class DEBUGGER__::ThreadClient::Recorder

def append frames
  @log << frames
end

def can_step_back?
  log.size > @index
end

def current_frame
  if @index == 0
    f = @backup_frames
    @backup_frames = nil
    f
  else
    frames = @log[log_index]
    frames
  end
end

def current_position
  puts "INDEX: #{@index}"
  li = log_index
  @log.each_with_index{|frame, i|
    loc = frame.first&.location
    prefix = i == li ? "=> " : '   '
    puts "#{prefix} #{loc}"
  }
end

def disable
  if @tp_recorder.enabled?
    @log.clear
    @tp_recorder.disable
  end
end

def enable
  unless @tp_recorder.enabled?
    @log.clear
    @tp_recorder.enable
  end
end

def enabled?
  @tp_recorder.enabled?
end

def initialize
  @log = []
  @index = 0
  @backup_frames = nil
  thread = Thread.current
  @tp_recorder ||= TracePoint.new(:line){|tp|
    next unless Thread.current == thread
    # can't be replaced by skip_location
    next if skip_internal_path?(tp.path)
    loc = caller_locations(1, 1).first
    next if skip_location?(loc)
    frames = DEBUGGER__.capture_frames(__dir__)
    frames.each{|frame|
      if b = frame.binding
        frame.binding = nil
        frame._local_variables = b.local_variables.map{|name|
          [name, b.local_variable_get(name)]
        }.to_h
        frame._callee = b.eval('__callee__')
      end
    }
    append(frames)
  }
end

def log_index
  @log.size - @index
end

def replaying?
  @index > 0
end

def step_back iter
  @index += iter
  if @index > @log.size
    @index = @log.size
  end
end

def step_forward iter
  @index -= iter
  if @index < 0
    @index = 0
  end
end

def step_reset
  @index = 0
  @backup_frames = nil
end