/**
 * @(#)MenuScroller.java	1.3.0 05/04/09
 */
package com.dmdirc.addons.ui_swing.components;

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.Icon;
import javax.swing.JComponent;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.JSeparator;
import javax.swing.MenuSelectionManager;
import javax.swing.Timer;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.MenuEvent;
import javax.swing.event.MenuListener;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;

/**
 * A class that provides scrolling capabilities to a long menu dropdown or
 * popup menu.  A number of items can optionally be frozen at the top and/or
 * bottom of the menu.
 * <P>
 * <B>Implementation note:</B>  The default number of items to display
 * at a time is 15, and the default scrolling interval is 125 milliseconds.
 * <P>
 * @author Darryl
 */
public class MenuScroller {

    private JMenu menu;
    private JPopupMenu popupMenu;
    private Component[] menuItems;
    private MenuScrollItem upItem;
    private MenuScrollItem downItem;
    private final MenuScrollListener menuListener = new MenuScrollListener();
    private int scrollCount;
    private int interval;
    private int topFixedCount;
    private int bottomFixedCount;
    private int firstIndex = 0;
    private boolean showSeperators = true;

    /**
     * Registers a menu to be scrolled with the default number of items to
     * display at a time and the default scrolling interval.
     * <P>
     * @param menu the menu
     * @return the MenuScroller
     */
    public static MenuScroller setScrollerFor(JMenu menu) {
        return new MenuScroller(menu);
    }

    /**
     * Registers a popup menu to be scrolled with the default number of items to
     * display at a time and the default scrolling interval.
     * <P>
     * @param menu the popup menu
     * @return the MenuScroller
     */
    public static MenuScroller setScrollerFor(JPopupMenu menu) {
        return new MenuScroller(menu);
    }

    /**
     * Registers a menu to be scrolled with the default number of items to
     * display at a time and the specified scrolling interval.
     * <P>
     * @param menu the menu
     * @param scrollCount the number of items to display at a time
     * @return the MenuScroller
     * @throws IllegalArgumentException if scrollCount is 0 or negative
     */
    public static MenuScroller setScrollerFor(JMenu menu, int scrollCount) {
        return new MenuScroller(menu, scrollCount);
    }

    /**
     * Registers a popup menu to be scrolled with the default number of items to
     * display at a time and the specified scrolling interval.
     * <P>
     * @param menu the popup menu
     * @param scrollCount the number of items to display at a time
     * @return the MenuScroller
     * @throws IllegalArgumentException if scrollCount is 0 or negative
     */
    public static MenuScroller setScrollerFor(JPopupMenu menu, int scrollCount) {
        return new MenuScroller(menu, scrollCount);
    }

    /**
     * Registers a menu to be scrolled, with the specified number of items to
     * display at a time and the specified scrolling interval.
     * <P>
     * @param menu the menu
     * @param scrollCount the number of items to be displayed at a time
     * @param interval the scroll interval, in milliseconds
     * @return the MenuScroller
     * @throws IllegalArgumentException if scrollCount or interval is 0 or negative
     */
    public static MenuScroller setScrollerFor(JMenu menu, int scrollCount,
            int interval) {
        return new MenuScroller(menu, scrollCount, interval);
    }

    /**
     * Registers a popup menu to be scrolled, with the specified number of items to
     * display at a time and the specified scrolling interval.
     * <P>
     * @param menu the popup menu
     * @param scrollCount the number of items to be displayed at a time
     * @param interval the scroll interval, in milliseconds
     * @return the MenuScroller
     * @throws IllegalArgumentException if scrollCount or interval is 0 or negative
     */
    public static MenuScroller setScrollerFor(JPopupMenu menu, int scrollCount,
            int interval) {
        return new MenuScroller(menu, scrollCount, interval);
    }

    /**
     * Registers a menu to be scrolled, with the specified number of items
     * to display in the scrolling region, the specified scrolling interval,
     * and the specified numbers of items fixed at the top and bottom of the
     * menu.
     * <P>
     * @param menu the menu
     * @param scrollCount the number of items to display in the scrolling portion
     * @param interval the scroll interval, in milliseconds
     * @param topFixedCount the number of items to fix at the top.  May be 0.
     * @param bottomFixedCount the number of items to fix at the bottom. May be 0
     * @throws IllegalArgumentException if scrollCount or interval is 0 or
     * negative or if topFixedCount or bottomFixedCount is negative
     * @return the MenuScroller
     */
    public static MenuScroller setScrollerFor(JMenu menu, int scrollCount,
            int interval, int topFixedCount, int bottomFixedCount) {
        return new MenuScroller(menu, scrollCount, interval,
                topFixedCount, bottomFixedCount);
    }

