(() => {
  const canvas = document.getElementById("canvas");
  const message = document.getElementById("runnerMessage");
  const PYODIDE_URL = "/classroom-assets/vendor/pyodide/";
  let pyodide = null;
  let busy = false;
  let outputDecoders = {};

  function tell(type, details = {}) {
    window.parent.postMessage({ type, ...details }, "*");
  }

  function showMessage(text) {
    message.textContent = text;
    message.hidden = false;
  }

  function hideMessage() {
    message.hidden = true;
  }

  function setStream(channel) {
    return {
      isatty: false,
      write(bytes) {
        const decoder = outputDecoders[channel];
        const text = decoder.decode(bytes, { stream: true });
        if (text) tell("output", { runId: window.currentRunId, text });
        return bytes.length;
      },
    };
  }

  async function initialize() {
    try {
      if (typeof loadPyodide !== "function") throw new Error("Pyodide 主程式沒有載入");
      pyodide = await loadPyodide({ indexURL: PYODIDE_URL });
      pyodide.canvas.setCanvas2D(canvas);
      pyodide._api._skip_unwind_fatal_error = true;
      tell("ready");
      showMessage("Pygame 已就緒，按下「執行」開始遊戲。");
    } catch (error) {
      const text = `瀏覽器版 Pygame 載入失敗：${String(error)}`;
      showMessage(text);
      tell("load_error", { text });
    }
  }

  async function run(files, runId) {
    if (!pyodide || busy) return;
    busy = true;
    window.currentRunId = runId;
    outputDecoders = { stdout: new TextDecoder(), stderr: new TextDecoder() };
    pyodide.setStdout(setStream("stdout"));
    pyodide.setStderr(setStream("stderr"));
    pyodide.setStdin({ stdin: () => { throw new Error("瀏覽器版 Pygame 不支援 input()；請改用 pygame 的鍵盤或滑鼠事件。"); } });
    showMessage("正在載入 Pygame…");
    tell("status", { runId, label: "載入 Pygame 套件…" });

    try {
      await pyodide.loadPackage("pygame-ce");
      pyodide.runPython(`
import os, shutil, sys
root = "/home/pyodide/classroom_pygame"
shutil.rmtree(root, ignore_errors=True)
os.makedirs(root, exist_ok=True)
for name, module in list(sys.modules.items()):
    if str(getattr(module, "__file__", "")).startswith(root):
        del sys.modules[name]
`);
      for (const [path, content] of Object.entries(files || {})) {
        if (path.startsWith("/") || path.split(/[\\/]/).includes("..")) continue;
        const fullPath = `/home/pyodide/classroom_pygame/${path}`;
        pyodide.FS.mkdirTree(fullPath.slice(0, fullPath.lastIndexOf("/")));
        pyodide.FS.writeFile(fullPath, content, { encoding: "utf8" });
      }
      pyodide.globals.set("classroom_entry", "main.py");
      canvas.focus();
      hideMessage();
      tell("status", { runId, label: "遊戲執行中" });
      const succeeded = await pyodide.runPythonAsync(`
import asyncio, inspect, os, sys, traceback
root = "/home/pyodide/classroom_pygame"
os.chdir(root)
if root not in sys.path:
    sys.path.insert(0, root)
entry = os.path.join(root, classroom_entry)
namespace = {"__name__": "__main__", "__file__": entry}
try:
    with open(entry, "r", encoding="utf-8") as source:
        exec(compile(source.read(), entry, "exec"), namespace)
    main = namespace.get("main")
    if inspect.iscoroutinefunction(main):
        await main()
    True
except BaseException:
    traceback.print_exc()
    raise
finally:
    import pygame
    pygame.quit()
`);
      for (const channel of ["stdout", "stderr"]) {
        const rest = outputDecoders[channel].decode();
        if (rest) tell("output", { runId, text: rest });
      }
      tell(succeeded ? "done" : "error", { runId });
      showMessage(succeeded ? "遊戲已結束。按「執行」可重新開始。" : "遊戲發生錯誤，請查看文字輸出。" );
    } catch (error) {
      for (const channel of ["stdout", "stderr"]) {
        const rest = outputDecoders[channel].decode();
        if (rest) tell("output", { runId, text: rest });
      }
      const text = String(error);
      tell("error", { runId, text });
      showMessage("遊戲發生錯誤，請查看文字輸出。");
    } finally {
      busy = false;
    }
  }

  window.addEventListener("message", event => {
    if (event.source !== window.parent || event.data?.type !== "run") return;
    run(event.data.files, event.data.runId);
  });

  initialize();
})();