/*

Miranda NG: the free IM client for Microsoft* Windows*

Copyright (ñ) 2012-15 Miranda NG project (http://miranda-ng.org),
Copyright (c) 2000-12 Miranda IM project,
all portions of this codebase are copyrighted to the people
listed in contributors.txt.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

implements services to handle location - based timezones, instead of
simple UTC offsets.
*/

#include "..\..\core\commonheaders.h"

TIME_API tmi;

typedef DWORD 	(WINAPI *pfnGetDynamicTimeZoneInformation_t)(DYNAMIC_TIME_ZONE_INFORMATION *pdtzi);
static pfnGetDynamicTimeZoneInformation_t pfnGetDynamicTimeZoneInformation;

struct REG_TZI_FORMAT
{
	LONG Bias;
	LONG StandardBias;
	LONG DaylightBias;
	SYSTEMTIME StandardDate;
	SYSTEMTIME DaylightDate;
};

#define MIM_TZ_DISPLAYLEN 128

struct MIM_TIMEZONE
{
	unsigned hash;
	int offset;

	TCHAR	tszName[MIM_TZ_NAMELEN];            // windows name for the time zone
	wchar_t	szDisplay[MIM_TZ_DISPLAYLEN];    // more descriptive display name (that's what usually appears in dialogs)
	                                          // every hour should be sufficient.
	TIME_ZONE_INFORMATION tzi;

	static int compareBias(const MIM_TIMEZONE* p1, const MIM_TIMEZONE* p2)
	{ return p2->tzi.Bias - p1->tzi.Bias; }
};

struct TZ_INT_INFO
{
	DWORD		timestamp;  // last time updated
	MIM_TIMEZONE myTZ;   // set to my own timezone
};

static TZ_INT_INFO myInfo;

static OBJLIST<MIM_TIMEZONE>  g_timezones(55, NumericKeySortT);
static LIST<MIM_TIMEZONE>     g_timezonesBias(55, MIM_TIMEZONE::compareBias);

void FormatTime(const SYSTEMTIME *st, const TCHAR *szFormat, TCHAR *szDest, int cbDest);
void UnixTimeToFileTime(mir_time ts, LPFILETIME pft);
mir_time FileTimeToUnixTime(LPFILETIME pft);

#define fnSystemTimeToTzSpecificLocalTime SystemTimeToTzSpecificLocalTime

static int timeapiGetTimeZoneTime(HANDLE hTZ, SYSTEMTIME *st)
{
	if (st == NULL) return 1;

	MIM_TIMEZONE *tz = (MIM_TIMEZONE*)hTZ;
	if (tz == UTC_TIME_HANDLE)
		GetSystemTime(st);
	else if (tz && tz != &myInfo.myTZ) {
		SYSTEMTIME sto;
		GetSystemTime(&sto);
		return !fnSystemTimeToTzSpecificLocalTime(&tz->tzi, &sto, st);
	}
	else
		GetLocalTime(st);

	return 0;
}

static LPCTSTR timeapiGetTzName(HANDLE hTZ)
{
	MIM_TIMEZONE *tz = (MIM_TIMEZONE*)hTZ;
	if (tz == NULL)
		return myInfo.myTZ.tszName;
	else if (tz == UTC_TIME_HANDLE)
		return _T("UTC");

	return tz->tszName;
}

static LPCTSTR timeapiGetTzDescription(LPCTSTR TZname)
{
	for (int i = 0; i < g_timezonesBias.getCount(); i++) {
		MIM_TIMEZONE *tz = g_timezonesBias[i];

		if (!mir_tstrcmp(tz->tszName, TZname))
			return tz->szDisplay;
	}
	return _T("");
}

static void CalcTsOffset(MIM_TIMEZONE *tz)
{
	SYSTEMTIME st, stl;
	GetSystemTime(&st);

	FILETIME ft;
	SystemTimeToFileTime(&st, &ft);
	mir_time ts1 = FileTimeToUnixTime(&ft);

	if (!fnSystemTimeToTzSpecificLocalTime(&tz->tzi, &st, &stl))
		return;

