#include <windows.h>
#include <windowsx.h>
#include <imm.h>
#include <stdio.h>

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);
HINSTANCE g_hInst;
HWND hWndMain;
LPCTSTR lpszClass=TEXT("Ime4");

// Àü¿ª º¯¼ö
TCHAR *buf;
BOOL bComp;
int off;
int FontHeight;

// ÇÔ¼ö ¿øÇü
BOOL OnCreate(HWND hWnd, LPCREATESTRUCT lpCreateStruct);
void OnChar(HWND hWnd, TCHAR ch, int cRepeat);
void OnKey(HWND hWnd, UINT vk, BOOL fDown, int cRepeat, UINT flags);
void OnPaint(HWND hWnd);
void OnSetFocus(HWND hWnd, HWND hwndOldFocus);
void OnKillFocus(HWND hWnd, HWND hwndNewFocus);
void OnDestroy(HWND hWnd);
LRESULT OnImeComposition(HWND hWnd, WPARAM wParam, LPARAM lParam);
LRESULT OnImeChar(HWND hWnd, WPARAM wParam, LPARAM lParam);
void OnLButtonDown(HWND hWnd, BOOL fDoubleClick, int x, int y, UINT keyFlags);
void OnMouseMove(HWND hWnd, int x, int y, UINT keyFlags);
void OnLButtonUp(HWND hWnd, int x, int y, UINT keyFlags);
void OnTimer(HWND hWnd, UINT id);
void OnSize(HWND hWnd, UINT state, int cx, int cy);
void OnHScroll(HWND hWnd, HWND hwndCtl, UINT code, int pos);
void OnVScroll(HWND hWnd, HWND hwndCtl, UINT code, int pos);
void OnContextMenu(HWND hWnd, HWND hwndContext, UINT xPos, UINT yPos);
void OnCommand(HWND hWnd, int id, HWND hwndCtl, UINT codeNotify);
BOOL OnSetCursor(HWND hWnd, HWND hwndCursor, UINT codeHitTest, UINT msg);
UINT OnGetDlgCode(HWND hWnd, LPMSG lpmsg);

int GetCharWidth(HDC hdc, TCHAR *ch, int len);
void SetCaret();
inline BOOL IsDBCS(int nPos);
int GetPrevOff(int nPos);
int GetNextOff(int nPos);
void Insert(int nPos, TCHAR *str);
void Delete(int nPos, int nCount);

int APIENTRY WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance
	  ,LPSTR lpszCmdParam,int nCmdShow)
{
	HWND hWnd;
	MSG Message;
	WNDCLASS WndClass;
	g_hInst=hInstance;
	
	WndClass.cbClsExtra=0;
	WndClass.cbWndExtra=0;
	WndClass.hbrBackground=(HBRUSH)(COLOR_WINDOW+1);
	WndClass.hCursor=LoadCursor(NULL,IDC_IBEAM);
	WndClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);
	WndClass.hInstance=hInstance;
	WndClass.lpfnWndProc=(WNDPROC)WndProc;
	WndClass.lpszClassName=lpszClass;
	WndClass.lpszMenuName=NULL;
	WndClass.style=CS_HREDRAW | CS_VREDRAW;
	RegisterClass(&WndClass);

	hWnd=CreateWindow(lpszClass,lpszClass,WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,
		NULL,(HMENU)NULL,hInstance,NULL);
	ShowWindow(hWnd,nCmdShow);
	
