Source code

001package org.apache.maven.plugins.maven_plugin_plugin;
002
003import org.apache.maven.plugin.AbstractMojo;
004import org.apache.maven.plugin.MojoExecutionException;
005import org.apache.maven.plugins.annotations.Mojo;
006import org.apache.maven.plugins.annotations.Parameter;
007
008import org.w3c.dom.Document;
009import org.w3c.dom.Element;
010import org.w3c.dom.Node;
011import org.w3c.dom.NodeList;
012import org.xml.sax.SAXException;
013
014import javax.xml.parsers.DocumentBuilder;
015import javax.xml.parsers.DocumentBuilderFactory;
016import javax.xml.parsers.ParserConfigurationException;
017import java.io.IOException;
018import java.io.InputStream;
019import java.util.ArrayList;
020import java.util.List;
021
022/**
023 * Display help information on maven-plugin-plugin.<br>
024 * Call <code>mvn plugin:help -Ddetail=true -Dgoal=&lt;goal-name&gt;</code> to display parameter details.
025 * @author maven-plugin-tools
026 */
027@Mojo( name = "help", requiresProject = false, threadSafe = true )
028public class HelpMojo
029    extends AbstractMojo
030{
031    /**
032     * If <code>true</code>, display all settable properties for each goal.
033     *
034     */
035    @Parameter( property = "detail", defaultValue = "false" )
036    private boolean detail;
037
038    /**
039     * The name of the goal for which to show help. If unspecified, all goals will be displayed.
040     *
041     */
042    @Parameter( property = "goal" )
043    private java.lang.String goal;
044
045    /**
046     * The maximum length of a display line, should be positive.
047     *
048     */
049    @Parameter( property = "lineLength", defaultValue = "80" )
050    private int lineLength;
051
052    /**
053     * The number of spaces per indentation level, should be positive.
054     *
055     */
056    @Parameter( property = "indentSize", defaultValue = "2" )
057    private int indentSize;
058
059    // /META-INF/maven/<groupId>/<artifactId>/plugin-help.xml
060    private static final String PLUGIN_HELP_PATH =
061                    "/META-INF/maven/org.apache.maven.plugins/maven-plugin-plugin/plugin-help.xml";
062
063    private static final int DEFAULT_LINE_LENGTH = 80;
064
065    private Document build()
066        throws MojoExecutionException
067    {
068        getLog().debug( "load plugin-help.xml: " + PLUGIN_HELP_PATH );
069        try ( InputStream is = getClass().getResourceAsStream( PLUGIN_HELP_PATH ) )
070        {
071            if ( is == null )
072            {
073                throw new MojoExecutionException( "Could not find plugin descriptor at " + PLUGIN_HELP_PATH );
074            }
075            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
076            DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
077            return dBuilder.parse( is );
078        }
079        catch ( IOException e )
080        {
081            throw new MojoExecutionException( e.getMessage(), e );
082        }
083        catch ( ParserConfigurationException e )
084        {
085            throw new MojoExecutionException( e.getMessage(), e );
086        }
087        catch ( SAXException e )
088        {
089            throw new MojoExecutionException( e.getMessage(), e );
090        }
091    }
092
093    /**
094     * {@inheritDoc}
095     */
096    @Override
097    public void execute()
098        throws MojoExecutionException
099    {
100        if ( lineLength <= 0 )
101        {
102            getLog().warn( "The parameter 'lineLength' should be positive, using '80' as default." );
103            lineLength = DEFAULT_LINE_LENGTH;
104        }
105        if ( indentSize <= 0 )
106        {
107            getLog().warn( "The parameter 'indentSize' should be positive, using '2' as default." );
108            indentSize = 2;
109        }
110
111        Document doc = build();
112
113        StringBuilder sb = new StringBuilder();
114        Node plugin = getSingleChild( doc, "plugin" );
115
116
117        String name = getValue( plugin, "name" );
118        String version = getValue( plugin, "version" );
119        String id = getValue( plugin, "groupId" ) + ":" + getValue( plugin, "artifactId" ) + ":" + version;
120        if ( isNotEmpty( name ) && !name.contains( id ) )
121        {
122            append( sb, name + " " + version, 0 );
123        }
124        else
125        {
126            if ( isNotEmpty( name ) )
127            {
128                append( sb, name, 0 );
129            }
130            else
131            {
132                append( sb, id, 0 );
133            }
134        }
135        append( sb, getValue( plugin, "description" ), 1 );
136        append( sb, "", 0 );
137
138        //<goalPrefix>plugin</goalPrefix>
139        String goalPrefix = getValue( plugin, "goalPrefix" );
140
141        Node mojos1 = getSingleChild( plugin, "mojos" );
142
143        List<Node> mojos = findNamedChild( mojos1, "mojo" );
144
145        if ( goal == null || goal.length() <= 0 )
146        {
147            append( sb, "This plugin has " + mojos.size() + ( mojos.size() > 1 ? " goals:" : " goal:" ), 0 );
148            append( sb, "", 0 );
149        }
150
151        for ( Node mojo : mojos )
152        {
153            writeGoal( sb, goalPrefix, (Element) mojo );
154        }
155
156        if ( getLog().isInfoEnabled() )
157        {
158            getLog().info( sb.toString() );
159        }
160    }
161
162
163    private static boolean isNotEmpty( String string )
164    {
165        return string != null && string.length() > 0;
166    }
167
168    private static String getValue( Node node, String elementName )
169        throws MojoExecutionException
170    {
171        return getSingleChild( node, elementName ).getTextContent();
172    }
173
174    private static Node getSingleChild( Node node, String elementName )
175        throws MojoExecutionException
