package com.atlassian.plugin.osgi.util;
   
   import aQute.lib.osgi.ClassDataCollector;
   import aQute.lib.osgi.Clazz;
   import aQute.lib.osgi.Resource;
   import com.google.common.collect.ImmutableSet;
   import org.apache.commons.io.IOUtils;
   import org.apache.commons.lang.StringUtils;
   
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.Set;
  
  /**
   * Contains all the utility methods and classes for scanning class file binary.
   *
   * @since 2.10
   */
  public class ClassBinaryScanner
  {
      /**
       * Scans class binary to extract 1) referred classes 2) imported packages 3) the class's superclass.
       *
       * @param clazz the input class binary
       * @return result, never null
       * @throws java.io.IOException if the scan dies along the way
       *
       * @since 2.10
       */
      public static ScanResult scanClassBinary(Clazz clazz) throws IOException
      {
          final ImmutableSet.Builder<String> allReferredClasses = new ImmutableSet.Builder<String>();
          final String[] superClassName = new String[] { null };
          try
          {
              // TODO: Perhaps, we should start scanning for annotations as well. This ClassDataCollector in bndlib 1.4.3 is quite powerful.
              clazz.parseClassFileWithCollector(new ClassDataCollector() {
  
                  @Override
                  public void extendsClass(String name)
                  {
                      superClassName[0] = name;
                      allReferredClasses.add(name);
                  }
  
                  @Override
                  public void implementsInterfaces(String[] names)
                  {
                      for(String name:names)
                      {
                          allReferredClasses.add(name);
                      }
                  }
  
                  @Override
                  public void addReference(String name)
                  {
                      // the class name is in the form "abc.def.ghi" instead of "abc/def/ghi" which is different from other methods for unknown reason.
                      allReferredClasses.add(StringUtils.replace(name, ".", "/"));
                  }
              });
          }
          catch (Exception e)
          {
              throw new IOException("Error parsing class file", e);
          }
  
          return new ScanResult(allReferredClasses.build(), ImmutableSet.copyOf(clazz.getReferred()), superClassName[0]);
      }
  
      /**
       * Contains the result of class binary scanning.
       *
       * @since 2.10
       */
      public static class ScanResult
      {
          // this classes are referred to as strings since we don't want to load them all at this stage.
          private Set<String> referredClasses;
          private Set<String> referredPackages;
          private String superClass;
  
          public ScanResult(Set<String> referredClasses,  Set<String> referredPackages, String superClass)
          {
              this.referredClasses = referredClasses;
              this.referredPackages = referredPackages;
              this.superClass = superClass;
          }
  
          public Set<String> getReferredClasses()
          {
              return referredClasses;
          }
  
          public Set<String> getReferredPackages()
          {
              return referredPackages;
          }
 
         public String getSuperClass()
         {
             return superClass;
         }
     }
 
     /**
      * InputStream-based resource for class scanning purpose (in the format required by bndlib).
      *
      * @since 2.10
      */
     public static class InputStreamResource implements Resource
     {
         private String extra;
         private InputStream inputStream;
 
         public InputStreamResource(InputStream inputStream)
         {
             this.inputStream = inputStream;
         }
 
         public InputStream openInputStream() throws Exception
         {
             return inputStream;
         }
 
         public void write(OutputStream out) throws Exception
         {
             throw new UnsupportedOperationException("Not for write");
         }
 
         public long lastModified()
         {
             return -1;
         }
 
         public void setExtra(String extra)
         {
             this.extra = extra;
         }
 
         public String getExtra()
         {
             return extra;
         }
 
         public void close()
         {
             IOUtils.closeQuietly(inputStream);
         }
     }
 }