#include <windows.h>
//#include <stdio.h>
//#include <string.h>
 
// Global variable
 
HINSTANCE hInst;
 
// Function prototypes.
int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int);
LRESULT CALLBACK MainWndProc(HWND, UINT, WPARAM, LPARAM);
 
// Application entry point.
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
		   LPSTR lpCmdLine, int nCmdShow)
{
    MSG msg;
    BOOL bRet;
    WNDCLASS wcx;		// register class
    HWND hWnd;
    //UINT uResult;             // SetTimer's return value
 
    hInst = hInstance;		// Save the application-instance handle.
    // Fill in the window class structure with parameters that describe the main window.
 
    wcx.style = CS_HREDRAW | CS_VREDRAW;	// redraw if size changes
    wcx.lpfnWndProc = (WNDPROC) MainWndProc;	// points to window procedure
    wcx.cbClsExtra = 0;		// no extra class memory
    wcx.cbWndExtra = 0;		// no extra window memory
    wcx.hInstance = hInstance;	// handle to instance
    wcx.hIcon = LoadIcon(NULL, IDI_APPLICATION);	// predefined app. icon
    wcx.hCursor = LoadCursor(NULL, IDC_ARROW);	// predefined arrow
    wcx.hbrBackground = GetStockObject(WHITE_BRUSH);	// white background brush
    wcx.lpszMenuName = (LPCSTR) "MainMenu";	// name of menu resource
    wcx.lpszClassName = (LPCSTR) "MainWClass";	// name of window class
 
    // Register the window class.
 
    if (!RegisterClass(&wcx))
	return FALSE;
 
    // create window of registered class
 
    hWnd = CreateWindow("MainWClass",	// name of window class
			"ITUedit",	// title-bar string
			WS_OVERLAPPEDWINDOW,	// top-level window
			100,	// default horizontal position
			100,	// default vertical position
			300,	// default width
			300,	// default height
			(HWND) NULL,	// no owner window
			(HMENU) NULL,	// use class menu
			hInstance,	// handle to application instance
			(LPVOID) NULL);	// no window-creation data
    if (!hWnd)
	return FALSE;
 
    // Show the window and send a WM_PAINT message to the window procedure.
    // Record the current cursor position.
 
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);
 
    // loop of message processing
 
    while ((bRet = GetMessage(&msg, NULL, 0, 0)) != 0) {
	if (bRet == -1) {
	    // handle the error and possibly exit
	} else {
	    TranslateMessage(&msg);
	    DispatchMessage(&msg);
	}
    }
    return (int) msg.wParam;
}
 
#define BUFSIZE 65535
 
LRESULT APIENTRY MainWndProc(HWND hwndMain, UINT uMsg, WPARAM wParam,
			     LPARAM lParam)
{
    static int nchLast;		// amount of chars in the input buffer
    static RECT TextArea;	// client area
    static PTCHAR pchInputBuf;	// input buffer
    int i;			// counter
    //int nVirtKey;             // virtual-key code
    HDC hdc;			// handle to device context
    PAINTSTRUCT ps;		// required by BeginPaint
    static DWORD dwCharY;	// height of characters
    static int nCaretPosX = 0;	// horizontal position of caret - real position
    static int nCaretPosY = 0;	// vertical position of caret - number of lines
    TCHAR ch;			// current character
    int chWidth;		// width of the actual character
    TEXTMETRIC tm;		// structure for text metrics
    POINT ReleasePoint;		// point where mouse button was released
    HWND hwndTmp;		// window handle where mouse button was released
    //HGLOBAL hglb;             // global memory object
    //LPTSTR lptstr;            // handle to the copied text buffer
    static int caretpos;
    static int bufptr;
    static int indent;
 
    switch (uMsg) {
    case WM_CREATE:
	// Allocate a buffer to store keyboard input.
	pchInputBuf = (LPTSTR) GlobalAlloc(GPTR, BUFSIZE * sizeof(TCHAR));
	nchLast = 0;
	caretpos = 0;
	pchInputBuf[nchLast] = TEXT('\0');
	// Get the metrics of the current font.
	hdc = GetDC(hwndMain);
	GetTextMetrics(hdc, &tm);
	ReleaseDC(hwndMain, hdc);
 
	// Save the average character width and height.
	dwCharY = tm.tmHeight;
 
	break;
 
    case WM_CHAR:
	switch (wParam) {
	case 0x08:		// backspace
	    //FIXME: Mazani odradkovani!!!
	    if (caretpos <= 0) {
		break;
	    }
	    ch = (TCHAR) pchInputBuf[--caretpos];
	    HideCaret(hwndMain);
 
