001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.nntp;
019
020/**
021 * This class is used to construct the bare minimum acceptable header for most newsreaders. To construct more complicated headers you should refer to RFC 822.
022 * When the Java Mail API is finalized, you will be able to use it to compose fully compliant Internet text messages.
023 * <p>
024 * The main purpose of the class is to faciliatate the article posting process, by relieving the programmer from having to explicitly format an article header.
025 * For example:
026 * </p>
027 *
028 * <pre>
029 * writer = client.postArticle();
030 * if (writer == null) // failure
031 *     return false;
032 * header = new SimpleNNTPHeader("foobar@foo.com", "Just testing");
033 * header.addNewsgroup("alt.test");
034 * header.addHeaderField("Organization", "Foobar, Inc.");
035 * writer.write(header.toString());
036 * writer.write("This is just a test");
037 * writer.close();
038 * if (!client.completePendingCommand()) // failure
039 *     return false;
040 * </pre>
041 *
042 * @see NNTPClient
043 */
044
045public class SimpleNNTPHeader {
046    private final String subject, from;
047    private final StringBuilder newsgroups;
048    private final StringBuilder headerFields;
049    private int newsgroupCount;
050
051    /**
052     * Creates a new SimpleNNTPHeader instance initialized with the given from and subject header field values.
053     *
054     * @param from    The value of the <code>From:</code> header field. This should be the article poster's email address.
055     * @param subject The value of the <code>Subject:</code> header field. This should be the subject of the article.
056     */
057    public SimpleNNTPHeader(final String from, final String subject) {
058        this.from = from;
059        this.subject = subject;
060        this.newsgroups = new StringBuilder();
061        this.headerFields = new StringBuilder();
062        this.newsgroupCount = 0;
063    }
064
065    /**
066     * Adds an arbitrary header field with the given value to the article header.
067     * These headers will be written after the {@code From}, Newsgroups, and Subject fields
068     * when the SimpleNNTPHeader is converted to a string. An example use would be:
069     *
070     * <pre>
071     * header.addHeaderField("Organization", "Foobar, Inc.");
072     * </pre>
073     *
074     * @param headerField The header field to add, not including the colon.
075     * @param value       The value of the added header field.
076     */
077    public void addHeaderField(final String headerField, final String value) {
078        headerFields.append(headerField);
079        headerFields.append(": ");
080        headerFields.append(value);
081        headerFields.append('\n');
082    }
083
084    /**
085     * Adds a newsgroup to the article <code>Newsgroups:</code> field.
086     *
087     * @param newsgroup The newsgroup to add to the article's newsgroup distribution list.
088     */
089    public void addNewsgroup(final String newsgroup) {
090        if (newsgroupCount++ > 0) {
091            newsgroups.append(',');
092        }
093        newsgroups.append(newsgroup);
094    }
095
096    /**
097     * Returns the address used in the <code>From:</code> header field.
098     *
099     * @return The from address.
100     */
101    public String getFromAddress() {
102        return from;
103    }
104
105    /**
106     * Returns the contents of the <code>Newsgroups:</code> header field.
107     *
108     * @return The comma-separated list of newsgroups to which the article is being posted.
109     */
110    public String getNewsgroups() {
111        return newsgroups.toString();
112    }
113
114    /**
115     * Returns the subject used in the <code>Subject:</code> header field.
116     *
117     * @return The subject.
118     */
119    public String getSubject() {
120        return subject;
121    }
122
123    /**
124     * Converts the SimpleNNTPHeader to a properly formatted header in the form of a String, including the blank line used to separate the header from the
125     * article body.
126     *
127     * @return The article header in the form of a String.
128     */
129    @Override
130    public String toString() {
131        final StringBuilder header = new StringBuilder();
132
133        header.append("From: ");
134        header.append(from);
135        header.append("\nNewsgroups: ");
136        header.append(newsgroups.toString());
137        header.append("\nSubject: ");
138        header.append(subject);
139        header.append('\n');
140        if (headerFields.length() > 0) {
141            header.append(headerFields.toString());
142        }
143        header.append('\n');
144
145        return header.toString();
146    }
147}