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