// KeyDemoGUI.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "KeyDemoGUI.h"
#include "Strsafe.h"  // for StringCchLength function

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;								// current instance
TCHAR szTitle[MAX_LOADSTRING];					// The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];			// the main window class name

// Forward declarations of functions included in this code module:
ATOM				MyRegisterClass(HINSTANCE hInstance);
BOOL				InitInstance(HINSTANCE, int);
LRESULT CALLBACK	WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK	About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY _tWinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
	UNREFERENCED_PARAMETER(hPrevInstance);
	UNREFERENCED_PARAMETER(lpCmdLine);

 	// TODO: Place code here.
	MSG msg;
	HACCEL hAccelTable;

	// Load the keystroke interference library:
	if(NULL == LoadLibrary(L"KeystrokeNoise.dll"))
	{
		MessageBox(NULL, L"Failed to load KeystrokeNoise.dll", L"Error", MB_OK);
	}

	// Initialize global strings
	LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
	LoadString(hInstance, IDC_KEYDEMOGUI, szWindowClass, MAX_LOADSTRING);
	MyRegisterClass(hInstance);

	// Perform application initialization:
	if (!InitInstance (hInstance, nCmdShow))
	{
		return FALSE;
	}

	hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_KEYDEMOGUI));

	// Main message loop:
	while (GetMessage(&msg, NULL, 0, 0))
	{
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
		{
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
	}

	return (int) msg.wParam;
}



//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
//  COMMENTS:
//
//    This function and its usage are only necessary if you want this code
//    to be compatible with Win32 systems prior to the 'RegisterClassEx'
//    function that was added to Windows 95. It is important to call this function
//    so that the application will get 'well formed' small icons associated
//    with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
	WNDCLASSEX wcex;

	wcex.cbSize = sizeof(WNDCLASSEX);

	wcex.style			= CS_HREDRAW | CS_VREDRAW;
	wcex.lpfnWndProc	= WndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= hInstance;
	wcex.hIcon			= LoadIcon(hInstance, MAKEINTRESOURCE(IDI_KEYDEMOGUI));
	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);
	wcex.lpszMenuName	= MAKEINTRESOURCE(IDC_KEYDEMOGUI);
	wcex.lpszClassName	= szWindowClass;
	wcex.hIconSm		= LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

	return RegisterClassEx(&wcex);
}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND	- process the application menu
//  WM_PAINT	- Paint the main window
//  WM_DESTROY	- post a quit message and return
//
//
#define BUFSIZE 65535 
#define SHIFTED 0x8000
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	int wmId, wmEvent;
	PAINTSTRUCT ps;
	HDC hdc;					// handle to device context 

	TEXTMETRIC tm;             // structure for text metrics 
    static DWORD dwCharX;      // average width of characters 
    static DWORD dwCharY;      // height of characters 
    static DWORD dwClientX;    // width of client area 
    static DWORD dwClientY;    // height of client area 
    static DWORD dwLineLen;    // line length 
    static DWORD dwLines;      // text lines in client area 
    static int nCaretPosX = 0; // horizontal position of caret 
    static int nCaretPosY = 0; // vertical position of caret 
    static int nCharWidth = 0; // width of a character 
    static int cch = 0;        // characters in buffer 
    static int nCurChar = 0;   // index of current character 
    static PTCHAR pchInputBuf; // input buffer 
    int i, j;                  // loop counters 
    int cCR = 0;               // count of carriage returns 
    int nCRIndex = 0;          // index of last carriage return 
    int nVirtKey;              // virtual-key code 
    TCHAR szBuf[128];          // temporary buffer 
    TCHAR ch;                  // current character 
    RECT rc;                   // output rectangle for DrawText 
    SIZE sz;                   // string dimensions 
    COLORREF crPrevText;       // previous text color 
    COLORREF crPrevBk;         // previous background color
	size_t * pcch = NULL;
	HRESULT hResult;

	switch (message)
	{
	case WM_COMMAND:
		wmId    = LOWORD(wParam);
		wmEvent = HIWORD(wParam);
		// Parse the menu selections:
		switch (wmId)
		{
		case IDM_ABOUT:
			DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
			break;
		case IDM_EXIT:
			DestroyWindow(hWnd);
			break;
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
		}
		break;

	case WM_CREATE: 
		// Get the metrics of the current font. 
		hdc = GetDC(hWnd);
		GetTextMetrics(hdc, &tm);
		ReleaseDC(hWnd, hdc);
 
