// GLibSharp.Marshaller.cs : Marshalling utils 
//
// Author: Rachel Hestilow <rachel@nullenvoid.com>
//         Mike Kestner  <mkestner@ximian.com>
//
// Copyright (c) 2002, 2003 Rachel Hestilow
// Copyright (c) 2004 Novell, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of version 2 of the Lesser GNU General 
// Public License as published by the Free Software Foundation.
//
// 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this program; if not, write to the
// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.


namespace Gst.GLib {
	using System;
	using System.Runtime.InteropServices;
	
	public class Marshaller {

		private Marshaller () {}
		
		[DllImport("libglib-2.0-0.dll")]
		static extern void g_free (IntPtr mem);

		public static void Free (IntPtr ptr)
		{
			g_free (ptr);
		}

		public static void Free (IntPtr[] ptrs)
		{
			if (ptrs == null)
				return;

			for (int i = 0; i < ptrs.Length; i++)
				g_free (ptrs [i]);
		}

		[DllImport("libglib-2.0-0.dll")]
		static extern IntPtr g_filename_to_utf8 (IntPtr mem, int len, IntPtr read, out IntPtr written, out IntPtr error);

		public static string FilenamePtrToString (IntPtr ptr) 
		{
			if (ptr == IntPtr.Zero) return null;
			
			IntPtr dummy, error;
			IntPtr utf8 = g_filename_to_utf8 (ptr, -1, IntPtr.Zero, out dummy, out error);
			if (error != IntPtr.Zero)
				throw new GLib.GException (error);
			return Utf8PtrToString (utf8);
		}

		public static string FilenamePtrToStringGFree (IntPtr ptr) 
		{
			string ret = FilenamePtrToString (ptr);
			g_free (ptr);
			return ret;
		}

		static unsafe ulong strlen (IntPtr s)
		{
			ulong cnt = 0;
			byte *b = (byte *)s;
			while (*b != 0) {
				b++;
				cnt++;
			}
			return cnt;
		}

		public static string Utf8PtrToString (IntPtr ptr) 
		{
			if (ptr == IntPtr.Zero)
				return null;

			int len = (int) (uint) strlen (ptr);
			byte[] bytes = new byte [len];
			Marshal.Copy (ptr, bytes, 0, len);
			return System.Text.Encoding.UTF8.GetString (bytes);
		}

		public static string[] Utf8PtrToString (IntPtr[] ptrs) {
			// The last pointer is a null terminator.
			string[] ret = new string[ptrs.Length - 1];
			for (int i = 0; i < ret.Length; i++)
				ret[i] = Utf8PtrToString (ptrs[i]);
			return ret;
		}

		public static string PtrToStringGFree (IntPtr ptr) 
		{
			string ret = Utf8PtrToString (ptr);
			g_free (ptr);
			return ret;
		}

		public static string[] PtrToStringGFree (IntPtr[] ptrs) {
			// The last pointer is a null terminator.
			string[] ret = new string[ptrs.Length - 1];
			for (int i = 0; i < ret.Length; i++) {
				ret[i] = Utf8PtrToString (ptrs[i]);
				g_free (ptrs[i]);
			}
			return ret;
		}

		[DllImport("libglib-2.0-0.dll")]
		static extern IntPtr g_filename_from_utf8 (IntPtr mem, int len, IntPtr read, out IntPtr written, out IntPtr error);

		public static IntPtr StringToFilenamePtr (string str) 
		{
			if (str == null)
				return IntPtr.Zero;

			IntPtr dummy, error;
			IntPtr utf8 = StringToPtrGStrdup (str);
			IntPtr result = g_filename_from_utf8 (utf8, -1, IntPtr.Zero, out dummy, out error);
			g_free (utf8);
			if (error != IntPtr.Zero)
				throw new GException (error);

			return result;
		}

		public static IntPtr StringToPtrGStrdup (string str) {
			if (str == null)
				return IntPtr.Zero;
			byte[] bytes = System.Text.Encoding.UTF8.GetBytes (str);
			IntPtr result = g_malloc (new UIntPtr ((ulong)bytes.Length + 1));
			Marshal.Copy (bytes, 0, result, bytes.Length);
			Marshal.WriteByte (result, bytes.Length, 0);
			return result;
		}

		public static string StringFormat (string format, params object[] args) {
			string ret = String.Format (format, args);
			if (ret.IndexOf ('%') == -1)
				return ret;
			else
				return ret.Replace ("%", "%%");
		}

		public static IntPtr[] StringArrayToNullTermPointer (string[] strs)
		{
			if (strs == null)
				return null;
			IntPtr[] result = new IntPtr [strs.Length + 1];
			for (int i = 0; i < strs.Length; i++)
				result [i] = StringToPtrGStrdup (strs [i]);
			result [strs.Length] = IntPtr.Zero;
			return result;
		}

