src/index.ts

/*!
 * Copyright 2019 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

const FULL_ISO_REG = /\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d{4,9}Z/;
const NO_BIG_INT =
  'BigInt only available in Node >= v10.7. Consider using getFullTimeString instead.';

export type DateTuple = [number, number];

export interface DateStruct {
  seconds: number;
  nanos: number;
}

// https://github.com/Microsoft/TypeScript/issues/27920
type DateFields = [number, number, number, number, number, number, number];

interface Long {
  toNumber(): number;
}

interface ProtobufDate {
  seconds?: number | string | Long;
  nanos?: number | string;
}

enum Sign {
  NEGATIVE = -1,
  POSITIVE = 1,
  ZERO = 0,
}

/**
 * The native Date object.
 * @external Date
 * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date}
 */
/**
 * @typedef {array} DateTuple
 * @property {number} 0 Represents seconds of UTC time since Unix epoch
 *     1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
 *     9999-12-31T23:59:59Z inclusive.
 * @property {number} 1 Non-negative fractions of a second at nanosecond
 *     resolution. Negative second values with fractions must still have
 *     non-negative nanos values that count forward in time. Must be from 0 to
 *     999,999,999 inclusive.
 */
/**
 * @typedef {object} DateStruct
 * @property {number} seconds Represents seconds of UTC time since Unix epoch
 *     1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
 *     9999-12-31T23:59:59Z inclusive.
 * @property {number} nanos Non-negative fractions of a second at nanosecond
 *     resolution. Negative second values with fractions must still have
 *     non-negative nanos values that count forward in time. Must be from 0 to
 *     999,999,999 inclusive.
 */
/**
 * Date object with nanosecond precision. Supports all standard Date arguments
 * in addition to several custom types as noted below.
 *
 * @class
 * @extends external:Date
 *
 * @param {number|string|bigint|Date|DateTuple|DateStruct} [time] The time
 *     value.
 * @param {...number} [dateFields] Additional date fields (month, date, hours,
 *     minutes, seconds, milliseconds, microseconds, nanoseconds).
 *
 * @example <caption>With a RFC 3339 formatted string.</caption>
 * const date = new PreciseDate('2019-02-08T10:34:29.481145231Z');
 *
 * @example <caption>With a nanosecond timestamp string.</caption>
 * const date = new PreciseDate('1549622069481320032');
 *
 * @example <caption>With a BigInt (requires Node >= v10.7)</caption>
 * const date = new PreciseDate(1549622069481320032n);
 *
 * @example <caption>With a tuple containing seconds and nanoseconds.</caption>
 * const date = new PreciseDate([1549622069, 481320032]);
 *
 * @example <caption>With an object containing `seconds` and `nanos`</caption>
 * const date = new PreciseDate({seconds: 1549622069, nanos: 481320032});
 *
 * @example <caption>Specifiying date fields</caption>
 * const date = new PreciseDate(2018, 5, 14, 41, 11, 34, 123, 874, 321);
 */
export class PreciseDate extends Date {
  private _micros = 0;
  private _nanos = 0;
  constructor(time?: number | Date);
  constructor(preciseTime: string | bigint | DateTuple | ProtobufDate);
  constructor(
    year: number,
    month?: number,
    date?: number,
    hours?: number,
    minutes?: number,
    seconds?: number,
    milliseconds?: number,
    microseconds?: number,
    nanoseconds?: number
  );
  constructor(
    time?: number | string | bigint | Date | DateTuple | ProtobufDate
  ) {
    super();

    if (time && typeof time !== 'number' && !(time instanceof Date)) {
      this.setFullTime(PreciseDate.parseFull(time));
      return;
    }

    // eslint-disable-next-line prefer-rest-params
    const args: number[] = Array.from(arguments);
    const dateFields = args.slice(0, 7) as DateFields;
    const date = new Date(...dateFields);
    const nanos = args.length === 9 ? args.pop()! : 0;
    const micros = args.length === 8 ? args.pop()! : 0;

    this.setTime(date.getTime());
    this.setMicroseconds(micros);
    this.setNanoseconds(nanos);
  }
  /**
   * Returns the specified date represented in nanoseconds according to
   * universal time.
   *
   * **NOTE:** Because this method returns a `BigInt` it requires Node >= v10.7.
   * Use {@link PreciseDate#getFullTimeString} to get the time as a string.
   *
   * @see {@link https://github.com/tc39/proposal-bigint|BigInt}
   *
   * @throws {error} If `BigInt` is unavailable.
   * @returns {bigint}
   *
   * @example
   * const date = new PreciseDate('2019-02-08T10:34:29.481145231Z');
   *
   * console.log(date.getFullTime());
   * // expected output: 1549622069481145231n
   */
  getFullTime(): bigint {
    if (typeof BigInt !== 'function') {
      throw new Error(NO_BIG_INT);
    }

