class RuboCop::Cop::Style::RedundantSort


arr.max_by(&:foo)
# good

arr.sort_by(&:foo).slice(-1)
arr.sort_by(&:foo).at(-1)
arr.sort_by(&:foo)[-1]
arr.sort_by(&:foo).last
# bad
arr.min_by(&:foo)
# good

arr.sort_by(&:foo).slice(0)
arr.sort_by(&:foo).at(0)
arr.sort_by(&:foo)[0]
arr.sort_by(&:foo).first
# bad
[2, 1, 3].max
# good
[2, 1, 3].sort.slice(-1)
[2, 1, 3].sort.at(-1)
[2, 1, 3].sort[-1]
[2, 1, 3].sort.last
# bad
[2, 1, 3].min
# good
[2, 1, 3].sort.slice(0)
[2, 1, 3].sort.at(0)
[2, 1, 3].sort[0]
[2, 1, 3].sort.first
# bad
@example
—-
words.max_by { |word| word.length } #=> ‘horse’
words.sort_by { |word| word.length }.last #=> ‘mouse’
words = %w(dog horse mouse)
—-
[source,ruby]

—-
strings.max.class #=> MyString
strings.sort.last.class #=> String
strings = [MyString.new(‘test’), ‘test’]
class MyString < String; end
—-
[source,ruby]

For example:
element but ‘max` will return the first element.
will return different elements. `sort.last` will return the last
same result, `sort.last` and `max` (or `sort_by.last` and `max_by`)
or where the transformation done by the `sort_by` block has the
In an enumerable where there are multiple elements where `a <=> b == 0`,
same element in all cases.
This cop is unsafe, because `sort…last` and `max` may not return the
@safety
after which only the first or last element is used.
`Enumerable#max_by` can replace `Enumerable#sort_by` calls
last element. Similarly, `Enumerable#min_by` and
element and `Enumerable#max` instead of sorting and taking the
`Enumerable#min` instead of sorting and taking the first
be accomplished without a relatively expensive sort by using
taking only the first or last element. The same behavior can
Identifies instances of sorting and then

def accessor_start(node)

(e.g. `.first`) or doesn't (e.g. `[0]`)
This gets the start of the accessor whether it has a dot 
def accessor_start(node)
  if node.loc.dot
    node.loc.dot.begin_pos
  else
    node.loc.selector.begin_pos
  end
end

def arg_node(node) 

def arg_node(node)
  node.arguments.first
end

def arg_value(node) 

def arg_value(node)
  arg_node(node)&.node_parts&.first
end

def autocorrect(corrector, node, sort_node, sorter, accessor) 

def autocorrect(corrector, node, sort_node, sorter, accessor)
  # Remove accessor, e.g. `first` or `[-1]`.
  corrector.remove(range_between(accessor_start(node), node.source_range.end_pos))
  # Replace "sort" or "sort_by" with the appropriate min/max method.
  corrector.replace(sort_node.loc.selector, suggestion(sorter, accessor, arg_value(node)))
  # Replace to avoid syntax errors when followed by a logical operator.
  replace_with_logical_operator(corrector, node) if with_logical_operator?(node)
end

def base(accessor, arg) 

def base(accessor, arg)
  if accessor == :first || arg&.zero?
    'min'
  elsif accessor == :last || arg == -1
    'max'
  end
end

def find_redundant_sort(*nodes) 

def find_redundant_sort(*nodes)
  nodes.each do |node|
    if (sort_node, sorter, accessor = redundant_sort?(node))
      return [node, sort_node, sorter, accessor]
    end
  end
  nil
end

def message(node, sorter, accessor) 

def message(node, sorter, accessor)
  accessor_source = range_between(
    node.loc.selector.begin_pos,
    node.source_range.end_pos
  ).source
  format(MSG,
         suggestion: suggestion(sorter, accessor, arg_value(node)),
         sorter: sorter,
         accessor_source: accessor_source)
end

def offense_range(sort_node, node) 

def offense_range(sort_node, node)
  range_between(sort_node.loc.selector.begin_pos, node.source_range.end_pos)
end

def on_send(node) 

def on_send(node)
  ancestor, sort_node, sorter, accessor =
    find_redundant_sort(node.parent, node.parent&.parent)
  return unless ancestor
  register_offense(ancestor, sort_node, sorter, accessor)
end

def register_offense(node, sort_node, sorter, accessor) 

def register_offense(node, sort_node, sorter, accessor)
  message = message(node, sorter, accessor)
  add_offense(offense_range(sort_node, node), message: message) do |corrector|
    autocorrect(corrector, node, sort_node, sorter, accessor)
  end
end

def replace_with_logical_operator(corrector, node) 

def replace_with_logical_operator(corrector, node)
  corrector.insert_after(node.child_nodes.first, " #{node.parent.loc.operator.source}")
  corrector.remove(node.parent.loc.operator)
end

def suffix(sorter) 

def suffix(sorter)
  case sorter
  when :sort
    ''
  when :sort_by
    '_by'
  end
end

def suggestion(sorter, accessor, arg) 

def suggestion(sorter, accessor, arg)
  base(accessor, arg) + suffix(sorter)
end

def with_logical_operator?(node) 

def with_logical_operator?(node)
  return unless (parent = node.parent)
  parent.or_type? || parent.and_type?
end