/*
 * Copyright 1999-2005 The Apache Software Foundation.
 *
 * Licensed 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.
 */

/* $Id: MainReference.java,v 1.2 2004/02/27 17:41:26 jeremias Exp $ */

package org.apache.fop.area;

import java.util.List;
import java.util.Iterator;

/**
 * The main-reference-area generated by an fo:region-body
 * This object holds one or more span-reference-areas (block-areas
 * stacked in the block progression direction)
 * See fo:region-body definition in the XSL Rec for more information.
 */
public class MainReference extends Area {

    private BodyRegion parent;
    private List spanAreas = new java.util.ArrayList();
    private int width;
    private boolean isEmpty = true;

    /**
     * Constructor
     *
     * @param parent the body region this reference area is placed in.
     */
    public MainReference(BodyRegion parent) {
        this.parent = parent;
        addTrait(Trait.IS_REFERENCE_AREA, Boolean.TRUE);
    }
      
    /**
     * Add a span area to this area.
     *
     * @param spanAll whether to make a single-column span
     * @return the created span area.
     */
    public Span createSpan(boolean spanAll) {
        if (spanAreas.size() > 0 && getCurrentSpan().getBPD() == 0) {
            //Remove the current one if it is empty
            spanAreas.remove(spanAreas.size() - 1);
        }
        RegionViewport rv = parent.getRegionViewport();
        int ipdWidth = (int) parent.getIPD()
            - rv.getBorderAndPaddingWidthStart() - rv.getBorderAndPaddingWidthEnd();
        
        Span newSpan = new Span(((spanAll) ? 1 : getColumnCount()), 
                getColumnGap(), ipdWidth);
        spanAreas.add(newSpan);
        return getCurrentSpan(); 
    }

    /**
     * Get the span areas from this area.
     *
     * @return the list of span areas
     */
    public List getSpans() {
        return spanAreas;
    }

    /**
     * Get the span area currently being filled (i.e., the last span created).
     * @return the active span.
     */
    public Span getCurrentSpan() {
        return (Span) spanAreas.get(spanAreas.size() - 1);
    }

    /**
     * Indicates whether any child areas have been added to this reference area.
     *
     * This is achieved by looping through each span.
     * @return true if no child areas have been added yet.
     */
    public boolean isEmpty() {
        if (isEmpty) {
            int areaCount = 0;
            if (spanAreas != null) {
                for (Iterator spaniter = spanAreas.iterator(); spaniter.hasNext();) {
                    Span spanArea = (Span) spaniter.next();
                    for (int i = 0; i < spanArea.getColumnCount(); i++) {
                        NormalFlow flow = spanArea.getNormalFlow(i);
                        if (flow != null) {
                            if (flow.getChildAreas() != null) {
                                areaCount += flow.getChildAreas().size();
                            }
                        }
                    }
                }
            }

            isEmpty = (areaCount == 0);
        }
        return isEmpty;
    }

    /** @return the number of columns */
    public int getColumnCount() {
        return parent.getColumnCount();
    }

    /** @return the column gap in millipoints */
    public int getColumnGap() {
        return parent.getColumnGap();
    }

    /**
     * Get the width of this reference area.
     *
     * @return the width
     */
    public int getWidth() {
        return width;
    }

}