// Copyright (c) 2010-2013 AlphaSierraPapa for the SharpDevelop Team
// 
// 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.

using System;

namespace ICSharpCode.Decompiler.Util
{
	/// <summary>
	/// Static helper method for converting between primitive types.
	/// </summary>
	public static class CSharpPrimitiveCast
	{
		/// <summary>
		/// Performs a conversion between primitive types.
		/// Unfortunately we cannot use Convert.ChangeType because it has different semantics
		/// (e.g. rounding behavior for floats, overflow, etc.), so we write down every possible primitive C# cast
		/// and let the compiler figure out the exact semantics.
		/// And we have to do everything twice, once in a checked-block, once in an unchecked-block.
		/// </summary>
		/// <exception cref="OverflowException">Overflow checking is enabled and an overflow occurred.</exception>
		/// <exception cref="InvalidCastException">The cast is invalid, e.g. casting a boolean to an integer.</exception>
		public static object Cast(TypeCode targetType, object input, bool checkForOverflow)
		{
			if (input == null)
				return null;
			if (checkForOverflow)
				return CSharpPrimitiveCastChecked(targetType, input);
			else
				return CSharpPrimitiveCastUnchecked(targetType, input);
		}
		
		static object CSharpPrimitiveCastChecked(TypeCode targetType, object input)
		{
			checked {
				TypeCode sourceType = Type.GetTypeCode(input.GetType());
				if (sourceType == targetType)
					return input;
				switch (targetType) {
					case TypeCode.Char:
						switch (sourceType) {
								case TypeCode.SByte:   return (char)(sbyte)input;
								case TypeCode.Byte:    return (char)(byte)input;
								case TypeCode.Int16:   return (char)(short)input;
								case TypeCode.UInt16:  return (char)(ushort)input;
								case TypeCode.Int32:   return (char)(int)input;
								case TypeCode.UInt32:  return (char)(uint)input;
								case TypeCode.Int64:   return (char)(long)input;
								case TypeCode.UInt64:  return (char)(ulong)input;
								case TypeCode.Single:  return (char)(float)input;
								case TypeCode.Double:  return (char)(double)input;
								case TypeCode.Decimal: return (char)(decimal)input;
								case TypeCode.Boolean: return (char)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.SByte:
						switch (sourceType) {
								case TypeCode.Char:    return (sbyte)(char)input;
								case TypeCode.Byte:    return (sbyte)(byte)input;
								case TypeCode.Int16:   return (sbyte)(short)input;
								case TypeCode.UInt16:  return (sbyte)(ushort)input;
								case TypeCode.Int32:   return (sbyte)(int)input;
								case TypeCode.UInt32:  return (sbyte)(uint)input;
								case TypeCode.Int64:   return (sbyte)(long)input;
								case TypeCode.UInt64:  return (sbyte)(ulong)input;
								case TypeCode.Single:  return (sbyte)(float)input;
								case TypeCode.Double:  return (sbyte)(double)input;
								case TypeCode.Decimal: return (sbyte)(decimal)input;
								case TypeCode.Boolean: return (sbyte)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Byte:
						switch (sourceType) {
								case TypeCode.Char:    return (byte)(char)input;
								case TypeCode.SByte:   return (byte)(sbyte)input;
								case TypeCode.Int16:   return (byte)(short)input;
								case TypeCode.UInt16:  return (byte)(ushort)input;
								case TypeCode.Int32:   return (byte)(int)input;
								case TypeCode.UInt32:  return (byte)(uint)input;
								case TypeCode.Int64:   return (byte)(long)input;
								case TypeCode.UInt64:  return (byte)(ulong)input;
								case TypeCode.Single:  return (byte)(float)input;
								case TypeCode.Double:  return (byte)(double)input;
								case TypeCode.Decimal: return (byte)(decimal)input;
								case TypeCode.Boolean: return (byte)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Int16:
						switch (sourceType) {
								case TypeCode.Char:    return (short)(char)input;
								case TypeCode.SByte:   return (short)(sbyte)input;
								case TypeCode.Byte:    return (short)(byte)input;
								case TypeCode.UInt16:  return (short)(ushort)input;
