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1   
2   package org.apache.maven.archetype.mojos;
3   
4   import org.apache.maven.plugin.AbstractMojo;
5   import org.apache.maven.plugin.MojoExecutionException;
6   import org.apache.maven.plugins.annotations.Mojo;
7   import org.apache.maven.plugins.annotations.Parameter;
8   
9   import org.w3c.dom.Document;
10  import org.w3c.dom.Element;
11  import org.w3c.dom.Node;
12  import org.w3c.dom.NodeList;
13  import org.xml.sax.SAXException;
14  
15  import javax.xml.parsers.DocumentBuilder;
16  import javax.xml.parsers.DocumentBuilderFactory;
17  import javax.xml.parsers.ParserConfigurationException;
18  import java.io.IOException;
19  import java.io.InputStream;
20  import java.util.ArrayList;
21  import java.util.List;
22  
23  /**
24   * Display help information on maven-archetype-plugin.<br>
25   * Call <code>mvn archetype:help -Ddetail=true -Dgoal=&lt;goal-name&gt;</code> to display parameter details.
26   * @author maven-plugin-tools
27   */
28  @Mojo( name = "help", requiresProject = false, threadSafe = true )
29  public class HelpMojo
30      extends AbstractMojo
31  {
32      /**
33       * If <code>true</code>, display all settable properties for each goal.
34       *
35       */
36      @Parameter( property = "detail", defaultValue = "false" )
37      private boolean detail;
38  
39      /**
40       * The name of the goal for which to show help. If unspecified, all goals will be displayed.
41       *
42       */
43      @Parameter( property = "goal" )
44      private java.lang.String goal;
45  
46      /**
47       * The maximum length of a display line, should be positive.
48       *
49       */
50      @Parameter( property = "lineLength", defaultValue = "80" )
51      private int lineLength;
52  
53      /**
54       * The number of spaces per indentation level, should be positive.
55       *
56       */
57      @Parameter( property = "indentSize", defaultValue = "2" )
58      private int indentSize;
59  
60      // groupId/artifactId/plugin-help.xml
61      private static final String PLUGIN_HELP_PATH =
62                      "/META-INF/maven/org.apache.maven.plugins/maven-archetype-plugin/plugin-help.xml";
63  
64      private static final int DEFAULT_LINE_LENGTH = 80;
65  
66      private Document build()
67          throws MojoExecutionException
68      {
69          getLog().debug( "load plugin-help.xml: " + PLUGIN_HELP_PATH );
70          InputStream is = null;
71          try
72          {
73              is = getClass().getResourceAsStream( PLUGIN_HELP_PATH );
74              DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
75              DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
76              return dBuilder.parse( is );
77          }
78          catch ( IOException e )
79          {
80              throw new MojoExecutionException( e.getMessage(), e );
81          }
82          catch ( ParserConfigurationException e )
83          {
84              throw new MojoExecutionException( e.getMessage(), e );
85          }
86          catch ( SAXException e )
87          {
88              throw new MojoExecutionException( e.getMessage(), e );
89          }
90          finally
91          {
92              if ( is != null )
93              {
94                  try
95                  {
96                      is.close();
97                  }
98                  catch ( IOException e )
99                  {
100                     throw new MojoExecutionException( e.getMessage(), e );
101                 }
102             }
103         }
104     }
105 
106     /**
107      * {@inheritDoc}
108      */
109     public void execute()
110         throws MojoExecutionException
111     {
112         if ( lineLength <= 0 )
113         {
114             getLog().warn( "The parameter 'lineLength' should be positive, using '80' as default." );
115             lineLength = DEFAULT_LINE_LENGTH;
116         }
117         if ( indentSize <= 0 )
118         {
119             getLog().warn( "The parameter 'indentSize' should be positive, using '2' as default." );
120             indentSize = 2;
121         }
122 
123         Document doc = build();
124 
125         StringBuilder sb = new StringBuilder();
126         Node plugin = getSingleChild( doc, "plugin" );
127 
128 
129         String name = getValue( plugin, "name" );
130         String version = getValue( plugin, "version" );
131         String id = getValue( plugin, "groupId" ) + ":" + getValue( plugin, "artifactId" ) + ":" + version;
132         if ( isNotEmpty( name ) && !name.contains( id ) )
133         {
134             append( sb, name + " " + version, 0 );
135         }
136         else
137         {
138             if ( isNotEmpty( name ) )
139             {
140                 append( sb, name, 0 );
141             }
142             else
143             {
144                 append( sb, id, 0 );
145             }
146         }
147         append( sb, getValue( plugin, "description" ), 1 );
148         append( sb, "", 0 );
149 
150         //<goalPrefix>plugin</goalPrefix>
151         String goalPrefix = getValue( plugin, "goalPrefix" );
152 
153         Node mojos1 = getSingleChild( plugin, "mojos" );
154 
155         List<Node> mojos = findNamedChild( mojos1, "mojo" );
156 
157         if ( goal == null || goal.length() <= 0 )
158         {
159             append( sb, "This plugin has " + mojos.size() + ( mojos.size() > 1 ? " goals:" : " goal:" ), 0 );
160             append( sb, "", 0 );
161         }
162 
163         for ( Node mojo : mojos )
164         {
165             writeGoal( sb, goalPrefix, (Element) mojo );
166         }
167 
168         if ( getLog().isInfoEnabled() )
169         {
170             getLog().info( sb.toString() );
171         }
172     }
173 
174 
175     private static boolean isNotEmpty( String string )
176     {
177         return string != null && string.length() > 0;
178     }
179 
180     private String getValue( Node node, String elementName )
