/*

 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.tools.jstat;

import sun.jvmstat.monitor.MonitorException;

/**

 * A class implementing the Closure interface that visits the nodes of

 * the nodes of a ColumFormat object and computes the header string for

 * the columns of data.

 *

 * @author Brian Doherty

 * @since 1.5

 */

public class HeaderClosure implements Closure {

    private static final char ALIGN_CHAR = '^';

    private StringBuilder header = new StringBuilder();

    /*

     * visit an object to perform some operation. In this case, the

     * object is a ColumnFormat we are building the header string.

     */

    public void visit(Object o, boolean hasNext) throws MonitorException {

        if (! (o instanceof ColumnFormat)) {

            return;

        }

        ColumnFormat c = (ColumnFormat)o;

        String h = c.getHeader();

        // check for special alignment character

        if (h.indexOf(ALIGN_CHAR) >= 0) {

            int len = h.length();

            if ((h.charAt(0) == ALIGN_CHAR)

                    && (h.charAt(len-1) == ALIGN_CHAR)) {

                // ^<header>^ case - center alignment

                c.setWidth(Math.max(c.getWidth(),

                                    Math.max(c.getFormat().length(), len-2)));

                h = h.substring(1, len-1);

                h = Alignment.CENTER.align(h, c.getWidth());

            } else if (h.charAt(0) == ALIGN_CHAR) {

                // ^<header> case - left alignment

                c.setWidth(Math.max(c.getWidth(),

                                    Math.max(c.getFormat().length(), len-1)));

                h = h.substring(1, len);

                h = Alignment.LEFT.align(h, c.getWidth());

            } else if (h.charAt(len-1) == ALIGN_CHAR) {

                // <header>^ case - right alignment

                c.setWidth(Math.max(c.getWidth(),

                           Math.max(c.getFormat().length(), len-1)));

                h = h.substring(0, len-1);

                h = Alignment.RIGHT.align(h, c.getWidth());

            } else {

                // an internal alignment character - ignore

            }

        } else {

            // User has provided their own padding for alignment purposes

        }

        header.append(h);

        if (hasNext) {

            header.append(" ");

        }

    }

    /*

     * get the header string.

     */

    public String getHeader() {

        return header.toString();

    }

}