/*
 * Copyright 2002-2017 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.scheduling.concurrent;

import java.util.concurrent.TimeUnit;

/**
 * JavaBean that describes a scheduled executor task, consisting of the
 * {@link Runnable} and a delay plus period. The period needs to be specified;
 * there is no point in a default for it.
 *
 * <p>The {@link java.util.concurrent.ScheduledExecutorService} does not offer
 * more sophisticated scheduling options such as cron expressions.
 * Consider using {@link ThreadPoolTaskScheduler} for such needs.
 *
 * <p>Note that the {@link java.util.concurrent.ScheduledExecutorService} mechanism
 * uses a {@link Runnable} instance that is shared between repeated executions,
 * in contrast to Quartz which creates a new Job instance for each execution.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see java.util.concurrent.ScheduledExecutorService#scheduleWithFixedDelay(java.lang.Runnable, long, long, java.util.concurrent.TimeUnit)
 * @see java.util.concurrent.ScheduledExecutorService#scheduleAtFixedRate(java.lang.Runnable, long, long, java.util.concurrent.TimeUnit)
 */
public class ScheduledExecutorTask {

        private Runnable runnable;

        private long delay = 0;

        private long period = -1;

        private TimeUnit timeUnit = TimeUnit.MILLISECONDS;

        private boolean fixedRate = false;


        /**
         * Create a new ScheduledExecutorTask,
         * to be populated via bean properties.
         * @see #setDelay
         * @see #setPeriod
         * @see #setFixedRate
         */
        public ScheduledExecutorTask() {
        }

        /**
         * Create a new ScheduledExecutorTask, with default
         * one-time execution without delay.
         * @param executorTask the Runnable to schedule
         */
        public ScheduledExecutorTask(Runnable executorTask) {
                this.runnable = executorTask;
        }

        /**
         * Create a new ScheduledExecutorTask, with default
         * one-time execution with the given delay.
         * @param executorTask the Runnable to schedule
         * @param delay the delay before starting the task for the first time (ms)
         */
        public ScheduledExecutorTask(Runnable executorTask, long delay) {
                this.runnable = executorTask;
                this.delay = delay;
        }

        /**
         * Create a new ScheduledExecutorTask.
         * @param executorTask the Runnable to schedule
         * @param delay the delay before starting the task for the first time (ms)
         * @param period the period between repeated task executions (ms)
         * @param fixedRate whether to schedule as fixed-rate execution
         */
        public ScheduledExecutorTask(Runnable executorTask, long delay, long period, boolean fixedRate) {
                this.runnable = executorTask;
                this.delay = delay;
                this.period = period;
                this.fixedRate = fixedRate;
        }


        /**
         * Set the Runnable to schedule as executor task.
         */
        public void setRunnable(Runnable executorTask) {
                this.runnable = executorTask;
        }

        /**
         * Return the Runnable to schedule as executor task.
         */
        public Runnable getRunnable() {
                return this.runnable;
        }

        /**
         * Set the delay before starting the task for the first time,
         * in milliseconds. Default is 0, immediately starting the
         * task after successful scheduling.
         */
        public void setDelay(long delay) {
                this.delay = delay;
        }

        /**
         * Return the delay before starting the job for the first time.
         */
        public long getDelay() {
                return this.delay;
        }

        /**
         * Set the period between repeated task executions, in milliseconds.
         * <p>Default is -1, leading to one-time execution. In case of a positive value,
         * the task will be executed repeatedly, with the given interval in-between executions.
         * <p>Note that the semantics of the period value vary between fixed-rate and
         * fixed-delay execution.
         * <p><b>Note:</b> A period of 0 (for example as fixed delay) is <i>not</i> supported,
         * simply because {@code java.util.concurrent.ScheduledExecutorService} itself
         * does not support it. Hence a value of 0 will be treated as one-time execution;
         * however, that value should never be specified explicitly in the first place!
         * @see #setFixedRate
         * @see #isOneTimeTask()
         * @see java.util.concurrent.ScheduledExecutorService#scheduleWithFixedDelay(Runnable, long, long, java.util.concurrent.TimeUnit)
         */
        public void setPeriod(long period) {
                this.period = period;
        }

        /**
         * Return the period between repeated task executions.
         */
        public long getPeriod() {
                return this.period;
        }

        /**
         * Is this task only ever going to execute once?
         * @return {@code true} if this task is only ever going to execute once
         * @see #getPeriod()
         */
        public boolean isOneTimeTask() {
                return (this.period <= 0);
        }

        /**
         * Specify the time unit for the delay and period values.
         * Default is milliseconds ({@code TimeUnit.MILLISECONDS}).
         * @see java.util.concurrent.TimeUnit#MILLISECONDS
         * @see java.util.concurrent.TimeUnit#SECONDS
         */
        public void setTimeUnit(TimeUnit timeUnit) {
                this.timeUnit = (timeUnit != null ? timeUnit : TimeUnit.MILLISECONDS);
        }

        /**
         * Return the time unit for the delay and period values.
         */
        public TimeUnit getTimeUnit() {
                return this.timeUnit;
        }

        /**
         * Set whether to schedule as fixed-rate execution, rather than
         * fixed-delay execution. Default is "false", that is, fixed delay.
         * <p>See ScheduledExecutorService javadoc for details on those execution modes.
         * @see java.util.concurrent.ScheduledExecutorService#scheduleWithFixedDelay(java.lang.Runnable, long, long, java.util.concurrent.TimeUnit)
         * @see java.util.concurrent.ScheduledExecutorService#scheduleAtFixedRate(java.lang.Runnable, long, long, java.util.concurrent.TimeUnit)
         */
        public void setFixedRate(boolean fixedRate) {
                this.fixedRate = fixedRate;
        }

        /**
         * Return whether to schedule as fixed-rate execution.
         */
        public boolean isFixedRate() {
                return this.fixedRate;
        }

}