Test sqlite extension for bhoptimer's GetWeightedPoints

sqlite3bhoptimerweightedpoints.c

// SPDX-License-Identifier: CC0
/* vim: set ts=2 : */

/*
This is basically:
SELECT SUM(p2)
FROM (
  SELECT (points * POW(?, ROW_NUMBER() OVER (ORDER BY points DESC) -1)) AS p2
  FROM playertimes WHERE auth = ? ORDER BY points DESC LIMIT ?;
);
*/

#include "sqlite/sqlite3ext.h"
SQLITE_EXTENSION_INIT1

// GetWeightedPoints(auth, "%splayertimes", weightingLimit, weightingMultiplier)
static void GetWeightedPointsFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  sqlite3 *db = sqlite3_context_db_handle(context);
  sqlite3_stmt *getPoints;

  // I would've preferred to cache the getPoints stmt.
  // But it makes closing the database messy and throw errors.
  // xDestroy isn't called soon enough to finalize it...
  // There's no extension de-init function to finalize it in...
  // Well, fuck me.

  char query[256];
  sqlite3_snprintf(sizeof(query), query,
    "SELECT points FROM `%s` WHERE auth = ? AND points > 0 ORDER BY points DESC LIMIT %d;",
    sqlite3_value_text(argv[1]), sqlite3_value_int(argv[2]));
  if (SQLITE_OK != sqlite3_prepare_v2(db, query, -1, &getPoints, 0)) {
    sqlite3_result_double(context, 0.0);
    return;
  }

  sqlite3_bind_int(getPoints, 1, sqlite3_value_int(argv[0])); // auth/steamid

  double weightingMultiplier = sqlite3_value_double(argv[3]);
  double total = 0.0, mult = 1.0;

  while (SQLITE_ROW == sqlite3_step(getPoints)) {
    double points = sqlite3_column_double(getPoints, 0);
    total += (points * mult);
    mult *= weightingMultiplier;
  }

  sqlite3_finalize(getPoints);
  sqlite3_result_double(context, total);
}

#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_sqlitebhoptimerweightedpoints_init(
  sqlite3 *db,
  char **pzErrMsg,
  const sqlite3_api_routines *pApi
){
  int rc = SQLITE_OK;
  SQLITE_EXTENSION_INIT2(pApi);
  rc = sqlite3_create_function_v2(db, "GetWeightedPoints", 4,
    SQLITE_UTF8, 0, GetWeightedPointsFunc, 0, 0, 0);
  return rc;
}