# frozen_string_literal: true

class Array
  # Returns a new array created by sorting +self+, using quicksort algorithm.
  #
  # Comparisons for the sort will be done using the <=> operator or using an optional code block.
  #
  # The block must implement a comparison between +a+ and +b+ and return an integer less than 0 when +b+ follows +a+,
  # +0+ when +a+ and +b+ are equivalent, or an integer greater than 0 when +a+ follows +b+.
  #
  # The result is not guaranteed to be stable. When the comparison of two elements returns +0+, the order of the
  # elements is unpredictable.
  #
  # @return [Array] the sorted array
  def quick_sort(&block)
    return dup if length <= 1
    left, right = self[1..-1].partition { |y| sort_compare(first, y, &block).positive? }
    left.quick_sort + [first] + right.quick_sort
  end

  # Sorts +self+ in place, using quicksort algorithm.
  #
  # Comparisons for the sort will be done using the <=> operator or using an optional code block.
  #
  # The block must implement a comparison between +a+ and +b+ and return an integer less than 0 when +b+ follows +a+,
  # +0+ when +a+ and +b+ are equivalent, or an integer greater than 0 when +a+ follows +b+.
  #
  # The result is not guaranteed to be stable. When the comparison of two elements returns +0+, the order of the
  # elements is unpredictable.
  #
  # @return [Array] +self+
  def quick_sort!(&block)
    become_clone_of quick_sort(&block)
  end

  # Returns a new array created by sorting +self+ with quicksort algorithm, using a set of keys generated by mapping
  # the values in self through the given block.
  #
  # The result is not guaranteed to be stable. When the comparison of two elements returns +0+, the order of the
  # elements is unpredictable.
  #
  # If no block is given, an Enumerator is returned instead.
  #
  # @return [Array] if a block is given, the sorted array
  # @return [Enumerator] if no block is given, an Enumerator
  def quick_sort_by(&_block)
    if block_given?
      quick_sort do |a, b|
        yield(a) <=> yield(b)
      end
    else
      to_enum :quick_sort_by
    end
  end

  # Sorts +self+ in place with quicksort algorithm, using a set of keys generated by mapping the values in self through
  # the given block.
  #
  # The result is not guaranteed to be stable. When the comparison of two elements returns +0+, the order of the
  # elements is unpredictable.
  #
  # If no block is given, an Enumerator is returned instead.
  #
  # @return [Array] if a block is given, the sorted array
  # @return [Enumerator] if no block is given, an Enumerator
  def quick_sort_by!(&block)
    if block_given?
      become_clone_of quick_sort_by(&block)
    else
      to_enum :quick_sort_by!
    end
  end
end