	    // Retrieve the character's width and output the character.
	    hdc = GetDC(hwndMain);
	    GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
	    nCaretPosX -= chWidth;
	    ReleaseDC(hwndMain, hdc);
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
 
	    bufptr = caretpos;
	    while (bufptr < nchLast) {
		pchInputBuf[bufptr] = pchInputBuf[bufptr + 1];
		bufptr++;
	    }
	    nchLast--;
 
	    ShowCaret(hwndMain);
	    break;
	case 0x0A:		// linefeed
	case 0x1B:		// escape
	    MessageBeep((UINT) - 1);
	    break;
 
	case 0x09:		// tab
	    // Convert tabs to four consecutive spaces.
	    for (i = 0; i < 4; i++)
		SendMessage(hwndMain, WM_CHAR, 0x20, 0);
	    break;
 
	case 0x0D:		// carriage return
	    // Record the carriage return and position the caret at the beginning of the new line.
	    pchInputBuf[nchLast++] = 0x0D;
	    nCaretPosY++;
	    nCaretPosX = 0;
	    caretpos++;
	    break;
 
	default:		// displayable character
	    ch = (TCHAR) wParam;
	    HideCaret(hwndMain);
 
	    // Retrieve the character's width and output the character.
	    hdc = GetDC(hwndMain);
	    TextOut(hdc, nCaretPosX, nCaretPosY * dwCharY, &ch, 1);
	    GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
	    nCaretPosX += chWidth;
	    ReleaseDC(hwndMain, hdc);
 
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	    ShowCaret(hwndMain);
 
	    // Store the character in the buffer.
	    if (nchLast != caretpos) {
		bufptr = nchLast;
		while (bufptr >= caretpos) {
		    pchInputBuf[bufptr + 1] = pchInputBuf[bufptr];
		    bufptr--;
		}
	    }
	    pchInputBuf[caretpos++] = ch;
	    nchLast++;
	    break;
	}
	InvalidateRect(hwndMain, NULL, TRUE);
	break;
 
    case WM_KEYDOWN:
	switch (wParam) {
	case VK_LEFT:		// LEFT ARROW
	    if (caretpos <= 0) {
		break;
	    }
	    HideCaret(hwndMain);
	    caretpos--;
	    ch = (TCHAR) pchInputBuf[caretpos];
	    if (ch == 0x0D) {
		nCaretPosY--;
		caretpos--;
		while (caretpos >= 0 && pchInputBuf[caretpos] != 0x0D) {
		    //printf("%d: %c\n", caretpos, (pchInputBuf[caretpos]));
		    caretpos--;
		}
		while (caretpos < nchLast
		       && pchInputBuf[++caretpos] != 0x0D) {
		    ch = (TCHAR) pchInputBuf[caretpos];
		    hdc = GetDC(hwndMain);
		    GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
		    nCaretPosX += chWidth;
		    ReleaseDC(hwndMain, hdc);
		}
	    } else {
		hdc = GetDC(hwndMain);
		GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
		nCaretPosX -= chWidth;
		ReleaseDC(hwndMain, hdc);
	    }
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	    ShowCaret(hwndMain);
	    break;
 
	case VK_RIGHT:		// RIGHT ARROW
	    if (caretpos >= nchLast) {
		break;
	    }
	    HideCaret(hwndMain);
	    ch = (TCHAR) pchInputBuf[caretpos];
	    caretpos++;
	    if (ch == 0x0D) {
		nCaretPosY++;
		nCaretPosX = 0;
	    } else {
		//caretpos++;
		hdc = GetDC(hwndMain);
		GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
		nCaretPosX += chWidth;
		ReleaseDC(hwndMain, hdc);
	    }
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	    ShowCaret(hwndMain);
	    break;
 
	case VK_UP:
	    HideCaret(hwndMain);
	    indent = 0;
	    while (caretpos > 0 && pchInputBuf[caretpos] != 0x0D) {
		caretpos--;
		indent++;
	    }
	    if (caretpos > 0) {
		indent--;
	    }
	    //printf("%d, %d\n", caretpos, indent);
	    if (caretpos == 0) {	// 1. radek -> nic se nestane
		caretpos += indent;
		ShowCaret(hwndMain);
		break;
	    }
	    nCaretPosY--;
	    nCaretPosX = 0;
	    caretpos--;
	    while (caretpos > 0 && pchInputBuf[caretpos] != 0x0D) {	//posune se na zacatek radku
		caretpos--;
	    }
	    if (caretpos > 0) {
		caretpos++;
	    }
	    //putchar(pchInputBuf[caretpos]);
	    for (; indent > 0; indent--) {
		ch = (TCHAR) pchInputBuf[caretpos];
		if (ch == 0x0D) {
		    break;
		}
		hdc = GetDC(hwndMain);
		GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
		nCaretPosX += chWidth;
		ReleaseDC(hwndMain, hdc);
		caretpos++;
	    }
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	    ShowCaret(hwndMain);
	    break;
 