    return BigInt(this.getFullTimeString());
  }
  /**
   * Returns a string of the specified date represented in nanoseconds according
   * to universal time.
   *
   * @returns {string}
   *
   * @example
   * const date = new PreciseDate('2019-02-08T10:34:29.481145231Z');
   *
   * console.log(date.getFullTimeString());
   * // expected output: "1549622069481145231"
   */
  getFullTimeString(): string {
    const seconds = this._getSeconds();
    let nanos = this._getNanos();

    if (nanos && Math.sign(seconds) === Sign.NEGATIVE) {
      nanos = 1e9 - nanos;
    }

    return `${seconds}${padLeft(nanos, 9)}`;
  }
  /**
   * Returns the microseconds in the specified date according to universal time.
   *
   * @returns {number}
   *
   * @example
   * const date = new PreciseDate('2019-02-08T10:34:29.481145Z');
   *
   * console.log(date.getMicroseconds());
   * // expected output: 145
   */
  getMicroseconds(): number {
    return this._micros;
  }
  /**
   * Returns the nanoseconds in the specified date according to universal time.
   *
   * @returns {number}
   *
   * @example
   * const date = new PreciseDate('2019-02-08T10:34:29.481145231Z');
   *
   * console.log(date.getNanoseconds());
   * // expected output: 231
   */
  getNanoseconds(): number {
    return this._nanos;
  }
  /**
   * Sets the microseconds for a specified date according to universal time.
   *
   * @param {number} microseconds A number representing the microseconds.
   * @returns {string} Returns a string representing the nanoseconds in the
   *     specified date according to universal time.
   *
   * @example
   * const date = new PreciseDate();
   *
   * date.setMicroseconds(149);
   *
   * console.log(date.getMicroseconds());
   * // expected output: 149
   */
  setMicroseconds(micros: number): string {
    const abs = Math.abs(micros);
    let millis = this.getUTCMilliseconds();

    if (abs >= 1000) {
      millis += Math.floor(abs / 1000) * Math.sign(micros);
      micros %= 1000;
    }

    if (Math.sign(micros) === Sign.NEGATIVE) {
      millis -= 1;
      micros += 1000;
    }

    this._micros = micros;
    this.setUTCMilliseconds(millis);

    return this.getFullTimeString();
  }
  /**
   * Sets the nanoseconds for a specified date according to universal time.
   *
   * @param {number} nanoseconds A number representing the nanoseconds.
   * @returns {string} Returns a string representing the nanoseconds in the
   *     specified date according to universal time.
   *
   * @example
   * const date = new PreciseDate();
   *
   * date.setNanoseconds(231);
   *
   * console.log(date.getNanoseconds());
   * // expected output: 231
   */
  setNanoseconds(nanos: number): string {
    const abs = Math.abs(nanos);
    let micros = this._micros;

    if (abs >= 1000) {
      micros += Math.floor(abs / 1000) * Math.sign(nanos);
      nanos %= 1000;
    }

    if (Math.sign(nanos) === Sign.NEGATIVE) {
      micros -= 1;
      nanos += 1000;
    }

    this._nanos = nanos;

    return this.setMicroseconds(micros);
  }
  /**
   * Sets the PreciseDate object to the time represented by a number of
   * nanoseconds since January 1, 1970, 00:00:00 UTC.
   *
   * @param {bigint|number|string} time Value representing the number of
   *     nanoseconds since January 1, 1970, 00:00:00 UTC.
   * @returns {string} Returns a string representing the nanoseconds in the
   *     specified date according to universal time (effectively, the value of
   *     the argument).
   *
   * @see {@link https://github.com/tc39/proposal-bigint|BigInt}
   *
   * @example <caption>With a nanosecond string.</caption>
   * const date = new PreciseDate();
   * date.setFullTime('1549622069481145231');
   *
   * @example <caption>With a BigInt</caption>
   * date.setFullTime(1549622069481145231n);
   */
  setFullTime(time: string | number | bigint): string {
    if (typeof time !== 'string') {
      time = time.toString();
    }

    const sign = Math.sign(Number(time));

    time = time.replace(/^-/, '');

    const seconds = Number(time.substr(0, time.length - 9)) * sign;
    const nanos = Number(time.substr(-9)) * sign;

