/*
 * $Id$
 * ============================================================================
 *                    The Apache Software License, Version 1.1
 * ============================================================================
 *
 * Copyright (C) 1999-2003 The Apache Software Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3. The end-user documentation included with the redistribution, if any, must
 *    include the following acknowledgment: "This product includes software
 *    developed by the Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself, if
 *    and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "FOP" and "Apache Software Foundation" must not be used to
 *    endorse or promote products derived from this software without prior
 *    written permission. For written permission, please contact
 *    apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache", nor may
 *    "Apache" appear in their name, without prior written permission of the
 *    Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * APACHE SOFTWARE FOUNDATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLU-
 * DING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ============================================================================
 *
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Apache Software Foundation and was originally created by
 * James Tauber <jtauber@jtauber.com>. For more information on the Apache
 * Software Foundation, please see <http://www.apache.org/>.
 */
package org.apache.fop.fo.pagination;

// Java
import java.util.ArrayList;

// XML
import org.xml.sax.Attributes;

// FOP
import org.apache.fop.fo.FONode;
import org.apache.fop.fo.FObj;
import org.apache.fop.fo.FOTreeVisitor;
import org.apache.fop.apps.FOPException;

/**
 * Class modelling the fo:flow object. See Sec. 6.4.18 in the XSL-FO Standard.
 */
public class Flow extends FObj {

    /**
     * PageSequence container
     */
    private PageSequence pageSequence;

    /**
     * ArrayList to store snapshot
     */
    private ArrayList markerSnapshot;

    /**
     * flow-name attribute
     */
    private String flowName;

    /**
     * Content-width of current column area during layout
     */
    private int contentWidth;

    /**
     * @param parent FONode that is the parent of this object
     */
    public Flow(FONode parent) {
        super(parent);
    }

    /**
     * @see org.apache.fop.fo.FObj#handleAttrs
     * @param attlist Collection of attributes passed to us from the parser.
     * @throws FOPException if parent is not a page-sequence object
     */
    public void handleAttrs(Attributes attlist) throws FOPException {
        super.handleAttrs(attlist);
        if (parent.getName().equals("fo:page-sequence")) {
            this.pageSequence = (PageSequence) parent;
        } else {
            throw new FOPException("flow must be child of "
                                 + "page-sequence, not " + parent.getName());
        }
        // according to communication from Paul Grosso (XSL-List,
        // 001228, Number 406), confusion in spec section 6.4.5 about
        // multiplicity of fo:flow in XSL 1.0 is cleared up - one (1)
        // fo:flow per fo:page-sequence only.

        /*        if (pageSequence.isFlowSet()) {
                    if (this.name.equals("fo:flow")) {
                        throw new FOPException("Only a single fo:flow permitted"
                                               + " per fo:page-sequence");
                    } else {
                        throw new FOPException(this.name
                                               + " not allowed after fo:flow");
                    }
                }
         */
        setFlowName(getProperty("flow-name").getString());
        // Now done in addChild of page-sequence
        //pageSequence.addFlow(this);

        getFOTreeControl().getFOInputHandler().startFlow(this);
    }

    /**
     * Tell the StructureRenderer that we are at the end of the flow.
     */
    public void end() {
        getFOTreeControl().getFOInputHandler().endFlow(this);
    }

    /**
     * @param name the name of the flow to set
     * @throws FOPException for an empty name
     */
    protected void setFlowName(String name) throws FOPException {
        if (name == null || name.equals("")) {
            throw new FOPException("A 'flow-name' is required for "
                         + getName());
        } else {
            flowName = name;
        }
    }

    /**
     * @return the name of this flow
     */
    public String getFlowName() {
        return flowName;
    }

    /**
     * @param contentWidth content width of this flow, in millipoints (??)
     */
    protected void setContentWidth(int contentWidth) {
        this.contentWidth = contentWidth;
    }
    /**
     * @return the content width of this flow (really of the region
     * in which it is flowing), in millipoints (??).
     */
    public int getContentWidth() {
        return this.contentWidth;
    }

    /**
     * @return true (Flow can generate reference areas)
     */
    public boolean generatesReferenceAreas() {
        return true;
    }

    /**
     * This is a hook for an FOTreeVisitor subclass to be able to access
     * this object.
     * @param fotv the FOTreeVisitor subclass that can access this object.
     * @see org.apache.fop.fo.FOTreeVisitor
     */
    public void acceptVisitor(FOTreeVisitor fotv) {
        fotv.serveFlow(this);
    }
}