/*
 * The MIT License
 *
 * Copyright (c) 2004-, Kohsuke Kawaguchi, Sun Microsystems, Inc., and a number of other of contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package hudson.plugins.ec2;

import hudson.model.Descriptor;
import hudson.slaves.RetentionStrategy;
import hudson.util.TimeUnit2;

import java.util.concurrent.locks.ReentrantLock;
import java.util.logging.Logger;

import org.kohsuke.stapler.DataBoundConstructor;

/**
 * {@link RetentionStrategy} for EC2.
 *
 * @author Kohsuke Kawaguchi
 */
public class EC2RetentionStrategy extends RetentionStrategy<EC2Computer> {
    /**
     * Number of minutes of idleness before an instance should be terminated. A value of zero indicates that the
     * instance should never be automatically terminated. Negative values are times in remaining minutes before end of
     * billing period.
     */
    public final int idleTerminationMinutes;

    private transient ReentrantLock checkLock;

    @DataBoundConstructor
    public EC2RetentionStrategy(String idleTerminationMinutes) {
        readResolve();
        if (idleTerminationMinutes == null || idleTerminationMinutes.trim() == "") {
            this.idleTerminationMinutes = 0;
        } else {
            int value = 30;
            try {
                value = Integer.parseInt(idleTerminationMinutes);
            } catch (NumberFormatException nfe) {
                LOGGER.info("Malformed default idleTermination value: " + idleTerminationMinutes);
            }

            this.idleTerminationMinutes = value;
        }
    }

    @Override
    public long check(EC2Computer c) {
        if (!checkLock.tryLock()) {
            return 1;
        } else {
            try {
                return _check(c);
            } finally {
                checkLock.unlock();
            }
        }
    }

    private long _check(EC2Computer c) {

        /* If we've been told never to terminate, then we're done. */
        if (idleTerminationMinutes == 0) {
            return 1;
        }

        /*
         * Don't idle-out instances that're offline, per JENKINS-23792. This prevents a node from being idled down while
         * it's still starting up.
         */
        if (c.isOffline()) {
            return 1;
        }

        if (c.isIdle() && !disabled) {
            final long idleMilliseconds = System.currentTimeMillis() - c.getIdleStartMilliseconds();
            if (idleTerminationMinutes > 0) {
                // TODO: really think about the right strategy here, see
                // JENKINS-23792
                if (idleMilliseconds > TimeUnit2.MINUTES.toMillis(idleTerminationMinutes)) {
                    LOGGER.info("Idle timeout of " + c.getName() + " after "
                            + TimeUnit2.MILLISECONDS.toMinutes(idleMilliseconds) + " idle minutes");
                    c.getNode().idleTimeout();
                }
            } else {
                final long uptime;
                try {
                    uptime = c.getUptime();
                } catch (InterruptedException e) {
                    // We'll just retry next time we test for idleness.
                    LOGGER.fine("Interrupted while checking host uptime for " + c.getName()
                            + ", will retry next check. Interrupted by: " + e);
                    return 1;
                }
                final int freeSecondsLeft = (60 * 60)
                        - (int) (TimeUnit2.SECONDS.convert(uptime, TimeUnit2.MILLISECONDS) % (60 * 60));
                // if we have less "free" (aka already paid for) time left than
                // our idle time, stop/terminate the instance
                // See JENKINS-23821
                if (freeSecondsLeft <= (Math.abs(idleTerminationMinutes * 60))) {
                    LOGGER.info("Idle timeout of " + c.getName() + " after "
                            + TimeUnit2.MILLISECONDS.toMinutes(idleMilliseconds) + " idle minutes, with "
                            + TimeUnit2.MILLISECONDS.toMinutes(freeSecondsLeft)
                            + " minutes remaining in billing period");
                    c.getNode().idleTimeout();
                }
            }
        }
        return 1;
    }

    /**
     * Try to connect to it ASAP.
     */
    @Override
    public void start(EC2Computer c) {
        LOGGER.info("Start requested for " + c.getName());
        c.connect(false);
    }

    // no registration since this retention strategy is used only for EC2 nodes
    // that we provision automatically.
    // @Extension
    public static class DescriptorImpl extends Descriptor<RetentionStrategy<?>> {
        @Override
        public String getDisplayName() {
            return "EC2";
        }
    }

    protected Object readResolve() {
        checkLock = new ReentrantLock(false);
        return this;
    }

    private static final Logger LOGGER = Logger.getLogger(EC2RetentionStrategy.class.getName());

    public static boolean disabled = Boolean.getBoolean(EC2RetentionStrategy.class.getName() + ".disabled");
}
