/*
 * Copyright 2006-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.batch.core.configuration.support;

import java.util.ArrayList;
import java.util.Collection;

import org.springframework.batch.core.Job;
import org.springframework.batch.core.configuration.DuplicateJobException;
import org.springframework.batch.core.configuration.JobRegistry;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.Lifecycle;
import org.springframework.context.SmartLifecycle;
import org.springframework.context.event.ApplicationContextEvent;
import org.springframework.core.Ordered;
import org.springframework.util.Assert;

/**
 * Loads and unloads {@link Job Jobs} when the application context is created and destroyed. Each resource provided is
 * loaded as an application context with the current context as its parent, and then all the jobs from the child context
 * are registered under their bean names. A {@link JobRegistry} is required.
 *
 * @author Lucas Ward
 * @author Dave Syer
 * @author Mahmoud Ben Hassine
 *
 * @since 2.1
 */
public class AutomaticJobRegistrar implements Ordered, SmartLifecycle, ApplicationContextAware,
                InitializingBean {

        private Collection<ApplicationContextFactory> applicationContextFactories = new ArrayList<ApplicationContextFactory>();

        private JobLoader jobLoader;

        private ApplicationContext applicationContext;

        private volatile boolean running = false;

        private int phase = Integer.MIN_VALUE + 1000;

        private boolean autoStartup = true;

        private Object lifecycleMonitor = new Object();

        private int order = Ordered.LOWEST_PRECEDENCE;

        /**
         * The enclosing application context, which can be used to check if {@link ApplicationContextEvent events} come
         * from the expected source.
         *
         * @param applicationContext the enclosing application context if there is one
         * @see ApplicationContextAware#setApplicationContext(ApplicationContext)
         */
        @Override
        public void setApplicationContext(ApplicationContext applicationContext) {
                this.applicationContext = applicationContext;
        }

        /**
         * Add some factories to the set that will be used to load contexts and jobs.
         *
         * @param applicationContextFactory the {@link ApplicationContextFactory} values to use
         */
        public void addApplicationContextFactory(ApplicationContextFactory applicationContextFactory) {
                if (applicationContextFactory instanceof ApplicationContextAware) {
                        ((ApplicationContextAware) applicationContextFactory).setApplicationContext(applicationContext);
                }
                this.applicationContextFactories.add(applicationContextFactory);
        }

        /**
         * Add some factories to the set that will be used to load contexts and jobs.
         *
         * @param applicationContextFactories the {@link ApplicationContextFactory} values to use
         */
        public void setApplicationContextFactories(ApplicationContextFactory[] applicationContextFactories) {
                for (ApplicationContextFactory applicationContextFactory : applicationContextFactories) {
                        this.applicationContextFactories.add(applicationContextFactory);
                }
        }

        /**
         * The job loader that will be used to load and manage jobs.
         *
         * @param jobLoader the {@link JobLoader} to set
         */
        public void setJobLoader(JobLoader jobLoader) {
                this.jobLoader = jobLoader;
        }

        @Override
        public int getOrder() {
                return order;
        }

        /**
         * The order to start up and shutdown.
         * @param order the order (default {@link Ordered#LOWEST_PRECEDENCE}).
         * @see Ordered
         */
        public void setOrder(int order) {
                this.order = order;
        }

        /**
         */
        @Override
        public void afterPropertiesSet() {

                Assert.state(jobLoader != null, "A JobLoader must be provided");

        }

        /**
         * Delegates to {@link JobLoader#clear()}.
         *
         * @see Lifecycle#stop()
         */
        @Override
        public void stop() {
                synchronized (this.lifecycleMonitor) {
                        jobLoader.clear();
                        running = false;
                }
        }

        /**
         * Take all the contexts from the factories provided and pass them to the {@link JobLoader}.
         *
         * @see Lifecycle#start()
         */
        @Override
        public void start() {
                synchronized (this.lifecycleMonitor) {
                        if (running) {
                                return;
                        }
                        for (ApplicationContextFactory factory : applicationContextFactories) {
                                try {
                                        jobLoader.load(factory);
                                }
                                catch (DuplicateJobException e) {
                                        throw new IllegalStateException(e);
                                }
                        }
                        running = true;
                }
        }

        /**
         * Check if this component has been started.
         *
         * @return true if started successfully and not stopped
         * @see Lifecycle#isRunning()
         */
        @Override
        public boolean isRunning() {
                synchronized (this.lifecycleMonitor) {
                        return running;
                }
        }

        @Override
        public boolean isAutoStartup() {
                return autoStartup;
        }

        /**
         * @param autoStartup true for auto start.
         * @see #isAutoStartup()
         */
        public void setAutoStartup(boolean autoStartup) {
                this.autoStartup = autoStartup;
        }

        @Override
        public int getPhase() {
                return phase;
        }

        /**
         * @param phase the phase.
         * @see #getPhase()
         */
        public void setPhase(int phase) {
                this.phase = phase;
        }

        @Override
        public void stop(Runnable callback) {
                stop();
                callback.run();
        }

}