	SystemTimeToFileTime(&stl, &ft);
	mir_time ts2 = FileTimeToUnixTime(&ft);

	tz->offset = ts2 - ts1;
}

static bool IsSameTime(MIM_TIMEZONE *tz)
{
	SYSTEMTIME st, stl;

	if (tz == &myInfo.myTZ)
		return true;

	timeapiGetTimeZoneTime(tz, &stl);
	timeapiGetTimeZoneTime(NULL, &st);

	return st.wHour == stl.wHour && st.wMinute == stl.wMinute;
}

static HANDLE timeapiGetInfoByName(LPCTSTR tszName, DWORD dwFlags)
{
	if (tszName == NULL)
		return (dwFlags & (TZF_DIFONLY | TZF_KNOWNONLY)) ? NULL : &myInfo.myTZ;

	if (mir_tstrcmp(myInfo.myTZ.tszName, tszName) == 0)
		return (dwFlags & TZF_DIFONLY) ? NULL : &myInfo.myTZ;

	MIM_TIMEZONE tzsearch;
	tzsearch.hash = mir_hashstrT(tszName);

	MIM_TIMEZONE *tz = g_timezones.find(&tzsearch);
	if (tz == NULL)
		return (dwFlags & (TZF_DIFONLY | TZF_KNOWNONLY)) ? NULL : &myInfo.myTZ;

	if (dwFlags & TZF_DIFONLY)
		return IsSameTime(tz) ? NULL : tz;

	return tz;
}

static HANDLE timeapiGetInfoByContact(MCONTACT hContact, LPCSTR szModule, DWORD dwFlags)
{
	if (hContact == NULL && szModule == NULL)
		return (dwFlags & (TZF_DIFONLY | TZF_KNOWNONLY)) ? NULL : &myInfo.myTZ;

	if (szModule == NULL) szModule = "UserInfo";

	DBVARIANT dbv;
	if (!db_get_ts(hContact, szModule, "TzName", &dbv)) {
		HANDLE res = timeapiGetInfoByName(dbv.ptszVal, dwFlags);
		db_free(&dbv);
		if (res) return res;
	}

	signed char timezone = (signed char)db_get_b(hContact, szModule, "Timezone", -1);
	if (timezone == -1) {
		char *szProto = GetContactProto(hContact);
		if (!db_get_ts(hContact, szProto, "TzName", &dbv)) {
			HANDLE res = timeapiGetInfoByName(dbv.ptszVal, dwFlags);
			db_free(&dbv);
			if (res) return res;
		}
		timezone = (signed char)db_get_b(hContact, szProto, "Timezone", -1);
	}

	if (timezone != -1) {
		MIM_TIMEZONE tzsearch;
		tzsearch.tzi.Bias = timezone * 30;
		if (myInfo.myTZ.tzi.Bias == tzsearch.tzi.Bias) {
			if (dwFlags & TZF_DIFONLY) return NULL;
			return &myInfo.myTZ;
		}

		int i = g_timezonesBias.getIndex(&tzsearch);
		while (i >= 0 && g_timezonesBias[i]->tzi.Bias == tzsearch.tzi.Bias) --i;

		int delta = LONG_MAX;
		for (int j = ++i; j < g_timezonesBias.getCount() && g_timezonesBias[j]->tzi.Bias == tzsearch.tzi.Bias; ++j) {
			int delta1 = abs(g_timezonesBias[j]->tzi.DaylightDate.wMonth - myInfo.myTZ.tzi.DaylightDate.wMonth);
			if (delta1 <= delta) {
				delta = delta1;
				i = j;
			}
		}

		if (i >= 0) {
			MIM_TIMEZONE *tz = g_timezonesBias[i];
			return ((dwFlags & TZF_DIFONLY) && IsSameTime(tz)) ? NULL : tz;
		}
	}
	return (dwFlags & (TZF_DIFONLY | TZF_KNOWNONLY)) ? NULL : &myInfo.myTZ;
}

static void timeapiSetInfoByContact(MCONTACT hContact, LPCSTR szModule, HANDLE hTZ)
{
	if (szModule == NULL) szModule = "UserInfo";

	MIM_TIMEZONE *tz = (MIM_TIMEZONE*)hTZ;
	if (tz) {
		db_set_ts(hContact, szModule, "TzName", tz->tszName);
		db_set_b(hContact, szModule, "Timezone", (char)((tz->tzi.Bias + tz->tzi.StandardBias) / 30));
	}
	else {
		db_unset(hContact, szModule, "TzName");
		db_unset(hContact, szModule, "Timezone");
	}
}

static int timeapiPrintDateTime(HANDLE hTZ, LPCTSTR szFormat, LPTSTR szDest, int cbDest, DWORD dwFlags)
{
	MIM_TIMEZONE *tz = (MIM_TIMEZONE*)hTZ;
	if (tz == NULL && (dwFlags & (TZF_DIFONLY | TZF_KNOWNONLY)))
		return 1;

