protected StreamTaskListener createListener()

in core/src/main/java/hudson/model/AsyncPeriodicWork.java [127:179]
51 lines of code
18 McCabe index (conditional complexity)

    protected StreamTaskListener createListener() {
        File f = getLogFile();
        if (!f.getParentFile().isDirectory()) {
            if (!f.getParentFile().mkdirs()) {
                logger.log(getErrorLoggingLevel(), "Could not create directory {0}", f.getParentFile());
            }
        }
        if (f.isFile()) {
            if ((lastRotateMillis + logRotateMillis < System.currentTimeMillis())
                    || (logRotateSize > 0 && f.length() > logRotateSize)) {
                lastRotateMillis = System.currentTimeMillis();
                File prev = null;
                for (int i = 5; i >= 0; i--) {
                    File curr = i == 0 ? f : new File(f.getParentFile(), f.getName() + "." + i);
                    if (curr.isFile()) {
                        if (prev != null && !prev.exists()) {
                            if (!curr.renameTo(prev)) {
                                logger.log(getErrorLoggingLevel(), "Could not rotate log files {0} to {1}",
                                        new Object[]{curr, prev});
                            }
                        } else {
                            if (!curr.delete()) {
                                logger.log(getErrorLoggingLevel(), "Could not delete log file {0} to enable rotation",
                                        curr);
                            }
                        }
                    }
                    prev = curr;
                }
            }
        } else {
            lastRotateMillis = System.currentTimeMillis();
            // migrate old log files the first time we start-up
            File oldFile = new File(Jenkins.get().getRootDir(), f.getName());
            if (oldFile.isFile()) {
                File newFile = new File(f.getParentFile(), f.getName() + ".1");
                if (!newFile.isFile()) {
                    // if there has never been rotation then this is the first time
                    if (oldFile.renameTo(newFile)) {
                        logger.log(getNormalLoggingLevel(), "Moved {0} to {1}", new Object[]{oldFile, newFile});
                    } else {
                        logger.log(getErrorLoggingLevel(), "Could not move {0} to {1}",
                                new Object[]{oldFile, newFile});
                    }
                }
            }
        }
        try {
            return new StreamTaskListener(f, true, null);
        } catch (IOException e) {
            throw new Error(e);
        }
    }