	while(GetMessage(&Message,0,0,0)) {
		TranslateMessage(&Message);
		DispatchMessage(&Message);
	}
	return (int)Message.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd,UINT iMessage,WPARAM wParam,LPARAM lParam)
{
	switch(iMessage) {
		HANDLE_MSG(hWnd, WM_CREATE, OnCreate);
		HANDLE_MSG(hWnd, WM_DESTROY, OnDestroy);
		HANDLE_MSG(hWnd, WM_CHAR, OnChar);
		HANDLE_MSG(hWnd, WM_KEYDOWN, OnKey);
		HANDLE_MSG(hWnd, WM_KEYUP, OnKey);
		HANDLE_MSG(hWnd, WM_PAINT, OnPaint);
		HANDLE_MSG(hWnd, WM_SETFOCUS, OnSetFocus);
		HANDLE_MSG(hWnd, WM_KILLFOCUS, OnKillFocus);
		HANDLE_MSG(hWnd, WM_LBUTTONDOWN, OnLButtonDown);
		HANDLE_MSG(hWnd, WM_LBUTTONDBLCLK, OnLButtonDown);
		HANDLE_MSG(hWnd, WM_MOUSEMOVE, OnMouseMove);
		HANDLE_MSG(hWnd, WM_LBUTTONUP, OnLButtonUp);
		HANDLE_MSG(hWnd, WM_TIMER, OnTimer);
		HANDLE_MSG(hWnd, WM_SIZE, OnSize);
		HANDLE_MSG(hWnd, WM_HSCROLL, OnHScroll);
		HANDLE_MSG(hWnd, WM_VSCROLL, OnVScroll);
		HANDLE_MSG(hWnd, WM_CONTEXTMENU, OnContextMenu);
		HANDLE_MSG(hWnd, WM_COMMAND, OnCommand);
		HANDLE_MSG(hWnd, WM_SETCURSOR, OnSetCursor);
		HANDLE_MSG(hWnd, WM_GETDLGCODE, OnGetDlgCode);
	case WM_IME_COMPOSITION:
		return OnImeComposition(hWnd, wParam, lParam);
	case WM_IME_CHAR:
		return OnImeChar(hWnd, wParam, lParam);
	case WM_IME_STARTCOMPOSITION:
		return 0;
	}
	return(DefWindowProc(hWnd,iMessage,wParam,lParam));
}

///////////////////////////////////////////////////////////////////////////////////
// ¸Þ½ÃÁö Çڵ鷯

BOOL OnCreate(HWND hWnd, LPCREATESTRUCT lpCreateStruct)
{
	HDC hdc;
	TEXTMETRIC tm;

	bComp=FALSE;
	buf=(TCHAR *)malloc(65536);
	memset(buf,0,65536);
	hWndMain=hWnd;
	off=0;
	hdc=GetDC(hWnd);
	GetTextMetrics(hdc,&tm);
	FontHeight=tm.tmHeight;
	ReleaseDC(hWnd,hdc);
	return TRUE;
}

void OnDestroy(HWND hWnd)
{
	PostQuitMessage(0);
	free(buf);
}

void OnSize(HWND hWnd, UINT state, int cx, int cy)
{
}

void OnKey(HWND hWnd, UINT vk, BOOL fDown, int cRepeat, UINT flags)
{
	if (fDown==FALSE)
		return;

	switch (vk)
	{
	case VK_LEFT:
		if (off > 0) {
			off=GetPrevOff(off);
			SetCaret();
		}
		return;
	case VK_RIGHT:
		if (off < (int)strlen(buf)) {
			off=GetNextOff(off);
			SetCaret();
		}
		return;
	case VK_HOME:
		off=0;
		SetCaret();
		return;
	case VK_END:
		off=lstrlen(buf);
		SetCaret();
		return;
	case VK_DELETE:
		if (IsDBCS(off)) {
			Delete(off, 2);
		} else {
			Delete(off, 1);
		}
		InvalidateRect(hWnd,NULL,TRUE);
		return;
	case VK_BACK:
		if (off == 0)
			return;
		off=GetPrevOff(off);
		SendMessage(hWnd,WM_KEYDOWN,VK_DELETE,0);
		SetCaret();
		return;
	}
}

void OnPaint(HWND hWnd)
{
	HDC hdc;
	PAINTSTRUCT ps;

	hdc=BeginPaint(hWnd,&ps);
	TextOut(hdc,0,0,buf,lstrlen(buf));
    //MessageBox(hWnd, buf, "Test", MB_OK);
	EndPaint(hWnd,&ps);
}

void OnSetFocus(HWND hWnd, HWND hwndOldFocus)
{
	SetCaret();
}

void OnKillFocus(HWND hWnd, HWND hwndNewFocus)
{
	DestroyCaret();
}

void OnChar(HWND hWnd, TCHAR ch, int cRepeat)
{
	TCHAR szChar[3];
	int i;

	if (ch == 8)
		return;
	szChar[0]=ch;
	szChar[1]=0;
	for (i=0;i<cRepeat;i++) {
		Insert(off,szChar);
		off+=lstrlen(szChar);
	}
	bComp=FALSE;
	InvalidateRect(hWnd,NULL,TRUE);
	SetCaret();
}

LRESULT OnImeChar(HWND hWnd, WPARAM wParam, LPARAM lParam)
{
	TCHAR szChar[3];

	if (IsDBCSLeadByte((BYTE)(wParam >> 8))) {
		szChar[0]=HIBYTE(LOWORD(wParam));
		szChar[1]=LOBYTE(LOWORD(wParam));
		szChar[2]=0;
	} else {
		szChar[0]=(BYTE)wParam;
		szChar[1]=0;
	}
	if (bComp) {
		off-=2;
		Delete(off,2);
	}
	Insert(off,szChar);
	off+=lstrlen(szChar);
	bComp=FALSE;
	InvalidateRect(hWnd,NULL,TRUE);
	SetCaret();
	return 0;
}

