import type { WorkbenchEvent } from "../api/workbench-sync-client";

export type WorkbenchStreamNotification =
  | { type: "open" | "disconnect" | "reset" }
  | { type: "events"; events: WorkbenchEvent[] };

/** Presentation observes wire events before business acknowledgements or snapshot filtering. */
export class WorkbenchEventChannel {
  private listeners = new Set<(notification: WorkbenchStreamNotification) => void>();
  private live = false;

  subscribe = (listener: (notification: WorkbenchStreamNotification) => void) => {
    this.listeners.add(listener);
    listener({ type: this.live ? "open" : "disconnect" });
    return () => { this.listeners.delete(listener); };
  };

  publish(notification: WorkbenchStreamNotification) {
    if (notification.type !== "events") this.live = notification.type === "open";
    for (const listener of this.listeners) {
      // One presentation observer must not interrupt authoritative business synchronization.
      try { listener(notification); } catch { /* Observers own their error presentation. */ }
    }
  }
}