import { useCallback, useMemo, useRef, useState, type ReactNode } from "react";
import { NotificationSessionContext } from "./notification-session-context";

function addAll<T>(current: ReadonlySet<T>, ids: T[]): ReadonlySet<T> {
  if (ids.every((id) => current.has(id))) {
    return current;
  }
  const next = new Set(current);
  ids.forEach((id) => next.add(id));
  return next;
}

/**
 * Dismissed and read notification ids for this app session only. Nothing is persisted, so a
 * reload starts over and a condition that still holds shows up again.
 */
export function NotificationSessionProvider({ children }: { children: ReactNode }) {
  const [dismissedIds, setDismissedIds] = useState<ReadonlySet<string>>(() => new Set());
  const [readIds, setReadIds] = useState<ReadonlySet<string>>(() => new Set());
  const [slaBannerDismissedIds, setSlaBannerDismissedIds] = useState<ReadonlySet<number>>(
    () => new Set(),
  );
  // A ref, not state: claiming must be synchronous so a re-run effect can never toast twice.
  const toastedSlaIds = useRef(new Set<number>());

  const dismiss = useCallback((ids: string[]) => {
    setDismissedIds((current) => addAll(current, ids));
  }, []);
  const markRead = useCallback((ids: string[]) => {
    setReadIds((current) => addAll(current, ids));
  }, []);
  const dismissSlaBanner = useCallback((workOrderIds: number[]) => {
    setSlaBannerDismissedIds((current) => addAll(current, workOrderIds));
  }, []);
  const claimSlaToasts = useCallback((workOrderIds: number[]) => {
    const claimed = workOrderIds.filter((id) => !toastedSlaIds.current.has(id));
    claimed.forEach((id) => toastedSlaIds.current.add(id));
    return claimed;
  }, []);

  const value = useMemo(
    () => ({
      dismissedIds,
      readIds,
      dismiss,
      markRead,
      slaBannerDismissedIds,
      dismissSlaBanner,
      claimSlaToasts,
    }),
    [
      dismissedIds,
      readIds,
      dismiss,
      markRead,
      slaBannerDismissedIds,
      dismissSlaBanner,
      claimSlaToasts,
    ],
  );

  return (
    <NotificationSessionContext.Provider value={value}>
      {children}
    </NotificationSessionContext.Provider>
  );
}