/*
 * 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
 *
 *   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.apache.maven.doxia.util;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.Writer;

/**
 * Allows to specify the line-length of an output writer.
 */
public class LineBreaker {
    /** The default maximal line length. */
    public static final int DEFAULT_MAX_LINE_LENGTH = 78;

    /** The system dependent EOL. */
    private static final String EOL = System.getProperty("line.separator");

    /** The destination writer. */
    private Writer destination;

    /** The writer to use. */
    private BufferedWriter writer;

    /** The maximal line length. */
    private int maxLineLength;

    /** The current line length. */
    private int lineLength = 0;

    /** The string buffer to store the current text. */
    private StringBuilder word = new StringBuilder(1024);

    /**
     * Constructs a new LineBreaker with DEFAULT_MAX_LINE_LENGTH.
     *
     * @param out The writer to use.
     */
    public LineBreaker(Writer out) {
        this(out, DEFAULT_MAX_LINE_LENGTH);
    }

    /**
     * Constructs a new LineBreaker with the given max line length.
     *
     * @param out The writer to use.
     * @param max The maximal line length.
     */
    public LineBreaker(Writer out, int max) {
        if (max <= 0) {
            throw new IllegalArgumentException("max must be a positive integer");
        }

        destination = out;
        this.maxLineLength = max;
        writer = new BufferedWriter(out);
    }

    /**
     * Returns the current destination writer.
     *
     * @return The destination.
     */
    public Writer getDestination() {
        return destination;
    }

    /**
     * Writes the given text to the writer. White space is not preserved.
     *
     * @param text The text to write.
     * @throws java.io.IOException if there's a problem writing the text.
     */
    public void write(String text) throws IOException {
        write(text, /*preserveSpace*/ false);
    }

    /**
     * Writes the given text to the writer.
     *
     * @param text The text to write.
     * @param preserveSpace True to preserve white space.
     */
    public void write(String text, boolean preserveSpace) {
        int length = text.length();

        try {
            for (int i = 0; i < length; ++i) {
                char c = text.charAt(i);

                switch (c) {
                    case ' ':
                        if (preserveSpace) {
                            word.append(c);
                        } else {
                            writeWord();
                        }
                        break;

                    case '\r':
                        // if \r\n (windows) then just pass along \n
                        if (i + 1 < length && text.charAt(i + 1) == '\n') {
                            break;
                        }

                    case '\n':
                        writeWord();
                        writer.write(EOL);
                        lineLength = 0;
                        break;

                    default:
                        word.append(c);
                }
            }
        } catch (Exception e) {
            // TODO: log
        }
    }

    /**
     * Write out the current StringBuilder and flush the writer.
     * Any IOException will be swallowed.
     */
    public void flush() {
        try {
            writeWord();
            writer.flush();
        } catch (IOException e) {
            // TODO: log
        }
    }

    /**
     * Writes the current StringBuilder to the writer.
     *
     * @throws IOException if an exception occurs during writing.
     */
    private void writeWord() throws IOException {
        int length = word.length();
        if (length > 0) {
            if (lineLength > 0) {
                if (lineLength + 1 + length > maxLineLength) {
                    writer.write(EOL);
                    lineLength = 0;
                } else {
                    writer.write(' ');
                    ++lineLength;
                }
            }

            writer.write(word.toString());
            word.setLength(0);

            lineLength += length;
        }
    }

    /**
     * Close the writer.
     */
    public void close() {
        if (writer == null) {
            return;
        }

        try {
            writer.close();
        } catch (IOException ex) {
            // ignore
        }
    }
}
