class Middleman::Logger

def self.singleton(*args)
  if !@_logger || args.length > 0
    if args.length == 1 && (args.first.is_a?(::String) || args.first.respond_to?(:write))
      args = [0, false, args.first]
    end
    @_logger = new(*args)
  end
  @_logger
end

def add(*args)
  @mutex.synchronize do
    super
  end
end

def call(message, *args)
  return if @instrumenting.is_a?(String) && @instrumenting != 'instrument' && !message.include?(@instrumenting)
  evt = ActiveSupport::Notifications::Event.new(message, *args)
  info "== Instrument (#{evt.name.sub(/.middleman$/, '')}): #{evt.duration}ms"
end

def initialize(log_level=1, is_instrumenting=false, target=$stdout)
  super(target)
  self.level = log_level
  @instrumenting = is_instrumenting
  if @instrumenting != false
    ::ActiveSupport::Notifications.subscribe(/\.middleman$/, self)
  end
  @mutex = Mutex.new
end