/*
** Load the record ID rid and up to N-1 closest descendants into
** the "ok" table.
*/
void compute_descendants(int rid, int N){
  Bag seen;
  PQueue queue;
  Stmt ins;
  Stmt q;

  bag_init(&seen);
  pqueuex_init(&queue);
  bag_insert(&seen, rid);
  pqueuex_insert(&queue, rid, 0.0, 0);
  db_prepare(&ins, "INSERT OR IGNORE INTO ok VALUES(:rid)");
  db_prepare(&q, "SELECT cid, mtime FROM plink WHERE pid=:rid");
  while( (N--)>0 && (rid = pqueuex_extract(&queue, 0))!=0 ){
    db_bind_int(&ins, ":rid", rid);
    db_step(&ins);
    db_reset(&ins);
    db_bind_int(&q, ":rid", rid);
    while( db_step(&q)==SQLITE_ROW ){
      int pid = db_column_int(&q, 0);
      double mtime = db_column_double(&q, 1);
      if( bag_insert(&seen, pid) ){
        pqueuex_insert(&queue, pid, mtime, 0);
      }
    }
    db_reset(&q);
  }
  bag_clear(&seen);
  pqueuex_clear(&queue);
  db_finalize(&ins);
  db_finalize(&q);
}
/*
** Load the record ID rid and up to N-1 closest ancestors into
** the "ok" table.
*/
void compute_ancestors(int rid, int N, int directOnly){
  Bag seen;
  PQueue queue;
  Stmt ins;
  Stmt q;
  bag_init(&seen);
  pqueuex_init(&queue);
  bag_insert(&seen, rid);
  pqueuex_insert(&queue, rid, 0.0, 0);
  db_prepare(&ins, "INSERT OR IGNORE INTO ok VALUES(:rid)");
  db_prepare(&q,
    "SELECT a.pid, b.mtime FROM plink a LEFT JOIN plink b ON b.cid=a.pid"
    " WHERE a.cid=:rid %s",
    directOnly ? " AND a.isprim" : ""
  );
  while( (N--)>0 && (rid = pqueuex_extract(&queue, 0))!=0 ){
    db_bind_int(&ins, ":rid", rid);
    db_step(&ins);
    db_reset(&ins);
    db_bind_int(&q, ":rid", rid);
    while( db_step(&q)==SQLITE_ROW ){
      int pid = db_column_int(&q, 0);
      double mtime = db_column_double(&q, 1);
      if( bag_insert(&seen, pid) ){
        pqueuex_insert(&queue, pid, -mtime, 0);
      }
    }
    db_reset(&q);
  }
  bag_clear(&seen);
  pqueuex_clear(&queue);
  db_finalize(&ins);
  db_finalize(&q);
}
/*
** Propagate the tag given by tagid to the children of pid.
**
** This routine assumes that tagid is a tag that should be
** propagated and that the tag is already present in pid.
**
** If tagtype is 2 then the tag is being propagated from an
** ancestor node.  If tagtype is 0 it means a propagating tag is
** being blocked.
*/
static void tag_propagate(
  int pid,             /* Propagate the tag to children of this node */
  int tagid,           /* Tag to propagate */
  int tagType,         /* 2 for a propagating tag.  0 for an antitag */
  int origId,          /* Artifact of tag, when tagType==2 */
  const char *zValue,  /* Value of the tag.  Might be NULL */
  double mtime         /* Timestamp on the tag */
){
  PQueue queue;        /* Queue of check-ins to be tagged */
  Stmt s;              /* Query the children of :pid to which to propagate */
  Stmt ins;            /* INSERT INTO tagxref */
  Stmt eventupdate;    /* UPDATE event */

  assert( tagType==0 || tagType==2 );
  pqueuex_init(&queue);
  pqueuex_insert(&queue, pid, 0.0, 0);

  /* Query for children of :pid to which to propagate the tag.
  ** Three returns:  (1) rid of the child.  (2) timestamp of child.
  ** (3) True to propagate or false to block.
  */
  db_prepare(&s, 
     "SELECT cid, plink.mtime,"
     "       coalesce(srcid=0 AND tagxref.mtime<:mtime, %d) AS doit"
     "  FROM plink LEFT JOIN tagxref ON cid=rid AND tagid=%d"
     " WHERE pid=:pid AND isprim",
     tagType==2, tagid
  );
  db_bind_double(&s, ":mtime", mtime);

  if( tagType==2 ){
    /* Set the propagated tag marker on checkin :rid */
    db_prepare(&ins,
       "REPLACE INTO tagxref(tagid, tagtype, srcid, origid, value, mtime, rid)"
       "VALUES(%d,2,0,%d,%Q,:mtime,:rid)",
       tagid, origId, zValue
    );
    db_bind_double(&ins, ":mtime", mtime);
  }else{
    /* Remove all references to the tag from checkin :rid */
    zValue = 0;
    db_prepare(&ins,
       "DELETE FROM tagxref WHERE tagid=%d AND rid=:rid", tagid
    );
  }
  if( tagid==TAG_BGCOLOR ){
    db_prepare(&eventupdate,
      "UPDATE event SET bgcolor=%Q WHERE objid=:rid", zValue
    );
  }
  while( (pid = pqueuex_extract(&queue, 0))!=0 ){
    db_bind_int(&s, ":pid", pid);
    while( db_step(&s)==SQLITE_ROW ){
      int doit = db_column_int(&s, 2);
      if( doit ){
        int cid = db_column_int(&s, 0);
        double mtime = db_column_double(&s, 1);
        pqueuex_insert(&queue, cid, mtime, 0);
        db_bind_int(&ins, ":rid", cid);
        db_step(&ins);
        db_reset(&ins);
        if( tagid==TAG_BGCOLOR ){
          db_bind_int(&eventupdate, ":rid", cid);
          db_step(&eventupdate);
          db_reset(&eventupdate);
        }
        if( tagid==TAG_BRANCH ){
          leaf_eventually_check(cid);
        }
      }
    }
    db_reset(&s);
  }
  pqueuex_clear(&queue);
  db_finalize(&ins);
  db_finalize(&s);
  if( tagid==TAG_BGCOLOR ){
    db_finalize(&eventupdate);
  }
}