/**
    * 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.core.helpers;
  
  import java.util.LinkedList;
  import java.util.List;
  
  import ch.qos.logback.core.CoreConstants;
  
  public class ThrowableToStringArray {
  
    public static String[] convert(Throwable t) {
      List<String> strList = new LinkedList<String>();
      extract(strList, t, null);
      return strList.toArray(new String[0]);
  
    }
  
    private static void extract(List<String> strList, Throwable t,
        StackTraceElement[] parentSTE) {
  
      StackTraceElement[] ste = t.getStackTrace();
      final int numberOfcommonFrames = findNumberOfCommonFrames(ste, parentSTE);
  
      strList.add(formatFirstLine(t, parentSTE));
      for (int i = 0; i < (ste.length - numberOfcommonFrames); i++) {
        strList.add("\tat "+ste[i].toString());
      }
  
      if (numberOfcommonFrames != 0) {
        strList.add("\t... "+numberOfcommonFrames + " common frames omitted");
      }
  
      Throwable cause = t.getCause();
      if (cause != null) {
        ThrowableToStringArray.extract(strList, cause, ste);
      }
    }
  
    private static String formatFirstLine(Throwable t,
        StackTraceElement[] parentSTE) {
      String prefix = "";
      if (parentSTE != null) {
        prefix = CoreConstants.CAUSED_BY;
      }
  
      String result = prefix + t.getClass().getName();
      if (t.getMessage() != null) {
        result += ": " + t.getMessage();
      }
      return result;
    }
  
    private static int findNumberOfCommonFrames(StackTraceElement[] ste,
        StackTraceElement[] parentSTE) {
      if (parentSTE == null) {
        return 0;
      }
  
      int steIndex = ste.length - 1;
      int parentIndex = parentSTE.length - 1;
      int count = 0;
      while (steIndex >= 0 && parentIndex >= 0) {
        if (ste[steIndex].equals(parentSTE[parentIndex])) {
          count++;
        } else {
          break;
        }
        steIndex--;
        parentIndex--;
      }
      return count;
    }
  
  }