/*

 * Copyright (c) 1995, 2015, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 sun.security.util;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.InputStream;

import java.io.PrintStream;

import java.io.OutputStream;

import java.io.IOException;

import java.nio.ByteBuffer;

/**

 * This class encodes a buffer into the classic: "Hexadecimal Dump" format of

 * the past. It is useful for analyzing the contents of binary buffers.

 * The format produced is as follows:

 * <pre>

 * xxxx: 00 11 22 33 44 55 66 77   88 99 aa bb cc dd ee ff ................

 * </pre>

 * Where xxxx is the offset into the buffer in 16 byte chunks, followed

 * by ascii coded hexadecimal bytes followed by the ASCII representation of

 * the bytes or '.' if they are not valid bytes.

 *

 * @author      Chuck McManis

 */

public class HexDumpEncoder {

    private int offset;

    private int thisLineLength;

    private int currentByte;

    private byte thisLine[] = new byte[16];

    static void hexDigit(PrintStream p, byte x) {

        char c;

        c = (char) ((x >> 4) & 0xf);

        if (c > 9)

            c = (char) ((c-10) + 'A');

        else

            c = (char)(c + '0');

        p.write(c);

        c = (char) (x & 0xf);

        if (c > 9)

            c = (char)((c-10) + 'A');

        else

            c = (char)(c + '0');

        p.write(c);

    }

    protected int bytesPerAtom() {

        return (1);

    }

    protected int bytesPerLine() {

        return (16);

    }

    protected void encodeBufferPrefix(OutputStream o) throws IOException {

        offset = 0;

        pStream = new PrintStream(o);

    }

    protected void encodeLinePrefix(OutputStream o, int len) throws IOException {

        hexDigit(pStream, (byte)((offset >>> 8) & 0xff));

        hexDigit(pStream, (byte)(offset & 0xff));

        pStream.print(": ");

        currentByte = 0;

        thisLineLength = len;

    }

    protected void encodeAtom(OutputStream o, byte buf[], int off, int len) throws IOException {

        thisLine[currentByte] = buf[off];

        hexDigit(pStream, buf[off]);

        pStream.print(" ");

        currentByte++;

        if (currentByte == 8)

            pStream.print("  ");

    }

    protected void encodeLineSuffix(OutputStream o) throws IOException {

        if (thisLineLength < 16) {

            for (int i = thisLineLength; i < 16; i++) {

                pStream.print("   ");

                if (i == 7)

                    pStream.print("  ");

            }

        }

        pStream.print(" ");

        for (int i = 0; i < thisLineLength; i++) {

            if ((thisLine[i] < ' ') || (thisLine[i] > 'z')) {

                pStream.print(".");

            } else {

                pStream.write(thisLine[i]);

            }

        }

        pStream.println();

        offset += thisLineLength;

    }

    /** Stream that understands "printing" */

    protected PrintStream pStream;

    /**

     * This method works around the bizarre semantics of BufferedInputStream's

     * read method.

     */

    protected int readFully(InputStream in, byte buffer[])

            throws java.io.IOException {

        for (int i = 0; i < buffer.length; i++) {

            int q = in.read();

            if (q == -1)

                return i;

            buffer[i] = (byte)q;

        }

        return buffer.length;

    }

    /**

     * Encode bytes from the input stream, and write them as text characters

     * to the output stream. This method will run until it exhausts the

     * input stream, but does not print the line suffix for a final

     * line that is shorter than bytesPerLine().

     */

    public void encode(InputStream inStream, OutputStream outStream)

        throws IOException

    {

        int     j;

        int     numBytes;

        byte    tmpbuffer[] = new byte[bytesPerLine()];

        encodeBufferPrefix(outStream);

        while (true) {

            numBytes = readFully(inStream, tmpbuffer);

            if (numBytes == 0) {

                break;

            }

            encodeLinePrefix(outStream, numBytes);

            for (j = 0; j < numBytes; j += bytesPerAtom()) {

                if ((j + bytesPerAtom()) <= numBytes) {

                    encodeAtom(outStream, tmpbuffer, j, bytesPerAtom());

                } else {

                    encodeAtom(outStream, tmpbuffer, j, (numBytes)- j);

                }

            }

            if (numBytes < bytesPerLine()) {

                break;

            } else {

                encodeLineSuffix(outStream);

            }

        }

    }

    /**

     * A 'streamless' version of encode that simply takes a buffer of

     * bytes and returns a string containing the encoded buffer.

