import { scheduleMicrotask } from './utils.esm.js';

function createNotifyManager() {
  let queue = [];
  let transactions = 0;

  let notifyFn = callback => {
    callback();
  };

  let batchNotifyFn = callback => {
    callback();
  };

  const batch = callback => {
    let result;
    transactions++;

    try {
      result = callback();
    } finally {
      transactions--;

      if (!transactions) {
        flush();
      }
    }

    return result;
  };

  const schedule = callback => {
    if (transactions) {
      queue.push(callback);
    } else {
      scheduleMicrotask(() => {
        notifyFn(callback);
      });
    }
  };
  /**
   * All calls to the wrapped function will be batched.
   */


  const batchCalls = callback => {
    return (...args) => {
      schedule(() => {
        callback(...args);
      });
    };
  };

  const flush = () => {
    const originalQueue = queue;
    queue = [];

    if (originalQueue.length) {
      scheduleMicrotask(() => {
        batchNotifyFn(() => {
          originalQueue.forEach(callback => {
            notifyFn(callback);
          });
        });
      });
    }
  };
  /**
   * Use this method to set a custom notify function.
   * This can be used to for example wrap notifications with `React.act` while running tests.
   */


  const setNotifyFunction = fn => {
    notifyFn = fn;
  };
  /**
   * Use this method to set a custom function to batch notifications together into a single tick.
   * By default React Query will use the batch function provided by ReactDOM or React Native.
   */


  const setBatchNotifyFunction = fn => {
    batchNotifyFn = fn;
  };

  return {
    batch,
    batchCalls,
    schedule,
    setNotifyFunction,
    setBatchNotifyFunction
  };
} // SINGLETON

const notifyManager = createNotifyManager();

export { createNotifyManager, notifyManager };
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