import { type SQL, sql } from 'drizzle-orm';

interface ChangesReader {
  get<T = unknown>(query: SQL): T;
}

function affectedRows(result: unknown): number {
  const changes = Array.isArray(result)
    ? result[0]
    : result && typeof result === 'object' && 'changes' in result
      ? result.changes
      : undefined;
  if (changes === undefined) {
    throw new Error('SQLite mutation did not return an affected-row count');
  }
  if (!Number.isSafeInteger(changes) || (changes as number) < 0) {
    throw new Error('SQLite returned an invalid affected-row count');
  }
  return changes as number;
}

/**
 * Run a synchronous Bun/Drizzle mutation and read SQLite's connection-local
 * `changes()` value before any other JavaScript can use that connection.
 *
 * Bun's statement `.run().changes` includes writes performed by FTS triggers,
 * so it cannot report the number of top-level Articles/Feeds affected. SQLite's
 * `changes()` excludes auxiliary trigger work. Keeping both calls synchronous
 * and adjacent also avoids a count/select race without materializing RETURNING
 * rows or holding an async transaction open.
 */
export function runAndCountChanges(connection: ChangesReader, mutation: () => unknown): number {
  mutation();
  return affectedRows(connection.get(sql`select changes()`));
}