/*
    * 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.IOException;
  import java.util.Objects;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.generic.Type;
  import org.apache.bcel.util.BCELComparator;
  
  /**
   * This class represents the field info structure, that is, the representation for a variable in the class. See JVM
   * specification for details.
   */
  public final class Field extends FieldOrMethod {
  
      /**
       * Empty array constant.
       *
       * @since 6.6.0
       */
      public static final Field[] EMPTY_ARRAY = {};
  
      private static BCELComparator<Field> bcelComparator = new BCELComparator<Field>() {
  
          @Override
          public boolean equals(final Field a, final Field b) {
              return a == b || a != null && b != null && Objects.equals(a.getName(), b.getName()) && Objects.equals(a.getSignature(), b.getSignature());
          }
  
          @Override
          public int hashCode(final Field o) {
              return o != null ? Objects.hash(o.getSignature(), o.getName()) : 0;
          }
      };
  
      /**
       * Gets the comparison strategy object.
       *
       * @return Comparison strategy object.
       */
      public static BCELComparator<Field> getComparator() {
          return bcelComparator;
      }
  
      /**
       * Sets the comparison strategy object.
       *
       * @param comparator Comparison strategy object.
       */
      public static void setComparator(final BCELComparator<Field> comparator) {
          bcelComparator = comparator;
      }
  
      /**
       * Constructs object from file stream.
       *
       * @param file Input stream.
       * @param constantPool the constant pool.
       */
      Field(final DataInput file, final ConstantPool constantPool) throws IOException, ClassFormatException {
          super(file, constantPool);
      }
  
      /**
       * 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 Field(final Field c) {
          super(c);
      }
  
      /**
       * Constructs a Field.
       *
       * @param accessFlags Access rights of field.
       * @param nameIndex Points to field name in constant pool.
       * @param signatureIndex Points to encoded signature.
       * @param attributes Collection of attributes.
      * @param constantPool Array of constants.
      */
     public Field(final int accessFlags, final int nameIndex, final int signatureIndex, final Attribute[] attributes, final ConstantPool constantPool) {
         super(accessFlags, nameIndex, signatureIndex, attributes, constantPool);
     }
 
     /**
      * 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.visitField(this);
     }
 
     /**
      * Creates a deep copy of this field.
      *
      * @param constantPool the constant pool.
      * @return deep copy of this field.
      */
     public Field copy(final ConstantPool constantPool) {
         return (Field) copy_(constantPool);
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default two Field objects are said to be equal when
      * their names and signatures are equal.
      *
      * @see Object#equals(Object)
      */
     @Override
     public boolean equals(final Object obj) {
         return obj instanceof Field && bcelComparator.equals(this, (Field) obj);
     }
 
     /**
      * Gets the constant value associated with this field.
      *
      * @return constant value associated with this field (may be null).
      */
     public ConstantValue getConstantValue() {
         for (final Attribute attribute : super.getAttributes()) {
             if (attribute.getTag() == Const.ATTR_CONSTANT_VALUE) {
                 return (ConstantValue) attribute;
             }
         }
         return null;
     }
 
     /**
      * See https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.2.2
      *
      * @return type of field.
      */
     public Type getType() {
         return Type.getType(getSignature());
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default return the hash code of the field's name XOR
      * signature.
      *
      * @see Object#hashCode()
      */
     @Override
     public int hashCode() {
         return bcelComparator.hashCode(this);
     }
 
     /**
      * Return string representation close to declaration format, for example: 'public static final short MAX = 100'.
      *
      * @return String representation of field, including the signature.
      */
     @Override
     public String toString() {
         // Get names from constant pool
         String access = Utility.accessToString(super.getAccessFlags());
         access = access.isEmpty() ? "" : access + " ";
         final String signature = Utility.signatureToString(getSignature());
         final String name = getName();
         final StringBuilder buf = new StringBuilder(64); // CHECKSTYLE IGNORE MagicNumber
         buf.append(access).append(signature).append(" ").append(name);
         final ConstantValue cv = getConstantValue();
         if (cv != null) {
             buf.append(" = ").append(cv);
         }
         for (final Attribute attribute : super.getAttributes()) {
             if (!(attribute instanceof ConstantValue)) {
                 buf.append(" [").append(attribute).append("]");
             }
         }
         return buf.toString();
     }
 }