181         throws MojoExecutionException
182     {
183         return getSingleChild( node, elementName ).getTextContent();
184     }
185 
186     private Node getSingleChild( Node node, String elementName )
187         throws MojoExecutionException
188     {
189         List<Node> namedChild = findNamedChild( node, elementName );
190         if ( namedChild.isEmpty() )
191         {
192             throw new MojoExecutionException( "Could not find " + elementName + " in plugin-help.xml" );
193         }
194         if ( namedChild.size() > 1 )
195         {
196             throw new MojoExecutionException( "Multiple " + elementName + " in plugin-help.xml" );
197         }
198         return namedChild.get( 0 );
199     }
200 
201     private List<Node> findNamedChild( Node node, String elementName )
202     {
203         List<Node> result = new ArrayList<Node>();
204         NodeList childNodes = node.getChildNodes();
205         for ( int i = 0; i < childNodes.getLength(); i++ )
206         {
207             Node item = childNodes.item( i );
208             if ( elementName.equals( item.getNodeName() ) )
209             {
210                 result.add( item );
211             }
212         }
213         return result;
214     }
215 
216     private Node findSingleChild( Node node, String elementName )
217         throws MojoExecutionException
218     {
219         List<Node> elementsByTagName = findNamedChild( node, elementName );
220         if ( elementsByTagName.isEmpty() )
221         {
222             return null;
223         }
224         if ( elementsByTagName.size() > 1 )
225         {
226             throw new MojoExecutionException( "Multiple " + elementName + "in plugin-help.xml" );
227         }
228         return elementsByTagName.get( 0 );
229     }
230 
231     private void writeGoal( StringBuilder sb, String goalPrefix, Element mojo )
232         throws MojoExecutionException
233     {
234         String mojoGoal = getValue( mojo, "goal" );
235         Node configurationElement = findSingleChild( mojo, "configuration" );
236         Node description = findSingleChild( mojo, "description" );
237         if ( goal == null || goal.length() <= 0 || mojoGoal.equals( goal ) )
238         {
239             append( sb, goalPrefix + ":" + mojoGoal, 0 );
240             Node deprecated = findSingleChild( mojo, "deprecated" );
241             if ( ( deprecated != null ) && isNotEmpty( deprecated.getTextContent() ) )
242             {
243                 append( sb, "Deprecated. " + deprecated.getTextContent(), 1 );
244                 if ( detail && description != null )
245                 {
246                     append( sb, "", 0 );
247                     append( sb, description.getTextContent(), 1 );
248                 }
249             }
250             else if ( description != null )
251             {
252                 append( sb, description.getTextContent(), 1 );
253             }
254             append( sb, "", 0 );
255 
256             if ( detail )
257             {
258                 Node parametersNode = getSingleChild( mojo, "parameters" );
259                 List<Node> parameters = findNamedChild( parametersNode, "parameter" );
260                 append( sb, "Available parameters:", 1 );
261                 append( sb, "", 0 );
262 
263                 for ( Node parameter : parameters )
264                 {
265                     writeParameter( sb, parameter, configurationElement );
266                 }
267             }
268         }
269     }
270 
271     private void writeParameter( StringBuilder sb, Node parameter, Node configurationElement )
272         throws MojoExecutionException
273     {
274         String parameterName = getValue( parameter, "name" );
275         String parameterDescription = getValue( parameter, "description" );
276 
277         Element fieldConfigurationElement = (Element) findSingleChild( configurationElement, parameterName );
278 
279         String parameterDefaultValue = "";
280         if ( fieldConfigurationElement != null && fieldConfigurationElement.hasAttribute( "default-value" ) )
281         {
282             parameterDefaultValue = " (Default: " + fieldConfigurationElement.getAttribute( "default-value" ) + ")";
283         }
284         append( sb, parameterName + parameterDefaultValue, 2 );
285         Node deprecated = findSingleChild( parameter, "deprecated" );
286         if ( ( deprecated != null ) && isNotEmpty( deprecated.getTextContent() ) )
287         {
288             append( sb, "Deprecated. " + deprecated.getTextContent(), 3 );
289             append( sb, "", 0 );
290         }
291         append( sb, parameterDescription, 3 );
292         if ( "true".equals( getValue( parameter, "required" ) ) )
293         {
294             append( sb, "Required: Yes", 3 );
295         }
296         if ( ( fieldConfigurationElement != null ) && isNotEmpty( fieldConfigurationElement.getTextContent() ) )
297         {
298             String property = getPropertyFromExpression( fieldConfigurationElement.getTextContent() );
299             append( sb, "User property: " + property, 3 );
300         }
301 
302         append( sb, "", 0 );
303     }
304 
305     /**
306      * <p>Repeat a String <code>n</code> times to form a new string.</p>
307      *
308      * @param str    String to repeat
309      * @param repeat number of times to repeat str
310      * @return String with repeated String
311      * @throws NegativeArraySizeException if <code>repeat < 0</code>
312      * @throws NullPointerException       if str is <code>null</code>
313      */
314     private static String repeat( String str, int repeat )
315     {
316         StringBuilder buffer = new StringBuilder( repeat * str.length() );
317 
318         for ( int i = 0; i < repeat; i++ )
319         {
320             buffer.append( str );
321         }
322 
323         return buffer.toString();
324     }
325 
326     /**
327      * Append a description to the buffer by respecting the indentSize and lineLength parameters.
