001/**
002 * Copyright (c) 2004-2011 QOS.ch
003 * All rights reserved.
004 *
005 * Permission is hereby granted, free  of charge, to any person obtaining
006 * a  copy  of this  software  and  associated  documentation files  (the
007 * "Software"), to  deal in  the Software without  restriction, including
008 * without limitation  the rights to  use, copy, modify,  merge, publish,
009 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
010 * permit persons to whom the Software  is furnished to do so, subject to
011 * the following conditions:
012 *
013 * The  above  copyright  notice  and  this permission  notice  shall  be
014 * included in all copies or substantial portions of the Software.
015 *
016 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
017 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
018 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
019 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
020 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
021 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
022 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
023 *
024 */
025package org.slf4j.migrator.helper;
026
027public class Abbreviator {
028    static final String FILLER = "...";
029
030    final char folderSeparator;
031    final int invariantPrefixLength;
032    final int desiredLength;
033
034    public Abbreviator(int invariantPrefixLength, int desiredLength, char folderSeparator) {
035        this.invariantPrefixLength = invariantPrefixLength;
036        this.desiredLength = desiredLength;
037        this.folderSeparator = folderSeparator;
038    }
039
040    public String abbreviate(String filename) {
041        if (filename.length() <= desiredLength) {
042            return filename;
043        } else {
044
045            int firstIndex = filename.indexOf(folderSeparator, invariantPrefixLength);
046            if (firstIndex == -1) {
047                // we can't process this string
048                return filename;
049            }
050            StringBuilder buf = new StringBuilder(desiredLength);
051            buf.append(filename, 0, firstIndex + 1);
052            buf.append(FILLER);
053            int nextIndex = computeNextIndex(filename, firstIndex);
054            if (nextIndex != -1) {
055                buf.append(filename.substring(nextIndex));
056            } else {
057                // better long than wrong
058                return filename;
059            }
060
061            if (buf.length() < filename.length()) {
062                return buf.toString();
063            } else {
064                // we tried our best but we are still could not shorten the input
065                return filename;
066            }
067        }
068    }
069
070    int computeNextIndex(String filename, int firstIndex) {
071        int nextIndex = firstIndex + 1;
072        int hitCount = 0;
073        int minToRemove = filename.length() - desiredLength + FILLER.length();
074        while (nextIndex < firstIndex + minToRemove) {
075            int tmpIndex = filename.indexOf(folderSeparator, nextIndex + 1);
076            if (tmpIndex == -1) {
077                if (hitCount == 0) {
078                    return -1;
079                } else {
080                    return nextIndex;
081                }
082            } else {
083                hitCount++;
084                nextIndex = tmpIndex;
085            }
086        }
087        return nextIndex;
088    }
089}