Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, 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.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, 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;
    }

}