		// Save the average character width and height.
		dwCharX = tm.tmAveCharWidth; 
		dwCharY = tm.tmHeight; 
 
		// Allocate a buffer to store keyboard input. 
		pchInputBuf = (LPTSTR) GlobalAlloc(GPTR, BUFSIZE * sizeof(TCHAR)); 
		return 0;

	case WM_SIZE: 
		// Save the new width and height of the client area. 
		dwClientX = LOWORD(lParam);
		dwClientY = HIWORD(lParam); 
 
		// Calculate the maximum width of a line and the 
		// maximum number of lines in the client area. 
		dwLineLen = dwClientX - dwCharX; 
		dwLines = dwClientY / dwCharY; 
		break;

	case WM_SETFOCUS: 
		// Create, position, and display the caret when the 
		// window receives the keyboard focus. 
		CreateCaret(hWnd, (HBITMAP) 1, 0, dwCharY); 
		SetCaretPos(nCaretPosX, nCaretPosY * dwCharY); 
		ShowCaret(hWnd); 
		break; 
 
	case WM_KILLFOCUS: 
        // Hide and destroy the caret when the window loses the keyboard focus.
        HideCaret(hWnd); 
        DestroyCaret(); 
        break; 
 
	case WM_CHAR:
		// check if current location is close enough to the
		// end of the buffer that a buffer overflow may
		// occur. If so, add null and display contents. 
		if (cch > BUFSIZE-5)
		{
			pchInputBuf[cch] = 0x00;
			SendMessage(hWnd, WM_PAINT, 0, 0);
		}
        switch (wParam) 
        { 
            case 0x08:  // backspace 
            case 0x0A:  // linefeed 
            case 0x1B:  // escape 
                MessageBeep((UINT) -1); 
                return 0; 
 
            case 0x09:  // tab 
 
                // Convert tabs to four consecutive spaces. 
                for (i = 0; i < 4; i++) 
                    SendMessage(hWnd, WM_CHAR, 0x20, 0); 
                return 0; 
 
            case 0x0D:  // carriage return 
 
                // Record the carriage return and position the 
                // caret at the beginning of the new line.
                pchInputBuf[cch++] = 0x0D; 
                nCaretPosX = 0; 
                nCaretPosY += 1; 
                break; 
 
            default:    // displayable character 
 
                ch = (TCHAR) wParam; 
                HideCaret(hWnd); 
 
                // Retrieve the character's width and output 
                // the character. 
                hdc = GetDC(hWnd); 
                GetCharWidth32(hdc, (UINT) wParam, (UINT) wParam, &nCharWidth); 
                TextOut(hdc, nCaretPosX, nCaretPosY * dwCharY, &ch, 1); 
                ReleaseDC(hWnd, hdc);

                // Store the character in the buffer. 
                pchInputBuf[cch++] = ch; 
 
                // Calculate the new horizontal position of the 
                // caret. If the position exceeds the maximum, 
                // insert a carriage return and move the caret 
                // to the beginning of the next line. 
 
                nCaretPosX += nCharWidth; 
                if ((DWORD) nCaretPosX > dwLineLen) 
                { 
                    nCaretPosX = 0;
                    pchInputBuf[cch++] = 0x0D; 
                    ++nCaretPosY; 
                }
                nCurChar = cch; 
                ShowCaret(hWnd); 
                break;
        }
        SetCaretPos(nCaretPosX, nCaretPosY * dwCharY); 
        break; 
 
        case WM_KEYDOWN: 
            switch (wParam) 
            { 
                case VK_LEFT:   // LEFT ARROW 
 
                    // The caret can move only to the beginning of 
                    // the current line. 
 
                    if (nCaretPosX > 0) 
                    { 
                        HideCaret(hWnd); 
 
                        // Retrieve the character to the left of 
                        // the caret, calculate the character's 
                        // width, then subtract the width from the 
                        // current horizontal position of the caret 
                        // to obtain the new position. 
 
                        ch = pchInputBuf[--nCurChar]; 
                        hdc = GetDC(hWnd); 
                        GetCharWidth32(hdc, ch, ch, &nCharWidth); 
                        ReleaseDC(hWnd, hdc); 
                        nCaretPosX = max(nCaretPosX - nCharWidth, 
                            0); 
                        ShowCaret(hWnd); 
                    } 
                    break; 
 
                case VK_RIGHT:  // RIGHT ARROW 
 
                    // Caret moves to the right or, when a carriage 
                    // return is encountered, to the beginning of 
                    // the next line. 
 
                    if (nCurChar < cch) 
                    { 
                        HideCaret(hWnd); 
 
                        // Retrieve the character to the right of 
                        // the caret. If it's a carriage return, 
                        // position the caret at the beginning of 
                        // the next line. 
 
