class Rubocop::Cop::Style::SpaceAroundBraces

def check(t1, t2, msg)
  unless space_between?(t1, t2)
    brace_token = msg == MSG_LEFT ? t1 : t2
    add_offence(:convention, brace_token.pos, msg)
  end
end

def investigate(processed_source)
  return unless processed_source.ast
  @processed_source = processed_source
  processed_source.tokens.each_cons(2) do |t1, t2|
    next if ([t1.pos, t2.pos] - positions_not_to_check).size < 2
    type1, type2 = t1.type, t2.type
    # :tLBRACE in hash literals, :tLCURLY otherwise.
    next if [:tLCURLY, :tLBRACE].include?(type1) && type2 == :tRCURLY
    check(t1, t2, MSG_LEFT) if type1 == :tLCURLY || type2 == :tLCURLY
    check(t1, t2, MSG_RIGHT) if type2 == :tRCURLY
  end
end

def positions_not_to_check
  @positions_not_to_check ||= begin
    positions = []
    ast = @processed_source.ast
    tokens = @processed_source.tokens
    on_node(:hash, ast) do |hash|
      b_ix = index_of_first_token(hash)
      e_ix = index_of_last_token(hash)
      positions << tokens[b_ix].pos << tokens[e_ix].pos
    end
    # TODO: Check braces inside string/symbol/regexp/xstr
    #   interpolation.
    on_node([:dstr, :dsym, :regexp, :xstr], ast) do |s|
      b_ix = index_of_first_token(s)
      e_ix = index_of_last_token(s)
      tokens[b_ix..e_ix].each do |t|
        positions << t.pos if t.type == :tRCURLY
      end
    end
    positions
  end
end