/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2011, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This 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.
 *
 * This software 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 this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.jboss.as.jpa.container;

import static org.jboss.as.jpa.messages.JpaLogger.ROOT_LOGGER;

import java.util.HashMap;
import java.util.Map;

import javax.persistence.EntityManager;

/**
 * Close the non tx invocations on transaction scoped entity manager
 *
 * @author Scott Marlow
 */
public class NonTxEmCloser {

    /**
     * Each thread will have its own list of SB invocations in progress.
     * Key = scoped persistence unit name
     */
    public static final ThreadLocalStack<Map<String, EntityManager>> nonTxStack = new ThreadLocalStack<Map<String, EntityManager>>();

    /**
     * entered new session bean invocation, start new collection for tracking transactional entity managers created
     * without a JTA transaction.
     */
    public static void pushCall() {
        nonTxStack.push(null);          // to conserve memory/cpu cycles, push a null placeholder that will only get replaced
        // with a Map if we actually need it (in add() below).
    }

    /**
     * current session bean invocation is ending, close any transactional entity managers created without a JTA
     * transaction.
     */
    public static void popCall() {
        Map<String, EntityManager> emStack = nonTxStack.pop();
        if (emStack != null) {
            for (EntityManager entityManager : emStack.values()) {
                try {
                    if (entityManager.isOpen()) {
                        entityManager.close();
                    }
                } catch (RuntimeException safeToIgnore) {
                    if (ROOT_LOGGER.isTraceEnabled()) {
                        ROOT_LOGGER.trace("Could not close (non-transactional) container managed entity manager." +
                            "  This shouldn't impact application functionality (only read " +
                            "operations occur in non-transactional mode)", safeToIgnore);
                    }
                }
            }
        }
    }

    /**
     * Return the transactional entity manager for the specified scoped persistence unit name
     *
     * @param puScopedName
     * @return
     */
    public static EntityManager get(String puScopedName) {
        Map<String, EntityManager> map = nonTxStack.peek();
        if (map != null) {
            return map.get(puScopedName);
        }
        return null;
    }

    public static void add(String puScopedName, EntityManager entityManager) {
        Map<String, EntityManager> map = nonTxStack.peek();
        if (map == null && !nonTxStack.isEmpty()) {
            // replace null with a collection to hold the entity managers.
            map = new HashMap<String, EntityManager>();
            nonTxStack.pop();
            nonTxStack.push(map);    // replace top of stack (currently null) with new collection
        }
        if (map != null) {
            map.put(puScopedName, entityManager);
        }
    }
}