/*
  This file is part of KOrganizer.
  Copyright (c) 2002 Cornelius Schumacher <schumacher@kde.org>
  Copyright (C) 2003-2004 Reinhold Kainhofer <reinhold@kainhofer.com>

  Copyright (C) 2010 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.net>
  Author: Sergio Martins <sergio@kdab.com>

  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.,
  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

  As a special exception, permission is given to link this program
  with any edition of Qt, and distribute the resulting executable,
  without including the source code for Qt in the source distribution.
*/

#include "datenavigator.h"
#include "koglobals.h"

#include <kcalendarsystem.h>
#include <kdebug.h>
#include <kglobal.h>
#include <klocale.h>

using namespace KCalCore;

DateNavigator::DateNavigator( QObject *parent ) : QObject( parent )
{
  mSelectedDates.append( QDate::currentDate() );
}

DateNavigator::~DateNavigator()
{
}

DateList DateNavigator::selectedDates()
{
  return mSelectedDates;
}

int DateNavigator::datesCount() const
{
  return mSelectedDates.count();
}

void DateNavigator::selectDates( const DateList &dateList, const QDate &preferredMonth )
{
  if ( dateList.count() > 0 ) {
    mSelectedDates = dateList;
    emitSelected( preferredMonth );
  }
}

void DateNavigator::selectDate( const QDate &date )
{
  QDate d = date;

  if ( !d.isValid() ) {
    kDebug() << "an invalid date was passed as a parameter!";
    d = QDate::currentDate();
  }
  mSelectedDates.clear();
  mSelectedDates.append( d );

  emitSelected();
}

void DateNavigator::selectDates( int count )
{
  count = qMin( count, static_cast<int>( MAX_SELECTABLE_DAYS ) );
  selectDates( mSelectedDates.first(), count );
}

void DateNavigator::selectDates( const QDate &d, int count,
                                 const QDate &preferredMonth )
{
  DateList dates;

  int i;
  for ( i = 0; i < count; ++i ) {
    dates.append( d.addDays( i ) );
  }

  mSelectedDates = dates;
  emitSelected( preferredMonth );
}

void DateNavigator::selectWeekByDay( int weekDay, const QDate &d, const QDate &preferredMonth )
{
  int dateCount = mSelectedDates.count();
  bool weekStart = ( weekDay == KGlobal::locale()->weekStartDay() );
  if ( weekStart && dateCount == 7 ) {
    selectWeek( d, preferredMonth );
  } else {
    selectDates( d, dateCount, preferredMonth );
  }
}

void DateNavigator::selectWeek()
{
  selectWeek( mSelectedDates.first() );
}

void DateNavigator::selectWeek( const QDate &d, const QDate &preferredMonth )
{
  const int dayOfWeek = KOGlobals::self()->calendarSystem()->dayOfWeek( d );
  const int weekStart = KGlobal::locale()->weekStartDay();

  QDate firstDate = d.addDays( weekStart - dayOfWeek );

  if ( weekStart != 1 && dayOfWeek < weekStart ) {
    firstDate = firstDate.addDays( -7 );
  }

  selectDates( firstDate, 7, preferredMonth );
}

void DateNavigator::selectWorkWeek()
{
  selectWorkWeek( mSelectedDates.first() );
}

void DateNavigator::selectWorkWeek( const QDate &d )
{
  const int weekStart = KGlobal::locale()->weekStartDay();
  const int dayOfWeek = KOGlobals::self()->calendarSystem()->dayOfWeek( d );
  QDate currentDate = d.addDays( weekStart - dayOfWeek );

  if ( weekStart != 1 && dayOfWeek < weekStart ) {
    currentDate = currentDate.addDays( -7 );
  }

  mSelectedDates.clear();
  const int mask = KOGlobals::self()->getWorkWeekMask();

  for ( int i = 0; i < 7; ++i ) {
    if ( ( 1 << ( ( i + weekStart + 6 ) % 7 ) ) & (mask) ) {
      mSelectedDates.append( currentDate.addDays( i ) );
    }
  }

  emitSelected();
}

void DateNavigator::selectToday()
{
  QDate d = QDate::currentDate();

  int dateCount = mSelectedDates.count();

  if ( dateCount == 7 ) {
    selectWeek( d );
  } else if ( dateCount == 5 ) {
    selectWorkWeek( d );
  } else {
    selectDates( d, dateCount );
  }
}

void DateNavigator::selectPreviousYear()
{
  QDate firstSelected = mSelectedDates.first();
  int weekDay = firstSelected.dayOfWeek();
  firstSelected = KOGlobals::self()->calendarSystem()->addYears( firstSelected, -1 );

