class SassListen::Adapter::Windows

def self.usable?
  return false unless super
  require 'wdm'
  true
rescue LoadError
  _log :debug, format('wdm - load failed: %s:%s', $ERROR_INFO,
                      $ERROR_POSITION * "\n")
  Kernel.warn BUNDLER_DECLARE_GEM
  false
end

def _change(type)
  { modified: [:modified, :attrib], # TODO: is attrib really passed?
    added:    [:added, :renamed_new_file],
    removed:  [:removed, :renamed_old_file] }.each do |change, types|
    return change if types.include?(type)
  end
  nil
end

def _configure(dir, &callback)
  require 'wdm'
  _log :debug, 'wdm - starting...'
  @worker ||= WDM::Monitor.new
  @worker.watch_recursively(dir.to_s, :files) do |change|
    callback.call([:file, change])
  end
  @worker.watch_recursively(dir.to_s, :directories) do |change|
    callback.call([:dir, change])
  end
  events = [:attributes, :last_write]
  @worker.watch_recursively(dir.to_s, *events) do |change|
    callback.call([:attr, change])
  end
end

def _process_event(dir, event)
  _log :debug, "wdm - callback: #{event.inspect}"
  type, change = event
  full_path = Pathname(change.path)
  rel_path = full_path.relative_path_from(dir).to_s
  options = { change: _change(change.type) }
  case type
  when :file
    _queue_change(:file, dir, rel_path, options)
  when :attr
    unless full_path.directory?
      _queue_change(:file, dir, rel_path, options)
    end
  when :dir
    if change.type == :removed
      # TODO: check if watched dir?
      _queue_change(:dir, dir, Pathname(rel_path).dirname.to_s, {})
    elsif change.type == :added
      _queue_change(:dir, dir, rel_path, {})
    else
      # do nothing - changed directory means either:
      #   - removed subdirs (handled above)
      #   - added subdirs (handled above)
      #   - removed files (handled by _file_callback)
      #   - added files (handled by _file_callback)
      # so what's left?
    end
  end
rescue
  details = event.inspect
  _log :error, format('wdm - callback (%): %s:%s', details, $ERROR_INFO,
                      $ERROR_POSITION * "\n")
  raise
end

def _run
  @worker.run!
end