maven-core/src/main/java/org/apache/maven/internal/MultilineMessageHelper.java

/*
 * 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.internal;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;

/**
 * Helper class to format multiline messages to the console
 */
public class MultilineMessageHelper {

    private static final int DEFAULT_MAX_SIZE = 65;
    private static final char BOX_CHAR = '*';

    private static final Pattern S_FILTER = Pattern.compile("\\s+");

    public static String separatorLine() {
        StringBuilder sb = new StringBuilder(DEFAULT_MAX_SIZE);
        repeat(sb, '*', DEFAULT_MAX_SIZE);
        return sb.toString();
    }

    public static List<String> format(String... lines) {
        int size = DEFAULT_MAX_SIZE;
        int remainder = size - 4; // 4 chars = 2 box_char + 2 spaces
        List<String> result = new ArrayList<>();
        StringBuilder sb = new StringBuilder(size);
        // first line
        sb.setLength(0);
        repeat(sb, BOX_CHAR, size);
        result.add(sb.toString());
        // lines
        for (String line : lines) {
            sb.setLength(0);
            String[] words = S_FILTER.split(line);
            for (String word : words) {
                if (sb.length() >= remainder - word.length() - (sb.length() > 0 ? 1 : 0)) {
                    repeat(sb, ' ', remainder - sb.length());
                    result.add(BOX_CHAR + " " + sb + " " + BOX_CHAR);
                    sb.setLength(0);
                }
                if (sb.length() > 0) {
                    sb.append(' ');
                }
                sb.append(word);
            }

            while (sb.length() < remainder) {
                sb.append(' ');
            }
            result.add(BOX_CHAR + " " + sb + " " + BOX_CHAR);
        }
        // last line
        sb.setLength(0);
        repeat(sb, BOX_CHAR, size);
        result.add(sb.toString());
        return result;
    }

    private static void repeat(StringBuilder sb, char c, int nb) {
        for (int i = 0; i < nb; i++) {
            sb.append(c);
        }
    }
}