/***************************************************************************
timezonerule.h - description
-------------------
begin : Tue Apr 2 2002
copyright : (C) 2002 by Jason Harris
email : kstars@30doradus.org
***************************************************************************/
/***************************************************************************
* *
* 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. *
* *
***************************************************************************/
#ifndef TIMEZONERULE_H
#define TIMEZONERULE_H
/**@class TimeZoneRule
*This class provides the information needed to determine whether Daylight
*Savings Time (DST; a.k.a. "Summer Time") is currently active at a given
*location. There are (at least) 25 different "rules" which govern DST
*around the world; a string identifying the appropriate rule is attachded
*to each city in Cities.dat.
*
*The rules themselves are stored in the TZrulebook.dat file, which is read
*on startup; each line in the file creates a TimeZoneRule object.
*
*TimeZoneRule consists of TQStrings identifying the months and days on which
*DST starts and ends, TQTime objects identifying the time at which the
*changes occur, and a double indicating the size of the offset in hours
*(probably always 1.00).
*
*Month names should be the English three-letter abbreviation, uncapitalized.
*Day names are either an integer indicating the calendar date (i.e., "15" is
*the fifteenth of the month), or a number paired with a three-letter
*abbreviation for a weekday. This indicates the Nth weekday of the month
*(i.e., "2sun" is the second Sunday of the Month). Finally, the weekday
*string on its own indicates the last weekday of the month (i.e.,
*"mon" is the last Monday of the month).
*
*The isDSTActive(KStarsDateTime) function returns true if DST is active for the
*DateTime given as an argument.
*
*The nextDSTChange(KStarsDateTime) function returns the KStarsDateTime of the moment
*at which the next DST change will occur for the current location.
*@author Jason Harris
*@version 1.0
*/
#include <tqstring.h>
#include "kstarsdatetime.h"
class TimeZoneRule {
public:
/**Default Constructor. Makes the "empty" time zone rule (i.e., no DST correction)*/
TimeZoneRule();
/**Constructor. Create a TZ rule according to the arguments.
*@p smonth the three-letter code for the month in which DST starts
*@p sday a string encoding the day on which DST starts (see the class description)
*@p stime the time at which DST starts
*@p rmonth the three-letter code for the month in which DST reverts
*@p rday a string encoding the day on which DST reverts (see the class description)
*@p rtime the time at which DST reverts
*@p offset the offset between normal time and DS time (always 1.00?)
*/
TimeZoneRule( const TQString &smonth, const TQString &sday, const TQTime &stime,
const TQString &rmonth, const TQString &rday, const TQTime &rtime, const double &offset=1.00 );
/**Destructor. (empty)*/
~TimeZoneRule();
/**Determine whether DST is in effect for the given DateTime, according to this rule
*@p date the date/time to test for DST
*/
bool isDSTActive( const KStarsDateTime &date );
/**@return TRUE if the rule is the "empty" TZ rule. */
bool isEmptyRule() { return ( HourOffset == 0.0 ); }
/** Toggle DST on/off. The @p activate argument should probably be isDSTActive()
*@param activate if TRUE, then set DST active; otherwise, deactivate DST
*/
void setDST( bool activate=true );
/**@return the current Timezone offset, compared to the timezone's Standard Time.
*This is typically 0.0 if DST is inactive, and 1.0 if DST is active. */
double deltaTZ() const { return dTZ; }
/** Recalculate next dst change and if DST is active by a given local time with
*timezone offset and time direction.
*@param ltime the time to be tested
*@param time_runs_forward time direction
*@param TZoffset offset of timezone in some fictional unit
*@param automaticDSTchange is automatic DST change?
*
* @todo Check dox for TZoffset
*/
void reset_with_ltime( KStarsDateTime <ime, const double TZoffset, const bool time_runs_forward,
const bool automaticDSTchange = false );
/**@return computed value for next DST change in universal time.
*/
KStarsDateTime nextDSTChange() { return next_change_utc; }
/**@return computed value for next DST change in local time.
*/
KStarsDateTime nextDSTChange_LTime() { return next_change_ltime; }
/**@return TRUE if this rule is the same as the argument.
*@p r the rule to check for equivalence
*/
bool equals( TimeZoneRule *r );
int StartMonth, RevertMonth;
private:
/**@return the KStarsDateTime of the moment when the next DST change will occur in local time
*This is useful because DST change times are saved in local times*/
void nextDSTChange_LTime( const KStarsDateTime &date );
/**@return the KStarsDateTime of the moment when the last DST change occurred in local time
*This is useful because DST change times are saved in local times
*We need this in case time is running backwards. */
void previousDSTChange_LTime( const KStarsDateTime &date );
/**calculate the next DST change in universal time for current location */
void nextDSTChange( const KStarsDateTime &local_date, const double TZoffset );
/**calculate the previous DST change in universal time for current location */
void previousDSTChange( const KStarsDateTime &local_date, const double TZoffset );
/**Interpret the string as a month of the year;
*@return the month integer (1=jan ... 12=dec)
*/
int initMonth( const TQString &m );
/**Interpret the day string as a week ID and a day-of-week ID. The day-of-week
*is an integer between 1 (sunday) and 7 (saturday); the week integer can
*be 1-3 (1st/2nd/third weekday of the month), or 5 (last weekday of the month)
*@p day the day integer is returned by reference through this value
*@p week the week integer is returned by reference through this value
*@return TRUE if the day string was successfully parsed
*/
bool initDay( const TQString &d, int &day, int &week );
/**Find the calendar date on which DST starts for the calendar year
*of the given KStarsDateTime.
*@p d the date containing the year to be tested
*@return the calendar date, an integer between 1 and 31. */
int findStartDay( const KStarsDateTime &d );
/**Find the calendar date on which DST ends for the calendar year
*of the given KStarsDateTime.
*@p d the date containing the year to be tested
*@return the calendar date, an integer between 1 and 31. */
int findRevertDay( const KStarsDateTime &d );
int StartDay, RevertDay;
int StartWeek, RevertWeek;
TQTime StartTime, RevertTime;
KStarsDateTime next_change_utc, next_change_ltime;
double dTZ, HourOffset;
};
#endif