\tfully qualified) to remove from the global assembly cache. If a \n" +
						"\tpartial name is specified all matching assemblies will be uninstalled.\n" +
						"\tExample: -u myDll,Version=1.2.1.0");
			}
			WriteLine ();

			WriteLine ("-ul <assembly_list_file> [-package NAME] [-root ROOTDIR] [-gacdir GACDIR]");
			WriteLine ("\tUninstalls one or more assemblies from the global assembly cache.");
			if (detailed) {
				WriteLine ("\t<assembly_list_file> is the path to a test file containing a list of\n" +
						"\tassembly names on separate lines.\n" +
						"\tExample -ul assembly_list.txt\n" +
						"\t\tassembly_list.txt contents:\n" +
						"\t\tassembly1,Version=1.0.0.0,Culture=en,PublicKeyToken=0123456789abcdef\n" +
						"\t\tassembly2,Version=2.0.0.0,Culture=en,PublicKeyToken=0123456789abcdef");
			}
			WriteLine ();

			WriteLine ("-us <assembly_path> [-package NAME] [-root ROOTDIR] [-gacdir GACDIR]");
			WriteLine ("\tUninstalls an assembly using the specifed assemblies full name.");
			if (detailed) {
				WriteLine ("\t<assembly path> is the path to an assembly. The full assembly name\n" +
						"\tis retrieved from the specified assembly if there is an assembly in\n" +
						"\tthe GAC with a matching name, it is removed.\n" +
						"\tExample: -us myDll.dll");
			}
			WriteLine ();

			WriteLine ("-l [assembly_name] [-root ROOTDIR] [-gacdir GACDIR]");
			WriteLine ("\tLists the contents of the global assembly cache.");
			if (detailed) {
				WriteLine ("\tWhen the <assembly_name> parameter is specified only matching\n" +
						"\tassemblies are listed.");
			}
			WriteLine ();

			WriteLine ("-?");
			WriteLine ("\tDisplays a detailed help screen");
			WriteLine ();

			if (!detailed)
				return;

			WriteLine ("Options:");
			WriteLine ("-package <NAME>");
			WriteLine ("\tUsed to create a directory in prefix/lib/mono with the name NAME, and a\n" +
					"\tsymlink is created from NAME/assembly_name to the assembly on the GAC.\n" +
					"\tThis is used so developers can reference a set of libraries at once.");
			WriteLine ();

			WriteLine ("-gacdir <GACDIR>");
			WriteLine ("\tUsed to specify the GACs base directory. Once an assembly has been installed\n" +
					"\tto a non standard gacdir the MONO_GAC_PREFIX environment variable must be used\n" +
					"\tto access the assembly.");
			WriteLine ();

			WriteLine ("-root <ROOTDIR>");
			WriteLine ("\tUsed by developers integrating this with automake tools or packaging tools\n" +
					"\tthat require a prefix directory to  be specified. The root represents the\n" +
					"\t\"libdir\" component of a prefix (typically prefix/lib).");
			WriteLine ();

			WriteLine ("-check_refs");
			WriteLine ("\tUsed to ensure that the assembly being installed into the GAC does not\n" +
					"\treference any non strong named assemblies. Assemblies being installed to\n" +
					"\tthe GAC should not reference non strong named assemblies, however the is\n" +
					"\tan optional check.");

			WriteLine ();
			WriteLine ("Ignored Options:");
			WriteLine ("-f");
			WriteLine ("\tThe Mono gacutil ignores the -f option to maintain commandline compatibility with");
			WriteLine ("\tother gacutils. gacutil will always force the installation of a new assembly.");

			WriteLine ();
			WriteLine ("-r <reference_scheme> <reference_id> <description>");
			WriteLine ("\tThe Mono gacutil has not implemented traced references and will emit a warning");
			WriteLine ("\twhen this option is used.");
		}
	}
}