#if DEBUG
#define GC_DEBUG
#endif
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;

namespace Indy.IL2CPU {
	public static class GCImplementation {
		public static uint AllocNewObject(uint aSize) {
			uint xNewObject = RuntimeEngine.Heap_AllocNewObject(aSize + 4);
#if GC_DEBUG
			Console.Write("New Object allocated: ");
			WriteNumber(xNewObject + 4, false);
			Console.WriteLine();
#endif
			return xNewObject + 4;
		}

		/// <summary>
		/// This function gets the pointer to the memory location of where it's stored. 
		/// </summary>
		/// <param name="aObject"></param>
		public static unsafe void IncRefCount(uint aObject) {
			if (aObject == 0) {
				return;
			}
			uint* xTheObject = (uint*)aObject;
			xTheObject -= 1;
			if ((*xTheObject & 0x80000000) != 0) {
				Console.Write("StaleObject: ");
				WriteNumber(aObject, false);
				Console.WriteLine();
				return;
			}
			//xTheObject -= 2;
#if GC_DEBUG
			uint xCount =
#endif
 *xTheObject = *xTheObject + 1;
#if GC_DEBUG
			if (xCount == 0x80000000) {
				Console.WriteLine("GC: RefCount Maximum Exceeded!");
				return;
			}
			Console.Write("ObjectIncRefCount, Object = ");
			WriteNumber(aObject, false);
			Console.Write(", RefCount = ");
			WriteNumber(xCount, false);
			Console.WriteLine();
#endif
		}

		/// <summary>
		/// This function gets the pointer to the memory location of where it's stored. 
		/// </summary>
		/// <param name="aObject"></param>
		public static unsafe void DecRefCount(uint aObject) {
			if (aObject == 0) {
				return;
			}
			uint* xTheObject = (uint*)aObject;
			xTheObject += 1;
			// check for staticly embedded arrays/objects. these are embedded as values in the binary target, and should
			// therefore not be collected.
			if ((*xTheObject & 0x80000000) == 0x80000000) {
				return;
			}
			xTheObject -= 2;
			uint xCount = *xTheObject;
			if (xCount == 0) {
				return;
			}
#if GC_DEBUG
			if ((xCount & 0x80000000) == 0x80000000) {
				Console.Write("StaleObject: ");
				WriteNumber(aObject, false);
				Console.WriteLine();
				return;
			}
#endif
			xCount = *xTheObject = xCount - 1;
			if (xCount == 0) {
#if !GC_DEBUG
				RuntimeEngine.Heap_Free(aObject - 4);
#endif
#if GC_DEBUG
				Console.Write("ObjectReclaimed, Object = ");
				WriteNumber(aObject, false);
				Console.WriteLine();
				xTheObject = (uint*)(aObject - 4);
				*xTheObject = 0x80000000;
			} else {
				Console.Write("ObjectDecRefCount, Object = ");
				WriteNumber(aObject, false);
				Console.Write(", RefCount = ");
				WriteNumber(xCount, false);
				Console.WriteLine();
#endif
			}
		}

#if GC_DEBUG
		private static void WriteNumber(uint aValue, bool aZeroFill) {
			uint xValue = aValue;
			byte xCurrentBits = 32;
			byte xCharsWritten = 0;
			bool xSignificantDigitWritten = aZeroFill;
			Console.Write("0x");
			while (xCurrentBits >= 4) {
				xCurrentBits -= 4;
				byte xCurrentDigit = (byte)((xValue >> xCurrentBits) & 0xF);
				string xDigitString = null;
				switch (xCurrentDigit) {
					case 0:
						if (xSignificantDigitWritten) {
							xDigitString = "0";
							goto default;
						}
						break;
					case 1:
						xDigitString = "1";
						goto default;
					case 2:
						xDigitString = "2";
						goto default;
					case 3:
						xDigitString = "3";
						goto default;
					case 4:
						xDigitString = "4";
						goto default;
					case 5:
						xDigitString = "5";
						goto default;
					case 6:
						xDigitString = "6";
						goto default;
					case 7:
						xDigitString = "7";
						goto default;
					case 8:
						xDigitString = "8";
						goto default;
					case 9:
						xDigitString = "9";
						goto default;
					case 10:
						xDigitString = "A";
						goto default;
					case 11:
						xDigitString = "B";
						goto default;
					case 12:
						xDigitString = "C";
						goto default;
					case 13:
						xDigitString = "D";
						goto default;
					case 14:
						xDigitString = "E";
						goto default;
					case 15:
						xDigitString = "F";
						goto default;
					default:
						if (xDigitString == null) {
							Console.Write("NoDigitSet");
						}
						xSignificantDigitWritten = true;
						xCharsWritten += 1;
						Console.Write(xDigitString);
						break;
				}
			}
		}
#endif
	}
}