                        ch = pchInputBuf[nCurChar]; 
                        if (ch == 0x0D) 
                        { 
                            nCaretPosX = 0; 
                            nCaretPosY++; 
                        } 
 
                        // If the character isn't a carriage 
                        // return, check to see whether the SHIFT 
                        // key is down. If it is, invert the text 
                        // colors and output the character. 
 
                        else 
                        { 
                            hdc = GetDC(hWnd); 
                            nVirtKey = GetKeyState(VK_SHIFT); 
                            if (nVirtKey & SHIFTED) 
                            { 
                                crPrevText = SetTextColor(hdc, 
                                    RGB(255, 255, 255)); 
                                crPrevBk = SetBkColor(hdc, 
                                    RGB(0,0,0)); 
                                TextOut(hdc, nCaretPosX, 
                                    nCaretPosY * dwCharY, 
                                    &ch, 1); 
                                SetTextColor(hdc, crPrevText); 
                                SetBkColor(hdc, crPrevBk); 
                            } 
 
                            // Get the width of the character and 
                            // calculate the new horizontal 
                            // position of the caret. 
 
                            GetCharWidth32(hdc, ch, ch, &nCharWidth); 
                            ReleaseDC(hWnd, hdc); 
                            nCaretPosX = nCaretPosX + nCharWidth; 
                        } 
                        nCurChar++; 
                        ShowCaret(hWnd); 
                        break; 
                    } 
                    break; 
 
                case VK_UP:     // UP ARROW 
                case VK_DOWN:   // DOWN ARROW 
                    MessageBeep((UINT) -1); 
                    return 0; 
 
                case VK_HOME:   // HOME 
 
                    // Set the caret's position to the upper left 
                    // corner of the client area. 
 
                    nCaretPosX = nCaretPosY = 0; 
                    nCurChar = 0; 
                    break; 
 
                case VK_END:    // END  
 
                    // Move the caret to the end of the text. 
 
                    for (i=0; i < cch; i++) 
                    { 
                        // Count the carriage returns and save the 
                        // index of the last one. 
 
                        if (pchInputBuf[i] == 0x0D) 
                        { 
                            cCR++; 
                            nCRIndex = i + 1; 
                        } 
                    } 
                    nCaretPosY = cCR; 
 
                    // Copy all text between the last carriage 
                    // return and the end of the keyboard input 
                    // buffer to a temporary buffer. 
 
                    for (i = nCRIndex, j = 0; i < cch; i++, j++) 
                        szBuf[j] = pchInputBuf[i]; 
                    szBuf[j] = TEXT('\0'); 
 
                    // Retrieve the text extent and use it 
                    // to set the horizontal position of the 
                    // caret. 
 
                    hdc = GetDC(hWnd);
					hResult = StringCchLength(szBuf, 128, pcch);
					if (FAILED(hResult))
					{
					// TODO: write error handler
					} 
                    GetTextExtentPoint32(hdc, szBuf, *pcch, 
                        &sz); 
                    nCaretPosX = sz.cx; 
                    ReleaseDC(hWnd, hdc); 
                    nCurChar = cch; 
                    break; 
 
                default: 
                    break; 
            } 
            SetCaretPos(nCaretPosX, nCaretPosY * dwCharY); 
            break;

	case WM_PAINT:
		hdc = BeginPaint(hWnd, &ps);

		// TODO: Add any drawing code here...
		if (cch == 0)       // nothing in input buffer 
			break;
		HideCaret(hWnd); 
        // Set the clipping rectangle, and then draw the text into it. 
		SetRect(&rc, 0, 0, dwLineLen, dwClientY); 
        DrawText(hdc, pchInputBuf, -1, &rc, DT_LEFT); 
		ShowCaret(hWnd);

		EndPaint(hWnd, &ps);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}

// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	UNREFERENCED_PARAMETER(lParam);
	switch (message)
	{
	case WM_INITDIALOG:
		return (INT_PTR)TRUE;

	case WM_COMMAND:
		if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
		{
			EndDialog(hDlg, LOWORD(wParam));
			return (INT_PTR)TRUE;
		}
		break;
	}
	return (INT_PTR)FALSE;
}