# encoding: utf-8

module RuboCop
  module Cop
    module Style
      # Checks that block braces have or don't have a space before the opening
      # brace depending on configuration.
      class SpaceBeforeBlockBraces < Cop
        include ConfigurableEnforcedStyle

        def on_block(node)
          return if node.loc.begin.is?('do') # No braces.

          # If braces are on separate lines, and the Blocks cop is enabled,
          # those braces will be changed to do..end by the user or by
          # auto-correct, so reporting space issues is not useful, and it
          # creates auto-correct conflicts.
          if config.for_cop('Style/Blocks')['Enabled'] &&
             Util.block_length(node) > 0
            return
          end

          left_brace = node.loc.begin
          space_plus_brace = range_with_surrounding_space(left_brace)
          used_style =
            space_plus_brace.source.start_with?('{') ? :no_space : :space

          case used_style
          when style  then correct_style_detected
          when :space then space_detected(left_brace, space_plus_brace)
          else             space_missing(left_brace)
          end
        end

        private

        def space_missing(left_brace)
          add_offense(left_brace, left_brace,
                      'Space missing to the left of {.') do
            opposite_style_detected
          end
        end

        def space_detected(left_brace, space_plus_brace)
          space = Parser::Source::Range.new(left_brace.source_buffer,
                                            space_plus_brace.begin_pos,
                                            left_brace.begin_pos)
          add_offense(space, space, 'Space detected to the left of {.') do
            opposite_style_detected
          end
        end

        def autocorrect(range)
          @corrections << lambda do |corrector|
            case range.source
            when /\s/ then corrector.remove(range)
            else           corrector.insert_before(range, ' ')
            end
          end
        end
      end
    end
  end
end