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/*
 * -----------------------------------------------------------------------
 * Copyright © 2013-2015 Meno Hochschild, 
 * -----------------------------------------------------------------------
 * This file (DateOperator.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;

import net.time4j.engine.ChronoElement;
import net.time4j.engine.ChronoEntity;
import net.time4j.engine.ChronoOperator;
import net.time4j.engine.StdOperator;


/**
 * Definiert eine Manipulation von Datumsobjekten nach
 * dem Strategy-Entwurfsmuster. 
 *
 * @author      Meno Hochschild
 * @doctags.concurrency {immutable}
 */
final class DateOperator
    extends ElementOperator {

    //~ Instanzvariablen --------------------------------------------------

    private final Object opDelegate;

    //~ Konstruktoren -----------------------------------------------------

    /**
     * Konstruiert eine neue Instanz. 
     *
     * @param   element         element an operator will be applied on
     * @param   type            type of operator
     */
    DateOperator(
        ChronoElement element,
        int type
    ) {
        this(element, type, null);

    }

    /**
     * Konstruiert eine neue Instanz. 
     *
     * @param   element         element an operator will be applied on
     * @param   type            operator type
     * @param   value           lenient or new value of element
     */
    DateOperator(
        ChronoElement element,
        int type,
        Object value // optional
    ) {
        super(element, type);

        switch (type) {
            case OP_NEW_VALUE:
                this.opDelegate = newValue(element, value);
                break;
            case OP_MINIMIZE:
                this.opDelegate = StdOperator.minimized(element);
                break;
            case OP_MAXIMIZE:
                this.opDelegate = StdOperator.maximized(element);
                break;
            case OP_DECREMENT:
                this.opDelegate = StdOperator.decremented(element);
                break;
            case OP_INCREMENT:
                this.opDelegate = StdOperator.incremented(element);
                break;
            case OP_FLOOR:
                this.opDelegate = StdOperator.atFloor(element);
                break;
            case OP_CEILING:
                this.opDelegate = StdOperator.atCeiling(element);
                break;
            case OP_LENIENT:
                this.opDelegate = lenient(element, value);
                break;
            default:
                throw new AssertionError("Unknown: " + this.getType());
        }

    }

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

    @Override
    @SuppressWarnings("unchecked")
    public PlainDate apply(PlainDate entity) {

        ChronoOperator operator = (ChronoOperator) this.opDelegate;
        return operator.apply(entity);

    }

    @Override
    @SuppressWarnings("unchecked")
    ChronoOperator onTimestamp() {

        return (ChronoOperator) this.opDelegate;

    }

    private static > Object newValue(
        ChronoElement element,
        Object value
    ) {

        V v = element.getType().cast(value);
        ChronoOperator operator = StdOperator.newValue(v, element);
        return ValueOperator.of(operator, value);

    }

    private static > Object lenient(
        ChronoElement element,
        Object value
    ) {

        V v = element.getType().cast(value);
        ChronoOperator operator = StdOperator.setLenient(v, element);
        return ValueOperator.of(operator, value);

    }

}