		[DllImport("libglib-2.0-0.dll")]
		static extern void g_strfreev (IntPtr mem);

		public static void StrFreeV (IntPtr null_term_array)
		{
			g_strfreev (null_term_array);
		}

		public static string[] NullTermPtrToStringArray (IntPtr null_term_array, bool owned)
		{
			if (null_term_array == IntPtr.Zero)
				return new string [0];

			int count = 0;
			System.Collections.ArrayList result = new System.Collections.ArrayList ();
			IntPtr s = Marshal.ReadIntPtr (null_term_array, count++ * IntPtr.Size);
			while (s != IntPtr.Zero) {
				result.Add (Utf8PtrToString (s));
				s = Marshal.ReadIntPtr (null_term_array, count++ * IntPtr.Size);
			}

			if (owned)
				g_strfreev (null_term_array);

			return (string[]) result.ToArray (typeof(string));
		}

		public static string[] PtrToStringArrayGFree (IntPtr string_array)
		{
			if (string_array == IntPtr.Zero)
				return new string [0];
	
			int count = 0;
			while (Marshal.ReadIntPtr (string_array, count*IntPtr.Size) != IntPtr.Zero)
				++count;
	
			string[] members = new string[count];
			for (int i = 0; i < count; ++i) {
				IntPtr s = Marshal.ReadIntPtr (string_array, i * IntPtr.Size);
				members[i] = GLib.Marshaller.PtrToStringGFree (s);
			}
			GLib.Marshaller.Free (string_array);
			return members;
		}

		// Argv marshalling -- unpleasantly complex, but
		// don't know of a better way to do it.
		//
		// Currently, the 64-bit cleanliness is
		// hypothetical. It's also ugly, but I don't know of a
		// construct to handle both 32 and 64 bitness
		// transparently, since we need to alloc buffers of
		// [native pointer size] * [count] bytes.

		[DllImport("libglib-2.0-0.dll")]
		static extern IntPtr g_malloc(UIntPtr size);

		public static IntPtr Malloc (ulong size)
		{
			return g_malloc (new UIntPtr (size));
		}

		static bool check_sixtyfour () {
			int szint = Marshal.SizeOf (typeof (int));
			int szlong = Marshal.SizeOf (typeof (long));
			int szptr = IntPtr.Size;

			if (szptr == szint)
				return false;
			if (szptr == szlong)
				return true;

			throw new Exception ("Pointers are neither int- nor long-sized???");
		}

		static IntPtr make_buf_32 (string[] args) 
		{
			int[] ptrs = new int[args.Length];

			for (int i = 0; i < args.Length; i++)
				ptrs[i] = (int) Marshal.StringToHGlobalAuto (args[i]);

			IntPtr buf = g_malloc (new UIntPtr ((ulong) Marshal.SizeOf(typeof(int)) * 
					       (ulong) args.Length));
			Marshal.Copy (ptrs, 0, buf, ptrs.Length);
			return buf;
		}

		static IntPtr make_buf_64 (string[] args) 
		{
			long[] ptrs = new long[args.Length];

			for (int i = 0; i < args.Length; i++)
				ptrs[i] = (long) Marshal.StringToHGlobalAuto (args[i]);
				
			IntPtr buf = g_malloc (new UIntPtr ((ulong) Marshal.SizeOf(typeof(long)) * 
					       (ulong) args.Length));
			Marshal.Copy (ptrs, 0, buf, ptrs.Length);
			return buf;
		}

		[Obsolete ("Use GLib.Argv instead to avoid leaks.")]
		public static IntPtr ArgvToArrayPtr (string[] args)
		{
			if (args.Length == 0)
				return IntPtr.Zero;

			if (check_sixtyfour ())
				return make_buf_64 (args);

			return make_buf_32 (args);
		}

		// should we be freeing these pointers? they're marshalled
		// from our own strings, so I think not ...

		static string[] unmarshal_32 (IntPtr buf, int argc)
		{
			int[] ptrs = new int[argc];
			string[] args = new string[argc];

