Manifest *pWiki;
  if( tagid==0 ) return;
  rid = db_int(0, "SELECT rid FROM tagxref WHERE tagid=%d"
                  " ORDER BY mtime DESC LIMIT 1", tagid);
  if( rid==0 ) return;
  pWiki = manifest_get(rid, CFTYPE_WIKI, 0);
  if( pWiki ){
    int mimetype = parse_mimetype( pWiki->zMimetype );
    backlink_extract(pWiki->zWiki, mimetype, tagid, BKLNK_WIKI,
                     pWiki->rDate, 1);
    manifest_destroy(pWiki);
  }
}

/*
** Structure used to pass down state information through the

  blob_init(&out, 0, 0);
  blob_init(&in, zInputText, -1);
  markdown(&out, &in, &html_renderer);
  blob_reset(&out);
  blob_reset(&in);
}

/*
** Transform mimetype string into an integer code.
** NOTE: In the sake of compatability empty string is parsed as MT_UNKNOWN;
**       it is yet unclear whether it can safely be changed to MT_NONE.
*/
int parse_mimetype(const char* zMimetype){
  if( zMimetype==0 ) return MT_NONE;
  if( strstr(zMimetype,"wiki")!=0 )     return MT_WIKI;
  if( strstr(zMimetype,"markdown")!=0 ) return MT_MARKDOWN;
  return MT_UNKNOWN;
}
/*
** Parse text looking for hyperlinks.  Insert references into the
** BACKLINK table.
*/
void backlink_extract(
  char *zSrc,            /* Input text from which links are extracted */
  int mimetype,          /* Mimetype of input. MT_NONE works as MT_WIKI */
  int srcid,             /* srcid for the source document */
  int srctype,           /* One of BKLNK_*.  0=comment 1=ticket 2=wiki */
  double mtime,          /* mtime field for new BACKLINK table entries */
  int replaceFlag        /* True to overwrite prior BACKLINK entries */
){
  Backlink bklnk;
  if( replaceFlag ){
    db_multi_exec("DELETE FROM backlink WHERE srctype=%d AND srcid=%d",
                  srctype, srcid);
  }
  bklnk.srcid = srcid;
  assert( ValidBklnk(srctype) );
  assert( ValidMTC(mimetype) );
  bklnk.srctype = srctype;
  bklnk.mtime = mtime;
  if( mimetype==MT_NONE || mimetype==MT_WIKI ){
    wiki_extract_links(zSrc, &bklnk, srctype==BKLNK_COMMENT ? WIKI_INLINE : 0);
  }else if( mimetype==MT_MARKDOWN ){
    markdown_extract_links(zSrc, &bklnk);
  }
}

/*
** COMMAND: test-backlinks
**

**    --mtime DATETIME        Use an alternative date/time.  Defaults to the
**                            current date/time.
**    --mimetype TYPE         Use an alternative mimetype.
*/
void test_backlinks_cmd(void){
  const char *zMTime = find_option("mtime",0,1);
  const char *zMimetype = find_option("mimetype",0,1);
  const int mimetype = parse_mimetype(zMimetype);
  Blob in;
  int srcid;
  int srctype;
  double mtime;

  verify_all_options();
  if( g.argc!=5 ){

    " 'target='||quote(new.target)||"
    " ' srctype='||quote(new.srctype)||"
    " ' srcid='||quote(new.srcid)||"
    " ' mtime='||datetime(new.mtime));\n"
    "  SELECT raise(ignore);\n"
    "END;"
  );
  backlink_extract(blob_str(&in),mimetype,srcid,srctype,mtime,0);
  blob_reset(&in);
}


/*
** COMMAND: test-wiki-relink
**

        "RETURNING coalesce(ecomment,comment);",
        TAG_DATE, rid, p->rDate,
        rid, p->zUser, p->zComment,
        TAG_BGCOLOR, rid,
        TAG_USER, rid,
        TAG_COMMENT, rid, p->rDate
      );
      backlink_extract(zCom, MT_NONE, rid, BKLNK_COMMENT, p->rDate, 1);
      fossil_free(zCom);

      /* If this is a delta-manifest, record the fact that this repository
      ** contains delta manifests, to free the "commit" logic to generate
      ** new delta manifests.
      */
      if( p->zBaseline!=0 ){

        "REPLACE INTO event(type,mtime,objid,user,comment)"
        "VALUES('f',%.17g,%d,%Q,'%q: %q')",
        p->rDate, rid, p->zUser, zFType, zTitle
      );
      fossil_free(zTitle);
    }
    if( p->zWiki[0] ){
      int mimetype = parse_mimetype(p->zMimetype);
      backlink_extract(p->zWiki, mimetype, rid, BKLNK_FORUM, p->rDate, 1);
    }
  }

  db_end_transaction(0);
  if( permitHooks ){
    rc = xfer_run_common_script();
    if( rc==TH_OK ){

