/**
 * Unified Storage Manager
 *
 * Handles all storage operations for sessions and users with consistent
 * cookie handling across different persistence methods.
 *
 * Storage methods:
 * - `cookie`: Browser cookies with cross-subdomain support
 * - `localStorage`: Persistent local storage
 * - `sessionStorage`: Tab-specific storage (cleared on tab close)
 * - `localStorage+cookie`: Hybrid mode (default) - full data in localStorage,
 *   critical identity properties also in cookies for SSR support
 * - `memory`: In-memory only (no persistence)
 *
 * The `localStorage+cookie` mode is designed for traditional server-side
 * rendered websites where each page navigation reloads JavaScript:
 * - Critical properties (anonymous_id, device_id, etc.) are stored in cookies
 * - Cookies ensure identity persists across full page reloads
 * - localStorage provides fast access for SPA-style navigation
 * - Falls back to cookie-only if localStorage is unavailable
 */
import { PersistenceMethod } from "./types";
/**
 * Critical properties persisted to cookies in `localStorage+cookie` mode.
 * These ensure identity survives full page reloads in traditional SSR websites.
 */
export declare const COOKIE_PERSISTED_PROPERTIES: readonly ["__vt_anonymous_id", "__vt_device_id", "__vt_distinct_id", "__vt_user_state"];
/** Session cookie TTL: 30 minutes */
export declare const SESSION_COOKIE_MAX_AGE = 1800;
/** User cookie TTL: 1 year */
export declare const USER_COOKIE_MAX_AGE = 31536000;
export interface StorageOptions {
    method: PersistenceMethod;
    /** Enable cross-subdomain cookies (auto-detected if not specified) */
    cross_subdomain?: boolean;
    /** Use secure cookies (auto-detected from protocol if not specified) */
    secure?: boolean;
    /** Cookie SameSite attribute */
    sameSite?: "Strict" | "Lax" | "None";
}
export interface StorageItem<T = string> {
    value: T;
    expiry?: number;
}
/**
 * Check if cross-subdomain cookies should be enabled.
 * Returns false for shared hosting platforms to prevent cookie conflicts.
 */
export declare function shouldUseCrossSubdomainCookie(): boolean;
/**
 * Unified Storage Manager
 *
 * Provides consistent storage operations across all persistence methods
 * with automatic fallbacks and SSR support.
 */
export declare class StorageManager {
    private method;
    private cross_subdomain;
    private secure;
    private sameSite;
    private memoryStorage;
    private _localStorageSupported;
    constructor(options: StorageOptions);
    /** Check if localStorage is available (result is cached) */
    private isLocalStorageSupported;
    /** Check if a key should be persisted to cookies */
    private isCriticalProperty;
    /**
     * Get a value from storage.
     *
     * For `localStorage+cookie` mode:
     * - Critical properties: read cookie first (for SSR), fall back to localStorage
     * - Non-critical properties: read from localStorage only
     */
    get(key: string): string | null;
    /**
     * Set a value in storage.
     * @param maxAge Cookie max age in seconds (only for cookie-based storage)
     *
     * For `localStorage+cookie` mode:
     * - All values stored in localStorage (if available)
     * - Critical properties ALWAYS stored in cookies for SSR support
     */
    set(key: string, value: string, maxAge?: number): void;
    /** Remove a value from storage */
    remove(key: string): void;
    private getLocalStoragePlusCookie;
    private setLocalStoragePlusCookie;
    private removeLocalStoragePlusCookie;
    private getLocalStorage;
    private setLocalStorage;
    private removeLocalStorage;
    private readFromSessionStorage;
    private writeToSessionStorage;
    private removeFromSessionStorage;
    private getCookie;
    private setCookie;
    private removeCookie;
    /** Get JSON value with expiry check */
    getWithExpiry<T>(key: string): T | null;
    /** Set JSON value with optional TTL */
    setWithExpiry<T>(key: string, value: T, ttlMs?: number): void;
    /** Get parsed JSON value */
    getJSON<T>(key: string): T | null;
    /** Set JSON value */
    setJSON<T>(key: string, value: T, maxAge?: number): void;
    /** Check if sessionStorage is available */
    canUseSessionStorage(): boolean;
    /** Get sessionStorage instance (for window_id which always uses sessionStorage) */
    getSessionStorage(): Storage | null;
    /** Update storage method at runtime */
    setMethod(method: PersistenceMethod): void;
    /** Get current storage method */
    getMethod(): PersistenceMethod;
}
/** Factory function to create a StorageManager with default settings */
export declare function createStorageManager(method: PersistenceMethod, cross_subdomain?: boolean): StorageManager;