/**
 * arcrun API component Worker (cron)
 *
 * POST / → JSON input → WASM (WASI preview1 stdin/stdout) → JSON output
 *
 * cron 純計算(cron 表達式 → 下一個觸發時間),沒有 host function 需求。
 * 方案 A:import cypher-executor/src/lib/wasi-shim.ts 的 `createWasiShim`,
 * 不提供任何 hostFunctions(WASM 側也沒 `//go:wasmimport u6u` 宣告)。
 */

import componentWasm from '../component.wasm' assert { type: 'webassembly' };
import { Hono } from 'hono';
import { cors } from 'hono/cors';
import { createWasiShim } from '../../../cypher-executor/src/lib/wasi-shim';

const app = new Hono();
app.use('*', cors());

app.get('/', (c) => c.json({ ok: true, component: 'cron' }));

app.post('/', async (c) => {
  let input: unknown;
  try {
    input = await c.req.json();
  } catch {
    return c.json({ success: false, error: 'request body must be JSON' }, 400);
  }

  try {
    const result = await runWasm(input);
    return c.json(result);
  } catch (e) {
    return c.json(
      { success: false, error: e instanceof Error ? e.message : String(e) },
      500,
    );
  }
});

export default app;

// ── WASM runner ──────────────────────────────────────────────────────────────

async function runWasm(input: unknown): Promise<unknown> {
  const shim = createWasiShim(JSON.stringify(input));

  const instance = await WebAssembly.instantiate(
    componentWasm as WebAssembly.Module,
    shim.imports,
  );
  shim.setMemory(instance.exports.memory as WebAssembly.Memory);

  const start = (instance.exports._start ?? instance.exports.main) as () => void;
  if (typeof start !== 'function') {
    throw new Error('WASM missing _start or main export');
  }

  try {
    start();
  } catch (e) {
    if (!(e instanceof Error && e.message === 'wasm exit: 0')) throw e;
  }

  const stdout = shim.getStdout().trim();
  if (!stdout) throw new Error('WASM component produced no output');
  return JSON.parse(stdout);
}