/*
 * 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;

/**
 * Field reference constant pool entry.
 */
public class CPFieldRef extends ConstantPoolEntry {

    CPClass className;
    transient int classNameIndex;
    private final CPNameAndType nameAndType;
    transient int nameAndTypeIndex;

    private boolean hashCodeComputed;

    private int cachedHashCode;

    public CPFieldRef(final CPClass className, final CPNameAndType descriptor, final int globalIndex) {
        super(CP_Fieldref, globalIndex);
        this.className = className;
        this.nameAndType = descriptor;
    }

    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }
        final CPFieldRef other = (CPFieldRef) obj;
        return Objects.equals(className, other.className)
                && Objects.equals(nameAndType, other.nameAndType);
    }

    private void generateHashCode() {
        hashCodeComputed = true;
        final int PRIME = 31;
        int result = 1;
        result = PRIME * result + (className == null ? 0 : className.hashCode());
        result = PRIME * result + (nameAndType == null ? 0 : nameAndType.hashCode());
        cachedHashCode = result;
    }

    @Override
    protected ClassFileEntry[] getNestedClassFileEntries() {
        return new ClassFileEntry[] { className, nameAndType };
    }

    @Override
    public int hashCode() {
        if (!hashCodeComputed) {
            generateHashCode();
        }
        return cachedHashCode;
    }

    @Override
    protected void resolve(final ClassConstantPool pool) {
        super.resolve(pool);
        nameAndTypeIndex = pool.indexOf(nameAndType);
        classNameIndex = pool.indexOf(className);
    }

    @Override
    public String toString() {
        return "FieldRef: " + className + "#" + nameAndType;
    }

    @Override
    protected void writeBody(final DataOutputStream dos) throws IOException {
        dos.writeShort(classNameIndex);
        dos.writeShort(nameAndTypeIndex);
    }

}
