/*

 * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.tools.jaotc.binformat;

import jdk.tools.jaotc.binformat.Symbol.Binding;

import jdk.tools.jaotc.binformat.Symbol.Kind;

import java.io.ByteArrayOutputStream;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.util.Arrays;

/**

 * Base class that represents content of all sections with byte-level granularity. The ByteContainer

 * class is backed by a ByteArrayOutputStream. This class supports writing all desired byte content

 * to the container using the method {@code appendBytes} and accessing the byte array using the

 * method {@code getByteArray}.

 *

 * The method {@code putIntAt} updates the content of {@code contentBytes}. Changes are not

 * reflected in {@code contentStream}.

 */

public class ByteContainer implements Container {

    /**

     * {@code ByteBuffer} representation of {@code BinaryContainer}.

     */

    private ByteBuffer contentBytes;

    /**

     * {@code ByteArrayoutputStream} to which all appends are done.

     */

    private ByteArrayOutputStream contentStream;

    /**

     * Boolean to indicate if contentBytes was modified.

     */

    private boolean bufferModified;

    /**

     * Boolean to indicate if this section contains any relocations.

     */

    private boolean hasRelocations;

    /**

     * Name of this container, used as section name.

     */

    private String containerName;

    private final SymbolTable symbolTable;

    /**

     * Contains a unique id.

     */

    private int sectionId = -1;

    /**

     * Construct a {@code ByteContainer} object.

     */

    public ByteContainer(String containerName, SymbolTable symbolTable) {

        this.containerName = containerName;

        this.symbolTable = symbolTable;

        this.contentBytes = null;

        this.bufferModified = false;

        this.hasRelocations = false;

        this.contentStream = new ByteArrayOutputStream();

    }

    /**

     * Update byte buffer to reflect the current contents of byte stream.

     *

     * @throws InternalError throws {@code InternalError} if buffer byte array was modified

     */

    private void updateByteBuffer() {

        if (!bufferModified) {

            contentBytes = ByteBuffer.wrap(contentStream.toByteArray());

            // Default byte order of ByteBuffer is BIG_ENDIAN.

            // Set it appropriately

            this.contentBytes.order(ByteOrder.nativeOrder());

        } else {

            throw new InternalError("Backing byte buffer no longer in sync with byte stream");

        }

    }

    /**

     * Get the byte array of {@code ByteContainer}.

     *

     * @return byte array

     * @throws InternalError throws {@code InternalError} if buffer byte array was modified

     */

    public byte[] getByteArray() {

        if (!bufferModified) {

            updateByteBuffer();

        }

        return contentBytes.array();

    }

    /**

     * Append to byte stream. It is an error to append to stream if the byte buffer version is

     * changed.

     *

     * @param newBytes new content

     * @param off offset start offset in {@code newBytes}

     * @param len length of data to write

     * @throws InternalError throws {@code InternalError} if buffer byte array was modified

     */

    public ByteContainer appendBytes(byte[] newBytes, int off, int len) {

        if (bufferModified) {

            throw new InternalError("Backing byte buffer no longer in sync with byte stream");

        }

        contentStream.write(newBytes, off, len);

        return this;

    }

    public ByteContainer appendBytes(byte[] newBytes) {

        appendBytes(newBytes, 0, newBytes.length);

        return this;

    }

    public ByteContainer appendInt(int i) {

        if (bufferModified) {

            throw new InternalError("Backing byte buffer no longer in sync with byte stream");

        }

        ByteBuffer b = ByteBuffer.allocate(Integer.BYTES);

        b.order(ByteOrder.nativeOrder());

        b.putInt(i);

        byte[] result = b.array();

        contentStream.write(result, 0, result.length);

        return this;

    }

    public ByteContainer appendInts(int[] newInts) {

        if (bufferModified) {

            throw new InternalError("Backing byte buffer no longer in sync with byte stream");

        }

        ByteBuffer b = ByteBuffer.allocate(Integer.BYTES * newInts.length).order(ByteOrder.nativeOrder());

        Arrays.stream(newInts).forEach(i -> b.putInt(i));

        byte[] result = b.array();

        contentStream.write(result, 0, result.length);

        return this;

    }

    public void appendLong(long l) {

        if (bufferModified) {

            throw new InternalError("Backing byte buffer no longer in sync with byte stream");

        }

        ByteBuffer b = ByteBuffer.allocate(8);

        b.order(ByteOrder.nativeOrder());

        b.putLong(l);

        byte[] result = b.array();

        contentStream.write(result, 0, result.length);

    }

    /**

     * Return the current size of byte stream backing the BinaryContainer.

     *

     * @return size of buffer stream

     */

    public int getByteStreamSize() {

        return contentStream.size();

    }

    /**

     * Return the name of this container.

     *

     * @return string containing name

     */

    @Override

    public String getContainerName() {

        return containerName;

    }

    /**

     * Modify the byte buffer version of the byte output stream. Note that after calling this method

     * all further updates to BinaryContainer will be out of sync with byte buffer content.

     *

     * @param index index of byte to be changed

     * @param value new value

     */

    public void putIntAt(int index, int value) {

        if (!bufferModified) {

            updateByteBuffer();

        }

        contentBytes.putInt(index, value);

        bufferModified = true;

    }

    public void putLongAt(int index, long value) {

        if (!bufferModified) {

            updateByteBuffer();

        }

        contentBytes.putLong(index, value);

        bufferModified = true;

    }

    public void setSectionId(int id) {

        if (sectionId != -1) {

            throw new InternalError("Assigning new sectionId (old: " + sectionId + ", new: " + id + ")");

        }

        sectionId = id;

    }

    @Override

    public int getSectionId() {

        if (sectionId == -1) {

            throw new InternalError("Using sectionId before assigned");

        }

        return sectionId;

    }

    public Symbol createSymbol(int offset, Kind kind, Binding binding, int size, String name) {

        Symbol symbol = new Symbol(offset, kind, binding, this, size, name);

        symbolTable.addSymbol(symbol);

        return symbol;

    }

    public GotSymbol createGotSymbol(String name) {

        GotSymbol symbol = new GotSymbol(Kind.OBJECT, Binding.LOCAL, this, name);

        symbolTable.addSymbol(symbol);

        return symbol;

    }

    public GotSymbol createGotSymbol(int offset, String name) {

        GotSymbol symbol = new GotSymbol(offset, Kind.OBJECT, Binding.LOCAL, this, name);

        symbolTable.addSymbol(symbol);

        return symbol;

    }

    public void clear() {

        this.contentBytes = null;

        this.contentStream = null;

    }

    public void setHasRelocations() {

        this.hasRelocations = true;

    }

    public boolean hasRelocations() {

        return this.hasRelocations;

    }

}