ditto/src/workers/sqlite.worker.ts

/// <reference lib="webworker" />
import { Database as SQLite } from '@db/sqlite';
import * as Comlink from 'comlink';
import { CompiledQuery, QueryResult } from 'kysely';
import { asyncGeneratorTransferHandler } from 'comlink-async-generator';

import '@/sentry.ts';

let db: SQLite | undefined;

export const SqliteWorker = {
  open(path: string): void {
    db = new SQLite(path);
  },
  executeQuery<R>({ sql, parameters }: CompiledQuery): QueryResult<R> {
    if (!db) throw new Error('Database not open');

    return {
      rows: db!.prepare(sql).all(...parameters as any[]) as R[],
      numAffectedRows: BigInt(db!.changes),
      insertId: BigInt(db!.lastInsertRowId),
    };
  },
  async *streamQuery<R>({ sql, parameters }: CompiledQuery): AsyncIterableIterator<QueryResult<R>> {
    if (!db) throw new Error('Database not open');

    const stmt = db.prepare(sql).bind(...parameters as any[]);
    for (const row of stmt) {
      yield {
        rows: [row],
      };
    }
  },
  destroy() {
    db?.close();
  },
};

Comlink.transferHandlers.set('asyncGenerator', asyncGeneratorTransferHandler);
Comlink.expose(SqliteWorker);

self.postMessage(['ready']);