import { BoardOp } from './history.js';
import { BoardScene } from './types.js';

/**
 * BoardStore — a framework-free state container over a BoardScene.
 *
 * Holds an immutable scene snapshot, an undo/redo history of
 * (forward, inverse) op pairs, and a plain set of subscribers. Hosts wrap
 * this in their own reactivity (e.g. Svelte `$state`); the store never
 * imports a UI framework.
 *
 * Subscribers receive the changed element ids so a host can re-render only
 * what moved instead of diffing the whole scene.
 */

type Subscriber = (scene: BoardScene, changedIds: string[]) => void;
interface ApplyOptions {
    /**
     * Coalesce with the previous entry if it shares this key and sits at the
     * top of the undo stack — so a 60fps drag collapses to one undo step.
     */
    mergeKey?: string;
}
declare class BoardStore {
    private scene;
    private undoStack;
    private redoStack;
    private subscribers;
    private txn;
    constructor(initial?: BoardScene);
    /** Current immutable scene snapshot. */
    getScene(): BoardScene;
    subscribe(fn: Subscriber): () => void;
    private emit;
    /**
     * Apply an op. Inside `transact`, ops accumulate into one history entry;
     * otherwise each apply is its own entry (subject to mergeKey coalescing).
     */
    apply(op: BoardOp, options?: ApplyOptions): void;
    /** Group every apply inside `fn` into a single, atomic history entry. */
    transact(fn: () => void): void;
    private push;
    canUndo(): boolean;
    canRedo(): boolean;
    undo(): void;
    redo(): void;
    /** Replace the whole scene (e.g. opening a file); clears history. */
    reset(scene: BoardScene): void;
}

export { type ApplyOptions, BoardStore };