/*
 * XML input/output support for FindBugs
 * Copyright (C) 2004, University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.xml;

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

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;

import edu.umd.cs.findbugs.util.Strings;

/**
 * Helper class to format attributes in an XML tag.
 *
 * @author David Hovemeyer
 */
public class XMLAttributeList {
    public static class NameValuePair {
        private final String name;

        private final String value;

        public NameValuePair(String name, String value) {
            this.name = name;
            this.value = value;
        }

        public String getName() {
            return name;
        }

        public String getValue() {
            return value;
        }
    }

    // Fields
    private final List<NameValuePair> nameValuePairList;

    /**
     * Constructor. Creates an empty object.
     */
    public XMLAttributeList() {
        this.nameValuePairList = new LinkedList<NameValuePair>();
    }

    /**
     * Add a single attribute name and value.
     *
     * @param name
     *            the attribute name
     * @param value
     *            the attribute value
     * @return this object (so calls to addAttribute() can be chained)
     */
    public XMLAttributeList addAttribute(@Nonnull String name, @Nonnull String value) {
        if (name == null) {
            throw new NullPointerException("name must be nonnull");
        }
        if (value == null) {
            throw new NullPointerException("value must be nonnull");
        }
        nameValuePairList.add(new NameValuePair(name, value));
        return this;
    }

    /**
     * Add a single attribute name and value.
     *
     * @param name
     *            the attribute name
     * @param value
     *            the attribute value
     * @return this object (so calls to addAttribute() can be chained)
     */
    public XMLAttributeList addOptionalAttribute(@Nonnull String name, @CheckForNull String value) {
        if (value == null) {
            return this;
        }
        return addAttribute(name, value);
    }

    /**
     * Return the attribute list as a String which can be directly output as
     * part of an XML tag.
     */
    @Override
    public String toString() {
        StringBuilder buf = new StringBuilder();
        for (NameValuePair pair : nameValuePairList) {
            buf.append(' ');
            buf.append(pair.getName());
            buf.append('=');
            buf.append('"');
            buf.append(getQuotedAttributeValue(pair.getValue()));
            buf.append('"');
        }
        return buf.toString();
    }

    /**
     * Return an Iterator over NameValuePairs.
     */
    public Iterator<NameValuePair> iterator() {
        return nameValuePairList.iterator();
    }

    /**
     * Return a properly quoted form for an attribute value.
     *
     * @param rawValue
     *            the raw value of the attribute
     * @return a properly quoted representation of the value
     */
    public static String getQuotedAttributeValue(@Nonnull String rawValue) {
        return Strings.escapeXml(rawValue);
    }
}