    this.setTime(seconds * 1000);
    return this.setNanoseconds(nanos);
  }
  /**
   * Sets the PreciseDate object to the time represented by a number of
   * milliseconds since January 1, 1970, 00:00:00 UTC. Calling this method will
   * reset both the microseconds and nanoseconds to 0.
   *
   * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/setTime|Date#setTime}
   *
   * @param {number} time Value representing the number of milliseconds since
   *     January 1, 1970, 00:00:00 UTC.
   * @returns {string} The number of milliseconds between January 1, 1970,
   *     00:00:00 UTC and the updated date (effectively, the value of the
   *     argument).
   */
  setTime(time: number): number {
    this._micros = 0;
    this._nanos = 0;
    return super.setTime(time);
  }
  /**
   * Returns a string in RFC 3339 format. Unlike the native `Date#toISOString`,
   * this will return 9 digits to represent sub-second precision.
   *
   * @see {@link https://tools.ietf.org/html/rfc3339|RFC 3339}
   *
   * @returns {string}
   *
   * @example
   * const date = new PreciseDate(1549622069481145231n);
   *
   * console.log(date.toISOString());
   * // expected output: "2019-02-08T10:34:29.481145231Z"
   */
  toISOString(): string {
    const micros = padLeft(this._micros, 3);
    const nanos = padLeft(this._nanos, 3);
    return super.toISOString().replace(/z$/i, `${micros}${nanos}Z`);
  }
  /**
   * Returns an object representing the specified date according to universal
   * time.
   *
   * @see {@link https://developers.google.com/protocol-buffers/docs/reference/google.protobuf#timestamp|google.protobuf.Timestamp}
   *
   * @returns {DateStruct}
   *
   * @example
   * const date = new PreciseDate('2019-02-08T10:34:29.481145231Z');
   *
   * console.log(date.toStruct());
   * // expected output: {seconds: 1549622069, nanos: 481145231}
   */
  toStruct(): DateStruct {
    let seconds = this._getSeconds();
    const nanos = this._getNanos();
    const sign = Math.sign(seconds);

    // These objects are essentially a mirror of protobuf timestamps.
    // `nanos` must always count forward in time, even if the date is <= Unix
    // epoch. To do this we just need to count backwards 1 second and return the
    // nanoseconds as is.
    if (sign === Sign.NEGATIVE && nanos) {
      seconds -= 1;
    }

    return {seconds, nanos};
  }
  /**
   * Returns a tuple representing the specified date according to universal
   * time.
   *
   * @returns {DateTuple}
   *
   * @example
   * const date = new PreciseDate('2019-02-08T10:34:29.481145231Z');
   *
   * console.log(date.toTuple());
   * // expected output: [1549622069, 481145231]
   */
  toTuple(): DateTuple {
    const {seconds, nanos} = this.toStruct();
    return [seconds, nanos];
  }
  /**
   * Returns the total number of seconds in the specified date since Unix epoch.
   * Numbers representing < epoch will be negative.
   *
   * @private
   *
   * @returns {number}
   */
  private _getSeconds(): number {
    const time = this.getTime();
    const sign = Math.sign(time);
    return Math.floor(Math.abs(time) / 1000) * sign;
  }
  /**
   * Returns the sub-second precision of the specified date. This will always be
   * a positive number.
   *
   * @private
   *
   * @returns {number}
   */
  private _getNanos(): number {
    const msInNanos = this.getUTCMilliseconds() * 1e6;
    const microsInNanos = this._micros * 1000;
    return this._nanos + msInNanos + microsInNanos;
  }
  /**
   * Parses a precise time.
   *
   * @static
   *
   * @param {string|bigint|DateTuple|DateStruct} time The precise time value.
   * @returns {string} Returns a string representing the nanoseconds in the
   *     specified date according to universal time.
   *
   * @example <caption>From a RFC 3339 formatted string.</caption>
   * const time = PreciseDate.parseFull('2019-02-08T10:34:29.481145231Z');
   * console.log(time); // expected output: "1549622069481145231"
   *
   * @example <caption>From a nanosecond timestamp string.</caption>
   * const time = PreciseDate.parseFull('1549622069481145231');
   * console.log(time); // expected output: "1549622069481145231"
   *
   * @example <caption>From a BigInt (requires Node >= v10.7)</caption>
   * const time = PreciseDate.parseFull(1549622069481145231n);
   * console.log(time); // expected output: "1549622069481145231"
   *
   * @example <caption>From a tuple.</caption>
   * const time = PreciseDate.parseFull([1549622069, 481145231]);
   * console.log(time); // expected output: "1549622069481145231"
   *
   * @example <caption>From an object.</caption>
   * const struct = {seconds: 1549622069, nanos: 481145231};
   * const time = PreciseDate.parseFull(struct);
   * console.log(time); // expected output: "1549622069481145231"
   */
  static parseFull(time: string | bigint | DateTuple | ProtobufDate): string {
    const date = new PreciseDate();

