/*
 *  Copyright 2005-2014 Fabrice Colin
 *
 *  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.
 */

#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_TIMEGM
#ifndef _XOPEN_SOURCE
#define _XOPEN_SOURCE
#include <time.h>
#undef _XOPEN_SOURCE
#else
#include <time.h>
#endif
#else
#include <time.h>
/* This comment and function are taken from Wget's mktime_from_utc()
   Converts struct tm to time_t, assuming the data in tm is UTC rather
   than local timezone.

   mktime is similar but assumes struct tm, also known as the
   "broken-down" form of time, is in local time zone.  mktime_from_utc
   uses mktime to make the conversion understanding that an offset
   will be introduced by the local time assumption.

   mktime_from_utc then measures the introduced offset by applying
   gmtime to the initial result and applying mktime to the resulting
   "broken-down" form.  The difference between the two mktime results
   is the measured offset which is then subtracted from the initial
   mktime result to yield a calendar time which is the value returned.

   tm_isdst in struct tm is set to 0 to force mktime to introduce a
   consistent offset (the non DST offset) since tm and tm+o might be
   on opposite sides of a DST change.

   Some implementations of mktime return -1 for the nonexistent
   localtime hour at the beginning of DST.  In this event, use
   mktime(tm - 1hr) + 3600.

   Schematically
     mktime(tm)   --> t+o
     gmtime(t+o)  --> tm+o
     mktime(tm+o) --> t+2o
     t+o - (t+2o - t+o) = t

   Note that glibc contains a function of the same purpose named
   `timegm' (reverse of gmtime).  But obviously, it is not universally
   available, and unfortunately it is not straightforwardly
   extractable for use here.  Perhaps configure should detect timegm
   and use it where available.

   Contributed by Roger Beeman <beeman@cisco.com>, with the help of
   Mark Baushke <mdb@cisco.com> and the rest of the Gurus at CISCO.
   Further improved by Roger with assistance from Edward J. Sabol
   based on input by Jamie Zawinski.  */
static time_t mktime_from_utc (struct tm *t)
{
  time_t tl, tb;
  struct tm *tg;

  tl = mktime (t);
  if (tl == -1)
    {
      t->tm_hour--;
      tl = mktime (t);
      if (tl == -1)
	return -1; /* can't deal with output from strptime */
      tl += 3600;
    }
  tg = gmtime (&tl);
  tg->tm_isdst = 0;
  tb = mktime (tg);
  if (tb == -1)
    {
      tg->tm_hour--;
      tb = mktime (tg);
      if (tb == -1)
	return -1; /* can't deal with output from gmtime */
      tb += 3600;
    }
  return (tl - (tb - tl));
}
#endif
#ifdef USE_NEON
#include <neon/ne_dates.h>
#else
#ifdef USE_CURL
#include <curl/curl.h>
#endif
#endif

#include <iostream>

#include "TimeConverter.h"

using std::clog;
using std::endl;
using std::string;

TimeConverter::TimeConverter()
{
}

// Inverse of gmtime().
time_t TimeConverter::timegm(struct tm *tm)
{
#ifdef HAVE_TIMEGM
	return ::timegm(tm);
#else
	return mktime_from_utc(tm);
#endif
}

/// Converts into an RFC 822 timestamp.
string TimeConverter::toTimestamp(time_t aTime, bool inGMTime)
{
	struct tm *pTimeTm = new struct tm;

	if (((inGMTime == true) &&
#ifdef HAVE_GMTIME_R
		(gmtime_r(&aTime, pTimeTm) != NULL)
#else
		((pTimeTm = gmtime(&aTime)) != NULL)
#endif
		) ||
#ifdef HAVE_LOCALTIME_R
		(localtime_r(&aTime, pTimeTm) != NULL)
#else
		((pTimeTm = localtime(&aTime)) != NULL)
#endif
		)
	{
		char timeStr[64];
		size_t formattedSize = 0;

		if (inGMTime == true)
		{
			formattedSize = strftime(timeStr, 64, "%a, %d %b %Y %H:%M:%S GMT", pTimeTm);
		}
		else
		{
			// FIXME: don't use this extension ?
#if defined(__GNU_LIBRARY__)
			// %z is a GNU extension
			formattedSize = strftime(timeStr, 64, "%a, %d %b %Y %H:%M:%S %z", pTimeTm);
#else
			formattedSize = strftime(timeStr, 64, "%a, %d %b %Y %H:%M:%S %Z", pTimeTm);
#endif
		}
		if (formattedSize > 0)
		{
			delete pTimeTm;

			return timeStr;
		}
	}
	delete pTimeTm;

	return "";
}

/// Converts from a RFC 822 timestamp.
time_t TimeConverter::fromTimestamp(const string &timestamp)
{
	if (timestamp.empty() == true)
	{
		return 0;
	}

#ifdef USE_NEON
	return ne_rfc1123_parse(timestamp.c_str());
#else
#ifdef USE_CURL
	return curl_getdate(timestamp.c_str(), NULL);
#else
	return time(NULL);
#endif
#endif
}

