/**
 * Lazy-initialized singleton AsyncDuckDB instance running the single-threaded
 * MVP wasm bundle only — never eh/coi, which need Cross-Origin-Opener-Policy /
 * Cross-Origin-Embedder-Policy response headers this static host doesn't send.
 * See docs/superpowers/specs/2026-08-11-empirical-draws-wasm-design.md.
 */

let dbPromise = null

/** @returns {Promise<import('@duckdb/duckdb-wasm').AsyncDuckDB>} */
export function getDb() {
  if (!dbPromise) dbPromise = initDb()
  return dbPromise
}

async function initDb() {
  const duckdb = await import('@duckdb/duckdb-wasm')
  const mvpWorkerUrl = (await import('@duckdb/duckdb-wasm/dist/duckdb-browser-mvp.worker.js?url')).default
  const mvpWasmUrl = (await import('@duckdb/duckdb-wasm/dist/duckdb-mvp.wasm?url')).default

  const worker = new Worker(mvpWorkerUrl)
  const logger = new duckdb.ConsoleLogger(duckdb.LogLevel.WARNING)
  const db = new duckdb.AsyncDuckDB(logger, worker)
  await db.instantiate(mvpWasmUrl, null)
  return db
}