gistfile1.rb

module Subjects
  class IndexCareerItemsService < ApplicationService
    def initialize(user:, query:, page:, per_page:)
      super()

      @user = user
      @page = page || Subjects::PAGE
      @per_page = per_page || Subjects::PER_PAGE
      @query = query
    end

    def call
      response(success: true, payload: paginated_items)
    rescue => error
      response(error:)
    end

    private

    attr_reader :user, :query, :page, :per_page

    def paginated_items
      service = Users::ShowSubjectsService.call(@user)
      raise(service.error) unless service.success?

      user_show_subjects = service.payload #esto es un boolean que nos servira como criterio de que se debe mostrar
      items =
        if user_show_subjects
          fetch_career_subjects + fetch_interests
        else
          fetch_interests
        end
      WillPaginate::Collection.create(@page, @per_page, items.size) do |pager|
        pager.replace(items.slice(pager.offset, pager.per_page))
      end
    end

    def fetch_career_subjects
      fetch_career_subjects = CareerSubject.includes(:subject).where("'documents_count > 0 and status = 'approved'")
      career_id = @user&.career&.id
      career_approved = @user&.career&.status == 'approved'
      university_id = @user&.university&.id
      university_approved = @user&.university&.status == 'approved'

      order_sql = []
      if university_id && university_approved
        order_sql << "CASE WHEN university_id = #{university_id} THEN 0 ELSE 1 END"
      end
      order_sql << "CASE WHEN career_id = #{career_id} THEN 0 ELSE 1 END" if career_id && career_approved
      order_sql << 'documents_count DESC'

      fetch_career_subjects.order(Arel.sql(order_sql.join(',')))
      fetch_career_subjects.joins(:subject).includes(:subject)

      if @query
        fetch_career_subjects = fetch_career_subjects.where('subjects.normalized_name % ?', @query)
                     .reorder(Arel.sql("subjects.normalized_name <-> #{@query}"))
      end

      fetch_career_subjects = fetch_career_subjects.joins(
        "LEFT JOIN follow_career_subjects fc ON fc.career_subject_id = career_subjects.id AND fc.user_id = #{@user.id}"
      ).where(fc: { career_subject_id: nil })

    end

    def fetch_interests
      fetch_interests = Tag.all
                          .where("normalized_description % #{ActiveRecord::Base.connection.quote(@query)} and documents_count > 0")
                          .order(Arel.sql("normalized_description <-> #{ActiveRecord::Base.connection.quote(@query)}"))
                          .limit(Interests::DEFAULT_LIMIT_SEARCH)
                          .order(documents_count: :desc)
      if @user
        followed_tag_ids = FollowTag.where(user_id: @user.id).pluck(:tag_id) # aqui devuelve un array de ids
        fetch_interests.where.not(id: followed_tag_ids)
      end
    end

end