import { MaybeRefOrGetter, Ref } from 'vue';
import { BehaviorClass, DeepReadonly, GameEntityType, OpsFor, OpsOf, StateFor, StateSliceOf } from '@skewedaspect/sage';
/** What a UI observes an entity through (design/ui.md#gameentityview). */
export interface GameEntityView<Type extends GameEntityType = GameEntityType> {
    readonly id: string | null;
    readonly present: boolean;
    readonly state: DeepReadonly<StateFor<Type['behaviors']>>;
    readonly ops: OpsFor<Type['behaviors']>;
    hasBehavior<Class extends BehaviorClass>(behaviorClass: Class): this is ViewNarrowedTo<Class>;
}
/** A view typed to one behavior's slice of state and operations (design/ui.md#gameentityview). */
export type ViewNarrowedTo<Class extends BehaviorClass> = GameEntityView & {
    readonly state: DeepReadonly<StateSliceOf<Class>>;
    readonly ops: OpsOf<Class>;
};
/**
 * Answers with a `Ref` holding a view of one entity, resolved by class and ID against the simulation the
 * engine currently holds. The view observes as it is created and refreshes once per rendered frame, pause
 * included (design/ui.md#when-a-view-observes). The `Ref` never changes what it holds, since the view is one
 * object for its life; what a refresh changes is inside the view (design/ui.md#gameentityview).
 *
 * @param entityClass - Types the view and checks it: another class leaves the view absent.
 * @param id - The entity ID, read on every refresh, so a `Ref` or a getter follows the entity it names at
 *     that moment and a null ID leaves the view absent (design/ui.md#which-entity-a-view-holds).
 */
export declare function useSageEntity<Type extends GameEntityType>(entityClass: Type, id: MaybeRefOrGetter<string | null>): Ref<GameEntityView<Type>>;