#include <windows.h>
#include "list.h"

BOOL CALLBACK digListEventListener (HWND hwnd, UINT event, WPARAM object, LPARAM lParam);

BOOL CALLBACK digListEventListener (HWND hwnd, UINT event, WPARAM object, LPARAM lParam)
{

	if (event == WM_INITDIALOG)
	{
		SetDlgItemText(hwnd, txtItem, "Dutch language");		
	}
	else if (event == WM_COMMAND)
	{
	
		int objectID = LOWORD(object);
		
		if (objectID == cmdAdd)
		{
		
			//Unlike in java where you use txtItem.getText(), in C++
			//you have to copy the text from the textfield into a variable (char array)
			//First need to find out how many chars are in the text. GetWindowTextLength
			//does not directly get the POINTER ID of the item on the dialogue box, so
			//have to use GetDlgItem, to get the POINTER ID.
			
			//IMPORTANT, GetWindowTextLength returns the amount of chars, minus the null terminator $
			//Thus it may say 14, but the actual text is 14 + $, so if you used that directly the null
			//terminator would overwrite the next space in memory, thus you must add 1 to length
			int len = GetWindowTextLength(GetDlgItem(hwnd, txtItem));
			
			if (len > 0) //Something is typed
			{
			
				len += 1;
				
				char* buffer;
				
				//GlobalAlloc reserves space in memory, filling it with 0's and returns
				//the pointer of where the space starts.
				buffer = (char*)GlobalAlloc(GPTR, len);
				GetDlgItemText(hwnd, txtItem, buffer, len);
				SendDlgItemMessage(hwnd, lstItems, LB_ADDSTRING, 0, (LPARAM)buffer);
				GlobalFree((HANDLE)buffer);
				
				SetDlgItemText(hwnd, txtItem, "");
			
			}
			else
			{
				MessageBox(hwnd, "Field is empty!", "Error", MB_OK | MB_ICONEXCLAMATION);
			}
		
		}
		else if (objectID == cmdRemove)
		{
		
			HWND handleDig = GetDlgItem(hwnd, lstItems);
			int index = SendMessage(handleDig, LB_GETCURSEL, 0, 0);
			
			if (index != LB_ERR)
			{
				SendMessage(handleDig, LB_DELETESTRING, (WPARAM)index, 0);			
			}	
			else
			{
				MessageBox(hwnd, "You must select an item to remove it", "Error", MB_OK | MB_ICONEXCLAMATION);
			}		 
	
		}
		else if (objectID == cmdClear)
		{
			SendDlgItemMessage(hwnd, lstItems, LB_RESETCONTENT, 0, 0);
		}		 
		else if (objectID == cmdClose)
		{
			EndDialog(hwnd, objectID);
		}
		
		
	}
	else if (event == WM_CLOSE)
	{		
		EndDialog(hwnd, object);
	}
	else
	{
		return false;
	}
	
	return true;

}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR args, int nCmdShow)
{
	return DialogBox(hInstance, MAKEINTRESOURCE(digList), NULL, digListEventListener);
}