Large custom query in postgreSQL for a Rails app

model_method.rb

  def moderate_plus_vigorous_durations_adjusted(start_date=(1.week.ago.beginning_of_day), end_date=(DateTime.now))
    query_args = [{value: self.id}, {value: start_date}, {value: end_date}]
    sql = %Q[
      WITH my_vars(intensity_2_duration, intensity_3_duration) AS (VALUES 
        (
          (SELECT SUM(duration) as intensity_2_duration
            FROM users 
            INNER JOIN workouts 
              ON workouts.user_id = users.id
            WHERE 
              workouts.intensity = 2
              AND 
              workouts.deleted_at IS NULL
              AND
              workouts.date > $2
              AND
              workouts.date < $3
              AND
              users.id = $1::int),
          (SELECT (SUM(duration)*2) as intensity_3_duration
            FROM users 
            INNER JOIN workouts 
              ON workouts.user_id = users.id
            WHERE 
              workouts.intensity = 3 
              AND 
              workouts.deleted_at IS NULL
              AND
              workouts.date > $2
              AND
              workouts.date < $3
              AND
              users.id = $1::int)
          )
      )
      SELECT MAX(date), (SELECT (COALESCE(intensity_2_duration,0) + COALESCE(intensity_3_duration, 0)) FROM my_vars) as total_duration, SUM(duration)
      FROM workouts
      INNER JOIN users on users.id = workouts.user_id
      WHERE 
        workouts.deleted_at IS NULL 
        AND 
        workouts.date > $2
        AND
        workouts.date < $3
        AND workouts.user_id = $1::int;
    ]
    ActiveRecord::Base.connection.raw_connection.exec(sql, query_args)
  end