/*
    * 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.commons.compress.harmony.unpack200.bytecode;
  
  import java.io.DataOutputStream;
  import java.io.IOException;
  import java.util.Objects;
  
  /**
   * An {@link Attribute} representing a constant.
   */
  public class ConstantValueAttribute extends Attribute {
  
      private static CPUTF8 attributeName;
  
      public static void setAttributeName(final CPUTF8 cpUTF8Value) {
          attributeName = cpUTF8Value;
      }
  
      private int constantIndex;
  
      private final ClassFileEntry entry;
  
      /**
       * Constructs a new instance.
       *
       * @param entry an entry.
       */
      public ConstantValueAttribute(final ClassFileEntry entry) {
          super(attributeName);
          this.entry = Objects.requireNonNull(entry, "entry");
      }
  
      @Override
      public boolean equals(final Object obj) {
          if (this == obj) {
              return true;
          }
          if (!super.equals(obj) || this.getClass() != obj.getClass()) {
              return false;
          }
          final ConstantValueAttribute other = (ConstantValueAttribute) obj;
          return Objects.equals(entry, other.entry);
      }
  
      @Override
      protected int getLength() {
          return 2;
      }
  
      @Override
      protected ClassFileEntry[] getNestedClassFileEntries() {
          return new ClassFileEntry[] { getAttributeName(), entry };
      }
  
      @Override
      public int hashCode() {
          final int PRIME = 31;
          int result = super.hashCode();
          result = PRIME * result + (entry == null ? 0 : entry.hashCode());
          return result;
      }
  
      @Override
      protected void resolve(final ClassConstantPool pool) {
          super.resolve(pool);
          entry.resolve(pool);
          this.constantIndex = pool.indexOf(entry);
      }
  
      @Override
      public String toString() {
          return "Constant:" + entry;
      }
  
      @Override
      protected void writeBody(final DataOutputStream dos) throws IOException {
          dos.writeShort(constantIndex);
      }
  
  }