								case TypeCode.Int32:   return (short)(int)input;
								case TypeCode.UInt32:  return (short)(uint)input;
								case TypeCode.Int64:   return (short)(long)input;
								case TypeCode.UInt64:  return (short)(ulong)input;
								case TypeCode.Single:  return (short)(float)input;
								case TypeCode.Double:  return (short)(double)input;
								case TypeCode.Decimal: return (short)(decimal)input;
								case TypeCode.Boolean: return (short)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.UInt16:
						switch (sourceType) {
								case TypeCode.Char:    return (ushort)(char)input;
								case TypeCode.SByte:   return (ushort)(sbyte)input;
								case TypeCode.Byte:    return (ushort)(byte)input;
								case TypeCode.Int16:   return (ushort)(short)input;
								case TypeCode.Int32:   return (ushort)(int)input;
								case TypeCode.UInt32:  return (ushort)(uint)input;
								case TypeCode.Int64:   return (ushort)(long)input;
								case TypeCode.UInt64:  return (ushort)(ulong)input;
								case TypeCode.Single:  return (ushort)(float)input;
								case TypeCode.Double:  return (ushort)(double)input;
								case TypeCode.Decimal: return (ushort)(decimal)input;
								case TypeCode.Boolean: return (ushort)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Int32:
						switch (sourceType) {
								case TypeCode.Char:    return (int)(char)input;
								case TypeCode.SByte:   return (int)(sbyte)input;
								case TypeCode.Byte:    return (int)(byte)input;
								case TypeCode.Int16:   return (int)(short)input;
								case TypeCode.UInt16:  return (int)(ushort)input;
								case TypeCode.UInt32:  return (int)(uint)input;
								case TypeCode.Int64:   return (int)(long)input;
								case TypeCode.UInt64:  return (int)(ulong)input;
								case TypeCode.Single:  return (int)(float)input;
								case TypeCode.Double:  return (int)(double)input;
								case TypeCode.Decimal: return (int)(decimal)input;
								case TypeCode.Boolean: return (int)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.UInt32:
						switch (sourceType) {
								case TypeCode.Char:    return (uint)(char)input;
								case TypeCode.SByte:   return (uint)(sbyte)input;
								case TypeCode.Byte:    return (uint)(byte)input;
								case TypeCode.Int16:   return (uint)(short)input;
								case TypeCode.UInt16:  return (uint)(ushort)input;
								case TypeCode.Int32:   return (uint)(int)input;
								case TypeCode.Int64:   return (uint)(long)input;
								case TypeCode.UInt64:  return (uint)(ulong)input;
								case TypeCode.Single:  return (uint)(float)input;
								case TypeCode.Double:  return (uint)(double)input;
								case TypeCode.Decimal: return (uint)(decimal)input;
								case TypeCode.Boolean: return (uint)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Int64:
						switch (sourceType) {
								case TypeCode.Char:    return (long)(char)input;
								case TypeCode.SByte:   return (long)(sbyte)input;
								case TypeCode.Byte:    return (long)(byte)input;
								case TypeCode.Int16:   return (long)(short)input;
								case TypeCode.UInt16:  return (long)(ushort)input;
								case TypeCode.Int32:   return (long)(int)input;
								case TypeCode.UInt32:  return (long)(uint)input;
								case TypeCode.UInt64:  return (long)(ulong)input;
								case TypeCode.Single:  return (long)(float)input;
								case TypeCode.Double:  return (long)(double)input;
								case TypeCode.Decimal: return (long)(decimal)input;
								case TypeCode.Boolean: return (long)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.UInt64:
						switch (sourceType) {
								case TypeCode.Char:    return (ulong)(char)input;
								case TypeCode.SByte:   return (ulong)(sbyte)input;
								case TypeCode.Byte:    return (ulong)(byte)input;
								case TypeCode.Int16:   return (ulong)(short)input;
								case TypeCode.UInt16:  return (ulong)(ushort)input;
								case TypeCode.Int32:   return (ulong)(int)input;
								case TypeCode.UInt32:  return (ulong)(uint)input;
								case TypeCode.Int64:   return (ulong)(long)input;
								case TypeCode.Single:  return (ulong)(float)input;
