/*
    *  Copyright 2012 Chris Pheby
    *
    *  Licensed under the Apache License, Version 2.0 (the "License");
    *  you may not use this file except in compliance with the License.
    *  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
    *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   */
  package org.jadira.scanner.core.helper;
  
  import java.io.BufferedInputStream;
  import java.io.DataInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.WeakHashMap;
  
  import javassist.bytecode.ClassFile;
  
  public final class JavassistClassFileHelper {
  
  	private static final WeakHashMap<String, ClassFile> CLASSFILES_BY_NAME = new WeakHashMap<String, ClassFile>(1024, 0.6f);
  	private static final WeakHashMap<String, ClassFile> CLASSFILES_BY_FILE = new WeakHashMap<String, ClassFile>(1024, 0.6f);
  	
  	private static final int MAXIMUM_SIZE = 2048;
  	
  	private JavassistClassFileHelper() {
  	}
  	
      public static ClassFile constructClassFile(String className, InputStream bits) throws IOException {
  
  		ClassFile cachedClassFile = CLASSFILES_BY_NAME.get(className);
  		if (cachedClassFile != null) {
  			return cachedClassFile;
  		}
      	
      	DataInputStream dstream = new DataInputStream(new BufferedInputStream(bits));
          ClassFile cf = null;
          try {
              cf = new ClassFile(dstream);
          } finally {
              dstream.close();
              bits.close();
          }
          
          if (cf != null) {
          	CLASSFILES_BY_NAME.put(className, cf);
          }
          return cf;
      }
      
      public static ClassFile constructClassFileForPath(String path, InputStream bits) throws IOException {
  
  		ClassFile cachedClassFile = CLASSFILES_BY_FILE.get(path);
  		if (cachedClassFile != null) {
  			return cachedClassFile;
  		}
      	
      	DataInputStream dstream = new DataInputStream(new BufferedInputStream(bits));
          ClassFile cf = null;
          try {
              cf = new ClassFile(dstream);
          } finally {
              dstream.close();
              bits.close();
          }
          
          if (cf != null) {
          	if (CLASSFILES_BY_NAME.size() < MAXIMUM_SIZE) {
          		CLASSFILES_BY_NAME.put(cf.getName(), cf);
          	}
          	if (CLASSFILES_BY_FILE.size() < MAXIMUM_SIZE) {
          		CLASSFILES_BY_FILE.put(path, cf);
          	}
          }
          return cf;
      }}