/*
    This file is part of the kcal library.

    Copyright (c) 2001-2003 Cornelius Schumacher <schumacher@kde.org>

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

    This library 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
*/
/**
  @file
  This file is part of the API for handling calendar data and
  defines the Period class.

  @brief
  Represents a period of time.

  @author Cornelius Schumacher \<schumacher@kde.org\>
*/

#ifndef KCAL_PERIOD_H
#define KCAL_PERIOD_H

#include "kcal_export.h"
#include "duration.h"

#include <kdatetime.h>
#include <QtCore/QList>

namespace KCal {

/**
  The period can be defined by either a start time and an end time or
  by a start time and a duration.
*/
class KCAL_EXPORT Period
{
  public:
   /**
      List of periods.
    */
    typedef QList<Period> List;

    /**
      Constructs a period without a duration.
    */
    Period();

    /**
      Constructs a period from @p start to @p end.

      @param start the time the period begins.
      @param end the time the period ends.
    */
    Period( const KDateTime &start, const KDateTime &end );

    /**
      Constructs a period from @p start and lasting @p duration.

      @param start the time when the period starts.
      @param duration how long the period lasts.
    */
    Period( const KDateTime &start, const Duration &duration );

    /**
      Constructs a period by copying another period object

      @param period the period to copy
     */

    Period( const Period &period );

    /**
      Destroys a period.
    */
    ~Period();

    /**
      Returns true if the start of this period is earlier than the start of
      the @p other one.

      @param other is the other period to compare.
    */
    bool operator<( const Period &other ) const;

    /**
      Returns true if the start of this period is later than the start of
      the @p other one.

      @param other the other period to compare
    */
    bool operator>( const Period &other ) const  { return other.operator<( *this ); }

    /**
      Returns true if this period is equal to the @p other one.
      Even if their start and end times are the same, two periods are
      considered not equal if one is defined in terms of a duration and the
      other in terms of a start and end time.

      @param other the other period to compare
    */
    bool operator==( const Period &other ) const;

    /**
      Returns true if this period is not equal to the @p other one.

      @param other the other period to compare
      @see operator==()
    */
    bool operator!=( const Period &other ) const  { return !operator==( other ); }

    /**
      Sets this period equal to the @p other one.

      @param other is the other period to compare.
    */
    Period &operator=( const Period &other );

    /**
      Returns when this period starts.
    */
    KDateTime start() const;

    /**
      Returns when this period ends.
    */
    KDateTime end() const;

    /**
      Returns the duration of the period.

      If the period is defined in terms of a start and end time, the duration
      is computed from these. In this case, if the time of day in @p start and
      @p end is equal, and their time specifications (i.e. time zone etc.) are
      the same, the duration will be set in terms of days. Otherwise, the
      duration will be set in terms of seconds.

      If the period is defined in terms of a duration, that duration is
      returned unchanged.
    */
    Duration duration() const;

    /**
      Returns the duration of the period.

      If the period is defined in terms of a start and end time, the duration
      is first computed from these.

      If @p type is Days, and the duration is not an exact number of days,
      the duration will be rounded down to the nearest whole number of days.

      @param type the unit of time to use (seconds or days)
    */
    Duration duration( Duration::Type type ) const;

    /**
      Returns true if this period has a set duration, false
      if it just has a start and an end.
    */
    bool hasDuration() const;

    /**
      Shift the times of the period so that they appear at the same clock
      time as before but in a new time zone. The shift is done from a viewing
      time zone rather than from the actual period time zone.

      For example, shifting a period whose start time is 09:00 America/New York,
      using an old viewing time zone (@p oldSpec) of Europe/London, to a new
      time zone (@p newSpec) of Europe/Paris, will result in the time being
      shifted from 14:00 (which is the London time of the period start) to
      14:00 Paris time.

      @param oldSpec the time specification which provides the clock times
      @param newSpec the new time specification
    */
    void shiftTimes( const KDateTime::Spec &oldSpec,
                     const KDateTime::Spec &newSpec );

  private:
    //@cond PRIVATE
    class Private;
    Private *const d;
    //@endcond
};

}

#endif
