class PryNav::Tracer

def initialize(pry_start_options = {})
  @step_in_lines = -1                      # Break after this many lines
  @frames_when_stepping = nil              # Only break at this frame level
  @frames = 0                              # Traced stack frame level
  @pry_start_options = pry_start_options   # Options to use for Pry.start
end

def process_command(command = {})
  times = (command[:times] || 1).to_i
  times = 1 if times <= 0
  case command[:action]
  when :step
    @step_in_lines = times
    @frames_when_stepping = nil
    true
  when :next
    @step_in_lines = times
    @frames_when_stepping = @frames
    true
  else
    false
  end
end

def run
  # For performance, disable any tracers while in the console.
  stop
  return_value = nil
  command = catch(:breakout_nav) do      # Coordinates with PryNav::Commands
    return_value = yield
    {}    # Nothing thrown == no navigational command
  end
  # Adjust tracer based on command
  if process_command(command)
    start
  else
    if @pry_start_options[:pry_remote] && PryNav.current_remote_server
      PryNav.current_remote_server.teardown
    end
  end
  return_value
end

def start
  set_trace_func method(:tracer).to_proc
end

def stop
  set_trace_func nil
end

def tracer(event, file, _line, _id, binding, _klass)
  # Ignore traces inside pry-nav code
  return if file && TRACE_IGNORE_FILES.include?(File.expand_path(file))
  case event
  when 'line'
    # Are we stepping? Or continuing by line ('next') and we're at the right
    # frame? Then decrement our line counter cause this line counts.
    if !@frames_when_stepping || @frames == @frames_when_stepping
      @step_in_lines -= 1
      @step_in_lines = -1 if @step_in_lines < 0
    # Did we go up a frame and not break for a 'next' yet?
    elsif @frames < @frames_when_stepping
      @step_in_lines = 0   # Break right away
    end
    # Break on this line?
    Pry.start(binding, @pry_start_options) if @step_in_lines.zero?
  when 'call', 'class'
    @frames += 1         # Track entering a frame
  when 'return', 'end'
    @frames -= 1         # Track leaving a stack frame
    @frames = 0 if @frames < 0
  end
end