rubocop-hq/rubocop

# frozen_string_literal: true

module RuboCop
  module Cop
    module Style
      # Checks for `when;` uses in `case` expressions.
      #
      # @example
      #   # bad
      #   case foo
      #   when 1; 'baz'
      #   when 2; 'bar'
      #   end
      #
      #   # good
      #   case foo
      #   when 1 then 'baz'
      #   when 2 then 'bar'
      #   end
      class WhenThen < Base
        extend AutoCorrector

        MSG = 'Do not use `when %<expression>s;`. Use `when %<expression>s then` instead.'

        def on_when(node)
          return if node.multiline? || node.then? || !node.body

          message = format(MSG, expression: node.conditions.map(&:source).join(', '))

          add_offense(node.loc.begin, message: message) do |corrector|
            corrector.replace(node.loc.begin, ' then')
          end
        end
      end
    end
  end
end