/* Q8. Central Person for a Tag
\set tag '\'Che_Guevara\''
\set date '\'2011-07-22T00:00:00.000+00:00\''::timestamp
 */
WITH person_tag_interest AS (
    SELECT p.p_personid AS personid
      FROM person p
         , person_tag pt
         , tag t
     WHERE 1=1
        -- join
       AND p.p_personid = pt.pt_personid
       AND pt.pt_tagid = t.t_tagid
        -- filter
       AND t.t_name = 'Che_Guevara'
)
   , person_message_score AS (
    SELECT p.p_personid AS personid
         , count(*) AS message_score
      FROM message m
         , person p
         , message_tag pt
         , tag t
     WHERE 1=1
        -- join
       AND m.m_creatorid = p.p_personid
       AND m.m_messageid = pt.mt_messageid
       AND pt.mt_tagid = t.t_tagid
        -- filter
       AND m.m_creationdate > '2011-07-22T00:00:00'
       AND t.t_name = 'Che_Guevara'
     GROUP BY p.p_personid
)
   , person_score AS (
    SELECT coalesce(pti.personid, pms.personid) AS personid
         , CASE WHEN pti.personid IS NULL then 0 ELSE 100 END -- scored from interest in the given tag
         + coalesce(pms.message_score, 0) AS score
      FROM person_tag_interest pti
           FULL JOIN person_message_score pms ON (pti.personid = pms.personid)
)
SELECT p.personid AS "person.id"
     , p.score AS score
     , sum(f.score) AS friendsScore
  FROM person_score p
     , knows k
     , person_score f -- the friend
 WHERE 1=1
    -- join
   AND p.personid = k.k_person1id
   AND k.k_person2id = f.personid
 GROUP BY p.personid, p.score
 ORDER BY p.score + sum(f.score) DESC, p.personid
 LIMIT 100
;