  selectWeekByDay( weekDay, firstSelected );
}

void DateNavigator::selectPreviousMonth( const QDate &currentMonth,
                                         const QDate &selectionLowerLimit,
                                         const QDate &selectionUpperLimit )
{
  shiftMonth( currentMonth,
              selectionLowerLimit,
              selectionUpperLimit,
              -1 );
}

void DateNavigator::selectPreviousWeek()
{
  QDate firstSelected = mSelectedDates.first();
  const int weekDay = firstSelected.dayOfWeek();
  firstSelected = KOGlobals::self()->calendarSystem()->addDays( firstSelected, -7 );

  selectWeekByDay( weekDay, firstSelected );
}

void DateNavigator::selectNextWeek()
{
  QDate firstSelected = mSelectedDates.first();
  const int weekDay = firstSelected.dayOfWeek();

  firstSelected = KOGlobals::self()->calendarSystem()->addDays( firstSelected, 7 );

  selectWeekByDay( weekDay, firstSelected );
}

void DateNavigator::shiftMonth( const QDate &currentMonth,
                                const QDate &selectionLowerLimit,
                                const QDate &selectionUpperLimit,
                                int offset )
{
  const KCalendarSystem *calSys = KOGlobals::self()->calendarSystem();

  QDate firstSelected = mSelectedDates.first();
  const int weekDay = firstSelected.dayOfWeek();
  firstSelected = calSys->addMonths( firstSelected, offset );

  /* Don't trust firstSelected to calculate the nextMonth. firstSelected
     can belong to a month other than currentMonth because KDateNavigator
     displays 7*6 days. firstSelected should only be used for selection
     purposes */
  const QDate nextMonth = currentMonth.isValid() ?
                          calSys->addMonths( currentMonth, offset ) : firstSelected;

  /* When firstSelected doesn't belong to currentMonth it can happen
     that the new selection won't be visible on our KDateNavigators
     so we must adjust it */
  if ( selectionLowerLimit.isValid() &&
       firstSelected < selectionLowerLimit ) {
    firstSelected = selectionLowerLimit;
  } else if ( selectionUpperLimit.isValid() &&
              firstSelected > selectionUpperLimit ) {
    firstSelected = selectionUpperLimit.addDays( -6 );
  }

  selectWeekByDay( weekDay, firstSelected, nextMonth );
}

void DateNavigator::selectNextMonth( const QDate &currentMonth,
                                     const QDate &selectionLowerLimit,
                                     const QDate &selectionUpperLimit )
{
  shiftMonth( currentMonth,
              selectionLowerLimit,
              selectionUpperLimit,
              1 );
}

void DateNavigator::selectNextYear()
{
  QDate firstSelected = mSelectedDates.first();
  int weekDay = firstSelected.dayOfWeek();
  firstSelected = KOGlobals::self()->calendarSystem()->addYears( firstSelected, 1 );

  selectWeekByDay( weekDay, firstSelected );
}

void DateNavigator::selectPrevious()
{
  int offset = -7;
  if ( datesCount() == 1 ) {
    offset = -1;
  }

  selectDates( mSelectedDates.first().addDays( offset ), datesCount() );
}

void DateNavigator::selectNext()
{
  int offset = 7;
  if ( datesCount() == 1 ) {
    offset = 1;
  }

  selectDates( mSelectedDates.first().addDays( offset ), datesCount() );
}

void DateNavigator::selectMonth( int month )
{
  const KCalendarSystem *calSys = KOGlobals::self()->calendarSystem();

  // always display starting at the first week of the specified month
  QDate firstSelected = QDate( mSelectedDates.first().year(), month, 1 );

  int day = calSys->day( firstSelected );
  calSys->setDate( firstSelected, calSys->year( firstSelected ), month, 1 );
  int days = calSys->daysInMonth( firstSelected );
  // As day we use either the selected date, or if the month has less days
  // than that, we use the max day of that month
  if ( day > days ) {
    day = days;
  }
  QDate requestedMonth;
  calSys->setDate( firstSelected, calSys->year( firstSelected ), month, day );
  calSys->setDate( requestedMonth, calSys->year( firstSelected ), month, 1 );

  selectWeekByDay( 1, firstSelected, requestedMonth );
}

void DateNavigator::selectYear( int year )
{
  QDate firstSelected = mSelectedDates.first();
  const int deltaYear = year - KOGlobals::self()->calendarSystem()->year( firstSelected );
  firstSelected = KOGlobals::self()->calendarSystem()->addYears( firstSelected, deltaYear );

  const int weekDay = firstSelected.dayOfWeek();
  selectWeekByDay( weekDay, firstSelected );
}

void DateNavigator::emitSelected( const QDate &preferredMonth )
{
  emit datesSelected( mSelectedDates, preferredMonth );
}

#include "datenavigator.moc"