    /**
     * Registers a popup menu to be scrolled, with the specified number of items
     * to display in the scrolling region, the specified scrolling interval,
     * and the specified numbers of items fixed at the top and bottom of the
     * popup menu.
     * <P>
     * @param menu the popup menu
     * @param scrollCount the number of items to display in the scrolling portion
     * @param interval the scroll interval, in milliseconds
     * @param topFixedCount the number of items to fix at the top.  May be 0
     * @param bottomFixedCount the number of items to fix at the bottom.  May be 0
     * @throws IllegalArgumentException if scrollCount or interval is 0 or
     * negative or if topFixedCount or bottomFixedCount is negative
     * @return the MenuScroller
     */
    public static MenuScroller setScrollerFor(JPopupMenu menu, int scrollCount,
            int interval, int topFixedCount, int bottomFixedCount) {
        return new MenuScroller(menu, scrollCount, interval,
                topFixedCount, bottomFixedCount);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a menu with the
     * default number of items to display at a time, and default scrolling
     * interval.
     * <P>
     * @param menu the menu
     */
    public MenuScroller(JMenu menu) {
        this(menu, 15);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a popup menu with the
     * default number of items to display at a time, and default scrolling
     * interval.
     * <P>
     * @param menu the popup menu
     */
    public MenuScroller(JPopupMenu menu) {
        this(menu, 15);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a menu with the
     * specified number of items to display at a time, and default scrolling
     * interval.
     * <P>
     * @param menu the menu
     * @param scrollCount the number of items to display at a time
     * @throws IllegalArgumentException if scrollCount is 0 or negative
     */
    public MenuScroller(JMenu menu, int scrollCount) {
        this(menu, scrollCount, 125);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a popup menu with the
     * specified number of items to display at a time, and default scrolling
     * interval.
     * <P>
     * @param menu the popup menu
     * @param scrollCount the number of items to display at a time
     * @throws IllegalArgumentException if scrollCount is 0 or negative
     */
    public MenuScroller(JPopupMenu menu, int scrollCount) {
        this(menu, scrollCount, 125);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a menu with the
     * specified number of items to display at a time, and specified scrolling
     * interval.
     * <P>
     * @param menu the menu
     * @param scrollCount the number of items to display at a time
     * @param interval the scroll interval, in milliseconds
     * @throws IllegalArgumentException if scrollCount or interval is 0 or negative
     */
    public MenuScroller(JMenu menu, int scrollCount, int interval) {
        this(menu, scrollCount, interval, 0, 0);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a popup menu with the
     * specified number of items to display at a time, and specified scrolling
     * interval.
     * <P>
     * @param menu the popup menu
     * @param scrollCount the number of items to display at a time
     * @param interval the scroll interval, in milliseconds
     * @throws IllegalArgumentException if scrollCount or interval is 0 or negative
     */
    public MenuScroller(JPopupMenu menu, int scrollCount, int interval) {
        this(menu, scrollCount, interval, 0, 0);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a menu with the
     * specified number of items to display in the scrolling region, the
     * specified scrolling interval, and the specified numbers of items fixed at
     * the top and bottom of the menu.
     * <P>
     * @param menu the menu
     * @param scrollCount the number of items to display in the scrolling portion
     * @param interval the scroll interval, in milliseconds
     * @param topFixedCount the number of items to fix at the top.  May be 0
     * @param bottomFixedCount the number of items to fix at the bottom.  May be 0
     * @throws IllegalArgumentException if scrollCount or interval is 0 or
     * negative or if topFixedCount or bottomFixedCount is negative
     */
    public MenuScroller(JMenu menu, int scrollCount, int interval,
            int topFixedCount, int bottomFixedCount) {
        setValues(scrollCount, interval, topFixedCount, bottomFixedCount);

        this.menu = menu;
        menu.addMenuListener(menuListener);
    }

    /**
     * Constructs a <code>MenuScroller</code> that scrolls a popup menu with the
     * specified number of items to display in the scrolling region, the
     * specified scrolling interval, and the specified numbers of items fixed at
     * the top and bottom of the popup menu.
     * <P>
     * @param menu the popup menu
     * @param scrollCount the number of items to display in the scrolling portion
     * @param interval the scroll interval, in milliseconds
     * @param topFixedCount the number of items to fix at the top.  May be 0
     * @param bottomFixedCount the number of items to fix at the bottom.  May be 0
     * @throws IllegalArgumentException if scrollCount or interval is 0 or
     * negative or if topFixedCount or bottomFixedCount is negative
     */
    public MenuScroller(JPopupMenu menu, int scrollCount, int interval,
            int topFixedCount, int bottomFixedCount) {
        setValues(scrollCount, interval, topFixedCount, bottomFixedCount);
        this.popupMenu = menu;
        menu.addPopupMenuListener(menuListener);
    }

