module ForestLiana
  class ValueStatGetter < StatGetter
    attr_accessor :record

    def perform
      return if @params[:aggregate].blank?
      valueCurrent = get_resource().eager_load(includes)
      valuePrevious = get_resource().eager_load(includes)
      filter_date_interval = false

      if @params[:filterType] && @params[:filters]
        conditions = []
        filter_operator = " #{@params[:filterType]} ".upcase

        @params[:filters].try(:each) do |filter|
          operator, filter_value = OperatorValueParser.parse(filter[:value])
          conditions << OperatorValueParser.get_condition(filter[:field],
            operator, filter_value, @resource, @params[:timezone])
        end

        valueCurrent = valueCurrent.where(conditions.join(filter_operator))

        # NOTICE: Search for previous interval value only if the filterType is
        #         'AND', it would not be pertinent for a 'OR' filterType.
        if @params[:filterType] == 'and'
          conditions = []
          @params[:filters].try(:each) do |filter|
            operator, filter_value = OperatorValueParser.parse(filter[:value])
            operator_date_interval_parser = OperatorDateIntervalParser
              .new(filter_value, @params[:timezone])
            if operator_date_interval_parser.has_previous_interval()
              field_name = OperatorValueParser.get_field_name(filter[:field], @resource)
              filter = operator_date_interval_parser
                .get_interval_date_filter_for_previous_interval()
              conditions << "#{field_name} #{filter}"
              filter_date_interval = true
            else
              conditions << OperatorValueParser.get_condition(filter[:field],
                operator, filter_value, @resource, @params[:timezone])
            end
          end

          valuePrevious = valuePrevious.where(conditions.join(filter_operator))
        end
      end

      @record = Model::Stat.new(value: {
        countCurrent: count(valueCurrent),
        countPrevious: filter_date_interval ? count(valuePrevious) : nil
      })
    end

    private

    def count(value)
      uniq = @params[:aggregate].downcase == 'count'

      if Rails::VERSION::MAJOR >= 4
        if uniq
          # NOTICE: uniq is deprecated since Rails 5.0
          value = Rails::VERSION::MAJOR >= 5 ? value.distinct : value.uniq
        end
        value.send(@params[:aggregate].downcase, aggregate_field)
      else
        value.send(@params[:aggregate].downcase, aggregate_field,
                   distinct: uniq)
      end
    end

    def aggregate_field
      @params[:aggregate_field] || @resource.primary_key
    end

  end
end