/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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.apache.bcel.classfile;
  
  import java.io.DataInput;
  import java.io.DataOutputStream;
  import java.io.IOException;
  import java.util.Arrays;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.util.Args;
  import org.apache.commons.lang3.ArrayUtils;
  
  /**
   * This class is derived from <em>Attribute</em> and records the classes and interfaces that are authorized to claim
   * membership in the nest hosted by the current class or interface. There may be at most one NestMembers attribute in a
   * ClassFile structure.
   *
   * @see Attribute
   */
  public final class NestMembers extends Attribute {
  
      private int[] classes;
  
      /**
       * Constructs object from input stream.
       *
       * @param nameIndex Index in constant pool
       * @param length Content length in bytes
       * @param input Input stream
       * @param constantPool Array of constants
       * @throws IOException if an I/O error occurs.
       */
      NestMembers(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
          this(nameIndex, length, (int[]) null, constantPool);
          final int classCount = input.readUnsignedShort();
          classes = new int[classCount];
          for (int i = 0; i < classCount; i++) {
              classes[i] = input.readUnsignedShort();
          }
      }
  
      /**
       * @param nameIndex Index in constant pool
       * @param length Content length in bytes
       * @param classes Table of indices in constant pool
       * @param constantPool Array of constants
       */
      public NestMembers(final int nameIndex, final int length, final int[] classes, final ConstantPool constantPool) {
          super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
          this.classes = ArrayUtils.nullToEmpty(classes);
          Args.requireU2(this.classes.length, "classes.length");
      }
  
      /**
       * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
       * physical copy.
       *
       * @param c Source to copy.
       */
      public NestMembers(final NestMembers c) {
          this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
      }
  
      /**
       * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
       * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
       *
       * @param v Visitor object
       */
      @Override
      public void accept(final Visitor v) {
          v.visitNestMembers(this);
      }
  
      /**
       * @return deep copy of this attribute
       */
      @Override
      public Attribute copy(final ConstantPool constantPool) {
          final NestMembers c = (NestMembers) clone();
          if (classes.length > 0) {
              c.classes = classes.clone();
          }
         c.setConstantPool(constantPool);
         return c;
     }
 
     /**
      * Dump NestMembers attribute to file stream in binary format.
      *
      * @param file Output file stream
      * @throws IOException if an I/O error occurs.
      */
     @Override
     public void dump(final DataOutputStream file) throws IOException {
         super.dump(file);
         file.writeShort(classes.length);
         for (final int index : classes) {
             file.writeShort(index);
         }
     }
 
     /**
      * @return array of indices into constant pool of class names.
      */
     public int[] getClasses() {
         return classes;
     }
 
     /**
      * @return string array of class names
      */
     public String[] getClassNames() {
         final String[] names = new String[classes.length];
         Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(classes[i], Const.CONSTANT_Class)));
         return names;
     }
 
     /**
      * @return Length of classes table.
      */
     public int getNumberClasses() {
         return classes.length;
     }
 
     /**
      * @param classes the list of class indexes Also redefines number_of_classes according to table length.
      */
     public void setClasses(final int[] classes) {
         this.classes = ArrayUtils.nullToEmpty(classes);
     }
 
     /**
      * @return String representation, i.e., a list of classes.
      */
     @Override
     public String toString() {
         final StringBuilder buf = new StringBuilder();
         buf.append("NestMembers(");
         buf.append(classes.length);
         buf.append("):\n");
         for (final int index : classes) {
             final String className = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
             buf.append("  ").append(Utility.compactClassName(className, false)).append("\n");
         }
         return buf.substring(0, buf.length() - 1); // remove the last newline
     }
 }