using System;
using System.Runtime.InteropServices;
using System.Threading;

namespace HelloWorldMetal {
	// Restrictions for Metal compile is that static members only, and no heap usage
	// Basic string support is provided by using c strings in data sections
	class Program {
		// These would be output in the data section. Since no heap exists, 
		// all are treated as globals and space is fixed and preallocated
		// MtW: 
		//	Don't make them consts, this will copy the value, and produce
		//  an ldstr, which Creates (which is evil in Metal mode) a new string.
		//  declaring as follows makes it reuse the code
		public static string Message = "Hello, World";

		static void Main() {
			// Local variables are ok too, since they are stack based
			// String literals translate to ldstr - these would automatically be pulled out
			// and put in the data section. String manipuation not permitted unless the actual
			// bytes are modified directly.
			//
			// Implement the P/Invoke interface. This will allow interfacing to Windows
			// and other systems.
			//
			// Certain statics can have points mapped and replaced with future metal code
			// or translations to P/Invokes.
			// Such as Console.Write. It can be determined by name and remapped to 
			// the Win32 calll.
			// Console.Write("Hello World");
			// For now - lets stick with P/Invoke only - I want to do some more investigation
			// around map replacement
			// So the current test would be - declare a P/Invoke for writing to console in Win32
			// then call it below with "HelloWorld"
			IntPtr xHandle = GetStdHandle(-11);
//			uint error = GetLastError();
			uint xCharsWritten;
			string theMessage = "Hello, World!";
			WriteConsole(xHandle, theMessage, 13, out xCharsWritten, IntPtr.Zero);
			//error = GetLastError();
		}

		[DllImport("kernel32.dll")]
		static extern IntPtr GetStdHandle(int nStdHandle);
		[DllImport("kernel32.dll")]
		static extern bool WriteConsole(IntPtr hConsoleOutput, string lpBuffer,
		   uint nNumberOfCharsToWrite, out uint lpNumberOfCharsWritten,
		   IntPtr lpReserved);

		[DllImport("kernel32.dll")]
		private static extern uint GetLastError();
	}
}