/**
 * The **Toast Queue Manager** — decides which toasts are *visible* versus
 * *pending* for each screen position, enforcing a per-position `maxVisible`
 * cap so a burst of notifications never floods the viewport.
 *
 * It is pure bookkeeping over opaque string ids (no DOM, no timers), which
 * keeps it trivially unit-testable and lets the {@link ToastService} own all
 * rendering. Each position maintains an ordered visible list and a FIFO pending
 * queue; dismissing a visible toast promotes the next pending one.
 *
 * @packageDocumentation
 */
import { ToastPosition } from './toast.types';
/** The outcome of enqueuing a toast. */
export interface EnqueueResult {
    /** `true` when the toast can be shown immediately (a visible slot was free). */
    readonly visible: boolean;
}
/** Pure, DOM-free visibility scheduler for toasts. */
export declare class ToastQueueManager {
    private maxVisible;
    private readonly queues;
    /**
     * @param maxVisible - Max simultaneously-visible toasts per position (min 1).
     */
    constructor(maxVisible: number);
    /** Updates the per-position visible cap (min 1). Does not retro-actively hide. */
    setMaxVisible(maxVisible: number): void;
    /** Lazily gets (creating if needed) the queue for a position. */
    private queueFor;
    /**
     * Registers a toast id at a position, marking it visible when a slot is free
     * or pending otherwise.
     *
     * @param id       - The toast id.
     * @param position - The docked position.
     * @returns Whether the toast is immediately visible.
     */
    enqueue(id: string, position: ToastPosition): EnqueueResult;
    /**
     * Removes a toast id from its position (whether visible or pending) and
     * returns the id promoted from pending to visible as a result, if any.
     *
     * @param id       - The toast id to remove.
     * @param position - The docked position.
     * @returns The newly-promoted id, or `null` when nothing was promoted.
     */
    remove(id: string, position: ToastPosition): string | null;
    /** @returns `true` if the id is currently in the visible set for its position. */
    isVisible(id: string, position: ToastPosition): boolean;
    /** @returns The ordered visible ids for a position. */
    getVisible(position: ToastPosition): readonly string[];
    /** @returns Every live id (visible + pending) across all positions. */
    getAll(): string[];
    /** @returns Every live id at a single position. */
    getAllAt(position: ToastPosition): string[];
    /** Clears all bookkeeping (used on destroy). */
    clear(): void;
}
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