/** YYYY */
export type YearKey = `${number}`;
/** YYYY-MM */
export type MonthKey = `${number}-${number}`;
/** YYYY-MM-DD */
export type DateKey = `${MonthKey}-${number}`;
/** YYYY-MM--W (0-3, aligned to month) */
export type WeekKey = `${MonthKey}--${number}`;
/**
 * Represents a day in the Gregorian calendar in the form of [year, month, day].
 * Note that `month` is one-based, not zero-based. As opposed to JS Date's `monthIndex`.
 *
 * I prefer working with Day objects instead of Date objects to avoid all kind of problems 😁
 */
export declare class Day {
    static readonly LOWEST: Day;
    static readonly HIGHEST: Day;
    readonly year: number;
    readonly month: number;
    readonly day: number;
    constructor(year: number, month: number, day: number);
    /** Creates a Day from a JS Date object */
    static fromDate(date: Date): Day;
    /** Creates a Day from a time key. If month or day is not provided, it will default to the earliest that matches */
    static fromKey(key: DateKey | WeekKey | MonthKey | YearKey): Day;
    /** Creates a Day from a binary number generated by `toBinary` */
    static fromBinary(binary: number): Day;
    /** Converts the day into a JS Date object */
    toDate(): Date;
    /** Converts the day into a binary number */
    toBinary(): number;
    /** Returns the UTC timestamp for this day */
    toTimestamp(): number;
    get yearKey(): YearKey;
    get monthKey(): MonthKey;
    get weekKey(): WeekKey;
    get dateKey(): DateKey;
    /** Returns a new Day instance for `days` days into the future */
    nextDays(days: number): Day;
    /** Returns a new Day instance for the following day */
    nextDay(): Day;
    /** Equal */
    static eq(a: Day, b: Day): boolean;
    /** Less than */
    static lt(a: Day, b: Day): boolean;
    /** Greater than */
    static gt(a: Day, b: Day): boolean;
    /** Min between two days (past) */
    static min(a: Day, b: Day): Day;
    /** Max between two days (future) */
    static max(a: Day, b: Day): Day;
    /** Clamp day between two days */
    static clamp(day: Day, a: Day, b: Day): Day;
}
export interface TimeKeysResult {
    dateKeys: DateKey[];
    weekKeys: WeekKey[];
    monthKeys: MonthKey[];
    yearKeys: YearKey[];
    dateToWeekIndex: number[];
    dateToMonthIndex: number[];
    dateToYearIndex: number[];
}
/**
 * Generates each time key contained in an interval of time [start, end].
 * Also generates indexes to map between date keys and the rest.
 */
export declare const genTimeKeys: (start: Day, end: Day) => TimeKeysResult;
/**
 * Available human-readable formats
 *
 * Examples for day="2020-12-25", seconds=12345:
 * - y: 2020
 * - ym: December 2020
 * - ymd: December 25, 2020
 * - symd: 12/25/2020
 * - ymdh: December 25, 2020, 03 AM
 * - ymdhm: December 25, 2020, 03:25 AM
 * - ymdhms: December 25, 2020, 03:25:45 AM
 */
export type TimeFormat = "y" | "ym" | "ymd" | "symd" | "ymdh" | "ymdhm" | "ymdhms";
/** Format a Day (+seconds) into a human-readable string */
export declare const formatTime: (format: TimeFormat, day: Day, secondsOfDay?: number) => string;
/** Point in time */
export interface Datetime {
    key: DateKey | WeekKey | MonthKey | YearKey;
    secondOfDay?: number;
}
/** Format a Datetime into a human-readable string. @see formatTime */
export declare const formatDatetime: (format: TimeFormat, datetime?: Datetime) => string;
/** Finds the time difference in seconds between two Datetimes */
export declare const diffDatetime: (a: Datetime, b: Datetime) => number;