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 *      https://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;
047    private final String from;
048    private final StringBuilder newsgroups;
049    private final StringBuilder headerFields;
050    private int newsgroupCount;
051
052    /**
053     * Creates a new SimpleNNTPHeader instance initialized with the given from and subject header field values.
054     *
055     * @param from    The value of the {@code From:} header field. This should be the article poster's email address.
056     * @param subject The value of the {@code Subject:} header field. This should be the subject of the article.
057     */
058    public SimpleNNTPHeader(final String from, final String subject) {
059        this.from = from;
060        this.subject = subject;
061        this.newsgroups = new StringBuilder();
062        this.headerFields = new StringBuilder();
063        this.newsgroupCount = 0;
064    }
065
066    /**
067     * Adds an arbitrary header field with the given value to the article header.
068     * These headers will be written after the {@code From}, Newsgroups, and Subject fields
069     * when the SimpleNNTPHeader is converted to a string. An example use would be:
070     *
071     * <pre>
072     * header.addHeaderField("Organization", "Foobar, Inc.");
073     * </pre>
074     *
075     * @param headerField The header field to add, not including the colon.
076     * @param value       The value of the added header field.
077     */
078    public void addHeaderField(final String headerField, final String value) {
079        headerFields.append(headerField);
080        headerFields.append(": ");
081        headerFields.append(value);
082        headerFields.append('\n');
083    }
084
085    /**
086     * Adds a newsgroup to the article {@code Newsgroups:} field.
087     *
088     * @param newsgroup The newsgroup to add to the article's newsgroup distribution list.
089     */
090    public void addNewsgroup(final String newsgroup) {
091        if (newsgroupCount++ > 0) {
092            newsgroups.append(',');
093        }
094        newsgroups.append(newsgroup);
095    }
096
097    /**
098     * Gets the address used in the {@code From:} header field.
099     *
100     * @return The from address.
101     */
102    public String getFromAddress() {
103        return from;
104    }
105
106    /**
107     * Gets the contents of the {@code Newsgroups:} header field.
108     *
109     * @return The comma-separated list of newsgroups to which the article is being posted.
110     */
111    public String getNewsgroups() {
112        return newsgroups.toString();
113    }
114
115    /**
116     * Gets the subject used in the {@code Subject:} header field.
117     *
118     * @return The subject.
119     */
120    public String getSubject() {
121        return subject;
122    }
123
124    /**
125     * 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
126     * article body.
127     *
128     * @return The article header in the form of a String.
129     */
130    @Override
131    public String toString() {
132        final StringBuilder header = new StringBuilder();
133
134        header.append("From: ");
135        header.append(from);
136        header.append("\nNewsgroups: ");
137        header.append(newsgroups.toString());
138        header.append("\nSubject: ");
139        header.append(subject);
140        header.append('\n');
141        if (headerFields.length() > 0) {
142            header.append(headerFields.toString());
143        }
144        header.append('\n');
145
146        return header.toString();
147    }
148}