Class ToastQueue

packages/react-stately/src/toast/useToastState.ts:89–177

 * A ToastQueue manages the order of toasts.
 */
export class ToastQueue<T> {
  private queue: QueuedToast<T>[] = [];
  private subscriptions: Set<() => void> = new Set();
  private maxVisibleToasts: number;
  private wrapUpdate?: (fn: () => void, action: ToastAction) => void;
  /** The currently visible toasts. */
  visibleToasts: QueuedToast<T>[] = [];

  constructor(options?: ToastStateProps) {
    this.maxVisibleToasts = options?.maxVisibleToasts ?? Infinity;
    this.wrapUpdate = options?.wrapUpdate;
  }

  private runWithWrapUpdate(fn: () => void, action: ToastAction): void {
    if (this.wrapUpdate) {
      this.wrapUpdate(fn, action);
    } else {
      fn();
    }
  }

  /** Subscribes to updates to the visible toasts. */
  subscribe(fn: () => void): () => void {
    this.subscriptions.add(fn);
    return () => this.subscriptions.delete(fn);
  }

  /** Adds a new toast to the queue. */
  add(content: T, options: ToastOptions = {}): string {
    let toastKey = '_' + Math.random().toString(36).slice(2);
    let toast: QueuedToast<T> = {
      ...options,
      content,
      key: toastKey,
      timer: options.timeout ? new Timer(() => this.close(toastKey), options.timeout) : undefined
    };

    this.queue.unshift(toast);

    this.updateVisibleToasts('add');
    return toastKey;
  }

  /**
   * Closes a toast.
   */
  close(key: string): void {
    let index = this.queue.findIndex(t => t.key === key);
    if (index >= 0) {
      this.queue[index].onClose?.();
      this.queue.splice(index, 1);
    }

    this.updateVisibleToasts('remove');
  }

  private updateVisibleToasts(action: ToastAction) {
    this.visibleToasts = this.queue.slice(0, this.maxVisibleToasts);