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/*
 * -----------------------------------------------------------------------
 * Copyright © 2013-2017 Meno Hochschild, 
 * -----------------------------------------------------------------------
 * This file (TransitionStrategy.java) is part of project Time4J.
 *
 * Time4J is free software: You can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * Time4J 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Time4J. If not, see .
 * -----------------------------------------------------------------------
 */

package net.time4j.tz;

import net.time4j.base.GregorianDate;
import net.time4j.base.WallTime;


/**
 * Serves for resolving of local timestamps to a global UNIX timestamp,
 * escpecially if there are conflicts due to gaps or overlaps on the local
 * timeline. 
 *
 * @author  Meno Hochschild
 * @doctags.spec    All implementations must be immutable, thread-safe and serializable.
 */
/*[deutsch]
 * Dient der Auflösung von lokalen Zeitangaben zu einer UTC-Weltzeit,
 * wenn wegen Lücken oder Überlappungen auf dem lokalen Zeitstrahl
 * Konflikte auftreten. 
 *
 * @author  Meno Hochschild
 * @doctags.spec    All implementations must be immutable, thread-safe and serializable.
 */
public interface TransitionStrategy {

    //~ Methoden ----------------------------------------------------------

    /**
     * Calculates a suitable global timestamp for given local timestamp. 
     *
     * The nanosecond fraction of given wall time will not be taken
     * into account. 
     *
     * @param   localDate   local calendar date in given timezone
     * @param   localTime   local wall time in given timezone
     * @param   timezone    timezone data containing offset history
     * @return  global timestamp as full seconds since UNIX epoch (posix time)
     * @since   1.2.1
     * @see     net.time4j.scale.TimeScale#POSIX
     * @see     net.time4j.PlainTimestamp#in(Timezone)
     * @see     Timezone#with(TransitionStrategy)
     */
    /*[deutsch]
     * Bestimmt einen geeigneten globalen Zeitstempel für eine
     * lokale Zeitangabe. 
     *
     * Der Nanosekundenteil der angegebenen Uhrzeit bleibt
     * unberücksichtigt. 
     *
     * @param   localDate   local calendar date in given timezone
     * @param   localTime   local wall time in given timezone
     * @param   timezone    timezone data containing offset history
     * @return  global timestamp as full seconds since UNIX epoch (posix time)
     * @since   1.2.1
     * @see     net.time4j.scale.TimeScale#POSIX
     * @see     net.time4j.PlainTimestamp#in(Timezone)
     * @see     Timezone#with(TransitionStrategy)
     */
    long resolve(
        GregorianDate localDate,
        WallTime localTime,
        Timezone timezone
    );

    /**
     * Calculates a suitable offset for given local timestamp. 
     *
     * @param   localDate   local calendar date in given timezone
     * @param   localTime   local wall time in given timezone
     * @param   timezone    timezone data containing offset history
     * @return  ZonalOffset
     * @since   1.2.1
     * @see     net.time4j.PlainTimestamp#in(Timezone)
     * @see     Timezone#with(TransitionStrategy)
     */
    /*[deutsch]
     * Bestimmt einen geeigneten Offset für eine lokale Zeitangabe. 
     *
     * @param   localDate   local calendar date in given timezone
     * @param   localTime   local wall time in given timezone
     * @param   timezone    timezone data containing offset history
     * @return  ZonalOffset
     * @since   1.2.1
     * @see     net.time4j.PlainTimestamp#in(Timezone)
     * @see     Timezone#with(TransitionStrategy)
     */
    ZonalOffset getOffset(
        GregorianDate localDate,
        WallTime localTime,
        Timezone timezone
    );

    /**
     * Tries to change the overlap handling. 
     *
     * The default implementation does nothing. 
     *
     * @param   resolver    strategy how to handle ambivalent mappings during an offset overlap
     * @return  possibly adjusted transition strategy
     * @since   3.32/4.27
     */
    /*[deutsch]
     * Versucht, die Übergangsstrategie für Überlappungen auf dem lokalen Zeitstrahl
     * zu ändern. 
     *
     * Die Standardimplementierung macht nichts. 
     *
     * @param   resolver    strategy how to handle ambivalent mappings during an offset overlap
     * @return  possibly adjusted transition strategy
     * @since   3.32/4.27
     */
    default TransitionStrategy using(OverlapResolver resolver) {
        return this;
    }

}