// A menu can outlive its MV3 service worker while the user runs the installer.
// Reopen the UI port on the next command; never replay requests already sent.
export function createUiConnection({ onEvent, onDisconnect, runtime = chrome.runtime }) {
  const requests = new Map();
  const disconnected = () => new Error("Связь с расширением прервана. Нажмите «Проверить подключение» или «Запустить» для повторного подключения.");
  let port = null;

  function drop(connection) {
    if (port !== connection) return;
    port = null;
    for (const [id, request] of requests) {
      if (request.port !== connection) continue;
      requests.delete(id); request.reject(disconnected());
    }
    onDisconnect?.();
  }
  function connect() {
    if (port) return port;
    const connection = runtime.connect({ name: "ytdl-ui" });
    port = connection;
    connection.onMessage.addListener(message => {
      if (port !== connection) return;
      if (message.event) { onEvent?.(message); return; }
      const request = requests.get(message.id);
      if (!request || request.port !== connection) return;
      requests.delete(message.id);
      message.ok ? request.resolve(message.result) : request.reject(new Error(message.error));
    });
    connection.onDisconnect.addListener(() => {
      // Read lastError in the callback to avoid an unchecked runtime error.
      void runtime.lastError?.message;
      drop(connection);
    });
    return connection;
  }
  function call(action, payload = {}) {
    return new Promise((resolve, reject) => {
      for (let attempt = 0; attempt < 2; attempt++) {
        let connection, id;
        try {
          connection = connect(); id = crypto.randomUUID();
          requests.set(id, { resolve, reject, port: connection });
          connection.postMessage({ id, action, payload });
          return;
        } catch (error) {
          if (id) requests.delete(id);
          if (connection) drop(connection);
          // A synchronous disconnected-port error means this command was not sent.
          if (attempt === 0 && /disconnected port/i.test(error.message)) continue;
          reject(/disconnected port/i.test(error.message) ? disconnected() : error);
          return;
        }
      }
    });
  }
  return { call };
}