DMDirc-Plugins/ui_swing/src/main/java/com/dmdirc/addons/ui_swing/injection/DialogProvider.java

/*
 * Copyright (c) 2006-2017 DMDirc Developers
 *
 * 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 com.dmdirc.addons.ui_swing.injection;

import com.dmdirc.addons.ui_swing.dialogs.StandardDialog;

import java.awt.Window;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.inject.Provider;

import static com.dmdirc.addons.ui_swing.SwingPreconditions.checkOnEDT;

/**
 * Simple provider for {@link StandardDialog} based windows.
 *
 * <p>
 * This provider will cache instances that are created until the windows are closed. Once a window
 * has been closed, the next call to {@link #get()} or {@link #displayOrRequestFocus()} will result
 * in a new instance being created.
 *
 * @param <T> The type of dialog that will be managed.
 */
public class DialogProvider<T extends StandardDialog> {

    /** Provider used to generate new instances. */
    private final Provider<T> provider;
    /** The existing instance being displayed, if any. */
    private T instance;

    /**
     * Creates a new instance of {@link DialogProvider}.
     *
     * @param provider The provider to use to generate new instances of the dialog, when required.
     */
    public DialogProvider(final Provider<T> provider) {
        this.provider = provider;
    }

    /**
     * Gets an instance of the dialog provided by this class.
     *
     * <p>
     * If there is an existing instance that hasn't been closed, it will be returned. Otherwise a
     * new instance will be created and returned. New instances will not be automatically be
     * displayed to the user - use {@link #displayOrRequestFocus()} to do so.
     *
     * <p>
     * This method <em>must</em> be called on the Event Dispatch Thread.
     *
     * @return An instance of the dialog.
     */
    public T get() {
        checkOnEDT();
        if (instance == null) {
            instance = provider.get();
            instance.addWindowListener(new Listener());
        }
        return instance;
    }

    /**
     * Ensures the dialog is visible to the user.
     *
     * <p>
     * If no dialog currently exists, a new one will be created and displayed to the user. If a
     * dialog existed prior to this method being invoked, it will request focus to bring it to the
     * user's attention.
     *
     * <p>
     * This method <em>must</em> be called on the Event Dispatch Thread.
     */
    public void displayOrRequestFocus() {
        checkOnEDT();
        get().displayOrRequestFocus();
    }

    /**
     * Ensures the dialog is visible to the user.
     *
     * <p>
     * The parent will only change if the dialog has not been made visible to the user.
     *
     * <p>
     * If no dialog currently exists, a new one will be created and displayed to the user. If a
     * dialog existed prior to this method being invoked, it will request focus to bring it to the
     * user's attention.
     *
     * <p>
     * This method <em>must</em> be called on the Event Dispatch Thread.
     *
     * @param parent Parent window for the dialog
     */
    public void displayOrRequestFocus(final Window parent) {
        checkOnEDT();
        get().displayOrRequestFocus(parent);
    }

    /**
     * Listens to window closing events to remove the cached instance of the dialog.
     */
    private class Listener extends WindowAdapter {

        @Override
        public void windowClosed(final WindowEvent e) {
            super.windowClosed(e);
            instance = null;
        }

    }

}