/*******************************************************************************
 *
 * Copyright (c) 2004-2009, Oracle Corporation
 *
 * 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:
 *
 *
 *
 *
 *******************************************************************************/ 

package hudson.init;

import org.jvnet.hudson.reactor.Executable;
import org.jvnet.hudson.reactor.Milestone;
import org.jvnet.hudson.reactor.TaskBuilder;
import org.jvnet.hudson.reactor.TaskGraphBuilder;

/**
 * Various key milestone in the initialization process of Hudson.
 *
 * <p> Plugins can use these milestones to execute their initialization at the
 * right moment (in addition to defining their own milestones by implementing
 * {@link Milestone}.
 *
 * <p> These milestones are achieve in this order.
 *
 * @author Kohsuke Kawaguchi
 */
public enum InitMilestone implements Milestone {

    /**
     * The very first milestone that gets achieved without doing anything.
     *
     * This is used in {@link Initializer#after()} since annotations cannot have
     * null as the default value.
     */
    STARTED("Started initialization"),
    /**
     * By this milestone, all plugins metadata are inspected and their
     * dependencies figured out.
     */
    PLUGINS_LISTED("Listed all plugins"),
    /**
     * By this milestone, all plugin metadata are loaded and its classloader set
     * up.
     */
    PLUGINS_PREPARED("Prepared all plugins"),
    /**
     * By this milestone, all plugins start executing, all extension points
     * loaded, descriptors instantiated and loaded.
     *
     * <p> This is a separate milestone from {@link #PLUGINS_PREPARED} since the
     * execution of a plugin often involves finding extension point
     * implementations, which in turn require all the classes from all the
     * plugins to be loadable.
     */
    PLUGINS_STARTED("Started all plugins"),
    /**
     * By this milestone, all programmatically constructed extension point
     * implementations should be added.
     */
    EXTENSIONS_AUGMENTED("Augmented all extensions"),
    /**
     * By this milestone, all jobs and their build records are loaded from disk.
     */
    JOB_LOADED("Loaded all jobs"),
    /**
     * The very last milestone
     *
     * This is used in {@link Initializer#before()} since annotations cannot
     * have null as the default value.
     */
    COMPLETED("Completed initialization");
    private final String message;

    InitMilestone(String message) {
        this.message = message;
    }

    /**
     * Creates a set of dummy tasks to enforce ordering among
     * {@link InitMilestone}s.
     */
    public static TaskBuilder ordering() {
        TaskGraphBuilder b = new TaskGraphBuilder();
        InitMilestone[] v = values();
        for (int i = 0; i < v.length - 1; i++) {
            b.add(null, Executable.NOOP).requires(v[i]).attains(v[i + 1]);
        }
        return b;
    }

    @Override
    public String toString() {
        return message;
    }
}