class RuboCop::Cop::Rails::AddColumnIndex


add_index :table, :column
add_column :table, :column, :integer
# good
add_column :table, :column, :integer, index: true
# bad (will not add an index)
@example
realizing it will not actually add an index.
error for extra keys, so it is possible to mistakenly add the key without
key. ‘add_column` does not accept `index`, but also does not raise an
Checks for migrations using `add_column` that have an `index`

def index_range(pair_node) 

def index_range(pair_node)
  range_with_surrounding_comma(range_with_surrounding_space(pair_node.source_range, side: :left), :left)
end

def on_send(node) 

def on_send(node)
  table, column, pair, value = add_column_with_index(node)
  return unless pair
  add_offense(pair) do |corrector|
    corrector.remove(index_range(pair))
    add_index = "add_index #{table.source}, #{column.source}"
    add_index_opts = ''
    if value.hash_type?
      hash = value.source_range.adjust(begin_pos: 1, end_pos: -1).source.strip
      add_index_opts = ", #{hash}"
    end
    corrector.insert_after(node, "\n#{add_index}#{add_index_opts}")
  end
end