/*
 * 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 org.apache.bcel.Const;
import org.apache.bcel.util.Args;

/**
 * Extends {@link Attribute} and records the classes and
 * interfaces that are authorized to claim membership in the nest hosted by the
 * current class or interface. There may be at most one Record attribute in a
 * ClassFile structure.
 *
 * @see Attribute
 * @since 6.9.0
 */
public final class Record extends Attribute {

    private static final RecordComponentInfo[] EMPTY_RCI_ARRAY = {};

    private static RecordComponentInfo[] readComponents(final DataInput input, final ConstantPool constantPool, final boolean compactCodeHeader)
            throws IOException {
        final int classCount = input.readUnsignedShort();
        final RecordComponentInfo[] components = new RecordComponentInfo[classCount];
        for (int i = 0; i < classCount; i++) {
            components[i] = new RecordComponentInfo(input, constantPool, compactCodeHeader);
        }
        return components;
    }

    private RecordComponentInfo[] components;

    /**
     * Constructs a Record attribute from a data input using standard Code headers for nested attributes.
     *
     * @param nameIndex    Constant pool index of the attribute name.
     * @param length       Content length in bytes.
     * @param input        Input stream.
     * @param constantPool The constant pool.
     * @throws IOException Thrown if an I/O error occurs.
     * @throws ClassFormatException Thrown if the attribute or one of its components is malformed.
     */
    Record(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool)
            throws IOException {
        this(nameIndex, length, input, constantPool, false);
    }

    /**
     * Constructs a Record attribute from a data input using the selected Code header layout for nested attributes.
     *
     * <p>
     * The header selection is forwarded when reading component attributes; it does not change the Record attribute or record component layout.
     * </p>
     *
     * @param nameIndex Constant pool index of the attribute name.
     * @param length Content length in bytes.
     * @param input Input stream.
     * @param constantPool The constant pool.
     * @param compactCodeHeader Whether to read any Code attributes encountered with compact four-byte headers ({@code true})
     *        or standard eight-byte headers ({@code false}).
     * @throws IOException Thrown if an I/O error occurs.
     * @throws ClassFormatException Thrown if the attribute or one of its components is malformed.
     * @see Attribute#readAttribute(DataInput, ConstantPool, boolean)
     */
    Record(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool, final boolean compactCodeHeader)
            throws IOException {
        this(nameIndex, length, readComponents(input, constantPool, compactCodeHeader), constantPool);
    }

    /**
     * Constructs a new instance using components.
     *
     * @param nameIndex    Index in constant pool.
     * @param length       Content length in bytes.
     * @param classes      Array of Record Component Info elements.
     * @param constantPool Array of constants.
     */
    public Record(final int nameIndex, final int length, final RecordComponentInfo[] classes,
            final ConstantPool constantPool) {
        super(Const.ATTR_RECORD, nameIndex, length, constantPool);
        this.components = classes != null ? classes : EMPTY_RCI_ARRAY;
        Args.requireU2(this.components.length, "attributes.length");
    }

    /**
     * Called by objects that are traversing the nodes of the tree implicitly
     * defined by the contents of a Java class. For example, the hierarchy of methods,
     * fields, attributes, and other elements forms a tree of objects.
     *
     * @param v Visitor object.
     */
    @Override
    public void accept(final Visitor v) {
        v.visitRecord(this);
    }

    /**
     * Copies this instance and its components.
     *
     * @return A deep copy of this instance and its components.
     */
    @Override
    public Attribute copy(final ConstantPool constantPool) {
        final Record c = (Record) clone();
        if (components.length > 0) {
            c.components = components.clone();
        }
        c.setConstantPool(constantPool);
        return c;
    }

    /**
     * Dumps this instance into a file stream in binary format.
     *
     * @param file output stream.
     * @throws IOException Thrown if an I/O error occurs.
     */
    @Override
    public void dump(final DataOutputStream file) throws IOException {
        super.dump(file);
        file.writeShort(Args.requireU2(components.length, "components.length"));
        for (final RecordComponentInfo component : components) {
            component.dump(file);
        }
    }

    /**
     * Gets all the record components.
     *
     * @return array of Record Component Info elements.
     */
    public RecordComponentInfo[] getComponents() {
        return components;
    }

    /**
     * Converts this instance to a String suitable for debugging.
     *
     * @return String a String suitable for debugging.
     */
    @Override
    public String toString() {
        final StringBuilder buf = new StringBuilder();
        buf.append("Record(");
        buf.append(components.length);
        buf.append("):\n");
        for (final RecordComponentInfo component : components) {
            buf.append("  ").append(component.toString()).append("\n");
        }
        return buf.substring(0, buf.length() - 1); // remove the last newline
    }

}