/*
 * Copyright 1999-2006 University of Chicago
 * 
 * Licensed 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
 * 
 * http://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.dcache.ftp.client.dc;

import java.io.ByteArrayOutputStream;

import org.dcache.ftp.client.Buffer;

public class AsciiTranslator
{

    public static final byte[] CRLF = {'\r', '\n'};

    protected boolean possibleBreak = false;

    /* enables checking for \r\n */
    protected final boolean rnSep;
    /* enables checking for \n */
    protected final boolean nSep;

    protected final byte[] lineSep;

    protected static final byte[] systemLineSep;

    static {
        systemLineSep = System.getProperty("line.separator").getBytes();
    }

    /**
     * Output tokens with system specific line separators
     */
    public AsciiTranslator(boolean rnSep,
                           boolean nSep)
    {
        this(rnSep, nSep, systemLineSep);
    }

    public AsciiTranslator(boolean rnSep,
                           boolean nSep,
                           byte[] lineSeparator)
    {
        this.rnSep = rnSep;
        this.nSep = nSep;
        this.lineSep = lineSeparator;
    }

    public Buffer translate(Buffer buffer)
    {
        // TODO: This can be optimized if destination line separator
        // is the same
        byte[] buf = buffer.getBuffer();
        int len = buffer.getLength();
        int bufLastPos = 0;

        ByteArrayOutputStream byteArray = new ByteArrayOutputStream(len);

        if (possibleBreak) {
            if (len > 0 && buf[0] == '\n') {
                byteArray.write(lineSep, 0, lineSep.length);
                bufLastPos = 1;
            } else {
                byteArray.write('\r');
            }
            possibleBreak = false;
        }

        byte ch;
        for (int i = bufLastPos; i < len; i++) {
            ch = buf[i];
            if (rnSep && ch == '\r') {
                if (i + 1 == len) {
                    // TODO: must test this condition but it might be rare
                    // append everything to the buffer except last byte
                    byteArray.write(buf, bufLastPos, i - bufLastPos);
                    bufLastPos = len;
                    possibleBreak = true;
                    break;
                }

                if (buf[i + 1] == '\n') {
                    i++;
                    byteArray.write(buf, bufLastPos, i - 1 - bufLastPos);
                    byteArray.write(lineSep, 0, lineSep.length);
                    bufLastPos = ++i;
                }
            } else if (nSep && ch == '\n') {
                byteArray.write(buf, bufLastPos, i - bufLastPos);
                byteArray.write(lineSep, 0, lineSep.length);
                bufLastPos = i + 1;
            }
        }

        if (bufLastPos < len) {
            byteArray.write(buf, bufLastPos, len - bufLastPos);
        }

        byte[] newBuf = byteArray.toByteArray();
        return new Buffer(newBuf, newBuf.length, buffer.getOffset());
    }

}