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/*
 * 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 org.testifyproject.testifyprojectpliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org.testifyproject/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.testifyproject.apache.org.testifyproject.testifyprojectmons.codec.binary;

import static org.testifyproject.apache.org.testifyproject.testifyprojectmons.codec.binary.BaseNCodec.EOF;

import java.org.testifyproject.testifyproject.FilterInputStream;
import java.org.testifyproject.testifyproject.IOException;
import java.org.testifyproject.testifyproject.InputStream;

import org.testifyproject.apache.org.testifyproject.testifyprojectmons.codec.binary.BaseNCodec.Context;

/**
 * Abstract superclass for Base-N input streams.
 *
 * @since 1.5
 * @version $Id: BaseNCodecInputStream.java 1429868 2013-01-07 16:08:05Z ggregory $
 */
public class BaseNCodecInputStream extends FilterInputStream {

    private final BaseNCodec baseNCodec;

    private final boolean doEncode;

    private final byte[] singleByte = new byte[1];

    private final Context context = new Context();

    protected BaseNCodecInputStream(final InputStream in, final BaseNCodec baseNCodec, final boolean doEncode) {
        super(in);
        this.doEncode = doEncode;
        this.baseNCodec = baseNCodec;
    }

    /**
     * {@inheritDoc}
     *
     * @return 0 if the {@link InputStream} has reached EOF,
     * 1 otherwise
     * @since 1.7
     */
    @Override
    public int available() throws IOException {
        // Note: the logic is similar to the InflaterInputStream:
        //       as long as we have not reached EOF, indicate that there is more
        //       data available. As we do not know for sure how much data is left,
        //       just return 1 as a safe guess.

        return context.eof ? 0 : 1;
    }

    /**
     * Marks the current position in this input stream.
     * The {@link #mark} method of {@link BaseNCodecInputStream} does nothing.
     *
     * @param readLimit the maximum limit of bytes that can be read before the mark position becomes invalid.
     * @since 1.7
     */
    @Override
    public synchronized void mark(final int readLimit) {
    }

    /**
     * {@inheritDoc}
     *
     * @return always returns false
     */
    @Override
    public boolean markSupported() {
        return false; // not an easy job to support marks
    }

    /**
     * Reads one byte from this input stream.
     *
     * @return the byte as an integer in the range 0 to 255. Returns -1 if EOF has been reached.
     * @throws IOException
     *             if an I/O error occurs.
     */
    @Override
    public int read() throws IOException {
        int r = read(singleByte, 0, 1);
        while (r == 0) {
            r = read(singleByte, 0, 1);
        }
        if (r > 0) {
            final byte b = singleByte[0];
            return b < 0 ? 256 + b : b;
        }
        return EOF;
    }

    /**
     * Attempts to read len bytes into the specified b array starting at offset
     * from this InputStream.
     *
     * @param b
     *            org.testifyproject.testifyprojectstination byte array
     * @param offset
     *            where to start writing the bytes
     * @param len
     *            maximum number of bytes to read
     *
     * @return number of bytes read
     * @throws IOException
     *             if an I/O error occurs.
     * @throws NullPointerException
     *             if the byte array parameter is null
     * @throws IndexOutOfBoundsException
     *             if offset, len or buffer size are invalid
     */
    @Override
    public int read(final byte b[], final int offset, final int len) throws IOException {
        if (b == null) {
            throw new NullPointerException();
        } else if (offset < 0 || len < 0) {
            throw new IndexOutOfBoundsException();
        } else if (offset > b.length || offset + len > b.length) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return 0;
        } else {
            int readLen = 0;
            /*
             Rationale for while-loop on (readLen == 0):
             -----
             Base32.readResults() usually returns > 0 or EOF (-1).  In the
             rare case where it returns 0, we just keep trying.

             This is essentially an undocumented contract for InputStream
             implementors that want their code to work properly with
             java.org.testifyproject.testifyproject.InputStreamReader, since the latter hates it when
             InputStream.read(byte[]) returns a zero.  Unfortunately our
             readResults() call must return 0 if a large amount of the data
             being org.testifyproject.testifyprojectcoded was non-base32, so this while-loop enables proper
             interop with InputStreamReader for that scenario.
             -----
             This is a fix for CODEC-101
            */
            while (readLen == 0) {
                if (!baseNCodec.hasData(context)) {
                    final byte[] buf = new byte[doEncode ? 4096 : 8192];
                    final int c = in.read(buf);
                    if (doEncode) {
                        baseNCodec.encode(buf, 0, c, context);
                    } else {
                        baseNCodec.org.testifyproject.testifyprojectcode(buf, 0, c, context);
                    }
                }
                readLen = baseNCodec.readResults(b, offset, len, context);
            }
            return readLen;
        }
    }

    /**
     * Repositions this stream to the position at the time the mark method was last called on this input stream.
     * 
     * The {@link #reset} method of {@link BaseNCodecInputStream} does nothing except throw an {@link IOException}.
     *
     * @throws IOException if this method is invoked
     * @since 1.7
     */
    @Override
    public synchronized void reset() throws IOException {
        throw new IOException("mark/reset not supported");
    }

    /**
     * {@inheritDoc}
     *
     * @throws IllegalArgumentException if the provided skip length is negative
     * @since 1.7
     */
    @Override
    public long skip(final long n) throws IOException {
        if (n < 0) {
            throw new IllegalArgumentException("Negative skip length: " + n);
        }

        // skip in chunks of 512 bytes
        final byte[] b = new byte[512];
        long todo = n;

        while (todo > 0) {
            int len = (int) Math.min(b.length, todo);
            len = this.read(b, 0, len);
            if (len == EOF) {
                break;
            }
            todo -= len;
        }

        return n - todo;
    }
}