# define BKLNK_TICKET     1   /* Ticket body or title */
# define BKLNK_WIKI       2   /* Wiki */
# define BKLNK_EVENT      3   /* Technote */
# define BKLNK_FORUM      4   /* Forum post */
# define ValidBklnk(X)   (X>=0 && X<=4)  /* True if backlink.srctype is valid */
#endif

/*
** Allowed values for MIMEtype codes
*/
#if INTERFACE
# define MT_NONE       0   /* unspecified */
# define MT_WIKI       1   /* Wiki */
# define MT_MARKDOWN   2   /* Markdonw */
# define MT_UNKNOWN    3   /* unknown  */
# define ValidMTC(X)  ((X)>=0 && (X)<=3)  /* True if MIMEtype code is valid */
#endif

/*
** Predefined tagid values
*/
#if INTERFACE
# define TAG_BGCOLOR    1     /* Set the background color for display */
# define TAG_COMMENT    2     /* The check-in comment */
# define TAG_USER       3     /* User who made a checking */

    }
  }
  if( zCol ){
    db_multi_exec("UPDATE event SET \"%w\"=%Q WHERE objid=%d",
                  zCol, zValue, rid);
    if( tagid==TAG_COMMENT ){
      char *zCopy = mprintf("%s", zValue);
      backlink_extract(zCopy, MT_NONE, rid, BKLNK_COMMENT, mtime, 1);
      free(zCopy);
    }
  }
  if( tagid==TAG_DATE ){
    db_multi_exec("UPDATE event "
                  "   SET mtime=julianday(%Q),"
                  "       omtime=coalesce(omtime,mtime)"

#define USEDBY_TICKETCHNG  02
#define USEDBY_BOTH        03
static u8 haveTicket = 0;        /* True if the TICKET table exists */
static u8 haveTicketCTime = 0;   /* True if TICKET.TKT_CTIME exists */
static u8 haveTicketChng = 0;    /* True if the TICKETCHNG table exists */
static u8 haveTicketChngRid = 0; /* True if TICKETCHNG.TKT_RID exists */
static u8 haveTicketChngUser = 0;/* True if TICKETCHNG.TKT_USER exists */
static u8 useTicketGenMt = 0;    /* use generated TICKET.MIMETYPE */
static u8 useTicketChngGenMt = 0;/* use generated TICKETCHNG.MIMETYPE */


/*
** Compare two entries in aField[] for sorting purposes
*/
static int nameCmpr(const void *a, const void *b){
  return fossil_strcmp(((const struct tktFieldInfo*)a)->zName,
                       ((const struct tktFieldInfo*)b)->zName);

** in sorted order in aField[].
**
** The haveTicket and haveTicketChng variables are set to 1 if the TICKET and
** TICKETCHANGE tables exist, respectively.
*/
static void getAllTicketFields(void){
  Stmt q;
  int i, noRegularMimetype;
  static int once = 0;
  if( once ) return;
  once = 1;
  db_prepare(&q, "PRAGMA table_info(ticket)");
  while( db_step(&q)==SQLITE_ROW ){
    const char *zFieldName = db_column_text(&q, 1);
    haveTicket = 1;

    }
    aField[nField].zName = mprintf("%s", zFieldName);
    aField[nField].mUsed = USEDBY_TICKETCHNG;
    nField++;
  }
  db_finalize(&q);
  qsort(aField, nField, sizeof(aField[0]), nameCmpr);
  noRegularMimetype = 1;
  for(i=0; i<nField; i++){
    aField[i].zValue = "";
    aField[i].zAppend = 0;
    if( strcmp(aField[i].zName,"mimetype")==0 ){
      noRegularMimetype = 0;
    }
  }
  if( noRegularMimetype ){ /* check for generated "mimetype" columns */
    useTicketGenMt = db_exists(
      "SELECT 1 FROM pragma_table_xinfo('ticket') "
      "WHERE name = 'mimetype'");
    useTicketChngGenMt = db_exists(
      "SELECT 1 FROM pragma_table_xinfo('ticketchng') "
      "WHERE name = 'mimetype'");
  }
}

/*
** Query the database for all TICKET fields for the specific
** ticket whose name is given by the "name" CGI parameter.
** Load the values for all fields into the interpreter.

