// This lesson --
// --- WIN32 Lean and Mean
// -- Optimize Message Pump
// -- Use Three different controls to create a calculator
// -- Use resources to make a dialog box appear

#define IDC_ADD 1001
#define IDC_SUB 1002
#define IDC_DIV 1003
#define IDC_MUL 1004
#define IDC_EQA 1005
#define IDC_OUTPUT 1006
#define IDC_Clear 1007

#define ADD 1
#define SUB 2
#define DIV 3
#define MUL 4
#define EQA 5

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

int recent,total,currentOperation;
bool first=true;

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);
int calc_total(int, int);


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
	WNDCLASSEX windowClass;	// class/struct for our main window-
	HWND hwnd;				// the handle to that window-
	MSG msg;				// message-

	windowClass.cbSize = sizeof WNDCLASSEX;
	windowClass.style = CS_HREDRAW | CS_VREDRAW;	// redraw on resize
	windowClass.lpfnWndProc = WndProc;	// WndProc() address to function pointer-
	windowClass.cbClsExtra=0;
	windowClass.cbWndExtra=0;
	windowClass.hInstance = hInstance;
	windowClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);				// Standard app icon-
	windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);					// Standard cursor-
	windowClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);	//paint the background with?
	windowClass.lpszMenuName = NULL;									// No menu
	windowClass.lpszClassName = "MyClass";								// Handle for this windows class-
	windowClass.hIconSm = LoadIcon(NULL, IDI_WINLOGO);

	if(!RegisterClassEx(&windowClass))
		return 0;
	
	// struct registered and valid, now create the window-

	hwnd = CreateWindowEx(NULL,						// extended styles-
						  "MyClass",				// struct/class name from earlier-
						  "Calc",		// Window title-
						  WS_OVERLAPPED |
						  WS_VISIBLE |
						  WS_SYSMENU,
						  100, 100,					//x,y
						  158, 75,					// width, height
						  NULL,
						  NULL,
						  hInstance,				// app instance-
						  NULL);

	if(!hwnd)
		return 0;

	while(GetMessage(&msg,NULL, 0,0) > 0){
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return (int)msg.wParam;
}


LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
	{
		
		HWND hAdd, hSub, hDiv, hMul, hEqa, hClear, hOutput;
		
		
		
		switch(message){
			case WM_CREATE:
				hAdd = CreateWindowEx(WS_EX_CLIENTEDGE, "BUTTON", "+",  WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON, 0, 26, 30, 25, hwnd, (HMENU)IDC_ADD, GetModuleHandle(NULL), NULL);
				if(hAdd == NULL)
					MessageBox(hwnd, "Could not create edit box.", "Error", MB_OK | MB_ICONERROR);

				hSub = CreateWindowEx(WS_EX_CLIENTEDGE, "BUTTON", "-",  WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON, 31, 26, 30, 25, hwnd, (HMENU)IDC_SUB, GetModuleHandle(NULL), NULL);
				if(hSub == NULL)
					MessageBox(hwnd, "Could not create edit box.", "Error", MB_OK | MB_ICONERROR);

				hDiv = CreateWindowEx(WS_EX_CLIENTEDGE, "BUTTON", "/",  WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON, 61, 26, 30, 25, hwnd, (HMENU)IDC_DIV, GetModuleHandle(NULL), NULL);
				if(hDiv == NULL)
					MessageBox(hwnd, "Could not create edit box.", "Error", MB_OK | MB_ICONERROR);

				hMul = CreateWindowEx(WS_EX_CLIENTEDGE, "BUTTON", "*",  WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON, 91, 26, 30, 25, hwnd, (HMENU)IDC_MUL, GetModuleHandle(NULL), NULL);
				if(hMul == NULL)
					MessageBox(hwnd, "Could not create edit box.", "Error", MB_OK | MB_ICONERROR);