	case VK_DOWN:
	    HideCaret(hwndMain);
	    indent = 0;
	    while (caretpos > 0 && pchInputBuf[caretpos] != 0x0D) {	//posun na zacatek radku a pocitani o kolik znaku
		caretpos--;
		indent++;
	    }
	    if (caretpos > 0) {
		indent--;
	    }
	    caretpos++;
	    while (caretpos < nchLast && pchInputBuf[caretpos] != 0x0D) {	//posun na konec radku
		//putchar(pchInputBuf[caretpos]);
		caretpos++;
	    }
	    caretpos++;		//preskocit odradkovani
	    //printf("%d %d\n", caretpos, nchLast);
	    if (caretpos >= nchLast) {	//kdyz jsem na konci textu
		//printf("Posledni radek!\n");
		caretpos = nchLast;
		while (caretpos > 0 && pchInputBuf[caretpos] != 0x0D) {	//posun na zacatek radku
		    //putchar(pchInputBuf[caretpos]);
		    caretpos--;
		}
		caretpos++;
		nCaretPosX = 0;
		for (; indent > 0; indent--) {	//posun od odsazeni
		    ch = (TCHAR) pchInputBuf[caretpos];
		    if (ch == 0x0D) {
			break;
		    }
		    hdc = GetDC(hwndMain);
		    GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
		    nCaretPosX += chWidth;
		    ReleaseDC(hwndMain, hdc);
		    caretpos++;
		}
		SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
		ShowCaret(hwndMain);
		break;
	    }
	    nCaretPosY++;
	    while (caretpos > 0 && pchInputBuf[caretpos] != 0x0D) {	//posun na zacatek radku
		//putchar(pchInputBuf[caretpos]);
		caretpos--;
	    }
	    caretpos++;
	    nCaretPosX = 0;
	    for (; indent > 0; indent--) {	//posun od odsazeni
		ch = (TCHAR) pchInputBuf[caretpos];
		if (ch == 0x0D) {
		    break;
		}
		hdc = GetDC(hwndMain);
		GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
		nCaretPosX += chWidth;
		ReleaseDC(hwndMain, hdc);
		caretpos++;
	    }
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	    ShowCaret(hwndMain);
	    break;
 
	case VK_HOME:
	    HideCaret(hwndMain);
	    caretpos--;		//zajima me predchozi znak
	    while (caretpos >= 0 && pchInputBuf[caretpos] != 0x0D) {	//posun na zacatek radku
		//printf("%d: %c\n", caretpos, (pchInputBuf[caretpos]));
		caretpos--;
	    }
	    caretpos++;		//preskoci odradkovani
	    nCaretPosX = 0;
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	    ShowCaret(hwndMain);
	    break;
 
	case VK_END:
	    HideCaret(hwndMain);
	    while (caretpos < nchLast && pchInputBuf[caretpos] != 0x0D) {
		ch = (TCHAR) pchInputBuf[caretpos];
		hdc = GetDC(hwndMain);
		GetCharWidth32(hdc, (UINT) ch, (UINT) ch, &chWidth);
		nCaretPosX += chWidth;
		ReleaseDC(hwndMain, hdc);
		caretpos++;
	    }
	    SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	    ShowCaret(hwndMain);
	    break;
 
	case VK_DELETE:
 
	    break;
	}
	break;
 
    case WM_SIZE:
	GetClientRect(hwndMain, &TextArea);
	break;
 
    case WM_SETFOCUS:
 
	// Create, position, and display the caret when the window receives the keyboard focus.
	CreateCaret(hwndMain, (HBITMAP) 0, 0, dwCharY);
	SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
	ShowCaret(hwndMain);
	break;
 
    case WM_KILLFOCUS:
 
	// Hide and destroy the caret when the window loses the keyboard focus.
	HideCaret(hwndMain);
	DestroyCaret();
	break;
 
    case WM_PAINT:
	hdc = BeginPaint(hwndMain, &ps);
 
	// Set the clipping rectangle, and then draw the text into it.
	DrawText(hdc, pchInputBuf, nchLast, &TextArea, DT_LEFT);
 
	SetCaretPos(nCaretPosX, nCaretPosY * dwCharY);
 
	EndPaint(hwndMain, &ps);
	break;
 
 
    case WM_DESTROY:
	PostQuitMessage(0);
 
	// Free the input buffer.
	GlobalFree((HGLOBAL) pchInputBuf);
	break;
 
    default:
	return DefWindowProc(hwndMain, uMsg, wParam, lParam);
    }
}