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1   package org.mybatis.maven.migrations_maven_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.List;
21  
22  /**
23   * Display help information on migrations-maven-plugin.<br>
24   * Call <code>mvn migration:help -Ddetail=true -Dgoal=&lt;goal-name&gt;</code> to display parameter details.
25   * @author maven-plugin-tools
26   */
27  @Mojo( name = "help", requiresProject = false, threadSafe = true )
28  public class HelpMojo
29      extends AbstractMojo
30  {
31      /**
32       * If <code>true</code>, display all settable properties for each goal.
33       *
34       */
35      @Parameter( property = "detail", defaultValue = "false" )
36      private boolean detail;
37  
38      /**
39       * The name of the goal for which to show help. If unspecified, all goals will be displayed.
40       *
41       */
42      @Parameter( property = "goal" )
43      private java.lang.String goal;
44  
45      /**
46       * The maximum length of a display line, should be positive.
47       *
48       */
49      @Parameter( property = "lineLength", defaultValue = "80" )
50      private int lineLength;
51  
52      /**
53       * The number of spaces per indentation level, should be positive.
54       *
55       */
56      @Parameter( property = "indentSize", defaultValue = "2" )
57      private int indentSize;
58  
59      // /META-INF/maven/<groupId>/<artifactId>/plugin-help.xml
60      private static final String PLUGIN_HELP_PATH =
61                      "/META-INF/maven/org.mybatis.maven/migrations-maven-plugin/plugin-help.xml";
62  
63      private static final int DEFAULT_LINE_LENGTH = 80;
64  
65      private Document build()
66          throws MojoExecutionException
67      {
68          getLog().debug( "load plugin-help.xml: " + PLUGIN_HELP_PATH );
69          try ( InputStream is = getClass().getResourceAsStream( PLUGIN_HELP_PATH ) )
70          {
71              if ( is == null )
72              {
73                  throw new MojoExecutionException( "Could not find plugin descriptor at " + PLUGIN_HELP_PATH );
74              }
75              DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
76              DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
77              return dBuilder.parse( is );
78          }
79          catch ( IOException e )
80          {
81              throw new MojoExecutionException( e.getMessage(), e );
82          }
83          catch ( ParserConfigurationException e )
84          {
85              throw new MojoExecutionException( e.getMessage(), e );
86          }
87          catch ( SAXException e )
88          {
89              throw new MojoExecutionException( e.getMessage(), e );
90          }
91      }
92  
93      /**
94       * {@inheritDoc}
95       */
96      @Override
97      public void execute()
98          throws MojoExecutionException
99      {
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 }