/// Converts to a YYYYMMDD-formatted string.
string TimeConverter::toYYYYMMDDString(int year, int month, int day)
{
	char dateStr[64];

	if (year < 0)
	{
		year = 0;
	}
	else if (year > 9999)
	{
		year = 9999;
	}
	if (month < 1)
	{
		month = 1;
	}
	else if (month > 12)
	{
		month = 12;
	}
	if (day < 1)
	{
		day = 1;
	}
	else if (day > 31)
	{
		day = 31;
	}

	if (snprintf(dateStr, 63, "%04d%02d%02d", year, month, day) > 0)
	{
		return dateStr;
	}

	return "";
}

/// Converts from a YYYYMMDD-formatted string.
time_t TimeConverter::fromYYYYMMDDString(const string &yyyymmdd, bool inGMTime)
{
	struct tm timeTm;
	time_t gmTime = 0;

	// Initialize the structure
	timeTm.tm_sec = timeTm.tm_min = timeTm.tm_hour = timeTm.tm_mday = 0;
	timeTm.tm_mon = timeTm.tm_year = timeTm.tm_wday = timeTm.tm_yday = timeTm.tm_isdst = 0;

#ifdef HAVE_STRPTIME
	strptime(yyyymmdd.c_str(), "%Y%m%d", &timeTm);
#else
	timeTm.tm_year = atoi(yyyymmdd.substr(0, 4).c_str());
	timeTm.tm_mon = atoi(yyyymmdd.substr(4, 2).c_str());
	timeTm.tm_mday = atoi(yyyymmdd.substr(6, 2).c_str());
#endif
#ifdef DEBUG
	clog << "TimeConverter::fromYYYYMMDDString: " << timeTm.tm_year << " " << timeTm.tm_mon << " " << timeTm.tm_mday << endl;
#endif
	if (inGMTime == true)
	{
		gmTime = timegm(&timeTm);
	}
	else
	{
		gmTime = mktime(&timeTm);
	}

	return gmTime;
}

/// Converts to a HHMMSS-formatted string.
string TimeConverter::toHHMMSSString(int hours, int minutes, int seconds)
{
	char timeStr[64];

	if (hours < 0)
	{
		hours = 0;
	}
	else if (hours > 23)
	{
		hours = 23;
	}
	if (minutes < 0)
	{
		minutes = 0;
	}
	else if (minutes > 59)
	{
		minutes = 59;
	}
	if (seconds < 0)
	{
		seconds = 0;
	}
	else if (seconds > 59)
	{
		seconds = 59;
	}

	if (snprintf(timeStr, 63, "%02d%02d%02d", hours, minutes, seconds) > 0)
	{
		return timeStr;
	}

	return "";
}

/// Converts from a HHMMSS-formatted string.
time_t TimeConverter::fromHHMMSSString(const string &hhmmss, bool inGMTime)
{
	struct tm timeTm;
	time_t gmTime = 0;

	// Initialize the structure
	timeTm.tm_sec = timeTm.tm_min = timeTm.tm_hour = timeTm.tm_mday = 0;
	timeTm.tm_mon = timeTm.tm_year = timeTm.tm_wday = timeTm.tm_yday = timeTm.tm_isdst = 0;

#ifdef HAVE_STRPTIME
	strptime(hhmmss.c_str(), "%H%M%S", &timeTm);
#else
	timeTm.tm_hour = atoi(hhmmss.substr(0, 2).c_str());
	timeTm.tm_min = atoi(hhmmss.substr(2, 2).c_str());
	timeTm.tm_sec = atoi(hhmmss.substr(4, 2).c_str());
#endif
#ifdef DEBUG
	clog << "TimeConverter::fromHHMMSSString: " << timeTm.tm_hour << " " << timeTm.tm_min << " " << timeTm.tm_sec << endl;
#endif
	if (inGMTime == true)
	{
		gmTime = timegm(&timeTm);
	}
	else
	{
		gmTime = mktime(&timeTm);
	}

	return gmTime;
}

string TimeConverter::toNormalDate(time_t aTime, DateFormat format)
{
	struct tm *pTimeTm = new struct tm;

	if (
#ifdef HAVE_LOCALTIME_R
		(localtime_r(&aTime, pTimeTm) != NULL)
#else
		((pTimeTm = localtime(&aTime)) != NULL)
#endif
		)
	{
		char timeStr[64];
		size_t formattedSize = 0;

		if (format == DATE_EUROPE)
		{
			// FIXME: don't use this extension ?
#if defined(__GNU_LIBRARY__)
			// %z is a GNU extension
			formattedSize = strftime(timeStr, 64, "%A, %d %B %Y %H:%M:%S %z", pTimeTm);
#else
			formattedSize = strftime(timeStr, 64, "%A, %d %B %Y %H:%M:%S %Z", pTimeTm);
#endif
		}
		else
		{
			// FIXME: don't use this extension ?
#if defined(__GNU_LIBRARY__)
			// %z is a GNU extension
			formattedSize = strftime(timeStr, 64, "%Y-%m-%d %a %H:%M:%S %z", pTimeTm);
#else
			formattedSize = strftime(timeStr, 64, "%Y-%m-%d %a %H:%M:%S %Z", pTimeTm);
#endif
		}
		if (formattedSize > 0)
		{
			delete pTimeTm;

			return timeStr;
		}
	}
	delete pTimeTm;

	return "";
}