/*
 * Copyright (c) 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Nuxeo - initial API and implementation
 *
 * $Id$
 */

package org.eclipse.ecr.core.lifecycle.event;

import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.eclipse.ecr.core.NXCore;
import org.eclipse.ecr.core.api.ClientException;
import org.eclipse.ecr.core.api.CoreSession;
import org.eclipse.ecr.core.api.DocumentModel;
import org.eclipse.ecr.core.api.DocumentModelList;
import org.eclipse.ecr.core.api.LifeCycleConstants;
import org.eclipse.ecr.core.event.Event;
import org.eclipse.ecr.core.event.EventBundle;
import org.eclipse.ecr.core.event.EventContext;
import org.eclipse.ecr.core.event.PostCommitEventListener;
import org.eclipse.ecr.core.event.impl.DocumentEventContext;

/**
 * Listener for life cycle change events.
 * <p>
 * If event occurs on a folder, it will recurse on children to perform the same
 * transition if possible.
 * <p>
 * If the transition event is about marking documents as "deleted", and a child
 * cannot perform the transition, it will be removed.
 * <p>
 * Undelete transitions are not processed, but this listener instead looks for a
 * specific documentUndeleted event. This is because we want to undelete
 * documents (parents) under which we don't want to recurse.
 */
public class BulkLifeCycleChangeListener implements PostCommitEventListener {

    private static final Log log = LogFactory.getLog(BulkLifeCycleChangeListener.class);

    @Override
    public void handleEvent(EventBundle events) throws ClientException {
        if (!events.containsEventName(LifeCycleConstants.TRANSITION_EVENT)
                && !events.containsEventName(LifeCycleConstants.DOCUMENT_UNDELETED)) {
            return;
        }
        for (Event event : events) {
            String name = event.getName();
            if (LifeCycleConstants.TRANSITION_EVENT.equals(name)
                    || LifeCycleConstants.DOCUMENT_UNDELETED.equals(name)) {
                processTransition(event);
            }
        }
    }

    protected void processTransition(Event event) {
        log.debug("Processing lifecycle change in async listener");
        EventContext ctx = event.getContext();
        if (!(ctx instanceof DocumentEventContext)) {
            return;
        }
        DocumentEventContext docCtx = (DocumentEventContext) ctx;
        DocumentModel doc = docCtx.getSourceDocument();
        if (!doc.isFolder()) {
            return;
        }
        CoreSession session = docCtx.getCoreSession();
        if (session == null) {
            log.error("Can not process lifeCycle change since session is null");
            return;
        }
        String transition;
        String targetState;
        if (LifeCycleConstants.TRANSITION_EVENT.equals(event.getName())) {
            transition = (String) docCtx.getProperty(LifeCycleConstants.TRANSTION_EVENT_OPTION_TRANSITION);
            if (isNonRecursiveTransition(transition, doc.getType())) {
                // transition should not recurse into children
                return;
            }
            if (LifeCycleConstants.UNDELETE_TRANSITION.equals(transition)) {
                // not processed (as we can undelete also parents)
                // a specific event documentUndeleted will be used instead
                return;
            }
            targetState = (String) docCtx.getProperty(LifeCycleConstants.TRANSTION_EVENT_OPTION_TO);
        } else { // LifeCycleConstants.DOCUMENT_UNDELETED
            transition = LifeCycleConstants.UNDELETE_TRANSITION;
            targetState = ""; // unused
        }
        try {
            DocumentModelList docs = session.getChildren(doc.getRef());
            changeDocumentsState(session, docs, transition, targetState);
            session.save();
        } catch (ClientException e) {
            log.error("Unable to get children", e);
            return;
        }
    }

    protected boolean isNonRecursiveTransition(String transition, String type) {
        List<String> nonRecursiveTransitions = NXCore.getLifeCycleService().getNonRecursiveTransitionForDocType(
                type);
        return nonRecursiveTransitions.contains(transition);
    }

    // change doc state and recurse in children
    protected void changeDocumentsState(CoreSession documentManager,
            DocumentModelList docModelList, String transition,
            String targetState) throws ClientException {
        for (DocumentModel docMod : docModelList) {
            boolean removed = false;
            if (docMod.getCurrentLifeCycleState() == null) {
                if (LifeCycleConstants.DELETED_STATE.equals(targetState)) {
                    log.debug("Doc has no lifecycle, deleting ...");
                    documentManager.removeDocument(docMod.getRef());
                    removed = true;
                }
            } else if (docMod.getAllowedStateTransitions().contains(transition)) {
                docMod.followTransition(transition);
            } else {
                if (targetState.equals(docMod.getCurrentLifeCycleState())) {
                    log.debug("Document" + docMod.getRef()
                            + " is already in the target LifeCycle state");
                } else if (LifeCycleConstants.DELETED_STATE.equals(targetState)) {
                    log.debug("Impossible to change state of "
                            + docMod.getRef() + " :removing");
                    documentManager.removeDocument(docMod.getRef());
                    removed = true;
                } else {
                    log.debug("Document"
                            + docMod.getRef()
                            + " has no transition to the target LifeCycle state");
                }
            }
            if (docMod.isFolder() && !removed) {
                changeDocumentsState(documentManager,
                        documentManager.getChildren(docMod.getRef()),
                        transition, targetState);
            }
        }
    }

}