class RuboCop::Cop::Layout::SpaceAroundBlockParameters

def autocorrect(target)
  lambda do |corrector|
    if target.is_a?(RuboCop::AST::Node)
      if target.parent.children.first == target
        corrector.insert_before(target.source_range, ' ')
      else
        corrector.insert_after(target.source_range, ' ')
      end
    elsif target.source =~ /^\s+$/
      corrector.remove(target)
    else
      corrector.insert_after(target, ' ')
    end
  end
end

def check_after_closing_pipe(arguments)
  _opening_pipe, closing_pipe = pipes(arguments)
  block = arguments.parent
  check_space(closing_pipe.end_pos, block.body.source_range.begin_pos,
              closing_pipe, 'after closing `|`')
end

def check_arg(arg)
  arg.children.each { |a| check_arg(a) } if arg.mlhs_type?
  expr = arg.source_range
  check_no_space(
    range_with_surrounding_space(range: expr, side: :left).begin_pos,
    expr.begin_pos - 1,
    'Extra space before'
  )
end

def check_closing_pipe_space(args, closing_pipe)
  last         = args.last.source_range
  last_end_pos = last_end_pos_inside_pipes(last.end_pos)
  check_space(last_end_pos, closing_pipe.begin_pos, last,
              'after last block parameter')
  check_no_space(last_end_pos + 1, closing_pipe.begin_pos,
                 'Extra space after last')
end

def check_each_arg(args)
  args.children.each do |arg|
    check_arg(arg)
  end
end

def check_inside_pipes(arguments)
  opening_pipe, closing_pipe = pipes(arguments)
  if style == :no_space
    check_no_space_style_inside_pipes(arguments.children,
                                      opening_pipe,
                                      closing_pipe)
  elsif style == :space
    check_space_style_inside_pipes(arguments.children,
                                   opening_pipe,
                                   closing_pipe)
  end
end

def check_no_space(space_begin_pos, space_end_pos, msg)
  return if space_begin_pos >= space_end_pos
  range = range_between(space_begin_pos, space_end_pos)
  add_offense(range, location: range,
                     message: "#{msg} block parameter detected.")
end

def check_no_space_style_inside_pipes(args, opening_pipe, closing_pipe)
  first = args.first.source_range
  last = args.last.source_range
  check_no_space(opening_pipe.end_pos, first.begin_pos,
                 'Space before first')
  check_no_space(last_end_pos_inside_pipes(last.end_pos),
                 closing_pipe.begin_pos, 'Space after last')
end

def check_opening_pipe_space(args, opening_pipe)
  first_arg = args.first
  range = first_arg.source_range
  check_space(opening_pipe.end_pos, range.begin_pos, range,
              'before first block parameter', first_arg)
  check_no_space(opening_pipe.end_pos, range.begin_pos - 1,
                 'Extra space before first')
end

def check_space(space_begin_pos, space_end_pos, range, msg, node = nil)
  return if space_begin_pos != space_end_pos
  target = node || range
  add_offense(target, location: range, message: "Space #{msg} missing.")
end

def check_space_style_inside_pipes(args, opening_pipe, closing_pipe)
  check_opening_pipe_space(args, opening_pipe)
  check_closing_pipe_space(args, closing_pipe)
end

def last_end_pos_inside_pipes(pos)
  processed_source.buffer.source[pos] == ',' ? pos + 1 : pos
end

def on_block(node)
  arguments = node.arguments
  return unless node.arguments? && pipes?(arguments)
  check_inside_pipes(arguments)
  check_after_closing_pipe(arguments) if node.body
  check_each_arg(arguments)
end

def pipes(arguments)
  [arguments.loc.begin, arguments.loc.end]
end

def pipes?(arguments)
  pipes(arguments).none?(&:nil?)
end

def style_parameter_name
  'EnforcedStyleInsidePipes'
end