								case TypeCode.Double:  return (ulong)(double)input;
								case TypeCode.Decimal: return (ulong)(decimal)input;
								case TypeCode.Boolean: return (ulong)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Single:
						switch (sourceType) {
								case TypeCode.Char:    return (float)(char)input;
								case TypeCode.SByte:   return (float)(sbyte)input;
								case TypeCode.Byte:    return (float)(byte)input;
								case TypeCode.Int16:   return (float)(short)input;
								case TypeCode.UInt16:  return (float)(ushort)input;
								case TypeCode.Int32:   return (float)(int)input;
								case TypeCode.UInt32:  return (float)(uint)input;
								case TypeCode.Int64:   return (float)(long)input;
								case TypeCode.UInt64:  return (float)(ulong)input;
								case TypeCode.Double:  return (float)(double)input;
								case TypeCode.Decimal: return (float)(decimal)input;
								case TypeCode.Boolean: return (float)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Double:
						switch (sourceType) {
								case TypeCode.Char:    return (double)(char)input;
								case TypeCode.SByte:   return (double)(sbyte)input;
								case TypeCode.Byte:    return (double)(byte)input;
								case TypeCode.Int16:   return (double)(short)input;
								case TypeCode.UInt16:  return (double)(ushort)input;
								case TypeCode.Int32:   return (double)(int)input;
								case TypeCode.UInt32:  return (double)(uint)input;
								case TypeCode.Int64:   return (double)(long)input;
								case TypeCode.UInt64:  return (double)(ulong)input;
								case TypeCode.Single:  return (double)(float)input;
								case TypeCode.Decimal: return (double)(decimal)input;
								case TypeCode.Boolean: return (double)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Decimal:
						switch (sourceType) {
								case TypeCode.Char:    return (decimal)(char)input;
								case TypeCode.SByte:   return (decimal)(sbyte)input;
								case TypeCode.Byte:    return (decimal)(byte)input;
								case TypeCode.Int16:   return (decimal)(short)input;
								case TypeCode.UInt16:  return (decimal)(ushort)input;
								case TypeCode.Int32:   return (decimal)(int)input;
								case TypeCode.UInt32:  return (decimal)(uint)input;
								case TypeCode.Int64:   return (decimal)(long)input;
								case TypeCode.UInt64:  return (decimal)(ulong)input;
								case TypeCode.Single:  return (decimal)(float)input;
								case TypeCode.Double:  return (decimal)(double)input;
								case TypeCode.Boolean: return (decimal)((bool)input ? 1 : 0);
						}
						break;
				}
				throw new InvalidCastException("Cast from " + sourceType + " to " + targetType + "not supported.");
			}
		}
		
		static object CSharpPrimitiveCastUnchecked(TypeCode targetType, object input)
		{
			unchecked {
				TypeCode sourceType = Type.GetTypeCode(input.GetType());
				if (sourceType == targetType)
					return input;
				switch (targetType) {
					case TypeCode.Char:
						switch (sourceType) {
								case TypeCode.SByte:   return (char)(sbyte)input;
								case TypeCode.Byte:    return (char)(byte)input;
								case TypeCode.Int16:   return (char)(short)input;
								case TypeCode.UInt16:  return (char)(ushort)input;
								case TypeCode.Int32:   return (char)(int)input;
								case TypeCode.UInt32:  return (char)(uint)input;
								case TypeCode.Int64:   return (char)(long)input;
								case TypeCode.UInt64:  return (char)(ulong)input;
								case TypeCode.Single:  return (char)(float)input;
								case TypeCode.Double:  return (char)(double)input;
								case TypeCode.Decimal: return (char)(decimal)input;
								case TypeCode.Boolean: return (char)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.SByte:
						switch (sourceType) {
								case TypeCode.Char:    return (sbyte)(char)input;
								case TypeCode.Byte:    return (sbyte)(byte)input;
								case TypeCode.Int16:   return (sbyte)(short)input;
								case TypeCode.UInt16:  return (sbyte)(ushort)input;
								case TypeCode.Int32:   return (sbyte)(int)input;
								case TypeCode.UInt32:  return (sbyte)(uint)input;
								case TypeCode.Int64:   return (sbyte)(long)input;
