module Tournaments
  class GenerateSlug
    def self.call(tournament)
      new(tournament).call
    end

    def initialize(tournament)
      @tournament = tournament
    end

    def call
      base = @tournament.name.to_s.parameterize.presence || "torneo"
      slug = base
      n = 2
      while conflict?(slug)
        slug = "#{base}-#{n}"
        n += 1
      end
      slug
    end

    private

    def conflict?(slug)
      scope = Tournament.where(slug: slug)
      scope = scope.where.not(id: @tournament.id) if @tournament.persisted?
      scope.exists?
    end
  end
end