/*
 * 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.nio.charset.StandardCharsets;
import java.util.Objects;

/**
 * UTF8 constant pool entry, used for storing long Strings.
 */
public class CPUTF8 extends ConstantPoolEntry {

    private final String utf8;

    private boolean hashCodeComputed;

    private int cachedHashCode;

    /**
     * Constructs a new instance.
     *
     * @param string a constant pool string.
     */
    public CPUTF8(final String string) {
        this(string, -1);
    }

    /**
     * Creates a new instance
     *
     * @param string      a constant pool string.
     * @param globalIndex index in CpBands
     * @throws NullPointerException if utf8 is null.
     */
    public CPUTF8(final String string, final int globalIndex) {
        super(CP_UTF8, globalIndex);
        this.utf8 = Objects.requireNonNull(string, "utf8");
    }

    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null || this.getClass() != obj.getClass()) {
            return false;
        }
        final CPUTF8 other = (CPUTF8) obj;
        return utf8.equals(other.utf8);
    }

    private void generateHashCode() {
        hashCodeComputed = true;
        final int PRIME = 31;
        cachedHashCode = PRIME + utf8.hashCode();
    }

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

    /**
     * Sets the global index.
     *
     * @param index the global index.
     */
    public void setGlobalIndex(final int index) {
        globalIndex = index;
    }

    @Override
    public String toString() {
        return StandardCharsets.UTF_8.name() + ":" + utf8;
    }

    /**
     * Gets the underlying string.
     *
     * @return the underlying string.
     */
    public String underlyingString() {
        return utf8;
    }

    @Override
    protected void writeBody(final DataOutputStream dos) throws IOException {
        dos.writeUTF(utf8);
    }
}
