// Match event type name strings that are registered on GlobalEventHandlersEventMap...
export type EventTypeRequiresDetail<T> = T extends keyof GlobalEventHandlersEventMap
  ? // ...where the event detail is an object...
  GlobalEventHandlersEventMap[T] extends CustomEvent<Record<PropertyKey, unknown>>
    ? // ...that is non-empty...
    GlobalEventHandlersEventMap[T] extends CustomEvent<Record<PropertyKey, never>>
      ? never
      : // ...and has at least one non-optional property
      Partial<GlobalEventHandlersEventMap[T]['detail']> extends GlobalEventHandlersEventMap[T]['detail']
        ? never
        : T
    : never
  : never;

// The inverse of the above (match any type that doesn't match EventTypeRequiresDetail)
export type EventTypeDoesNotRequireDetail<T> = T extends keyof GlobalEventHandlersEventMap
  ? GlobalEventHandlersEventMap[T] extends CustomEvent<Record<PropertyKey, unknown>>
    ? GlobalEventHandlersEventMap[T] extends CustomEvent<Record<PropertyKey, never>>
      ? T
      : Partial<GlobalEventHandlersEventMap[T]['detail']> extends GlobalEventHandlersEventMap[T]['detail']
        ? T
        : never
    : T
  : T;

// `keyof EventTypesWithRequiredDetail` lists all registered event types that require detail
export type EventTypesWithRequiredDetail = {
  [EventType in keyof GlobalEventHandlersEventMap as EventTypeRequiresDetail<EventType>]: true;
};

// `keyof EventTypesWithoutRequiredDetail` lists all registered event types that do NOT require detail
export type EventTypesWithoutRequiredDetail = {
  [EventType in keyof GlobalEventHandlersEventMap as EventTypeDoesNotRequireDetail<EventType>]: true;
};

// Helper to make a specific property of an object non-optional
type WithRequired<T, K extends keyof T> = T & { [P in K]-?: T[P] };

// Given an event name string, get a valid type for the options to initialize the event that is more restrictive than
// just CustomEventInit when appropriate (validate the type of the event detail, and require it to be provided if the
// event requires it)
export type ZincEventInit<T> = T extends keyof GlobalEventHandlersEventMap
  ? GlobalEventHandlersEventMap[T] extends CustomEvent<Record<PropertyKey, unknown>>
    ? GlobalEventHandlersEventMap[T] extends CustomEvent<Record<PropertyKey, never>>
      ? CustomEventInit<GlobalEventHandlersEventMap[T]['detail']>
      : Partial<GlobalEventHandlersEventMap[T]['detail']> extends GlobalEventHandlersEventMap[T]['detail']
        ? CustomEventInit<GlobalEventHandlersEventMap[T]['detail']>
        : WithRequired<CustomEventInit<GlobalEventHandlersEventMap[T]['detail']>, 'detail'>
    : CustomEventInit
  : CustomEventInit;

// Given an event name string, get the type of the event
export type GetCustomEventType<T> = T extends keyof GlobalEventHandlersEventMap
  ? GlobalEventHandlersEventMap[T] extends CustomEvent<unknown>
    ? GlobalEventHandlersEventMap[T]
    : CustomEvent<unknown>
  : CustomEvent<unknown>;

// `keyof ValidEventTypeMap` is equivalent to `keyof GlobalEventHandlersEventMap` but gives a nicer error message
export type ValidEventTypeMap = EventTypesWithRequiredDetail | EventTypesWithoutRequiredDetail;


export function waitForEvent(el: HTMLElement, eventName: string) {
  return new Promise<void>(resolve => {
    function done(event: Event) {
      if (event.target === el) {
        el.removeEventListener(eventName, done);
        resolve();
      }
    }


    el.addEventListener(eventName, done);
  });
}