/*
 *  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 compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      https://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.apache.tools.ant.filters;

import java.io.IOException;
import java.io.Reader;

import org.apache.tools.ant.types.Parameter;

Attaches a prefix to every line.
Example:
<prefixlines prefix="Foo"/>
Or:
<filterreader classname="org.apache.tools.ant.filters.PrefixLines">
 <param name="prefix" value="Foo"/>
</filterreader>
/**
 * Attaches a prefix to every line.
 *
 * Example:
 * <pre>&lt;prefixlines prefix=&quot;Foo&quot;/&gt;</pre>
 *
 * Or:
 *
 * <pre>&lt;filterreader classname=&quot;org.apache.tools.ant.filters.PrefixLines&quot;&gt;
 *  &lt;param name=&quot;prefix&quot; value=&quot;Foo&quot;/&gt;
 * &lt;/filterreader&gt;</pre>
 *
 */
public final class PrefixLines
    extends BaseParamFilterReader
    implements ChainableReader {
    
Parameter name for the prefix. /** Parameter name for the prefix. */
    private static final String PREFIX_KEY = "prefix";

    
The prefix to be used. /** The prefix to be used. */
    private String prefix = null;

    
Data that must be read from, if not null. /** Data that must be read from, if not null. */
    private String queuedData = null;

    
Constructor for "dummy" instances.
See Also:
BaseFilterReader.BaseFilterReader()/**
     * Constructor for "dummy" instances.
     *
     * @see BaseFilterReader#BaseFilterReader()
     */
    public PrefixLines() {
        super();
    }

    
Creates a new filtered reader.
Params:
in – A Reader object providing the underlying stream.
          Must not be null./**
     * Creates a new filtered reader.
     *
     * @param in A Reader object providing the underlying stream.
     *           Must not be <code>null</code>.
     */
    public PrefixLines(final Reader in) {
        super(in);
    }

    
Returns the next character in the filtered stream. One line is read
from the original input, and the prefix added. The resulting
line is then used until it ends, at which point the next original line
is read, etc.
Throws:
IOException – if the underlying stream throws an IOException
during reading
Returns:
the next character in the resulting stream, or -1
if the end of the resulting stream has been reached/**
     * Returns the next character in the filtered stream. One line is read
     * from the original input, and the prefix added. The resulting
     * line is then used until it ends, at which point the next original line
     * is read, etc.
     *
     * @return the next character in the resulting stream, or -1
     * if the end of the resulting stream has been reached
     *
     * @exception IOException if the underlying stream throws an IOException
     * during reading
     */
    public int read() throws IOException {
        if (!getInitialized()) {
            initialize();
            setInitialized(true);
        }

        int ch = -1;

        if (queuedData != null && queuedData.isEmpty()) {
            queuedData = null;
        }

        if (queuedData != null) {
            ch = queuedData.charAt(0);
            queuedData = queuedData.substring(1);
            if (queuedData.isEmpty()) {
                queuedData = null;
            }
        } else {
            queuedData = readLine();
            if (queuedData == null) {
                ch = -1;
            } else {
                if (prefix != null) {
                    queuedData = prefix + queuedData;
                }
                return read();
            }
        }
        return ch;
    }

    
Sets the prefix to add at the start of each input line.
Params:
prefix – The prefix to add at the start of each input line.
              May be null, in which case no prefix
              is added./**
     * Sets the prefix to add at the start of each input line.
     *
     * @param prefix The prefix to add at the start of each input line.
     *               May be <code>null</code>, in which case no prefix
     *               is added.
     */
    public void setPrefix(final String prefix) {
        this.prefix = prefix;
    }

    
Returns the prefix which will be added at the start of each input line.
Returns:
the prefix which will be added at the start of each input line/**
     * Returns the prefix which will be added at the start of each input line.
     *
     * @return the prefix which will be added at the start of each input line
     */
    private String getPrefix() {
        return prefix;
    }

    
Creates a new PrefixLines filter using the passed in
Reader for instantiation.
Params:
rdr – A Reader object providing the underlying stream.
           Must not be null.
Returns:
a new filter based on this configuration, but filtering
        the specified reader/**
     * Creates a new PrefixLines filter using the passed in
     * Reader for instantiation.
     *
     * @param rdr A Reader object providing the underlying stream.
     *            Must not be <code>null</code>.
     *
     * @return a new filter based on this configuration, but filtering
     *         the specified reader
     */
    public Reader chain(final Reader rdr) {
        PrefixLines newFilter = new PrefixLines(rdr);
        newFilter.setPrefix(getPrefix());
        newFilter.setInitialized(true);
        return newFilter;
    }

    
Initializes the prefix if it is available from the parameters.
/**
     * Initializes the prefix if it is available from the parameters.
     */
    private void initialize() {
        Parameter[] params = getParameters();
        if (params != null) {
            for (Parameter param : params) {
                if (PREFIX_KEY.equals(param.getName())) {
                    prefix = param.getValue();
                    break;
                }
            }
        }
    }
}