** the appropriate TICKET table entry if tktid is zero.  If tktid is nonzero
** then it will be the ROWID of an existing TICKET entry.
**
** Parameter rid is the recordID for the ticket artifact in the BLOB table.
**
** Return the new rowid of the TICKET table entry.
*/
static int ticket_insert(const Manifest *p, const int rid, int tktid){
  Blob sql1; /* update or replace TICKET ... */
  Blob sql2; /* list of TICKETCHNG's fields that are in the manifest */
  Blob sql3; /* list of values which correspond to the previous list */
  Stmt q;
  int i, j;
  char *aUsed;
  int mimetype_tkt = MT_NONE, mimetype_tktchng = MT_NONE;

  if( tktid==0 ){
    db_multi_exec("INSERT INTO ticket(tkt_uuid, tkt_mtime) "
                  "VALUES(%Q, 0)", p->zTicketUuid);
    tktid = db_last_insert_rowid();
  }
  blob_zero(&sql1);

      }
    }
    if( aField[j].mUsed & USEDBY_TICKETCHNG ){
      blob_append_sql(&sql2, ",\"%w\"", zBaseName);
      blob_append_sql(&sql3, ",%Q", p->aField[i].zValue);
    }
    if( strcmp(zBaseName,"mimetype")==0 ){
      const char *zMimetype = p->aField[i].zValue;


      /* "mimetype" is a regular column => these two flags must be 0 */
      assert(!useTicketGenMt);
      assert(!useTicketChngGenMt);





      mimetype_tkt = mimetype_tktchng = parse_mimetype( zMimetype );

    }
  }
  blob_append_sql(&sql1, " WHERE tkt_id=%d", tktid);
  if( useTicketGenMt ){
    blob_append_literal(&sql1, " RETURNING mimetype");
  }
  db_prepare(&q, "%s", blob_sql_text(&sql1));
  db_bind_double(&q, ":mtime", p->rDate);
  db_step(&q);
  if( useTicketGenMt ){
    mimetype_tkt = parse_mimetype( db_column_text(&q,0) );
    if( !useTicketChngGenMt ){
      mimetype_tktchng = mimetype_tkt;
    }
  }
  db_finalize(&q);
  blob_reset(&sql1);
  if( blob_size(&sql2)>0 || haveTicketChngRid || haveTicketChngUser ){
    int fromTkt = 0;
    if( haveTicketChngRid ){
      blob_append_literal(&sql2, ",tkt_rid");
      blob_append_sql(&sql3, ",%d", rid);

        fromTkt = 1;
        blob_append_sql(&sql2, ",\"%w\"", z);
        blob_append_sql(&sql3, ",\"%w\"", z);
      }
    }
    if( fromTkt ){
      db_prepare(&q, "INSERT INTO ticketchng(tkt_id,tkt_mtime%s)"
                     "SELECT %d,:mtime%s FROM ticket WHERE tkt_id=%d%s",
                     blob_sql_text(&sql2), tktid,
                     blob_sql_text(&sql3), tktid,
                     useTicketChngGenMt ? " RETURNING mimetype" : "");
    }else{
      db_prepare(&q, "INSERT INTO ticketchng(tkt_id,tkt_mtime%s)"
                     "VALUES(%d,:mtime%s)%s",
                     blob_sql_text(&sql2), tktid, blob_sql_text(&sql3),
                     useTicketChngGenMt ? " RETURNING mimetype" : "");
    }
    db_bind_double(&q, ":mtime", p->rDate);
    db_step(&q);
    if( useTicketChngGenMt ){
      mimetype_tktchng = parse_mimetype( db_column_text(&q, 0) );
      /* substitute NULL with a value generated within another table */
      if( !useTicketGenMt ){
        mimetype_tkt = mimetype_tktchng;
      }else if( mimetype_tktchng==MT_NONE ){
        mimetype_tktchng = mimetype_tkt;
      }else if( mimetype_tkt==MT_NONE ){
        mimetype_tkt = mimetype_tktchng;
      }
    }
    db_finalize(&q);
  }
  blob_reset(&sql2);
  blob_reset(&sql3);
  fossil_free(aUsed);
  if( rid>0 ){                   /* extract backlinks */
    int bReplace = 1, mimetype;
    for(i=0; i<p->nField; i++){
      const char *zName = p->aField[i].zName;
      const char *zBaseName = zName[0]=='+' ? zName+1 : zName;
      j = fieldId(zBaseName);
      if( j<0 ) continue;
      if( aField[j].mUsed & USEDBY_TICKETCHNG ){
        mimetype = mimetype_tktchng;
      }else{
        mimetype = mimetype_tkt;
      }
      backlink_extract(p->aField[i].zValue, mimetype, rid, BKLNK_TICKET,
                       p->rDate, bReplace);
      bReplace = 0;
    }
  }
  return tktid;
}

/*
** Returns non-zero if moderation is required for ticket changes and ticket
** attachments.
*/