	SYSTEMTIME st;
	if (timeapiGetTimeZoneTime(tz, &st))
		return 1;

	FormatTime(&st, szFormat, szDest, cbDest);
	return 0;
}

static int timeapiPrintTimeStamp(HANDLE hTZ, mir_time ts, LPCTSTR szFormat, LPTSTR szDest, int cbDest, DWORD dwFlags)
{
	MIM_TIMEZONE *tz = (MIM_TIMEZONE*)hTZ;
	if (tz == NULL && (dwFlags & (TZF_DIFONLY | TZF_KNOWNONLY)))
		return 1;

	if (tz == NULL)
		tz = &myInfo.myTZ;
	
	FILETIME ft;
	if (tz == UTC_TIME_HANDLE)
		UnixTimeToFileTime(ts, &ft);
	else {
		if (tz->offset == INT_MIN)
			CalcTsOffset(tz);

		UnixTimeToFileTime(ts + tz->offset, &ft);
	}

	SYSTEMTIME st;
	FileTimeToSystemTime(&ft, &st);

	FormatTime(&st, szFormat, szDest, cbDest);
	return 0;
}

static LPTIME_ZONE_INFORMATION timeapiGetTzi(HANDLE hTZ)
{
	MIM_TIMEZONE *tz = (MIM_TIMEZONE*)hTZ;
	return tz ? &tz->tzi : &myInfo.myTZ.tzi;
}

static mir_time timeapiTimeStampToTimeZoneTimeStamp(HANDLE hTZ, mir_time ts)
{
	MIM_TIMEZONE *tz = (MIM_TIMEZONE*)hTZ;
	if (tz == NULL)
		tz = &myInfo.myTZ;

	if (tz == UTC_TIME_HANDLE)
		return ts;

	if (tz->offset == INT_MIN)
		CalcTsOffset(tz);

	return ts + tz->offset;
}

struct ListMessages
{
	UINT addStr, getSel, setSel, getData, setData;
};

static const ListMessages lbMessages = { LB_ADDSTRING, LB_GETCURSEL, LB_SETCURSEL, LB_GETITEMDATA, LB_SETITEMDATA };
static const ListMessages cbMessages = { CB_ADDSTRING, CB_GETCURSEL, CB_SETCURSEL, CB_GETITEMDATA, CB_SETITEMDATA };

static const ListMessages* GetListMessages(HWND hWnd, DWORD dwFlags)
{
	if (hWnd == NULL)
		return NULL;

	if (!(dwFlags & (TZF_PLF_CB | TZF_PLF_LB))) {
		TCHAR	tszClassName[128];
		GetClassName(hWnd, tszClassName, SIZEOF(tszClassName));
		if (!mir_tstrcmpi(tszClassName, _T("COMBOBOX")))
			dwFlags |= TZF_PLF_CB;
		else if (!mir_tstrcmpi(tszClassName, _T("LISTBOX")))
			dwFlags |= TZF_PLF_LB;
	}
	if (dwFlags & TZF_PLF_CB)
		return &cbMessages;
	else if (dwFlags & TZF_PLF_LB)
		return &lbMessages;
	else
		return NULL;
}

///////////////////////////////////////////////////////////////////////////////

static int timeapiSelectListItem(MCONTACT hContact, LPCSTR szModule, HWND hWnd, DWORD dwFlags)
{
	const ListMessages *lstMsg = GetListMessages(hWnd, dwFlags);
	if (lstMsg == NULL)
		return -1;

	if (szModule == NULL) szModule = "UserInfo";

	int iSelection = 0;
	ptrT tszName(db_get_tsa(hContact, szModule, "TzName"));
	if (tszName != NULL) {
		unsigned hash = mir_hashstrT(tszName);
		for (int i = 0; i < g_timezonesBias.getCount(); i++) {
			if (hash == g_timezonesBias[i]->hash) {
				iSelection = i + 1;
				break;
			}
		}
	}
	else {
		signed char cBias = db_get_b(hContact, szModule, "Timezone", -100);
		if (cBias != -100) {
			int iBias = cBias * 30;
			for (int i = 0; i < g_timezonesBias.getCount(); i++) {
				if (iBias == g_timezonesBias[i]->tzi.Bias) {
					iSelection = i + 1;
					break;
				}
			}
		}
	}

	SendMessage(hWnd, lstMsg->setSel, iSelection, 0);
	return iSelection;
}

static int timeapiPrepareList(MCONTACT hContact, LPCSTR szModule, HWND hWnd, DWORD dwFlags)
{
	const ListMessages *lstMsg = GetListMessages(hWnd, dwFlags);
	if (lstMsg == NULL)
		return 0;