				hEqa = CreateWindowEx(WS_EX_CLIENTEDGE, "BUTTON", "=",  WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON, 121, 26, 30, 25, hwnd, (HMENU)IDC_EQA, GetModuleHandle(NULL), NULL);
				if(hEqa == NULL)
					MessageBox(hwnd, "Could not create edit box.", "Error", MB_OK | MB_ICONERROR);

				hClear = CreateWindowEx(WS_EX_CLIENTEDGE, "BUTTON", "CE",  WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON, 121, 0, 30, 25, hwnd, (HMENU)IDC_Clear, GetModuleHandle(NULL), NULL);
				if(hClear == NULL)
					MessageBox(hwnd, "Could not create edit box.", "Error", MB_OK | MB_ICONERROR);
				
				hOutput = CreateWindowEx(WS_EX_CLIENTEDGE, "EDIT", "",  WS_CHILD | WS_VISIBLE | ES_NUMBER , 0, 0, 121, 25, hwnd, (HMENU)IDC_OUTPUT, GetModuleHandle(NULL), NULL);
				if(hOutput == NULL)
					MessageBox(hwnd, "Could not create edit box.", "Error", MB_OK | MB_ICONERROR);

				


				break;
			case WM_DESTROY:
				PostQuitMessage(WM_QUIT);
				break;

			case WM_COMMAND:
				switch(LOWORD(wParam)){
					case IDC_ADD:
						switch(HIWORD(wParam)){
							case BN_CLICKED:
								
								recent=GetDlgItemInt(hwnd, IDC_OUTPUT, NULL, FALSE);
								total=calc_total(ADD, recent);
								SetDlgItemInt(hwnd, IDC_OUTPUT, total, FALSE);
								break;
						}
					break;

					case IDC_SUB:
						switch(HIWORD(wParam)){
							case BN_CLICKED:
								recent=GetDlgItemInt(hwnd, IDC_OUTPUT, NULL, FALSE);
								total=calc_total(SUB, recent);
								SetDlgItemInt(hwnd, IDC_OUTPUT, total, FALSE);
								break;
						}
					break;

					case IDC_DIV:
						switch(HIWORD(wParam)){
							case BN_CLICKED:
								recent=GetDlgItemInt(hwnd, IDC_OUTPUT, NULL, FALSE);
								total=calc_total(DIV, recent);
								SetDlgItemInt(hwnd, IDC_OUTPUT, total, FALSE);
								break;
						}
					break;

					case IDC_MUL:
						switch(HIWORD(wParam)){
							case BN_CLICKED:
								recent=GetDlgItemInt(hwnd, IDC_OUTPUT, NULL, FALSE);
								total=calc_total(MUL, recent);
								SetDlgItemInt(hwnd, IDC_OUTPUT, total, FALSE);
								break;
						}
					break;

					case IDC_Clear:
						switch(HIWORD(wParam)){
							case BN_CLICKED:
								recent=0; total=0;
								SetDlgItemInt(hwnd, IDC_OUTPUT, total, FALSE);
								break;
						}
					break;

					case IDC_EQA:
						switch(HIWORD(wParam)){
							case BN_CLICKED:
								recent=GetDlgItemInt(hwnd, IDC_OUTPUT, NULL, FALSE);
								total=calc_total(EQA, recent);
								SetDlgItemInt(hwnd, IDC_OUTPUT, total, FALSE);
								break;
						}
					break;

				}
			break;
				
			default:
				break;
		}
		return (DefWindowProc(hwnd, message, wParam, lParam));
}

int calc_total(int OperationType, int newInput){
	

	switch(currentOperation){									
		case ADD:								
			total=total+newInput;
			break;							
		case SUB:						
			total=total-newInput;							
			break;							
		case DIV:						
			total=total/newInput;		
			break;						
		case MUL:					
			total=total*newInput;						
			break;
	}
				
	currentOperation=OperationType;
						
	if(first){				
		total=newInput;				
		first=false;
								
	}

	return total;
}