001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks.header;
021
022import java.io.BufferedInputStream;
023import java.io.IOException;
024import java.io.InputStreamReader;
025import java.io.LineNumberReader;
026import java.io.Reader;
027import java.io.StringReader;
028import java.net.URI;
029import java.nio.charset.Charset;
030import java.nio.charset.UnsupportedCharsetException;
031import java.util.ArrayList;
032import java.util.List;
033import java.util.Set;
034import java.util.regex.Pattern;
035
036import com.puppycrawl.tools.checkstyle.PropertyType;
037import com.puppycrawl.tools.checkstyle.XdocsPropertyType;
038import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
039import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
040import com.puppycrawl.tools.checkstyle.api.ExternalResourceHolder;
041import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
042
043/**
044 * Abstract super class for header checks.
045 * Provides support for header and headerFile properties.
046 */
047public abstract class AbstractHeaderCheck extends AbstractFileSetCheck
048    implements ExternalResourceHolder {
049
050    /** Pattern to detect occurrences of '\n' in text. */
051    private static final Pattern ESCAPED_LINE_FEED_PATTERN = Pattern.compile("\\\\n");
052
053    /** The lines of the header file. */
054    private final List<String> readerLines = new ArrayList<>();
055
056    /** Specify the name of the file containing the required header. */
057    private URI headerFile;
058
059    /** Specify the character encoding to use when reading the headerFile. */
060    @XdocsPropertyType(PropertyType.STRING)
061    private Charset charset;
062
063    /**
064     * Hook method for post-processing header lines.
065     * This implementation does nothing.
066     */
067    protected abstract void postProcessHeaderLines();
068
069    /**
070     * Return the header lines to check against.
071     *
072     * @return the header lines to check against.
073     */
074    protected List<String> getHeaderLines() {
075        return List.copyOf(readerLines);
076    }
077
078    /**
079     * Setter to specify the character encoding to use when reading the headerFile.
080     *
081     * @param charset the charset name to use for loading the header from a file
082     */
083    public void setCharset(String charset) {
084        this.charset = createCharset(charset);
085    }
086
087    /**
088     * Setter to specify the name of the file containing the required header.
089     *
090     * @param uri the uri of the header to load.
091     * @throws CheckstyleException if fileName is empty.
092     */
093    public void setHeaderFile(URI uri) throws CheckstyleException {
094        if (uri == null) {
095            throw new CheckstyleException(
096                "property 'headerFile' is missing or invalid in module "
097                    + getConfiguration().getName());
098        }
099
100        headerFile = uri;
101    }
102
103    /**
104     * Load the header from a file.
105     *
106     * @throws CheckstyleException if the file cannot be loaded
107     */
108    private void loadHeaderFile() throws CheckstyleException {
109        checkHeaderNotInitialized();
110        try (Reader headerReader = new InputStreamReader(new BufferedInputStream(
111                    headerFile.toURL().openStream()), charset)) {
112            loadHeader(headerReader);
113        }
114        catch (final IOException ex) {
115            throw new CheckstyleException(
116                    "unable to load header file " + headerFile, ex);
117        }
118    }
119
120    /**
121     * Called before initializing the header.
122     *
123     * @throws IllegalArgumentException if header has already been set
124     */
125    private void checkHeaderNotInitialized() {
126        if (!readerLines.isEmpty()) {
127            throw new IllegalArgumentException(
128                    "header has already been set - "
129                    + "set either header or headerFile, not both");
130        }
131    }
132
133    /**
134     * Creates charset by name.
135     *
136     * @param name charset name
137     * @return created charset
138     * @throws UnsupportedCharsetException if charset is unsupported
139     */
140    private static Charset createCharset(String name) {
141        if (!Charset.isSupported(name)) {
142            final String message = "unsupported charset: '" + name + "'";
143            throw new UnsupportedCharsetException(message);
144        }
145        return Charset.forName(name);
146    }
147
148    /**
149     * Specify the required header specified inline.
150     * Individual header lines must be separated by the string
151     * {@code "\n"}(even on platforms with a different line separator).
152     *
153     * @param header header content to check against.
154     * @throws IllegalArgumentException if the header cannot be interpreted
155     */
156    public void setHeader(String header) {
157        if (!CommonUtil.isBlank(header)) {
158            checkHeaderNotInitialized();
159
160            final String headerExpandedNewLines = ESCAPED_LINE_FEED_PATTERN
161                    .matcher(header).replaceAll("\n");
162
163            try (Reader headerReader = new StringReader(headerExpandedNewLines)) {
164                loadHeader(headerReader);
165            }
166            catch (final IOException ex) {
167                throw new IllegalArgumentException("unable to load header", ex);
168            }
169        }
170    }
171
172    /**
173     * Load header to check against from a Reader into readerLines.
174     *
175     * @param headerReader delivers the header to check against
176     * @throws IOException if
177     */
178    private void loadHeader(final Reader headerReader) throws IOException {
179        try (LineNumberReader lnr = new LineNumberReader(headerReader)) {
180            String line;
181            do {
182                line = lnr.readLine();
183                if (line != null) {
184                    readerLines.add(line);
185                }
186            } while (line != null);
187            postProcessHeaderLines();
188        }
189    }
190
191    @Override
192    protected final void finishLocalSetup() throws CheckstyleException {
193        if (headerFile != null) {
194            loadHeaderFile();
195        }
196    }
197
198    @Override
199    public Set<String> getExternalResourceLocations() {
200        final Set<String> result;
201
202        if (headerFile == null) {
203            result = Set.of();
204        }
205        else {
206            result = Set.of(headerFile.toASCIIString());
207        }
208
209        return result;
210    }
211
212}