176    {
177        List<Node> namedChild = findNamedChild( node, elementName );
178        if ( namedChild.isEmpty() )
179        {
180            throw new MojoExecutionException( "Could not find " + elementName + " in plugin-help.xml" );
181        }
182        if ( namedChild.size() > 1 )
183        {
184            throw new MojoExecutionException( "Multiple " + elementName + " in plugin-help.xml" );
185        }
186        return namedChild.get( 0 );
187    }
188
189    private static List<Node> findNamedChild( Node node, String elementName )
190    {
191        List<Node> result = new ArrayList<Node>();
192        NodeList childNodes = node.getChildNodes();
193        for ( int i = 0; i < childNodes.getLength(); i++ )
194        {
195            Node item = childNodes.item( i );
196            if ( elementName.equals( item.getNodeName() ) )
197            {
198                result.add( item );
199            }
200        }
201        return result;
202    }
203
204    private static Node findSingleChild( Node node, String elementName )
205        throws MojoExecutionException
206    {
207        List<Node> elementsByTagName = findNamedChild( node, elementName );
208        if ( elementsByTagName.isEmpty() )
209        {
210            return null;
211        }
212        if ( elementsByTagName.size() > 1 )
213        {
214            throw new MojoExecutionException( "Multiple " + elementName + "in plugin-help.xml" );
215        }
216        return elementsByTagName.get( 0 );
217    }
218
219    private void writeGoal( StringBuilder sb, String goalPrefix, Element mojo )
220        throws MojoExecutionException
221    {
222        String mojoGoal = getValue( mojo, "goal" );
223        Node configurationElement = findSingleChild( mojo, "configuration" );
224        Node description = findSingleChild( mojo, "description" );
225        if ( goal == null || goal.length() <= 0 || mojoGoal.equals( goal ) )
226        {
227            append( sb, goalPrefix + ":" + mojoGoal, 0 );
228            Node deprecated = findSingleChild( mojo, "deprecated" );
229            if ( ( deprecated != null ) && isNotEmpty( deprecated.getTextContent() ) )
230            {
231                append( sb, "Deprecated. " + deprecated.getTextContent(), 1 );
232                if ( detail && description != null )
233                {
234                    append( sb, "", 0 );
235                    append( sb, description.getTextContent(), 1 );
236                }
237            }
238            else if ( description != null )
239            {
240                append( sb, description.getTextContent(), 1 );
241            }
242            append( sb, "", 0 );
243
244            if ( detail )
245            {
246                Node parametersNode = getSingleChild( mojo, "parameters" );
247                List<Node> parameters = findNamedChild( parametersNode, "parameter" );
248                append( sb, "Available parameters:", 1 );
249                append( sb, "", 0 );
250
251                for ( Node parameter : parameters )
252                {
253                    writeParameter( sb, parameter, configurationElement );
254                }
255            }
256        }
257    }
258
259    private void writeParameter( StringBuilder sb, Node parameter, Node configurationElement )
260        throws MojoExecutionException
261    {
262        String parameterName = getValue( parameter, "name" );
263        String parameterDescription = getValue( parameter, "description" );
264
265        Element fieldConfigurationElement = null;
266        if ( configurationElement != null )
267        {
268          fieldConfigurationElement =  (Element) findSingleChild( configurationElement, parameterName );
269        }
270
271        String parameterDefaultValue = "";
272        if ( fieldConfigurationElement != null && fieldConfigurationElement.hasAttribute( "default-value" ) )
273        {
274            parameterDefaultValue = " (Default: " + fieldConfigurationElement.getAttribute( "default-value" ) + ")";
275        }
276        append( sb, parameterName + parameterDefaultValue, 2 );
277        Node deprecated = findSingleChild( parameter, "deprecated" );
278        if ( ( deprecated != null ) && isNotEmpty( deprecated.getTextContent() ) )
279        {
280            append( sb, "Deprecated. " + deprecated.getTextContent(), 3 );
281            append( sb, "", 0 );
282        }
283        if ( isNotEmpty( parameterDescription ) ) {
284            append( sb, parameterDescription, 3 );
285        }
286        if ( "true".equals( getValue( parameter, "required" ) ) )
287        {
288            append( sb, "Required: Yes", 3 );
289        }
290        if ( ( fieldConfigurationElement != null ) && isNotEmpty( fieldConfigurationElement.getTextContent() ) )
291        {
292            String property = getPropertyFromExpression( fieldConfigurationElement.getTextContent() );
293            append( sb, "User property: " + property, 3 );
294        }
295
296        append( sb, "", 0 );
297    }
298
299    /**
300     * <p>Repeat a String <code>n</code> times to form a new string.</p>
301     *
302     * @param str    String to repeat
303     * @param repeat number of times to repeat str
304     * @return String with repeated String
305     * @throws NegativeArraySizeException if <code>repeat &lt; 0</code>
306     * @throws NullPointerException       if str is <code>null</code>
307     */
308    private static String repeat( String str, int repeat )
309    {
310        StringBuilder buffer = new StringBuilder( repeat * str.length() );
311
312        for ( int i = 0; i < repeat; i++ )
313        {
314            buffer.append( str );
315        }
316
317        return buffer.toString();
318    }
319
320    /**
321     * Append a description to the buffer by respecting the indentSize and lineLength parameters.
