/* 22 may 2015 */
#include "uipriv_windows.hpp"

struct uiDateTimePicker {
	uiWindowsControl c;
	HWND hwnd;
};

#ifndef DTM_GETIDEALSIZE
#define DTM_GETIDEALSIZE 0x100f
#endif

/* utility functions */

#define GLI(what, buf, n) GetLocaleInfoEx(LOCALE_NAME_USER_DEFAULT, what, buf, n)

/* The real date/time picker does a manual replacement of "yy" with "yyyy" for DTS_SHORTDATECENTURYFORMAT.
 * Because we're also duplicating its functionality (see below), we have to do it too. */
static WCHAR *expandYear(WCHAR *dts, int n)
{
	WCHAR *p   = NULL;
	int ny     = 0;

	/* allocate more than we need to be safe */
	WCHAR *out = (WCHAR *) uiAlloc((n * 3) * sizeof (WCHAR), "WCHAR[]");
	WCHAR *q   = out;

	for (p = dts; *p != L'\0'; p++)
   {
      /* first, if the current character is a y, increment the number of consecutive ys
       * otherwise, stop counting, and if there were only two, add two more to make four */
      if (*p != L'y') {
         if (ny == 2) {
            *q++ = L'y';
            *q++ = L'y';
         }
         ny = 0;
      } else
         ny++;
      /* next, handle quoted blocks
       * we do this AFTER the above so yy'abc' becomes yyyy'abc' and not yy'abc'yy
       * this handles the case of 'a''b' elegantly as well */
      if (*p == L'\'') {
         /* copy the opening quote */
         *q++ = *p;
         /* copy the contents */
         for (;;) {
            p++;
            if (*p == L'\'')
               break;
            if (*p == L'\0')
               implbug("unterminated quote in system-provided locale date string in expandYear()");
            *q++ = *p;
         }
         /* and fall through to copy the closing quote */
      }
      /* copy the current character */
      *q++ = *p;
   }
	/* handle trailing yy */
	if (ny == 2) {
		*q++ = L'y';
		*q++ = L'y';
	}
	*q++ = L'\0';
	return out;
}

/* Windows has no combined date/time prebuilt constant; 
 * we have to build the format string ourselves
 * TODO use a default format if one fails */
static void setDateTimeFormat(HWND hwnd)
{
	WCHAR *unexpandedDate, *date;
	WCHAR *time;
	WCHAR *datetime;
	int ntime;
	int ndate = GLI(LOCALE_SSHORTDATE, NULL, 0);

	if (ndate == 0)
		logLastError(L"error getting date string length");
	date = (WCHAR *) uiAlloc(ndate * sizeof (WCHAR), "WCHAR[]");
	if (GLI(LOCALE_SSHORTDATE, date, ndate) == 0)
		logLastError(L"error geting date string");
	unexpandedDate = date;		/* so we can free it */
	date = expandYear(unexpandedDate, ndate);
	uiFree(unexpandedDate);

	ntime = GLI(LOCALE_STIMEFORMAT, NULL, 0);
	if (ndate == 0)
		logLastError(L"error getting time string length");
	time = (WCHAR *) uiAlloc(ntime * sizeof (WCHAR), "WCHAR[]");
	if (GLI(LOCALE_STIMEFORMAT, time, ntime) == 0)
		logLastError(L"error geting time string");

	datetime = strf(L"%s %s", date, time);
	if (SendMessageW(hwnd, DTM_SETFORMAT, 0, (LPARAM) datetime) == 0)
		logLastError(L"error applying format string to date/time picker");

	uiFree(datetime);
	uiFree(time);
	uiFree(date);
}

/* control implementation */

static void uiDateTimePickerDestroy(uiControl *c)
{
	uiDateTimePicker *d = uiDateTimePicker(c);

	uiWindowsUnregisterReceiveWM_WININICHANGE(d->hwnd);
	uiWindowsEnsureDestroyWindow(d->hwnd);
	uiFreeControl(uiControl(d));
}

uiWindowsControlAllDefaultsExceptDestroy(uiDateTimePicker)

/* the height returned from DTM_GETIDEALSIZE is unreliable; see http://stackoverflow.com/questions/30626549/what-is-the-proper-use-of-dtm-getidealsize-treating-the-returned-size-as-pixels
 * from http://msdn.microsoft.com/en-us/library/windows/desktop/dn742486.aspx#sizingandspacing */
#define entryHeight 14

static void uiDateTimePickerMinimumSize(uiWindowsControl *c, int *width, int *height)
{
	SIZE s;
	uiWindowsSizing sizing;
	uiDateTimePicker *d = uiDateTimePicker(c);
	int y;

	s.cx = 0;
	s.cy = 0;
	SendMessageW(d->hwnd, DTM_GETIDEALSIZE, 0, (LPARAM) (&s));
	*width = s.cx;

	y = entryHeight;
	uiWindowsGetSizing(d->hwnd, &sizing);
	uiWindowsSizingDlgUnitsToPixels(&sizing, NULL, &y);
	*height = y;
}

static uiDateTimePicker *finishNewDateTimePicker(DWORD style)
{
	uiDateTimePicker *d;

	uiWindowsNewControl(uiDateTimePicker, d);

	d->hwnd = uiWindowsEnsureCreateControlHWND(WS_EX_CLIENTEDGE,
		DATETIMEPICK_CLASSW, L"",
		style | WS_TABSTOP,
		hInstance, NULL,
		TRUE);

	/* automatically update date/time format when user changes locale settings
	 * for the standard styles, this is in the date-time picker itself
	 * for our date/time mode, we do it in a subclass assigned in uiNewDateTimePicker() */
	uiWindowsRegisterReceiveWM_WININICHANGE(d->hwnd);

	return d;
}

static LRESULT CALLBACK datetimepickerSubProc(HWND hwnd, UINT uMsg, WPARAM wParam,
      LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
   switch (uMsg)
   {
      case WM_WININICHANGE:
         // we can optimize this by only doing it when the real date/time picker does it
         // unfortunately, I don't know when that is :/
         // hopefully this won't hurt
         setDateTimeFormat(hwnd);
         return 0;
      case WM_NCDESTROY:
         if (RemoveWindowSubclass(hwnd, datetimepickerSubProc, uIdSubclass) == FALSE)
            logLastError(L"error removing date-time picker locale change handling subclass");
         break;
   }
   return DefSubclassProc(hwnd, uMsg, wParam, lParam);
}

uiDateTimePicker *uiNewDateTimePicker(void)
{
   uiDateTimePicker *d = finishNewDateTimePicker(0);

   setDateTimeFormat(d->hwnd);
   if (SetWindowSubclass(d->hwnd, datetimepickerSubProc, 0, (DWORD_PTR) d) == FALSE)
      logLastError(L"error subclassing date-time-picker to assist in locale change handling");
   /* TODO set a suitable default in this case */
   return d;
}

uiDateTimePicker *uiNewDatePicker(void)
{
	return finishNewDateTimePicker(DTS_SHORTDATECENTURYFORMAT);
}

uiDateTimePicker *uiNewTimePicker(void)
{
	return finishNewDateTimePicker(DTS_TIMEFORMAT);
}