LRESULT OnImeComposition(HWND hWnd, WPARAM wParam, LPARAM lParam)
{
	HIMC hImc;
	TCHAR *szComp;
	int len;

	hImc=ImmGetContext(hWnd);
	if (lParam & GCS_COMPSTR) {
		len=ImmGetCompositionString(hImc,GCS_COMPSTR,NULL,0);
		szComp=(TCHAR *)malloc(len+1);
		ImmGetCompositionString(hImc,GCS_COMPSTR,szComp,len);
		szComp[len]=0;
		if (bComp) {
			off-=2;
			Delete(off,2);
		}
		if (len == 0) {
			bComp=FALSE;
		} else {
			bComp=TRUE;
		}

		Insert(off,szComp);
		off+=len;
		ImmReleaseContext(hWnd,hImc);
		free(szComp);
		InvalidateRect(hWnd,NULL,TRUE);
		SetCaret();
	}

	return DefWindowProc(hWnd,WM_IME_COMPOSITION,wParam,lParam);
}

void OnHScroll(HWND hWnd, HWND hwndCtl, UINT code, int pos)
{
}

void OnVScroll(HWND hWnd, HWND hwndCtl, UINT code, int pos)
{
}

void OnContextMenu(HWND hWnd, HWND hwndContext, UINT xPos, UINT yPos)
{
}

void OnCommand(HWND hWnd, int id, HWND hwndCtl, UINT codeNotify)
{
}

void OnLButtonDown(HWND hWnd, BOOL fDoubleClick, int x, int y, UINT keyFlags)
{
}

void OnMouseMove(HWND hWnd, int x, int y, UINT keyFlags)
{
}

void OnLButtonUp(HWND hWnd, int x, int y, UINT keyFlags)
{
}

void OnTimer(HWND hWnd, UINT id)
{
}

BOOL OnSetCursor(HWND hWnd, HWND hwndCursor, UINT codeHitTest, UINT msg)
{
	return FORWARD_WM_SETCURSOR(hWnd,hwndCursor,codeHitTest,msg,DefWindowProc);
}

UINT OnGetDlgCode(HWND hWnd, LPMSG lpmsg)
{
	return 0;
}

///////////////////////////////////////////////////////////////////////////////////
// ÀÏ¹Ý ÇÔ¼öµé

int GetCharWidth(HDC hdc, TCHAR *ch, int len)
{
	SIZE sz;
	GetTextExtentPoint32(hdc, ch, len, &sz);
	return sz.cx;
}

void SetCaret()
{
	SIZE sz;
	HDC hdc;
	int toff;
	int caretwidth;

	hdc=GetDC(hWndMain);
	if (bComp) {
		toff=off-2;
		caretwidth=GetCharWidth(hdc,buf+toff,2);
	} else {
		toff=off;
		caretwidth=2;
	}
	CreateCaret(hWndMain,NULL,caretwidth,FontHeight);
	ShowCaret(hWndMain);

	GetTextExtentPoint32(hdc,buf,toff,&sz);
	SetCaretPos(sz.cx,0);
    ReleaseDC(hWndMain,hdc);
}

inline BOOL IsDBCS(int nPos)
{
	return (IsDBCSLeadByte(buf[nPos]));
}

int GetPrevOff(int nPos)
{
	int n, size;

	if (nPos==0) {
		return 0;
	}

	for (n=0;;) {
		if (IsDBCS(n)) {
			size=2;
		} else {
			size=1;
		}
		n+=size;
		if (n >= nPos)
			break;
	}
	return n-size;
}

int GetNextOff(int nPos)
{
	if (IsDBCS(nPos)) {
		return nPos+2;
	} else {
		return nPos+1;
	}
}

void Insert(int nPos, TCHAR *str)
{
	int len;
	int movelen;

	len=lstrlen(str);
	if (len==0) return;
	movelen=lstrlen(buf+nPos)+1;
	memmove(buf+nPos+len,buf+nPos,movelen);
	memcpy(buf+nPos,str,len);
}

void Delete(int nPos, int nCount)
{
	int movelen;

	if (nCount == 0) return;
	if (lstrlen(buf) < nPos+nCount) return;

	movelen=lstrlen(buf+nPos+nCount)+1;
	memmove(buf+nPos, buf+nPos+nCount, movelen);
}