			Marshal.Copy (buf, ptrs, 0, argc);

			for (int i = 0; i < ptrs.Length; i++)
				args[i] = Marshal.PtrToStringAuto ((IntPtr) ptrs[i]);
			
			return args;
		}

		static string[] unmarshal_64 (IntPtr buf, int argc)
		{
			long[] ptrs = new long[argc];
			string[] args = new string[argc];

			Marshal.Copy (buf, ptrs, 0, argc);

			for (int i = 0; i < ptrs.Length; i++)
				args[i] = Marshal.PtrToStringAuto ((IntPtr) ptrs[i]);
			
			return args;
		}		

		[Obsolete ("Use GLib.Argv instead to avoid leaks.")]
		public static string[] ArrayPtrToArgv (IntPtr array, int argc)
		{
			if (argc == 0)
				return new string[0];

			if (check_sixtyfour ())
				return unmarshal_64 (array, argc);

			return unmarshal_32 (array, argc);
		}

		static DateTime local_epoch = new DateTime (1970, 1, 1, 0, 0, 0);
		static int utc_offset = (int) (TimeZone.CurrentTimeZone.GetUtcOffset (DateTime.Now)).TotalSeconds;

		public static IntPtr DateTimeTotime_t (DateTime time)
		{
			return new IntPtr (((long)time.Subtract (local_epoch).TotalSeconds) - utc_offset);
		}

		public static DateTime time_tToDateTime (IntPtr time_t)
		{
			return local_epoch.AddSeconds (time_t.ToInt64 () + utc_offset);
		}

		[DllImport("libglib-2.0-0.dll")]
		static extern IntPtr g_malloc0 (UIntPtr size);

		[DllImport("libglib-2.0-0.dll")]
		static extern int g_unichar_to_utf8 (uint c, IntPtr buf);

		public static char GUnicharToChar (uint ucs4_char)
		{ 
			if (ucs4_char == 0)
				return (char) 0;

			string ret = GUnicharToString (ucs4_char);
			if (ret.Length != 1)
				throw new ArgumentOutOfRangeException ("ucs4char is not representable by a char.");

			return ret [0];
		}

		public static string GUnicharToString (uint ucs4_char)
		{ 
			if (ucs4_char == 0)
				return String.Empty;

			IntPtr buf = g_malloc0 (new UIntPtr (7));
			g_unichar_to_utf8 (ucs4_char, buf);
			return PtrToStringGFree (buf);
		}

		[DllImport("libglib-2.0-0.dll")]
		static extern IntPtr g_utf16_to_ucs4 (ref ushort c, IntPtr len, IntPtr d1, IntPtr d2, IntPtr d3);

		public static uint CharToGUnichar (char c)
		{
			ushort val = (ushort) c;
			IntPtr ucs4_str = g_utf16_to_ucs4 (ref val, new IntPtr (1), IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
			uint result = (uint) Marshal.ReadInt32 (ucs4_str);
			g_free (ucs4_str);
			return result;
		}

		public static IntPtr StructureToPtrAlloc (object o)
		{
			IntPtr result = Marshal.AllocHGlobal (Marshal.SizeOf (o));
			Marshal.StructureToPtr (o, result, false);
			return result;
		}

		public static Array ListPtrToArray (IntPtr list_ptr, Type list_type, bool owned, bool elements_owned, Type elem_type)
		{
			Type array_type = elem_type == typeof (ListBase.FilenameString) ? typeof (string) : elem_type;
			ListBase list;
			if (list_type == typeof(GLib.List))
				list = new GLib.List (list_ptr, elem_type, owned, elements_owned);
			else
				list = new GLib.SList (list_ptr, elem_type, owned, elements_owned);

			using (list)
				return ListToArray (list, array_type);
		}

		public static Array PtrArrayToArray (IntPtr list_ptr, bool owned, bool elements_owned, Type elem_type)
		{
			GLib.PtrArray array = new GLib.PtrArray (list_ptr, elem_type, owned, elements_owned);
			Array ret = Array.CreateInstance (elem_type, array.Count);
			array.CopyTo (ret, 0);
			array.Dispose ();
			return ret;
		}

		public static Array ListToArray (ListBase list, System.Type type)
		{
			Array result = Array.CreateInstance (type, list.Count);
			if (list.Count > 0)
				list.CopyTo (result, 0);

			if (type.IsSubclassOf (typeof (GLib.Opaque)))
				list.elements_owned = false;

			return result;
		}
	}
}