/**
 * Default refresh threshold: 5 minutes (300,000 ms)
 * This is the default time before token expiration when a refresh should be triggered
 */
export declare const DEFAULT_REFRESH_THRESHOLD_MS = 300000;
/**
 * Schwab refresh token expiration: 7 days (604,800,000 ms)
 * Schwab refresh tokens expire after 7 days of inactivity
 */
export declare const REFRESH_TOKEN_EXPIRATION_MS = 604800000;
/**
 * Schwab refresh token warning threshold: 6 days (518,400,000 ms)
 * We warn about refresh token expiration when it's 6 days old (1 day before expiry)
 */
export declare const REFRESH_TOKEN_WARNING_THRESHOLD_MS = 518400000;
/**
 * Sanitize authorization code for Schwab's OAuth requirements
 * This handles any encoding issues that might come up with special characters
 * and ensures base64 padding is correctly handled.
 *
 * Specifically addresses:
 * - Removing invalid base64 characters
 * - Converting from base64url to standard base64 format
 * - Adding proper padding to make length a multiple of 4
 * - Handling URL-encoded characters
 *
 * @param code The authorization code to sanitize
 * @param debug Optional flag to enable debug logging
 * @returns The sanitized authorization code
 */
export declare function sanitizeAuthCode(code: string, debug?: boolean): string;
/**
 * Unified method to check if any token is approaching expiration
 * Can be used for both access tokens and refresh tokens with appropriate parameters
 *
 * @param expirationTime The timestamp to check against, or undefined
 * @param thresholdMs Time threshold before expiration to return true
 * @returns True if the token is expiring within the threshold window
 */
export declare function tokenIsExpiringSoon(expirationTime?: number, thresholdMs?: number): boolean;
/**
 * Safe Base64 decoding using native Node.js Buffer
 * - Handles standard base64 and base64url formats
 * - Provides consistent behavior and error handling
 *
 * @param input The Base64 or Base64URL string to decode
 * @returns The decoded string
 */
export declare function safeBase64Decode(input: string): string;
/**
 * Safe Base64 encoding using native Node.js Buffer
 * - Encodes strings to base64 with consistent behavior
 * - Supports URL-safe base64 format (base64url)
 * - Enhanced error handling
 *
 * @param input The string to encode
 * @param urlSafe Whether to make the output URL-safe (default: true)
 * @returns The Base64 encoded string
 */
export declare function safeBase64Encode(input: string, urlSafe?: boolean): string;