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/* ====================================================================
 * 
 * The ObjectStyle Group Software License, version 1.1
 * ObjectStyle Group - http://objectstyle.org/
 * 
 * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
 * of the software. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 
 * 3. The end-user documentation included with the redistribution, if any,
 *    must include the following acknowlegement:
 *    "This product includes software developed by independent contributors
 *    and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 * 
 * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
 *    or promote products derived from this software without prior written
 *    permission. For written permission, email
 *    "andrus at objectstyle dot org".
 * 
 * 5. Products derived from this software may not be called "ObjectStyle"
 *    or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
 *    names without prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE OBJECTSTYLE GROUP OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 * 
 * This software consists of voluntary contributions made by many
 * individuals and hosted on ObjectStyle Group web site.  For more
 * information on the ObjectStyle Group, please see
 * .
 */
package org.objectstyle.cayenne.access;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.objectstyle.cayenne.DataObject;
import org.objectstyle.cayenne.ObjectId;
import org.objectstyle.cayenne.PersistenceState;
import org.objectstyle.cayenne.Persistent;
import org.objectstyle.cayenne.graph.CompoundDiff;
import org.objectstyle.cayenne.graph.GraphChangeHandler;
import org.objectstyle.cayenne.graph.GraphDiff;
import org.objectstyle.cayenne.validation.ValidationException;
import org.objectstyle.cayenne.validation.ValidationResult;

/**
 * A GraphDiff facade for the ObjectStore changes. Provides a way for the lower layers of
 * the access stack to speed up processing of presorted ObjectStore diffs.
 * 
 * @author Andrus Adamchik
 * @since 1.2
 */
class ObjectStoreGraphDiff implements GraphDiff {

    private ObjectStore objectStore;
    private GraphDiff resolvedDiff;

    ObjectStoreGraphDiff(ObjectStore objectStore) {
        this.objectStore = objectStore;
        preprocess(objectStore);
    }

    Map getChangesByObjectId() {
        return objectStore.getChangesByObjectId();
    }

    /**
     * Requires external synchronization on ObjectStore.
     */
    boolean validateAndCheckNoop() {
        if (getChangesByObjectId().isEmpty()) {
            return true;
        }

        ValidationResult result = new ValidationResult();
        boolean noop = true;

        Iterator it = getChangesByObjectId().entrySet().iterator();
        while (it.hasNext()) {

            Map.Entry entry = (Map.Entry) it.next();

            if (!((ObjectDiff) entry.getValue()).isNoop()) {

                noop = false;

                // accessing objectMap directly to avoid unneeded synchronization.
                DataObject object = (DataObject) objectStore.getNodeNoSync(entry.getKey());
                switch (object.getPersistenceState()) {
                    case PersistenceState.NEW:
                        object.validateForInsert(result);
                        break;
                    case PersistenceState.MODIFIED:
                        object.validateForUpdate(result);
                        break;
                    case PersistenceState.DELETED:
                        object.validateForDelete(result);
                        break;
                }
            }
        }

        if (result.hasFailures()) {
            throw new ValidationException(result);
        }

        return noop;
    }

    public boolean isNoop() {
        if (getChangesByObjectId().isEmpty()) {
            return true;
        }

        Iterator it = getChangesByObjectId().values().iterator();
        while (it.hasNext()) {
            if (!((ObjectDiff) it.next()).isNoop()) {
                return false;
            }
        }

        return true;
    }

    public void apply(GraphChangeHandler handler) {
        resolveDiff();
        resolvedDiff.apply(handler);
    }

    public void undo(GraphChangeHandler handler) {
        resolveDiff();
        resolvedDiff.undo(handler);
    }

    /**
     * Converts diffs organized by ObjectId in a collection of diffs sorted by diffId
     * (same as creation order).
     */
    private void resolveDiff() {
        if (resolvedDiff == null) {

            CompoundDiff diff = new CompoundDiff();
            Map changes = getChangesByObjectId();

            if (!changes.isEmpty()) {
                List allChanges = new ArrayList(changes.size() * 2);

                Iterator it = changes.values().iterator();
                while (it.hasNext()) {
                    ((ObjectDiff) it.next()).appendDiffs(allChanges);
                }

                Collections.sort(allChanges);
                diff.addAll(allChanges);
            }

            this.resolvedDiff = diff;
        }
    }

    private void preprocess(ObjectStore objectStore) {

        Map changes = getChangesByObjectId();
        if (!changes.isEmpty()) {

            Iterator it = changes.entrySet().iterator();
            while (it.hasNext()) {
                Map.Entry entry = (Map.Entry) it.next();

                ObjectId id = (ObjectId) entry.getKey();

                Persistent object = (Persistent) objectStore.getNode(id);

                // address manual id override.
                ObjectId objectId = object.getObjectId();
                if (!id.equals(objectId)) {

                    if (objectId != null) {
                        Map replacement = id.getReplacementIdMap();
                        replacement.clear();
                        replacement.putAll(objectId.getIdSnapshot());
                    }

                    object.setObjectId(id);
                }
            }
        }
    }
}