class ActiveSupport::EventedFileUpdateChecker::PathHelper

def ascendant_of?(base, other)
  base != other && other.ascend do |ascendant|
    break true if base == ascendant
  end
end

def existing_parent(dir)
  dir.ascend do |ascendant|
    break ascendant if ascendant.directory?
  end
end

def filter_out_descendants(dirs)
  return dirs if dirs.length < 2
  dirs_sorted_by_nparts = dirs.sort_by { |dir| dir.each_filename.to_a.length }
  descendants = []
  until dirs_sorted_by_nparts.empty?
    dir = dirs_sorted_by_nparts.shift
    dirs_sorted_by_nparts.reject! do |possible_descendant|
      ascendant_of?(dir, possible_descendant) && descendants << possible_descendant
    end
  end
  # Array#- preserves order.
  dirs - descendants
end

def longest_common_subpath(paths)
  return if paths.empty?
  lcsp = Pathname.new(paths[0])
  paths[1..-1].each do |path|
    until ascendant_of?(lcsp, path)
      if lcsp.root?
        # If we get here a root directory is not an ascendant of path.
        # This may happen if there are paths in different drives on
        # Windows.
        return
      else
        lcsp = lcsp.parent
      end
    end
  end
  lcsp
end

def normalize_extension(ext)
  ext.to_s.sub(/\A\./, '')
end

def xpath(path)
  Pathname.new(path).expand_path
end