     */

    public String encode(byte aBuffer[]) {

        ByteArrayOutputStream outStream = new ByteArrayOutputStream();

        ByteArrayInputStream    inStream = new ByteArrayInputStream(aBuffer);

        String retVal = null;

        try {

            encode(inStream, outStream);

            // explicit ascii->unicode conversion

            retVal = outStream.toString("ISO-8859-1");

        } catch (Exception IOException) {

            // This should never happen.

            throw new Error("CharacterEncoder.encode internal error");

        }

        return (retVal);

    }

    /**

     * Return a byte array from the remaining bytes in this ByteBuffer.

     * <P>

     * The ByteBuffer's position will be advanced to ByteBuffer's limit.

     * <P>

     * To avoid an extra copy, the implementation will attempt to return the

     * byte array backing the ByteBuffer.  If this is not possible, a

     * new byte array will be created.

     */

    private byte [] getBytes(ByteBuffer bb) {

        /*

         * This should never return a BufferOverflowException, as we're

         * careful to allocate just the right amount.

         */

        byte [] buf = null;

        /*

         * If it has a usable backing byte buffer, use it.  Use only

         * if the array exactly represents the current ByteBuffer.

         */

        if (bb.hasArray()) {

            byte [] tmp = bb.array();

            if ((tmp.length == bb.capacity()) &&

                    (tmp.length == bb.remaining())) {

                buf = tmp;

                bb.position(bb.limit());

            }

        }

        if (buf == null) {

            /*

             * This class doesn't have a concept of encode(buf, len, off),

             * so if we have a partial buffer, we must reallocate

             * space.

             */

            buf = new byte[bb.remaining()];

            /*

             * position() automatically updated

             */

            bb.get(buf);

        }

        return buf;

    }

    /**

     * A 'streamless' version of encode that simply takes a ByteBuffer

     * and returns a string containing the encoded buffer.

     * <P>

     * The ByteBuffer's position will be advanced to ByteBuffer's limit.

     */

    public String encode(ByteBuffer aBuffer) {

        byte [] buf = getBytes(aBuffer);

        return encode(buf);

    }

    /**

     * Encode bytes from the input stream, and write them as text characters

     * to the output stream. This method will run until it exhausts the

     * input stream. It differs from encode in that it will add the

     * line at the end of a final line that is shorter than bytesPerLine().

     */

    public void encodeBuffer(InputStream inStream, OutputStream outStream)

        throws IOException

    {

        int     j;

        int     numBytes;

        byte    tmpbuffer[] = new byte[bytesPerLine()];

        encodeBufferPrefix(outStream);

        while (true) {

            numBytes = readFully(inStream, tmpbuffer);

            if (numBytes == 0) {

                break;

            }

            encodeLinePrefix(outStream, numBytes);

            for (j = 0; j < numBytes; j += bytesPerAtom()) {

                if ((j + bytesPerAtom()) <= numBytes) {

                    encodeAtom(outStream, tmpbuffer, j, bytesPerAtom());

                } else {

                    encodeAtom(outStream, tmpbuffer, j, (numBytes)- j);

                }

            }

            encodeLineSuffix(outStream);

            if (numBytes < bytesPerLine()) {

                break;

            }

        }

    }

    /**

     * Encode the buffer in <i>aBuffer</i> and write the encoded

     * result to the OutputStream <i>aStream</i>.

     */

    public void encodeBuffer(byte aBuffer[], OutputStream aStream)

        throws IOException

    {

        ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer);

        encodeBuffer(inStream, aStream);

    }

    /**

     * A 'streamless' version of encode that simply takes a buffer of

     * bytes and returns a string containing the encoded buffer.

     */

    public String encodeBuffer(byte aBuffer[]) {

        ByteArrayOutputStream   outStream = new ByteArrayOutputStream();

        ByteArrayInputStream    inStream = new ByteArrayInputStream(aBuffer);

        try {

            encodeBuffer(inStream, outStream);

        } catch (Exception IOException) {

            // This should never happen.

            throw new Error("CharacterEncoder.encodeBuffer internal error");

        }

        return (outStream.toString());

    }

    /**

     * Encode the <i>aBuffer</i> ByteBuffer and write the encoded

     * result to the OutputStream <i>aStream</i>.

     * <P>

     * The ByteBuffer's position will be advanced to ByteBuffer's limit.

     */

    public void encodeBuffer(ByteBuffer aBuffer, OutputStream aStream)

        throws IOException

    {

        byte [] buf = getBytes(aBuffer);

        encodeBuffer(buf, aStream);

    }

}