/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jorphan.gui.layout;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.io.Serializable;

/**
 * A vertical layout manager similar to java.awt.FlowLayout. Like FlowLayout
 * components do not expand to fill available space except when the horizontal
 * alignment is <code>BOTH</code> in which case components are stretched
 * horizontally. Unlike FlowLayout, components will not wrap to form another
 * column if there isn't enough space vertically. VerticalLayout can optionally
 * anchor components to the top or bottom of the display area or center them
 * between the top and bottom. Revision date 04 April 1999
 *
 */
public class VerticalLayout implements LayoutManager, Serializable {
    private static final long serialVersionUID = 240L;

    /**
     * The horizontal alignment constant that designates centering. Also used to
     * designate center anchoring.
     */
    public static final int CENTER = 0;

    /**
     * The horizontal alignment constant that designates right justification.
     */
    public static final int RIGHT = 1;

    /**
     * The horizontal alignment constant that designates left justification.
     */
    public static final int LEFT = 2;

    /**
     * The horizontal alignment constant that designates stretching the
     * component horizontally.
     */
    public static final int BOTH = 3;

    /**
     * The anchoring constant that designates anchoring to the top of the
     * display area.
     */
    public static final int TOP = 1;

    /**
     * The anchoring constant that designates anchoring to the bottom of the
     * display area.
     */
    public static final int BOTTOM = 2;

    /** The vertical vgap between components...defaults to 5. */
    private final int vgap;

    /** LEFT, RIGHT, CENTER or BOTH...how the components are justified. */
    private final int alignment;

    /**
     * TOP, BOTTOM or CENTER ...where are the components positioned in an
     * overlarge space.
     */
    private final int anchor;

    // Constructors
    /**
     * Constructs an instance of VerticalLayout with a vertical vgap of 5
     * pixels, horizontal centering and anchored to the top of the display area.
     */
    public VerticalLayout() {
        this(5, CENTER, TOP);
    }

    /**
     * Constructs a VerticalLayout instance with horizontal centering, anchored
     * to the top with the specified vgap.
     *
     * @param vgap
     *            an int value indicating the vertical separation of the
     *            components
     */
    public VerticalLayout(int vgap) {
        this(vgap, CENTER, TOP);
    }

    /**
     * Constructs a VerticalLayout instance anchored to the top with the
     * specified vgap and horizontal alignment.
     *
     * @param vgap
     *            an int value indicating the vertical separation of the
     *            components
     * @param alignment
     *            an int value which is one of <code>RIGHT, LEFT,
     *                   CENTER, BOTH</code>
     *            for the horizontal alignment.
     */
    public VerticalLayout(int vgap, int alignment) {
        this(vgap, alignment, TOP);
    }

    /**
     * Constructs a VerticalLayout instance with the specified vgap, horizontal
     * alignment and anchoring
     *
     * @param vgap
     *            an int value indicating the vertical separation of the
     *            components
     * @param alignment
     *            an int value which is one of <code>RIGHT, LEFT, CENTER,
     *                  BOTH</code>
     *            for the horizontal alignment.
     * @param anchor
     *            an int value which is one of <code>TOP, BOTTOM,
     *                  CENTER</code>
     *            indicating where the components are to appear if the display
     *            area exceeds the minimum necessary.
     */
    public VerticalLayout(int vgap, int alignment, int anchor) {
        this.vgap = vgap;
        this.alignment = alignment;
        this.anchor = anchor;
    }

    /**
     * Lays out the container.
     */
    @Override
    public void layoutContainer(Container parent) {
        Insets insets = parent.getInsets();
        synchronized (parent.getTreeLock()) {
            int n = parent.getComponentCount();
            Dimension pd = parent.getSize();
            int y = 0;
            // work out the total size
            for (int i = 0; i < n; i++) {
                Component c = parent.getComponent(i);
                Dimension d = c.getPreferredSize();
                y += d.height + vgap;
            }
            y -= vgap; // otherwise there's a vgap too many
            // Work out the anchor paint
            if (anchor == TOP) {
                y = insets.top;
            } else if (anchor == CENTER) {
                y = (pd.height - y) / 2;
            } else {
                y = pd.height - y - insets.bottom;
            }
            // do layout
            for (int i = 0; i < n; i++) {
                Component c = parent.getComponent(i);
                Dimension d = c.getPreferredSize();
                int x = insets.left;
                int wid = d.width;
                if (alignment == CENTER) {
                    x = (pd.width - d.width) / 2;
                } else if (alignment == RIGHT) {
                    x = pd.width - d.width - insets.right;
                } else if (alignment == BOTH) {
                    wid = pd.width - insets.left - insets.right;
                }
                c.setBounds(x, y, wid, d.height);
                y += d.height + vgap;
            }
        }
    }

    @Override
    public Dimension minimumLayoutSize(Container parent) {
        return layoutSize(parent, true);
    }

    @Override
    public Dimension preferredLayoutSize(Container parent) {
        return layoutSize(parent, false);
    }

    /**
     * Not used by this class.
     */
    @Override
    public void addLayoutComponent(String name, Component comp) {
    }

    /**
     * Not used by this class.
     */
    @Override
    public void removeLayoutComponent(Component comp) {
    }

    @Override
    public String toString() {
        return getClass().getName() + "[vgap=" + vgap + " align=" + alignment + " anchor=" + anchor + "]";
    }

    private Dimension layoutSize(Container parent, boolean minimum) {
        Dimension dim = new Dimension(0, 0);
        Dimension d;
        synchronized (parent.getTreeLock()) {
            int n = parent.getComponentCount();
            for (int i = 0; i < n; i++) {
                Component c = parent.getComponent(i);
                if (c.isVisible()) {
                    d = minimum ? c.getMinimumSize() : c.getPreferredSize();
                    dim.width = Math.max(dim.width, d.width);
                    dim.height += d.height;
                    if (i > 0) {
                        dim.height += vgap;
                    }
                }
            }
        }
        Insets insets = parent.getInsets();
        dim.width += insets.left + insets.right;
        dim.height += insets.top + insets.bottom + vgap + vgap;
        return dim;
    }
}
