jam-cloud/ruby/lib/jam_ruby/models/email_batch_scheduled_sessions.rb

module JamRuby
  class EmailBatchScheduledSessions < EmailBatchPeriodic

    BATCH_SIZE = 500
    SINCE_DAYS = 2
    MIN_HOURS_START = 2

    TMP_SESS = 'tmp_candidate_sessions'
    TMP_RECIP = 'tmp_candidate_recipients'
    TMP_MATCH = 'tmp_matches'

    def self.subject
      "New sessions have been scheduled that may be a good match for you!"
    end

    # inserts eligible sessions to temp table
    def _collect_eligible_sessions
      ActiveRecord::Base.connection.execute("DROP TABLE IF EXISTS #{TMP_SESS}")
      sql =<<SQL
SELECT 
    msess.id AS session_id, 
    msess.user_id AS creator_id,
    users.last_jam_locidispid AS creator_score_idx,
    rs.instrument_id
INTO TEMP TABLE #{TMP_SESS} 
FROM music_sessions msess
INNER JOIN users ON users.id = msess.user_id
INNER JOIN rsvp_slots AS rs ON rs.music_session_id = msess.id
LEFT JOIN rsvp_requests_rsvp_slots AS rrrs ON rrrs.rsvp_slot_id = rs.id
WHERE
    musician_access = 't' AND
    approval_required = 'f' AND
    msess.created_at > '#{time_since_last_batch(SINCE_DAYS)}' AND
    msess.created_at < '#{self.created_at}' AND
    scheduled_start >= '#{Time.now() + MIN_HOURS_START.hours}' AND
    (rrrs.rsvp_slot_id IS NULL OR rrrs.chosen != 't')
SQL
      ActiveRecord::Base.connection.execute(sql)
    end

    def _collect_eligible_recipients
      ActiveRecord::Base.connection.execute("DROP TABLE IF EXISTS #{TMP_RECIP}")
      # load eligible recipients into tmp table
      sql =<<SQL
SELECT 
    users.id AS receiver_id, 
    users.last_jam_locidispid AS receiver_score_idx
INTO TEMP TABLE #{TMP_RECIP}
FROM users
INNER JOIN musicians_instruments AS mi ON mi.user_id = users.id
INNER JOIN #{TMP_SESS} ON #{TMP_SESS}.instrument_id = mi.instrument_id
WHERE
    users.musician = 't' AND
    users.subscribe_email = 't' 
SQL
      ActiveRecord::Base.connection.execute(sql)
    end

    def _collect_scored_recipients
      ActiveRecord::Base.connection.execute("DROP TABLE IF EXISTS #{TMP_MATCH}")
      sql =<<SQL
SELECT 
    DISTINCT #{TMP_RECIP}.receiver_id, 
    #{TMP_SESS}.session_id,
    scores.score AS latency
INTO TEMP TABLE #{TMP_MATCH}
FROM scores
INNER JOIN #{TMP_SESS} ON #{TMP_SESS}.creator_score_idx = scores.alocidispid
INNER JOIN #{TMP_RECIP} ON #{TMP_RECIP}.receiver_score_idx = scores.blocidispid
WHERE
    scores.score < #{Score::MAX_YELLOW_LATENCY} AND
    #{TMP_RECIP}.receiver_id != #{TMP_SESS}.creator_id
GROUP BY 
    #{TMP_RECIP}.receiver_id, 
    #{TMP_SESS}.session_id, 
    latency
SQL
      ActiveRecord::Base.connection.execute(sql)
    end

    # select recipients whose score is below minimum threshold
    def _select_scored_recipients(offset=0)
      if 0 > offset
        sql = "SELECT COUNT(DISTINCT receiver_id) AS num FROM #{TMP_MATCH}"
        rr = ActiveRecord::Base.connection.execute(sql)
        return 0 < rr.count ? rr[0]['num'].to_i : 0
      else
        sql =<<SQL
SELECT DISTINCT receiver_id 
FROM #{TMP_MATCH} 
ORDER BY receiver_id ASC
LIMIT #{@per_page}
OFFSET #{offset}
SQL
        return ActiveRecord::Base.connection.execute(sql)
      end
    end

    def fetch_recipients(per_page=500)
      objs = []

      # load eligible sessions into tmp table
      self._collect_eligible_sessions

      # load eligible mail recipients into tmp table
      self._collect_eligible_recipients

      # load mail recipients with minimum score into tmp table
      self._collect_scored_recipients

      @per_page = per_page
      num_recip = _select_scored_recipients(-1)
      loops = (num_recip / @per_page) + (num_recip % @per_page) - 1

      0.upto(loops) do |nn|
        offset = nn * @per_page
        # now just get the sessions/latency for each distinct mail recipient
        _select_scored_recipients(offset).each do |result|
          receiver = User.find_by_id(result['receiver_id'])
          sessions = MusicSession.select("music_sessions.*, #{TMP_MATCH}.latency")
            .joins("INNER JOIN #{TMP_MATCH} ON #{TMP_MATCH}.session_id = music_sessions.id")
            .where(["#{TMP_MATCH}.receiver_id = ?", receiver.id])
            .includes([:genre, :creator])
          block_given? ? yield(receiver, sessions) : objs << [receiver, sessions]
        end
      end
      objs
    end

    def deliver_batch_sets!
      self.opt_in_count = 0
      self.fetch_recipients do |receiver, sessions_and_latency|
        self.opt_in_count += 1
        bset = EmailBatchSet.scheduled_session_set(self, receiver, sessions_and_latency)
        UserMailer.scheduled_session_daily(receiver, sessions_and_latency).deliver
      end
      self.sent_count = self.opt_in_count
      self.save
      self.did_batch_run!
    end

    def self.send_daily_session_batch
      oo = self.create
      oo.deliver_batch
      oo
    end

  end
end