	SendMessage(hWnd, lstMsg->addStr, 0, (LPARAM)TranslateT("<unspecified>"));

	for (int i = 0; i < g_timezonesBias.getCount(); i++) {
		MIM_TIMEZONE *tz = g_timezonesBias[i];

		SendMessage(hWnd, lstMsg->addStr, 0, (LPARAM)tz->szDisplay);
		SendMessage(hWnd, lstMsg->setData, i + 1, (LPARAM)tz);
	}

	return timeapiSelectListItem(hContact, szModule, hWnd, dwFlags);
}

static void timeapiStoreListResult(MCONTACT hContact, LPCSTR szModule, HWND hWnd, DWORD dwFlags)
{
	if (szModule == NULL) szModule = "UserInfo";

	const ListMessages *lstMsg = GetListMessages(hWnd, dwFlags);
	if (lstMsg) {
		LRESULT offset = SendMessage(hWnd, lstMsg->getSel, 0, 0);
		if (offset > 0) {
			MIM_TIMEZONE *tz = (MIM_TIMEZONE*)SendMessage(hWnd, lstMsg->getData, offset, 0);
			if ((INT_PTR)tz != CB_ERR && tz != NULL)
				timeapiSetInfoByContact(hContact, szModule, tz);
		}
		else timeapiSetInfoByContact(hContact, szModule, NULL);
	}
}

///////////////////////////////////////////////////////////////////////////////

static INT_PTR GetTimeApi(WPARAM, LPARAM lParam)
{
	TIME_API* tmi = (TIME_API*)lParam;
	if (tmi == NULL)
		return FALSE;

	if (tmi->cbSize != sizeof(TIME_API))
		return FALSE;

	tmi->createByName = timeapiGetInfoByName;
	tmi->createByContact = timeapiGetInfoByContact;
	tmi->storeByContact = timeapiSetInfoByContact;

	tmi->printDateTime = timeapiPrintDateTime;
	tmi->printTimeStamp = timeapiPrintTimeStamp;

	tmi->prepareList = timeapiPrepareList;
	tmi->selectListItem = timeapiSelectListItem;
	tmi->storeListResults = timeapiStoreListResult;

	tmi->getTimeZoneTime = timeapiGetTimeZoneTime;
	tmi->timeStampToTimeZoneTimeStamp = timeapiTimeStampToTimeZoneTimeStamp;
	tmi->getTzi = timeapiGetTzi;
	tmi->getTzName = timeapiGetTzName;
	tmi->getTzDescription = timeapiGetTzDescription;

	return TRUE;
}

static INT_PTR TimestampToLocal(WPARAM wParam, LPARAM)
{
	return timeapiTimeStampToTimeZoneTimeStamp(NULL, (mir_time)wParam);
}

static INT_PTR TimestampToStringT(WPARAM wParam, LPARAM lParam)
{
	DBTIMETOSTRINGT *tts = (DBTIMETOSTRINGT*)lParam;
	if (tts != NULL)
		timeapiPrintTimeStamp(NULL, (mir_time)wParam, tts->szFormat, tts->szDest, tts->cbDest, 0);
	return 0;
}

static INT_PTR TimestampToStringA(WPARAM wParam, LPARAM lParam)
{
	DBTIMETOSTRING *tts = (DBTIMETOSTRING*)lParam;
	if (tts != NULL) {
		TCHAR *szDest = (TCHAR*)alloca(tts->cbDest*sizeof(TCHAR));
		timeapiPrintTimeStamp(NULL, (mir_time)wParam, _A2T(tts->szFormat), szDest, tts->cbDest, 0);
		WideCharToMultiByte(CP_ACP, 0, szDest, -1, tts->szDest, tts->cbDest, NULL, NULL);
	}
	return 0;
}

void GetLocalizedString(HKEY hSubKey, const TCHAR *szName, wchar_t *szBuf, DWORD cbLen)
{
	DWORD dwLength = cbLen * sizeof(wchar_t);
	RegQueryValueEx(hSubKey, szName, NULL, NULL, (unsigned char *)szBuf, &dwLength);
	szBuf[min(dwLength / sizeof(TCHAR), cbLen - 1)] = 0;
}

extern "C" __declspec(dllexport) void RecalculateTime(void)
{
	GetTimeZoneInformation(&myInfo.myTZ.tzi);
	myInfo.timestamp = time(NULL);
	myInfo.myTZ.offset = INT_MIN;