328      * <b>Note</b>: The last character is always a new line.
329      *
330      * @param sb          The buffer to append the description, not <code>null</code>.
331      * @param description The description, not <code>null</code>.
332      * @param indent      The base indentation level of each line, must not be negative.
333      */
334     private void append( StringBuilder sb, String description, int indent )
335     {
336         for ( String line : toLines( description, indent, indentSize, lineLength ) )
337         {
338             sb.append( line ).append( '\n' );
339         }
340     }
341 
342     /**
343      * Splits the specified text into lines of convenient display length.
344      *
345      * @param text       The text to split into lines, must not be <code>null</code>.
346      * @param indent     The base indentation level of each line, must not be negative.
347      * @param indentSize The size of each indentation, must not be negative.
348      * @param lineLength The length of the line, must not be negative.
349      * @return The sequence of display lines, never <code>null</code>.
350      * @throws NegativeArraySizeException if <code>indent < 0</code>
351      */
352     private static List<String> toLines( String text, int indent, int indentSize, int lineLength )
353     {
354         List<String> lines = new ArrayList<String>();
355 
356         String ind = repeat( "\t", indent );
357 
358         String[] plainLines = text.split( "(\r\n)|(\r)|(\n)" );
359 
360         for ( String plainLine : plainLines )
361         {
362             toLines( lines, ind + plainLine, indentSize, lineLength );
363         }
364 
365         return lines;
366     }
367 
368     /**
369      * Adds the specified line to the output sequence, performing line wrapping if necessary.
370      *
371      * @param lines      The sequence of display lines, must not be <code>null</code>.
372      * @param line       The line to add, must not be <code>null</code>.
373      * @param indentSize The size of each indentation, must not be negative.
374      * @param lineLength The length of the line, must not be negative.
375      */
376     private static void toLines( List<String> lines, String line, int indentSize, int lineLength )
377     {
378         int lineIndent = getIndentLevel( line );
379         StringBuilder buf = new StringBuilder( 256 );
380 
381         String[] tokens = line.split( " +" );
382 
383         for ( String token : tokens )
384         {
385             if ( buf.length() > 0 )
386             {
387                 if ( buf.length() + token.length() >= lineLength )
388                 {
389                     lines.add( buf.toString() );
390                     buf.setLength( 0 );
391                     buf.append( repeat( " ", lineIndent * indentSize ) );
392                 }
393                 else
394                 {
395                     buf.append( ' ' );
396                 }
397             }
398 
399             for ( int j = 0; j < token.length(); j++ )
400             {
401                 char c = token.charAt( j );
402                 if ( c == '\t' )
403                 {
404                     buf.append( repeat( " ", indentSize - buf.length() % indentSize ) );
405                 }
406                 else if ( c == '\u00A0' )
407                 {
408                     buf.append( ' ' );
409                 }
410                 else
411                 {
412                     buf.append( c );
413                 }
414             }
415         }
416         lines.add( buf.toString() );
417     }
418 
419     /**
420      * Gets the indentation level of the specified line.
421      *
422      * @param line The line whose indentation level should be retrieved, must not be <code>null</code>.
423      * @return The indentation level of the line.
424      */
425     private static int getIndentLevel( String line )
426     {
427         int level = 0;
428         for ( int i = 0; i < line.length() && line.charAt( i ) == '\t'; i++ )
429         {
430             level++;
431         }
432         for ( int i = level + 1; i <= level + 4 && i < line.length(); i++ )
433         {
434             if ( line.charAt( i ) == '\t' )
435             {
436                 level++;
437                 break;
438             }
439         }
440         return level;
441     }
442     
443     private String getPropertyFromExpression( String expression )
444     {
445         if ( expression != null && expression.startsWith( "${" ) && expression.endsWith( "}" )
446             && !expression.substring( 2 ).contains( "${" ) )
447         {
448             // expression="${xxx}" -> property="xxx"
449             return expression.substring( 2, expression.length() - 1 );
450         }
451         // no property can be extracted
452         return null;
453     }
454 }