322     * <b>Note</b>: The last character is always a new line.
323     *
324     * @param sb          The buffer to append the description, not <code>null</code>.
325     * @param description The description, not <code>null</code>.
326     * @param indent      The base indentation level of each line, must not be negative.
327     */
328    private void append( StringBuilder sb, String description, int indent )
329    {
330        for ( String line : toLines( description, indent, indentSize, lineLength ) )
331        {
332            sb.append( line ).append( '\n' );
333        }
334    }
335
336    /**
337     * Splits the specified text into lines of convenient display length.
338     *
339     * @param text       The text to split into lines, must not be <code>null</code>.
340     * @param indent     The base indentation level of each line, must not be negative.
341     * @param indentSize The size of each indentation, must not be negative.
342     * @param lineLength The length of the line, must not be negative.
343     * @return The sequence of display lines, never <code>null</code>.
344     * @throws NegativeArraySizeException if <code>indent &lt; 0</code>
345     */
346    private static List<String> toLines( String text, int indent, int indentSize, int lineLength )
347    {
348        List<String> lines = new ArrayList<String>();
349
350        String ind = repeat( "\t", indent );
351
352        String[] plainLines = text.split( "(\r\n)|(\r)|(\n)" );
353
354        for ( String plainLine : plainLines )
355        {
356            toLines( lines, ind + plainLine, indentSize, lineLength );
357        }
358
359        return lines;
360    }
361
362    /**
363     * Adds the specified line to the output sequence, performing line wrapping if necessary.
364     *
365     * @param lines      The sequence of display lines, must not be <code>null</code>.
366     * @param line       The line to add, must not be <code>null</code>.
367     * @param indentSize The size of each indentation, must not be negative.
368     * @param lineLength The length of the line, must not be negative.
369     */
370    private static void toLines( List<String> lines, String line, int indentSize, int lineLength )
371    {
372        int lineIndent = getIndentLevel( line );
373        StringBuilder buf = new StringBuilder( 256 );
374
375        String[] tokens = line.split( " +" );
376
377        for ( String token : tokens )
378        {
379            if ( buf.length() > 0 )
380            {
381                if ( buf.length() + token.length() >= lineLength )
382                {
383                    lines.add( buf.toString() );
384                    buf.setLength( 0 );
385                    buf.append( repeat( " ", lineIndent * indentSize ) );
386                }
387                else
388                {
389                    buf.append( ' ' );
390                }
391            }
392
393            for ( int j = 0; j < token.length(); j++ )
394            {
395                char c = token.charAt( j );
396                if ( c == '\t' )
397                {
398                    buf.append( repeat( " ", indentSize - buf.length() % indentSize ) );
399                }
400                else if ( c == '\u00A0' )
401                {
402                    buf.append( ' ' );
403                }
404                else
405                {
406                    buf.append( c );
407                }
408            }
409        }
410        lines.add( buf.toString() );
411    }
412
413    /**
414     * Gets the indentation level of the specified line.
415     *
416     * @param line The line whose indentation level should be retrieved, must not be <code>null</code>.
417     * @return The indentation level of the line.
418     */
419    private static int getIndentLevel( String line )
420    {
421        int level = 0;
422        for ( int i = 0; i < line.length() && line.charAt( i ) == '\t'; i++ )
423        {
424            level++;
425        }
426        for ( int i = level + 1; i <= level + 4 && i < line.length(); i++ )
427        {
428            if ( line.charAt( i ) == '\t' )
429            {
430                level++;
431                break;
432            }
433        }
434        return level;
435    }
436
437    private static String getPropertyFromExpression( String expression )
438    {
439        if ( expression != null && expression.startsWith( "${" ) && expression.endsWith( "}" )
440            && !expression.substring( 2 ).contains( "${" ) )
441        {
442            // expression="${xxx}" -> property="xxx"
443            return expression.substring( 2, expression.length() - 1 );
444        }
445        // no property can be extracted
446        return null;
447    }
448}