/*
 * Copyright (c) 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 com.sun.tools.sjavac.server;

import java.io.FilterWriter;
import java.io.IOException;
import java.io.Writer;

/**
 * Inserts {@literal prefix} in front of each line written.
 *
 * A line is considered to be terminated by any one of a line feed, a carriage
 * return, or a carriage return followed immediately by a line feed.
 */
public class LinePrefixFilterWriter extends FilterWriter {

    private final String prefix;
    private boolean atBeginningOfLine = true;
    private char lastChar = '\0';

    protected LinePrefixFilterWriter(Writer out, String prefix) {
        super(out);
        this.prefix = prefix;
    }

    @Override
    public void write(String str, int off, int len) throws IOException {
        for (int i = 0; i < len; i++) {
            write(str.charAt(off + i));
        }
    }

    @Override
    public void write(char[] cbuf, int off, int len) throws IOException {
        for (int i = 0; i < len; i++) {
            write(cbuf[off + i]);
        }
    }

    @Override
    public void write(int c) throws IOException {
        if (lastChar == '\r' && c == '\n') {
            // Second character of CR+LF sequence.
            // Do nothing. We already started a new line on last character.
        } else {
            if (atBeginningOfLine) {
                super.write(prefix, 0, prefix.length());
            }
            super.write(c);
            atBeginningOfLine = c == '\r' || c == '\n';
        }
        lastChar = (char) c;
    }
}