lib/cops/add_concurrent_index.rb
# frozen_string_literal: true

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if defined?(RuboCop)
  module RuboCop
    module Cop
      module DS
        # Cop that checks if `add_concurrent_index` is used with `up`/`down` methods
        # and not `change`.
        class AddConcurrentIndex < Base
          MSG = '`add_concurrent_index` is not reversible so you must manually define ' \
            'the `up` and `down` methods in your migration class, using `remove_index` in `down`'

          def on_send(node)
            dirname = File.dirname(node.location.expression.source_buffer.name)
            return unless dirname.end_with?('db/migrate')

            name = node.children[1]

            return unless name == :add_concurrent_index

            node.each_ancestor(:def) do |def_node|
              next unless method_name(def_node) == :change

              add_offense(def_node, location: :name)
            end
          end

          def method_name(node)
            node.children.first
          end
        end
      end
    end
  end
end
