/**
 * Time unit constants and helper functions for duration calculations.
 *
 * Provides millisecond values for common time units (seconds, minutes, hours, etc.)
 * and functions to multiply these units. Useful for setTimeout, interval calculations,
 * cache TTLs, and any duration-based logic.
 *
 * WHY: Improves code readability by using human-friendly time units instead of raw milliseconds.
 * Instead of writing `setTimeout(fn, 300000)`, you can write `setTimeout(fn, timeUnits.min15)`.
 *
 * @example
 * // Using predefined constants
 * setTimeout(cleanup, timeUnits.min15);  // 15 minutes
 * cache.set('key', value, { ttl: timeUnits.hour });  // 1 hour
 *
 * @example
 * // Using helper functions
 * const backoffDelay = timeUnits.secs(30);  // 30 seconds
 * const cacheExpiry = timeUnits.days(7);    // 7 days
 * const sessionTimeout = timeUnits.hours(2); // 2 hours
 */
export declare const timeUnits: {
    sec: number;
    min: number;
    min15: number;
    min30: number;
    hour: number;
    hour2: number;
    hour4: number;
    hour8: number;
    hour12: number;
    day: number;
    week: number;
    secs(n: number): number;
    mins(n: number): number;
    hours(n: number): number;
    days(n: number): number;
    weeks(n: number): number;
    months(n: number): number;
    years(n: number): number;
};
/**
 * Creates a duration in seconds (converted to milliseconds).
 *
 * WHY: Provides a more readable way to specify durations in seconds.
 *
 * @param n number of seconds
 * @returns milliseconds equivalent
 *
 * @example
 * setTimeout(fn, seconds(30));  // 30 seconds = 30000ms
 * cache.set('key', value, { ttl: seconds(120) });  // 2 minutes
 */
export declare const seconds: (n: number) => number;
/**
 * Creates a duration in minutes (converted to milliseconds).
 *
 * WHY: Provides a more readable way to specify durations in minutes.
 *
 * @param n number of minutes
 * @returns milliseconds equivalent
 *
 * @example
 * setTimeout(fn, minutes(5));  // 5 minutes = 300000ms
 * const pollInterval = minutes(2);  // Poll every 2 minutes
 */
export declare const minutes: (n: number) => number;
/**
 * Creates a duration in hours (converted to milliseconds).
 *
 * WHY: Provides a more readable way to specify durations in hours.
 *
 * @param n number of hours
 * @returns milliseconds equivalent
 *
 * @example
 * setTimeout(fn, hours(1));  // 1 hour = 3600000ms
 * const sessionExpiry = hours(24);  // 24 hour session
 */
export declare const hours: (n: number) => number;
/**
 * Creates a duration in days (converted to milliseconds).
 *
 * WHY: Provides a more readable way to specify durations in days.
 *
 * @param n number of days
 * @returns milliseconds equivalent
 *
 * @example
 * const cacheExpiry = days(7);  // 7 days = 604800000ms
 * setTimeout(cleanup, days(30));  // 30 day cleanup cycle
 */
export declare const days: (n: number) => number;
/**
 * Creates a duration in weeks (converted to milliseconds).
 *
 * WHY: Provides a more readable way to specify durations in weeks.
 *
 * @param n number of weeks
 * @returns milliseconds equivalent
 *
 * @example
 * const backupInterval = weeks(2);  // Backup every 2 weeks
 * setTimeout(archive, weeks(4));  // Archive after 4 weeks
 */
export declare const weeks: (n: number) => number;
/**
 * Creates a duration in months (converted to milliseconds).
 *
 * WHY: Provides a more readable way to specify durations in months.
 * Uses 30.4 days as average month length for accuracy.
 *
 * @param n number of months
 * @returns milliseconds equivalent (rounded)
 *
 * @example
 * const subscriptionExpiry = months(1);  // 1 month subscription
 * setTimeout(fn, months(3));  // Quarterly task
 */
export declare const months: (n: number) => number;
/**
 * Creates a duration in years (converted to milliseconds).
 *
 * WHY: Provides a more readable way to specify durations in years.
 * Uses 365 days (does not account for leap years).
 *
 * @param n number of years
 * @returns milliseconds equivalent
 *
 * @example
 * const licenseExpiry = years(1);  // 1 year license
 * const longTermCache = years(5);  // 5 year retention
 */
export declare const years: (n: number) => number;
/**
 * Parses a time duration string into milliseconds.
 *
 * WHY: Allows reading durations from configuration files or user input in a human-friendly format.
 * Supports decimal values, plurals, full words, and is case-insensitive.
 *
 * Accepts formats:
 * - Short: "30sec", "5min", "2hour"
 * - Plural: "30secs", "5mins", "2hours"
 * - Full words: "30 seconds", "5 minutes", "2 hours"
 *
 * @param str time duration string (format: "<number> <unit>")
 * @returns milliseconds as number
 * @throws Error if string format is invalid or unit is unknown
 *
 * @example
 * parseTimeDuration('30sec');       // 30000
 * parseTimeDuration('30 secs');     // 30000
 * parseTimeDuration('30 seconds');  // 30000
 * parseTimeDuration('5 min');       // 300000
 * parseTimeDuration('5 minutes');   // 300000
 * parseTimeDuration('2.5 hours');   // 9000000
 *
 * @example
 * // Using in configuration
 * const config = {
 *     sessionTimeout: parseTimeDuration(process.env.SESSION_TIMEOUT || '1hour'),
 *     cacheExpiry: parseTimeDuration(process.env.CACHE_TTL || '15min')
 * };
 */
export declare const parseTimeDuration: (str: string) => number;
/**
 * Formats a millisecond duration into a human-readable string.
 *
 * WHY: Converts raw millisecond values into user-friendly strings for display.
 * Automatically selects the most appropriate unit (sec, min, hour, day, etc.).
 *
 * @param ms number of milliseconds to format
 * @param opts optional formatting options
 * @param opts.decimals number of decimal places (default: 0 for whole units, 1 for fractional)
 * @param opts.unit force a specific unit instead of auto-selecting
 * @returns formatted string (e.g., "30sec", "5min", "2hour")
 *
 * @example
 * formatTimeDuration(1000);          // "1sec"
 * formatTimeDuration(30000);         // "30sec"
 * formatTimeDuration(90000);         // "1.5min"
 * formatTimeDuration(3600000);       // "1hour"
 * formatTimeDuration(86400000);      // "1day"
 *
 * @example
 * // Force specific unit
 * formatTimeDuration(90000, { unit: 'sec' });  // "90sec"
 * formatTimeDuration(90000, { unit: 'min' });  // "1.5min"
 *
 * @example
 * // Control decimals
 * formatTimeDuration(90000, { decimals: 0 });  // "2min"
 * formatTimeDuration(90000, { decimals: 2 });  // "1.50min"
 *
 * @example
 * // Display cache expiry times
 * console.log(`Cache expires in: ${formatTimeDuration(cache.ttl)}`);
 */
export declare const formatTimeDuration: (ms: number, opts?: {
    decimals?: number;
    unit?: "sec" | "min" | "hour" | "day" | "week" | "month" | "year";
}) => string;