/**
 * C-03 Pyodide 懒加载运行器（浏览器内 WASM，无服务端执行）。
 * 安全约束：
 * - 默认断网：不 loadPackage、不拉取额外包；只运行解释器自带能力。
 * - 超时由调用方（CodeRunner.tsx）经 Promise.race + runId 丢弃过期结果保证；
 *   Pyodide 本体不支持强制 terminate，超时后输出"执行超时"并忽略迟到结果。
 */

export const PYODIDE_VERSION = "0.26.4";
export const PYODIDE_CDN = `https://cdn.jsdelivr.net/pyodide/v${PYODIDE_VERSION}/full/`;

type PyodideRuntime = {
  runPython: (code: string) => unknown;
  setStdout: (opts: { batched: (s: string) => void }) => void;
  setStderr: (opts: { batched: (s: string) => void }) => void;
};

declare global {
  interface Window {
    __pyodidePromise?: Promise<PyodideRuntime> | null;
  }
}

function loadPyodideScript(): Promise<void> {
  return new Promise((resolve, reject) => {
    if (document.querySelector('script[data-pyodide="1"]')) {
      resolve();
      return;
    }
    const s = document.createElement("script");
    s.dataset.pyodide = "1";
    s.src = `${PYODIDE_CDN}pyodide.js`;
    s.onload = () => resolve();
    s.onerror = () => reject(new Error("Pyodide 运行时加载失败，请检查网络后重试"));
    document.head.appendChild(s);
  });
}

async function bootPyodide(
  onStdout: (s: string) => void,
  onStderr: (s: string) => void,
): Promise<PyodideRuntime> {
  await loadPyodideScript();
  const factory = (window as unknown as { loadPyodide?: (opts: { indexURL: string }) => Promise<PyodideRuntime> }).loadPyodide;
  if (!factory) throw new Error("Pyodide 运行时初始化失败");
  const py = await factory({ indexURL: PYODIDE_CDN });
  py.setStdout({ batched: onStdout });
  py.setStderr({ batched: onStderr });
  return py;
}

export function getPyodide(
  onStdout: (s: string) => void,
  onStderr: (s: string) => void,
): Promise<PyodideRuntime> {
  if (!window.__pyodidePromise) {
    window.__pyodidePromise = bootPyodide(onStdout, onStderr).catch((e) => {
      window.__pyodidePromise = null;
      throw e;
    });
  }
  return window.__pyodidePromise;
}