								case TypeCode.UInt64:  return (sbyte)(ulong)input;
								case TypeCode.Single:  return (sbyte)(float)input;
								case TypeCode.Double:  return (sbyte)(double)input;
								case TypeCode.Decimal: return (sbyte)(decimal)input;
								case TypeCode.Boolean: return (sbyte)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Byte:
						switch (sourceType) {
								case TypeCode.Char:    return (byte)(char)input;
								case TypeCode.SByte:   return (byte)(sbyte)input;
								case TypeCode.Int16:   return (byte)(short)input;
								case TypeCode.UInt16:  return (byte)(ushort)input;
								case TypeCode.Int32:   return (byte)(int)input;
								case TypeCode.UInt32:  return (byte)(uint)input;
								case TypeCode.Int64:   return (byte)(long)input;
								case TypeCode.UInt64:  return (byte)(ulong)input;
								case TypeCode.Single:  return (byte)(float)input;
								case TypeCode.Double:  return (byte)(double)input;
								case TypeCode.Decimal: return (byte)(decimal)input;
								case TypeCode.Boolean: return (byte)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Int16:
						switch (sourceType) {
								case TypeCode.Char:    return (short)(char)input;
								case TypeCode.SByte:   return (short)(sbyte)input;
								case TypeCode.Byte:    return (short)(byte)input;
								case TypeCode.UInt16:  return (short)(ushort)input;
								case TypeCode.Int32:   return (short)(int)input;
								case TypeCode.UInt32:  return (short)(uint)input;
								case TypeCode.Int64:   return (short)(long)input;
								case TypeCode.UInt64:  return (short)(ulong)input;
								case TypeCode.Single:  return (short)(float)input;
								case TypeCode.Double:  return (short)(double)input;
								case TypeCode.Decimal: return (short)(decimal)input;
								case TypeCode.Boolean: return (short)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.UInt16:
						switch (sourceType) {
								case TypeCode.Char:    return (ushort)(char)input;
								case TypeCode.SByte:   return (ushort)(sbyte)input;
								case TypeCode.Byte:    return (ushort)(byte)input;
								case TypeCode.Int16:   return (ushort)(short)input;
								case TypeCode.Int32:   return (ushort)(int)input;
								case TypeCode.UInt32:  return (ushort)(uint)input;
								case TypeCode.Int64:   return (ushort)(long)input;
								case TypeCode.UInt64:  return (ushort)(ulong)input;
								case TypeCode.Single:  return (ushort)(float)input;
								case TypeCode.Double:  return (ushort)(double)input;
								case TypeCode.Decimal: return (ushort)(decimal)input;
								case TypeCode.Boolean: return (ushort)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Int32:
						switch (sourceType) {
								case TypeCode.Char:    return (int)(char)input;
								case TypeCode.SByte:   return (int)(sbyte)input;
								case TypeCode.Byte:    return (int)(byte)input;
								case TypeCode.Int16:   return (int)(short)input;
								case TypeCode.UInt16:  return (int)(ushort)input;
								case TypeCode.UInt32:  return (int)(uint)input;
								case TypeCode.Int64:   return (int)(long)input;
								case TypeCode.UInt64:  return (int)(ulong)input;
								case TypeCode.Single:  return (int)(float)input;
								case TypeCode.Double:  return (int)(double)input;
								case TypeCode.Decimal: return (int)(decimal)input;
								case TypeCode.Boolean: return (int)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.UInt32:
						switch (sourceType) {
								case TypeCode.Char:    return (uint)(char)input;
								case TypeCode.SByte:   return (uint)(sbyte)input;
								case TypeCode.Byte:    return (uint)(byte)input;
								case TypeCode.Int16:   return (uint)(short)input;
								case TypeCode.UInt16:  return (uint)(ushort)input;
								case TypeCode.Int32:   return (uint)(int)input;
								case TypeCode.Int64:   return (uint)(long)input;
								case TypeCode.UInt64:  return (uint)(ulong)input;
								case TypeCode.Single:  return (uint)(float)input;
								case TypeCode.Double:  return (uint)(double)input;
								case TypeCode.Decimal: return (uint)(decimal)input;