    private void setValues(int scrollCount, int interval,
            int topFixedCount, int bottomFixedCount) {
        if (scrollCount <= 0 || interval <= 0) {
            throw new IllegalArgumentException(
                    "scrollCount and interval must be greater than 0");
        }

        if (topFixedCount < 0 || bottomFixedCount < 0) {
            throw new IllegalArgumentException(
                    "topFixedCount and bottomFixedCount cannot be negative");
        }
        upItem = new MenuScrollItem(MenuIcon.UP, -1);
        downItem = new MenuScrollItem(MenuIcon.DOWN, +1);
        setScrollCount(scrollCount);
        setInterval(interval);
        setTopFixedCount(topFixedCount);
        setBottomFixedCount(bottomFixedCount);
    }

    /**
     * Returns the scroll interval in milliseconds
     * <P>
     * @return the scroll interval in milliseconds
     */
    public int getInterval() {
        return interval;
    }

    /**
     * Sets the scroll interval in milliseconds
     * <P>
     * @param interval the scroll interval in milliseconds
     * @throws IllegalArgumentException if interval is 0 or negative
     */
    public void setInterval(int interval) {
        if (interval <= 0) {
            throw new IllegalArgumentException(
                    "interval must be greater than 0");
        }
        upItem.setInterval(interval);
        downItem.setInterval(interval);
        this.interval = interval;
    }

    /**
     * Returns the number of items in the scrolling portion of the menu.
     * <P>
     * @return the number of items to display at a time
     */
    public int getscrollCount() {
        return scrollCount;
    }

    /**
     * Sets the number of items in the scrolling portion of the menu.
     * <P>
     * @param scrollCount the number of items to display at a time
     * @throws IllegalArgumentException if scrollCount is 0 or negative
     */
    public void setScrollCount(int scrollCount) {
        if (scrollCount <= 0) {
            throw new IllegalArgumentException(
                    "scrollCount must be greater than 0");
        }
        this.scrollCount = scrollCount;
        if (menu != null) {
            menu.doClick();
        }
        MenuSelectionManager.defaultManager().clearSelectedPath();
    }

    /**
     * Returns the number of items fixed at the top of the menu or popup menu.
     * <P>
     * @return the number of items
     */
    public int getTopFixedCount() {
        return topFixedCount;
    }

    /**
     * Sets the number of items to fix at the top of the menu or popup menu.
     * <P>
     * @param topFixedCount the number of items
     */
    public void setTopFixedCount(int topFixedCount) {
        firstIndex = Math.max(firstIndex, topFixedCount);
        this.topFixedCount = topFixedCount;
    }

    /**
     * Returns the number of items fixed at the bottom of the menu or popup menu.
     * <P>
     * @return the number of items
     */
    public int getBottomFixedCount() {
        return bottomFixedCount;
    }

    /**
     * Sets the number of items to fix at the bottom of the menu or popup menu.
     * <P>
     * @param bottomFixedCount the number of items
     */
    public void setBottomFixedCount(int bottomFixedCount) {
        this.bottomFixedCount = bottomFixedCount;
    }

    /**
     * Returns whether to show seperators when scrolling is required.
     *
     * @return Whether to show seperators when scrolling is required
     */
    public boolean getShowSeperators() {
        return showSeperators;
    }

    /**
     * Sets whether we show seperators when a menu requires scrolling.
     *
     * @param showSeperators true to add seperators
     */
    public void setShowSeperators(boolean showSeperators) {
        this.showSeperators = showSeperators;
    }

    /**
     * Removes this MenuScroller from the associated menu and restores the
     * default behavior of the menu.
     */
    public void dispose() {
        if (menu != null) {
            menu.removeMenuListener(menuListener);
            menu = null;
        }

        if (popupMenu != null) {
            popupMenu.removePopupMenuListener(menuListener);
            popupMenu = null;
        }
    }

