/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.classic.pattern;
  
  import ch.qos.logback.classic.ClassicConstants;
  import ch.qos.logback.core.CoreConstants;
  
  public class TargetLengthBasedClassNameAbbreviator implements Abbreviator {
  
    final int targetLength;
  
    public TargetLengthBasedClassNameAbbreviator(int targetLength) {
      this.targetLength = targetLength;
    }
  
    public String abbreviate(String fqClassName) {
      StringBuilder buf = new StringBuilder(targetLength);
      if (fqClassName == null) {
        throw new IllegalArgumentException("Class name may not be null");
      }
  
      int inLen = fqClassName.length();
      if (inLen < targetLength) {
        return fqClassName;
      }
  
      int[] dotIndexesArray = new int[ClassicConstants.MAX_DOTS];
      // a.b.c contains 2 dots but 2+1 parts.
      // see also http://jira.qos.ch/browse/LBCLASSIC-110
      int[] lengthArray = new int[ClassicConstants.MAX_DOTS + 1];
  
      int dotCount = computeDotIndexes(fqClassName, dotIndexesArray);
  
      // System.out.println();
      // System.out.println("Dot count for [" + className + "] is " + dotCount);
      // if there are not dots than abbreviation is not possible
      if (dotCount == 0) {
        return fqClassName;
      }
      // printArray("dotArray: ", dotArray);
      computeLengthArray(fqClassName, dotIndexesArray, lengthArray, dotCount);
      // printArray("lengthArray: ", lengthArray);
      for (int i = 0; i <= dotCount; i++) {
        if (i == 0) {
          buf.append(fqClassName.substring(0, lengthArray[i] - 1));
        } else {
          buf.append(fqClassName.substring(dotIndexesArray[i - 1],
              dotIndexesArray[i - 1] + lengthArray[i]));
        }
        // System.out.println("i=" + i + ", buf=" + buf);
      }
  
      return buf.toString();
    }
  
    static int computeDotIndexes(final String className, int[] dotArray) {
      int dotCount = 0;
      int k = 0;
      while (true) {
        // ignore the $ separator in our computations. This is both convenient
        // and sensible.
        k = className.indexOf(CoreConstants.DOT, k);
        if (k != -1 && dotCount < ClassicConstants.MAX_DOTS) {
          dotArray[dotCount] = k;
          dotCount++;
          k++;
        } else {
          break;
        }
      }
      return dotCount;
    }
  
    void computeLengthArray(final String className, int[] dotArray,
        int[] lengthArray, int dotCount) {
      int toTrim = className.length() - targetLength;
      // System.out.println("toTrim=" + toTrim);
  
      // int toTrimAvarage = 0;
  
      int len;
      for (int i = 0; i < dotCount; i++) {
        int previousDotPosition = -1;
        if (i > 0) {
          previousDotPosition = dotArray[i - 1];
        }
        int available = dotArray[i] - previousDotPosition - 1;
        // System.out.println("i=" + i + ", available = " + available);
 
       len = (available < 1) ? available : 1;
       // System.out.println("i=" + i + ", toTrim = " + toTrim);
 
       if (toTrim > 0) {
         len = (available < 1) ? available : 1;
       } else {
         len = available;
       }
       toTrim -= (available - len);
       lengthArray[i] = len + 1;
     }
 
     int lastDotIndex = dotCount - 1;
     lengthArray[dotCount] = className.length() - dotArray[lastDotIndex];
   }
 
   static void printArray(String msg, int[] ia) {
     System.out.print(msg);
     for (int i = 0; i < ia.length; i++) {
       if (i == 0) {
         System.out.print(ia[i]);
       } else {
         System.out.print(", " + ia[i]);
       }
     }
     System.out.println();
   }
 }