								case TypeCode.Boolean: return (uint)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Int64:
						switch (sourceType) {
								case TypeCode.Char:    return (long)(char)input;
								case TypeCode.SByte:   return (long)(sbyte)input;
								case TypeCode.Byte:    return (long)(byte)input;
								case TypeCode.Int16:   return (long)(short)input;
								case TypeCode.UInt16:  return (long)(ushort)input;
								case TypeCode.Int32:   return (long)(int)input;
								case TypeCode.UInt32:  return (long)(uint)input;
								case TypeCode.UInt64:  return (long)(ulong)input;
								case TypeCode.Single:  return (long)(float)input;
								case TypeCode.Double:  return (long)(double)input;
								case TypeCode.Decimal: return (long)(decimal)input;
								case TypeCode.Boolean: return (long)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.UInt64:
						switch (sourceType) {
								case TypeCode.Char:    return (ulong)(char)input;
								case TypeCode.SByte:   return (ulong)(sbyte)input;
								case TypeCode.Byte:    return (ulong)(byte)input;
								case TypeCode.Int16:   return (ulong)(short)input;
								case TypeCode.UInt16:  return (ulong)(ushort)input;
								case TypeCode.Int32:   return (ulong)(int)input;
								case TypeCode.UInt32:  return (ulong)(uint)input;
								case TypeCode.Int64:   return (ulong)(long)input;
								case TypeCode.Single:  return (ulong)(float)input;
								case TypeCode.Double:  return (ulong)(double)input;
								case TypeCode.Decimal: return (ulong)(decimal)input;
								case TypeCode.Boolean: return (ulong)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Single:
						switch (sourceType) {
								case TypeCode.Char:    return (float)(char)input;
								case TypeCode.SByte:   return (float)(sbyte)input;
								case TypeCode.Byte:    return (float)(byte)input;
								case TypeCode.Int16:   return (float)(short)input;
								case TypeCode.UInt16:  return (float)(ushort)input;
								case TypeCode.Int32:   return (float)(int)input;
								case TypeCode.UInt32:  return (float)(uint)input;
								case TypeCode.Int64:   return (float)(long)input;
								case TypeCode.UInt64:  return (float)(ulong)input;
								case TypeCode.Double:  return (float)(double)input;
								case TypeCode.Decimal: return (float)(decimal)input;
								case TypeCode.Boolean: return (float)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Double:
						switch (sourceType) {
								case TypeCode.Char:    return (double)(char)input;
								case TypeCode.SByte:   return (double)(sbyte)input;
								case TypeCode.Byte:    return (double)(byte)input;
								case TypeCode.Int16:   return (double)(short)input;
								case TypeCode.UInt16:  return (double)(ushort)input;
								case TypeCode.Int32:   return (double)(int)input;
								case TypeCode.UInt32:  return (double)(uint)input;
								case TypeCode.Int64:   return (double)(long)input;
								case TypeCode.UInt64:  return (double)(ulong)input;
								case TypeCode.Single:  return (double)(float)input;
								case TypeCode.Decimal: return (double)(decimal)input;
								case TypeCode.Boolean: return (double)((bool)input ? 1 : 0);
						}
						break;
					case TypeCode.Decimal:
						switch (sourceType) {
								case TypeCode.Char:    return (decimal)(char)input;
								case TypeCode.SByte:   return (decimal)(sbyte)input;
								case TypeCode.Byte:    return (decimal)(byte)input;
								case TypeCode.Int16:   return (decimal)(short)input;
								case TypeCode.UInt16:  return (decimal)(ushort)input;
								case TypeCode.Int32:   return (decimal)(int)input;
								case TypeCode.UInt32:  return (decimal)(uint)input;
								case TypeCode.Int64:   return (decimal)(long)input;
								case TypeCode.UInt64:  return (decimal)(ulong)input;
								case TypeCode.Single:  return (decimal)(float)input;
								case TypeCode.Double:  return (decimal)(double)input;
								case TypeCode.Boolean: return (decimal)((bool)input ? 1 : 0);
						}
						break;
				}
				throw new InvalidCastException("Cast from " + sourceType + " to " + targetType + " not supported.");
			}
		}
	}
}