    /**
     * Ensures that the <code>dispose</code> method of this MenuScroller is
     * called when there are no more refrences to it.
     * <P>
     * @exception  Throwable if an error occurs.
     * @see MenuScroller#dispose()
     */
    @Override
    public void finalize() throws Throwable {
        dispose();
    }

    private void setMenuItems() {
        if (menu != null) {
            menuItems = menu.getMenuComponents();
        }
        if (popupMenu != null) {
            menuItems = popupMenu.getComponents();
        }
        if (menuItems.length > topFixedCount + scrollCount + bottomFixedCount) {
            refreshMenu();
        }
    }

    private void restoreMenuItems() {
        JComponent container = menu == null ? popupMenu : menu;
        container.removeAll();
        for (Component component : menuItems) {
            container.add(component);
        }
    }

    private void refreshMenu() {
        firstIndex = Math.max(topFixedCount, firstIndex);
        firstIndex = Math.min(menuItems.length - bottomFixedCount - scrollCount,
                firstIndex);

        upItem.setEnabled(firstIndex > topFixedCount);
        downItem.setEnabled(
                firstIndex + scrollCount < menuItems.length - bottomFixedCount);

        JComponent container = menu == null ? popupMenu : menu;
        container.removeAll();
        for (int i = 0; i < topFixedCount; i++) {
            container.add(menuItems[i]);
        }
        if (topFixedCount > 0 && showSeperators) {
            container.add(new JSeparator());
        }

        container.add(upItem);
        for (int i = firstIndex; i < scrollCount + firstIndex; i++) {
            container.add(menuItems[i]);
        }
        container.add(downItem);

        if (bottomFixedCount > 0 && showSeperators) {
            container.add(new JSeparator());
        }
        for (int i = menuItems.length - bottomFixedCount; i < menuItems.length;
                i++) {
            container.add(menuItems[i]);
        }
        upItem.getParent().validate();
    }

    private class MenuScrollItem extends JMenuItem
            implements MouseListener, ChangeListener {

        private static final long serialVersionUID = -9164893168723608060L;
        private MenuScrollTimer timer;
        private MouseListener[] mouseListeners;

        public MenuScrollItem(MenuIcon icon, int increment) {
            setIcon(icon);
            setDisabledIcon(icon);
            timer = new MenuScrollTimer(increment, interval);
            mouseListeners = getMouseListeners();
            addMouseListener(this);
            addChangeListener(this);
        }

        public void setInterval(int interval) {
            timer.setDelay(interval);
        }

        // MouseListener methods
        @Override
        public void mouseClicked(MouseEvent e) {
        }

        @Override
        public void mousePressed(MouseEvent e) {
        }

        @Override
        public void mouseReleased(MouseEvent e) {
        }

        @Override
        public void mouseEntered(MouseEvent e) {
            for (MouseListener mouseListener : mouseListeners) {
                mouseListener.mouseEntered(e);
            }
        }

        @Override
        public void mouseExited(MouseEvent e) {
            for (MouseListener mouseListener : mouseListeners) {
                mouseListener.mouseExited(e);
            }
        }

        // ChangeListener method
        @Override
        public void stateChanged(ChangeEvent e) {
            if (isArmed() && !timer.isRunning()) {
                timer.start();
            }
            if (!isArmed() && timer.isRunning()) {
                timer.stop();
            }
        }
    }

    private class MenuScrollTimer extends Timer {

        private static final long serialVersionUID = 1329095900644142841L;

        public MenuScrollTimer(final int increment, int interval) {
            super(interval, new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent e) {
                    firstIndex += increment;
                    refreshMenu();
                }
            });
        }
    }

    private class MenuScrollListener
            implements MenuListener, PopupMenuListener {

        // MenuListener methods
        @Override
        public void menuSelected(MenuEvent e) {
            setMenuItems();
        }

        @Override
        public void menuDeselected(MenuEvent e) {
            restoreMenuItems();
        }

        @Override
        public void menuCanceled(MenuEvent e) {
            restoreMenuItems();
        }

        // PopupMenuListener methods
        @Override
        public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
            setMenuItems();
        }

        @Override
        public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
            restoreMenuItems();
        }

        @Override
        public void popupMenuCanceled(PopupMenuEvent e) {
            restoreMenuItems();
        }
    }

    private static enum MenuIcon implements Icon {

        UP(9, 1, 9),
        DOWN(1, 9, 1);
        final int[] xPoints = {1, 5, 9};
        final int[] yPoints;

        MenuIcon(int... yPoints) {
            this.yPoints = yPoints;
        }

        @Override
        public void paintIcon(Component c, Graphics g, int x, int y) {
            Dimension size = c.getSize();
            Graphics g2 = g.create(size.width / 2 - 5, size.height / 2 - 5, 10,
                    10);
            g2.setColor(Color.GRAY);
            g2.drawPolygon(xPoints, yPoints, 3);
            if (c.isEnabled()) {
                g2.setColor(Color.BLACK);
                g2.fillPolygon(xPoints, yPoints, 3);
            }
            g2.dispose();
        }

        @Override
        public int getIconWidth() {
            return 0;
        }

        @Override
        public int getIconHeight() {
            return 10;
        }
    }

}