/* BigOperatorAtom.java
 * =========================================================================
 * This file is part of the JMathTeX Library - http://jmathtex.sourceforge.net
 *
 * Copyright (C) 2004-2007 Universiteit Gent
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * A copy of the GNU General Public License can be found in the file
 * LICENSE.txt provided with the source distribution of this program (see
 * the META-INF directory in the source jar). This license can also be
 * found on the GNU website at http://www.gnu.org/licenses/gpl.html.
 *
 * If you did not receive a copy of the GNU General Public License along
 * with this program, contact the lead developer, or write to the Free
 * Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 */

package be.ugent.caagt.jmathtex;

/**
 * An atom representing a "big operator" (or an atom that acts as one) together
 * with its limits.
 */
class BigOperatorAtom extends Atom {
    
    // limits
    private Atom under = null, over = null;
    
    // atom representing a big operator
    protected Atom base = null;
    
    // whether the "limits"-value should be taken into account
    // (otherwise the default rules will be applied)
    private boolean limitsSet = false;
    
    // whether limits should be drawn over and under the base (<-> as scripts)
    private boolean limits = false;
    
    /**
     * Creates a new BigOperatorAtom from the given atoms.
     * The default rules the positioning of the limits will be applied.
     *
     * @param base atom representing the big operator
     * @param under atom representing the under limit
     * @param over atom representing the over limit
     */
    public BigOperatorAtom(Atom base, Atom under, Atom over) {
        this.base = base;
        this.under = under;
        this.over = over;
        type = TeXConstants.TYPE_BIG_OPERATOR;
    }
    
    /**
     * Creates a new BigOperatorAtom from the given atoms.
     * Limits will be drawn according to the "limits"-value
     *
     * @param base atom representing the big operator
     * @param under atom representing the under limit
     * @param over atom representing the over limit
     * @param limits whether limits should be drawn over and under the base (<-> as scripts)
     */
    public BigOperatorAtom(Atom base, Atom under, Atom over, boolean limits) {
        this(base, under, over);
        this.limits = limits;
        limitsSet = true;
    }
    
    public Box createBox(TeXEnvironment env) {
        TeXFont tf = env.getTeXFont();
        int style = env.getStyle();
        
        Box y;
        float delta;
        
        if ((limitsSet && !limits)
        || (!limitsSet && style >= TeXConstants.STYLE_TEXT))
            // if explicitly set to not display as limits or if not set and style
            // is not display, then attach over and under as regular sub- en
            // superscript
            return new ScriptsAtom(base, under, over).createBox(env);
        else {
            if (base instanceof SymbolAtom
                    && base.type == TeXConstants.TYPE_BIG_OPERATOR) { // single
                // bigop
                // symbol
                Char c = tf.getChar(((SymbolAtom) base).getName(), style);
                if (style < TeXConstants.STYLE_TEXT && tf.hasNextLarger(c)) // display
                    // style
                    c = tf.getNextLarger(c, style);
                Box x = new CharBox(c);
                x.setShift(-(x.getHeight() + x.getDepth()) / 2
                        - env.getTeXFont().getAxisHeight(env.getStyle()));
                y = new HorizontalBox(x);
                
                // include delta in width
                delta = c.getItalic();
                if (delta > TeXFormula.PREC)
                    y.add(new StrutBox(delta, 0, 0, 0));
            } else { // formula
                delta = 0;
                y = new HorizontalBox(base == null ? new StrutBox(0, 0, 0, 0)
                : base.createBox(env));
            }
            
            // limits
            Box x = null, z = null;
            if (over != null)
                x = over.createBox(env.supStyle());
            if (under != null)
                z = under.createBox(env.subStyle());
            
            // make boxes equally wide
            float maxWidth = Math.max(Math.max(x == null ? 0 : x.getWidth(), y
                    .getWidth()), z == null ? 0 : z.getWidth());
            x = changeWidth(x, maxWidth);
            y = changeWidth(y, maxWidth);
            z = changeWidth(z, maxWidth);
            
            // build vertical box
            VerticalBox vBox = new VerticalBox();
            
            float bigop5 = tf.getBigOpSpacing5(style), kern = 0;
            float xh = 0; // TODO: check why this is not used // NOPMD
            
            // over
            if (over != null) {
                vBox.add(new StrutBox(0, bigop5, 0, 0));
                x.setShift(delta / 2);
                vBox.add(x);
                kern = Math.max(tf.getBigOpSpacing1(style), tf
                        .getBigOpSpacing3(style)
                        - x.getDepth());
                vBox.add(new StrutBox(0, kern, 0, 0));
                xh = vBox.getHeight() + vBox.getDepth();
            }
            
            // base
            vBox.add(y);
            
            // under
            if (under != null) {
                float k = Math.max(tf.getBigOpSpacing2(style), tf
                        .getBigOpSpacing4(style)
                        - z.getHeight());
                vBox.add(new StrutBox(0, k, 0, 0));
                z.setShift(-delta / 2);
                vBox.add(z);
                vBox.add(new StrutBox(0, bigop5, 0, 0));
            }
            
            // set height and depth vertical box and return it
            float h = y.getHeight(), total = vBox.getHeight() + vBox.getDepth();
            if (x != null)
                h += bigop5 + kern + x.getHeight() + x.getDepth();
            vBox.setHeight(h);
            vBox.setDepth(total - h);
            return vBox;
        }
    }
    
   /*
    * Centers the given box in a new box that has the given width
    */
    private static Box changeWidth(Box b, float maxWidth) {
        if (b != null && Math.abs(maxWidth - b.getWidth()) > TeXFormula.PREC)
            return new HorizontalBox(b, maxWidth, TeXConstants.ALIGN_CENTER);
        else
            return b;
    }
}