class Listen::Directory

def self._async_changes(snapshot, path, previous, options)
  fail "Not a Pathname: #{path.inspect}" unless path.respond_to?(:children)
  previous.each do |entry, data|
    # TODO: this is a hack with insufficient testing
    type = data.key?(:mtime) ? :file : :dir
    rel_path_s = (path + entry).to_s
    _change(snapshot, type, rel_path_s, options)
  end
end

def self._change(snapshot, type, path, options)
  return snapshot.invalidate(type, path, options) if type == :dir
  # Minor param cleanup for tests
  # TODO: use a dedicated Event class
  opts = options.dup
  opts.delete(:recursive)
  snapshot.invalidate(type, path, opts)
end

def self._children(path)
  return path.children unless RUBY_ENGINE == 'jruby'
  # JRuby inconsistency workaround, see:
  # https://github.com/jruby/jruby/issues/3840
  exists = path.exist?
  directory = path.directory?
  exists && !directory and raise Errno::ENOTDIR, path.to_s
  path.children
end

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

def self.scan(snapshot, rel_path, options)
  record = snapshot.record
  dir = Pathname.new(record.root)
  previous = record.dir_entries(rel_path)
  record.add_dir(rel_path)
  # TODO: use children(with_directory: false)
  path = dir + rel_path
  current = Set.new(_children(path))
  Listen.logger.debug do
    format('%s: %s(%s): %s -> %s',
           (options[:silence] ? 'Recording' : 'Scanning'),
           rel_path, options.inspect, previous.inspect, current.inspect)
  end
  begin
    current.each do |full_path|
      type = ::File.lstat(full_path.to_s).directory? ? :dir : :file
      item_rel_path = full_path.relative_path_from(dir).to_s
      _change(snapshot, type, item_rel_path, options)
    end
  rescue Errno::ENOENT
    # The directory changed meanwhile, so rescan it
    current = Set.new(_children(path))
    retry
  end
  # TODO: this is not tested properly
  previous = previous.reject { |entry, _| current.include?(path + entry) }
  _async_changes(snapshot, Pathname.new(rel_path), previous, options)
rescue Errno::ENOENT, Errno::EHOSTDOWN
  record.unset_path(rel_path)
  _async_changes(snapshot, Pathname.new(rel_path), previous, options)
rescue Errno::ENOTDIR
  # TODO: path not tested
  record.unset_path(rel_path)
  _async_changes(snapshot, path, previous, options)
  _change(snapshot, :file, rel_path, options)
rescue
  Listen.logger.warn { format('scan DIED: %s:%s', $ERROR_INFO, $ERROR_POSITION * "\n") }
  raise
end