module Eco
  module API
    class MicroCases
      # Unique access point to set the `supervisor_id` value on a person.
      # @note
      #   - It prevents the basic cyclic supervisor case (supervisor to be supervisor of themselves)
      # @param person [Ecoportal::API::V1::Person] the person we want to update, carrying the changes to be done.
      # @param sup_id [nil, String] the **supervisor id** we should set on the `person`.
      # @param people [Eco::API::Organization::People] _People_ involved in the current update.
      # @param options [Hash] the options.
      # @yield [supervisor_id] callback when the supervisor_id is **unknown** (not `nil` nor any one's in `people`).
      # @yieldparam supervisor_id [String] the **unknown** `supervisor_id`.
      def set_supervisor(person, sup_id, people, options)
        return false if options.dig(:exclude, :core) || options.dig(:exclude, :supervisor)
        return false if sup_id && ((person.id == sup_id) || (person.external_id == sup_id))

        cur_id    = person.supervisor_id
        cur_super = cur_id && with_supervisor(cur_id, people)

        micro.with_supervisor(sup_id, people) do |new_super|
          if !sup_id
            person.supervisor_id = nil
            descrease_subordinates(cur_super)
          elsif new_super && (id = new_super.id)
            set_supervisor(new_super, nil, people, options) if new_super_direct_cyclic?(person, new_super)
            person.supervisor_id = id
            descrease_subordinates(cur_super)
            increase_subordinates(new_super)
          elsif !block_given?
            descrease_subordinates(cur_super)
            person.supervisor_id = sup_id
          elsif block_given?
            yield(sup_id)
          end
        end
      end

      private

      def new_super_direct_cyclic?(person, new_super)
        return false unless new_super.is_a?(Ecoportal::API::V1::Person)
        return false if new_super.supervisor_id.nil?
        return true  if person.id == new_super.id
        return true  if new_super.supervisor_id == person.id
        return true  if new_super.supervisor_id == person.external_id
        false
      end

      def descrease_subordinates(person, by = 1)
        return unless person.is_a?(Ecoportal::API::V1::Person)

        person.subordinates -= by
      end

      def increase_subordinates(person, by = 1)
        return unless person.is_a?(Ecoportal::API::V1::Person)

        person.subordinates += by
      end
    end
  end
end