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/*
 * Copyright (c) 1997, 2023 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.eclipse.angus.mail.util;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.logging.Level;

/**
 * This class is a FilterInputStream that writes the bytes
 * being read from the given input stream into the given output
 * stream. This class is typically used to provide a trace of
 * the data that is being retrieved from an input stream.
 *
 * @author John Mani
 */

public class TraceInputStream extends FilterInputStream {
    private boolean trace = false;
    private boolean quote = false;
    private OutputStream traceOut;

    /**
     * Creates an input stream filter built on top of the specified
     * input stream.
     *
     * @param in     the underlying input stream.
     * @param logger log trace here
     */
    public TraceInputStream(InputStream in, MailLogger logger) {
        super(in);
        this.trace = logger.isLoggable(Level.FINEST);
        this.traceOut = new LogOutputStream(logger);
    }

    /**
     * Creates an input stream filter built on top of the specified
     * input stream.
     *
     * @param in the underlying input stream.
     * @param    traceOut    the trace stream.
     */
    public TraceInputStream(InputStream in, OutputStream traceOut) {
        super(in);
        this.traceOut = traceOut;
    }

    /**
     * Set trace mode.
     *
     * @param    trace    the trace mode
     */
    public void setTrace(boolean trace) {
        this.trace = trace;
    }

    /**
     * Set quote mode.
     *
     * @param    quote    the quote mode
     */
    public void setQuote(boolean quote) {
        this.quote = quote;
    }

    /**
     * Reads the next byte of data from this input stream. Returns
     * -1 if no data is available. Writes out the read
     * byte into the trace stream, if trace mode is true
     */
    @Override
    public int read() throws IOException {
        int b = in.read();
        if (trace && b != -1) {
            if (quote)
                writeByte(b);
            else
                traceOut.write(b);
        }
        return b;
    }

    /**
     * Reads up to len bytes of data from this input stream
     * into an array of bytes. Returns -1 if no more data
     * is available. Writes out the read bytes into the trace stream, if
     * trace mode is true
     */
    @Override
    public int read(byte[] b, int off, int len) throws IOException {
        int count = in.read(b, off, len);
        if (trace && count != -1) {
            if (quote) {
                for (int i = 0; i < count; i++)
                    writeByte(b[off + i]);
            } else
                traceOut.write(b, off, count);
        }
        return count;
    }

    /**
     * Write a byte in a way that every byte value is printable ASCII.
     */
    private final void writeByte(int b) throws IOException {
        b &= 0xff;
        if (b > 0x7f) {
            traceOut.write('M');
            traceOut.write('-');
            b &= 0x7f;
        }
        if (b == '\r') {
            traceOut.write('\\');
            traceOut.write('r');
        } else if (b == '\n') {
            traceOut.write('\\');
            traceOut.write('n');
            traceOut.write('\n');
        } else if (b == '\t') {
            traceOut.write('\\');
            traceOut.write('t');
        } else if (b < ' ') {
            traceOut.write('^');
            traceOut.write('@' + b);
        } else {
            traceOut.write(b);
        }
    }
}