/*******************************************************************************
 *
 * Copyright (c) 2004-2010 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.model;

import hudson.ExtensionList;
import hudson.ExtensionPoint;
import hudson.scm.SCMDescriptor;

import java.util.ArrayList;
import java.util.List;

/**
 * Hides {@link Descriptor}s from users.
 *
 * @author Kohsuke Kawaguchi
 * @since 1.393
 */
public abstract class DescriptorVisibilityFilter implements ExtensionPoint {

    /**
     * Decides if the given descriptor should be visible to the user.
     *
     * @param context The object that indicates where the visibility of a
     * descriptor is evaluated. For example, if Hudson is deciding whether a
     * {@link FreeStyleProject} should gets a {@link SCMDescriptor}, the context
     * object will be the {@link FreeStyleProject}. The caller can pass in null
     * if there's no context.
     * @param descriptor Descriptor whose visibility is evaluated. Never null.
     *
     * @return true to allow the descriptor to be visible. false to hide it. If
     * any of the installed {@link DescriptorVisibilityFilter} returns false,
     * the descriptor is not shown.
     */
    public abstract boolean filter(Object context, Descriptor descriptor);

    public static ExtensionList<DescriptorVisibilityFilter> all() {
        return Hudson.getInstance().getExtensionList(DescriptorVisibilityFilter.class);
    }

    public static <T extends Descriptor> List<T> apply(Object context, Iterable<T> source) {
        ExtensionList<DescriptorVisibilityFilter> filters = all();
        List<T> r = new ArrayList<T>();

        OUTER:
        for (T d : source) {
            for (DescriptorVisibilityFilter f : filters) {
                if (!f.filter(context, d)) {
                    continue OUTER; // veto-ed. not shown
                }
            }
            r.add(d);
        }
        return r;
    }
}