	bool found = false;
	DYNAMIC_TIME_ZONE_INFORMATION dtzi;

	if (pfnGetDynamicTimeZoneInformation && pfnGetDynamicTimeZoneInformation(&dtzi) != TIME_ZONE_ID_INVALID) {
		TCHAR *myTzKey = mir_u2t(dtzi.TimeZoneKeyName);
		_tcsncpy_s(myInfo.myTZ.tszName, myTzKey, _TRUNCATE);
		mir_free(myTzKey);
		found = true;
	}

	for (int i = 0; i < g_timezones.getCount(); i++) {
		MIM_TIMEZONE &tz = g_timezones[i];
		if (tz.offset != INT_MIN)
			tz.offset = INT_MIN;

		if (!found) {
			if (!wcscmp(tz.tzi.StandardName, myInfo.myTZ.tzi.StandardName) || !wcscmp(tz.tzi.DaylightName, myInfo.myTZ.tzi.DaylightName)) {
				_tcsncpy_s(myInfo.myTZ.tszName, tz.tszName, _TRUNCATE);
				found = true;
			}
		}
	}
}

void InitTimeZones(void)
{
	REG_TZI_FORMAT	tzi;
	HKEY			hKey;

	const TCHAR *tszKey = _T("SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones");

	/*
	 * use GetDynamicTimeZoneInformation() on Vista+ - this will return a structure with
	 * the registry key name, so finding our own time zone later will be MUCH easier for
	 * localized systems or systems with a MUI pack installed
	 */
	if (IsWinVerVistaPlus())
		pfnGetDynamicTimeZoneInformation = (pfnGetDynamicTimeZoneInformation_t)GetProcAddress(GetModuleHandle(_T("kernel32")), "GetDynamicTimeZoneInformation");

	if (ERROR_SUCCESS == RegOpenKeyEx(HKEY_LOCAL_MACHINE, tszKey, 0, KEY_ENUMERATE_SUB_KEYS, &hKey)) {
		DWORD	dwIndex = 0;
		HKEY	hSubKey;
		TCHAR	tszName[MIM_TZ_NAMELEN];

		DWORD dwSize = SIZEOF(tszName);
		while (ERROR_NO_MORE_ITEMS != RegEnumKeyEx(hKey, dwIndex++, tszName, &dwSize, NULL, NULL, 0, NULL)) {
			if (ERROR_SUCCESS == RegOpenKeyEx(hKey, tszName, 0, KEY_QUERY_VALUE, &hSubKey)) {
				dwSize = sizeof(tszName);

				DWORD dwLength = sizeof(tzi);
				if (ERROR_SUCCESS != RegQueryValueEx(hSubKey, _T("TZI"), NULL, NULL, (unsigned char *)&tzi, &dwLength))
					continue;

				MIM_TIMEZONE *tz = new MIM_TIMEZONE;

				tz->tzi.Bias = tzi.Bias;
				tz->tzi.StandardDate = tzi.StandardDate;
				tz->tzi.StandardBias = tzi.StandardBias;
				tz->tzi.DaylightDate = tzi.DaylightDate;
				tz->tzi.DaylightBias = tzi.DaylightBias;

				mir_tstrcpy(tz->tszName, tszName);
				tz->hash = mir_hashstrT(tszName);
				tz->offset = INT_MIN;

				GetLocalizedString(hSubKey, _T("Display"), tz->szDisplay, SIZEOF(tz->szDisplay));
				GetLocalizedString(hSubKey, _T("Std"), tz->tzi.StandardName, SIZEOF(tz->tzi.StandardName));
				GetLocalizedString(hSubKey, _T("Dlt"), tz->tzi.DaylightName, SIZEOF(tz->tzi.DaylightName));

				g_timezones.insert(tz);
				g_timezonesBias.insert(tz);

				RegCloseKey(hSubKey);
			}
			dwSize = SIZEOF(tszName);
		}
		RegCloseKey(hKey);
	}

	RecalculateTime();

	CreateServiceFunction(MS_SYSTEM_GET_TMI, GetTimeApi);

	CreateServiceFunction(MS_DB_TIME_TIMESTAMPTOLOCAL, TimestampToLocal);
	CreateServiceFunction(MS_DB_TIME_TIMESTAMPTOSTRINGT, TimestampToStringT);

	CreateServiceFunction(MS_DB_TIME_TIMESTAMPTOSTRING, TimestampToStringA);

	tmi.cbSize = sizeof(tmi);
	GetTimeApi(0, (LPARAM)&tmi);
}