/*
    * 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
    *
   *   https://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 java.util.Iterator;
  import java.util.stream.Stream;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.util.Args;
  
  /**
   * This class is derived from <em>Attribute</em> and denotes that this class is an Inner class of another. to the source
   * file of this class. It is instantiated from the <em>Attribute.readAttribute()</em> method.
   *
   * @see Attribute
   */
  public final class InnerClasses extends Attribute implements Iterable<InnerClass> {
  
      /**
       * Empty array.
       */
      private static final InnerClass[] EMPTY_ARRAY = {};
  
      private InnerClass[] innerClasses;
  
      /**
       * Initialize from another object. Note that both objects use the same references (shallow copy). Use clone() for a
       * physical copy.
       *
       * @param c Source to copy.
       */
      public InnerClasses(final InnerClasses c) {
          this(c.getNameIndex(), c.getLength(), c.getInnerClasses(), c.getConstantPool());
      }
  
      /**
       * Constructs object from input stream.
       *
       * @param nameIndex Index in constant pool to CONSTANT_Utf8.
       * @param length Content length in bytes.
       * @param input Input stream.
       * @param constantPool Array of constants.
       * @throws IOException if an I/O error occurs.
       */
      InnerClasses(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
          this(nameIndex, length, (InnerClass[]) null, constantPool);
          final int classCount = input.readUnsignedShort();
          innerClasses = new InnerClass[classCount];
          for (int i = 0; i < classCount; i++) {
              innerClasses[i] = new InnerClass(input);
          }
      }
  
      /**
       * Constructs an InnerClasses attribute.
       *
       * @param nameIndex Index in constant pool to CONSTANT_Utf8.
       * @param length Content length in bytes.
       * @param innerClasses array of inner classes attributes.
       * @param constantPool Array of constants.
       */
      public InnerClasses(final int nameIndex, final int length, final InnerClass[] innerClasses, final ConstantPool constantPool) {
          super(Const.ATTR_INNER_CLASSES, nameIndex, length, constantPool);
          this.innerClasses = innerClasses != null ? innerClasses : EMPTY_ARRAY;
          Args.requireU2(this.innerClasses.length, "innerClasses.length");
      }
  
      /**
       * 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.visitInnerClasses(this);
      }
  
      /**
      * Creates a deep copy of this attribute.
      *
      * @return deep copy of this attribute.
      */
     @Override
     public Attribute copy(final ConstantPool constantPool) {
         // TODO this could be recoded to use a lower level constructor after creating a copy of the inner classes
         final InnerClasses c = (InnerClasses) clone();
         c.innerClasses = new InnerClass[innerClasses.length];
         Arrays.setAll(c.innerClasses, i -> innerClasses[i].copy());
         c.setConstantPool(constantPool);
         return c;
     }
 
     /**
      * Dumps source file 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(innerClasses.length);
         for (final InnerClass innerClass : innerClasses) {
             innerClass.dump(file);
         }
     }
 
     /**
      * Gets the array of inner class records.
      *
      * @return array of inner class "records".
      */
     public InnerClass[] getInnerClasses() {
         return innerClasses;
     }
 
     @Override
     public Iterator<InnerClass> iterator() {
         return Stream.of(innerClasses).iterator();
     }
 
     /**
      * Sets the array of inner classes.
      *
      * @param innerClasses the array of inner classes.
      */
     public void setInnerClasses(final InnerClass[] innerClasses) {
         this.innerClasses = innerClasses != null ? innerClasses : EMPTY_ARRAY;
     }
 
     /**
      * @return String representation.
      */
     @Override
     public String toString() {
         final StringBuilder buf = new StringBuilder();
         buf.append("InnerClasses(");
         buf.append(innerClasses.length);
         buf.append("):\n");
         for (final InnerClass innerClass : innerClasses) {
             buf.append(innerClass.toString(super.getConstantPool())).append("\n");
         }
         return buf.substring(0, buf.length() - 1); // remove the last newline
     }
 }