protected void RollOverRenameFiles()

in src/log4net/Appender/RollingFileAppender.cs [1453:1529]
59 lines of code
13 McCabe index (conditional complexity)

		protected void RollOverRenameFiles(string baseFileName) 
		{
			// If maxBackups <= 0, then there is no file renaming to be done.
			if (m_maxSizeRollBackups != 0) 
			{
				if (m_countDirection < 0) 
				{
					// Delete the oldest file, to keep Windows happy.
					if (m_curSizeRollBackups == m_maxSizeRollBackups) 
					{
                        DeleteFile(CombinePath(baseFileName, "." + m_maxSizeRollBackups));
						m_curSizeRollBackups--;
					}
	
					// Map {(maxBackupIndex - 1), ..., 2, 1} to {maxBackupIndex, ..., 3, 2}
					for (var i = m_curSizeRollBackups; i >= 1; i--) 
					{
                        RollFile((CombinePath(baseFileName, "." + i)), (CombinePath(baseFileName, "." + (i + 1))));
					}
	
					m_curSizeRollBackups++;

					// Rename fileName to fileName.1
                    RollFile(baseFileName, CombinePath(baseFileName, ".1"));
				} 
				else 
				{
					//countDirection >= 0
					if (m_curSizeRollBackups >= m_maxSizeRollBackups && m_maxSizeRollBackups > 0) 
					{
						//delete the first and keep counting up.
						var oldestFileIndex = m_curSizeRollBackups - m_maxSizeRollBackups;

						// If static then there is 1 file without a number, therefore 1 less archive
						if (m_staticLogFileName)
						{
							oldestFileIndex++;
						}

						// If using a static log file then the base for the numbered sequence is the baseFileName passed in
						// If not using a static log file then the baseFileName will already have a numbered postfix which
						// we must remove, however it may have a date postfix which we must keep!
						var archiveFileBaseName = baseFileName;
						if (!m_staticLogFileName)
						{
                                                    if (m_preserveLogFileNameExtension)
                                                    {
                                                        var extension = Path.GetExtension(archiveFileBaseName);
                                                        var baseName = Path.GetFileNameWithoutExtension(archiveFileBaseName);
							var lastDotIndex = baseName.LastIndexOf(".");
							if (lastDotIndex >= 0)
							{
								archiveFileBaseName = baseName.Substring(0, lastDotIndex) + extension;
							}
                                                    }
                                                    else
                                                    {
							var lastDotIndex = archiveFileBaseName.LastIndexOf(".");
							if (lastDotIndex >= 0) 
							{
								archiveFileBaseName = archiveFileBaseName.Substring(0, lastDotIndex);
							}
                                                    }
						}

						// Delete the archive file
                        DeleteFile(CombinePath(archiveFileBaseName, "." + oldestFileIndex));
					}
	
					if (m_staticLogFileName) 
					{
						m_curSizeRollBackups++;
                        RollFile(baseFileName, CombinePath(baseFileName, "." + m_curSizeRollBackups));
					}
				}
			}
		}