    if (Array.isArray(time)) {
      const [seconds, nanos] = time as DateTuple;
      time = {seconds, nanos} as DateStruct;
    }

    if (isFullTime(time)) {
      date.setFullTime(time as string | bigint);
    } else if (isStruct(time)) {
      const {seconds, nanos} = parseProto(time as ProtobufDate);
      date.setTime(seconds * 1000);
      date.setNanoseconds(nanos);
    } else if (isFullISOString(time)) {
      date.setFullTime(parseFullISO(time as string));
    } else {
      date.setTime(new Date(time as string).getTime());
    }

    return date.getFullTimeString();
  }
  /**
   * Accepts the same number parameters as the PreciseDate constructor, but
   * treats them as UTC. It returns a string that represents the number of
   * nanoseconds since January 1, 1970, 00:00:00 UTC.
   *
   * **NOTE:** Because this method returns a `BigInt` it requires Node >= v10.7.
   *
   * @see {@link https://github.com/tc39/proposal-bigint|BigInt}
   *
   * @static
   *
   * @throws {error} If `BigInt` is unavailable.
   *
   * @param {...number} [dateFields] The date fields.
   * @returns {bigint}
   *
   * @example
   * const time = PreciseDate.fullUTC(2019, 1, 8, 10, 34, 29, 481, 145, 231);
   * console.log(time); // expected output: 1549622069481145231n
   */
  static fullUTC(...args: number[]): bigint {
    if (typeof BigInt !== 'function') {
      throw new Error(NO_BIG_INT);
    }

    return BigInt(PreciseDate.fullUTCString(...args));
  }
  /**
   * Accepts the same number parameters as the PreciseDate constructor, but
   * treats them as UTC. It returns a string that represents the number of
   * nanoseconds since January 1, 1970, 00:00:00 UTC.
   *
   * @static
   *
   * @param {...number} [dateFields] The date fields.
   * @returns {string}
   *
   * @example
   * const time = PreciseDate.fullUTCString(2019, 1, 8, 10, 34, 29, 481, 145,
   * 231); console.log(time); // expected output: '1549622069481145231'
   */
  static fullUTCString(...args: number[]): string {
    const milliseconds = Date.UTC(...(args.slice(0, 7) as DateFields));
    const date = new PreciseDate(milliseconds);

    if (args.length === 9) {
      date.setNanoseconds(args.pop()!);
    }

    if (args.length === 8) {
      date.setMicroseconds(args.pop()!);
    }

    return date.getFullTimeString();
  }
}

/**
 * Parses a RFC 3339 formatted string representation of the date, and returns
 * a string representing the nanoseconds since January 1, 1970, 00:00:00.
 *
 * @private
 *
 * @param {string} time The RFC 3339 formatted string.
 * @returns {string}
 */
function parseFullISO(time: string): string {
  let digits = '0';

  time = time.replace(/\.(\d+)/, ($0, $1) => {
    digits = $1;
    return '.000';
  });

  const nanos = Number(padRight(digits, 9));
  const date = new PreciseDate(time);

  return date.setNanoseconds(nanos);
}

/**
 * Normalizes a {@link google.protobuf.Timestamp} object.
 *
 * @private
 *
 * @param {google.protobuf.Timestamp} timestamp The timestamp object.
 * @returns {DateStruct}
 */
function parseProto({seconds = 0, nanos = 0}: ProtobufDate): DateStruct {
  if (typeof (seconds as Long).toNumber === 'function') {
    seconds = (seconds as Long).toNumber();
  }

  seconds = Number(seconds);
  nanos = Number(nanos);

  return {seconds, nanos};
}

/**
 * Checks to see if time value is specified in nanoseconds. We assume that all
 * BigInt and string timestamps represent nanoseconds.
 *
 * @private
 *
 * @param {*} time The time to check.
 * @returns {boolean}
 */
function isFullTime(time: unknown): boolean {
  return (
    typeof time === 'bigint' || (typeof time === 'string' && /^\d+$/.test(time))
  );
}

/**
 * Checks to see if time value is a {@link DateStruct}.
 *
 * @private
 *
 * @param {*} time The time to check.
 * @returns {boolean}
 */
function isStruct(time: unknown): time is DateStruct {
  return (
    (typeof time === 'object' &&
      typeof (time as DateStruct).seconds !== 'undefined') ||
    typeof (time as DateStruct).nanos === 'number'
  );
}

/**
 * Checks to see if the time value is a RFC 3339 formatted string.
 *
 * @private
 *
 * @param {*} time The time to check.
 * @returns {boolean}
 */
function isFullISOString(time: unknown): boolean {
  return typeof time === 'string' && FULL_ISO_REG.test(time);
}

/**
 * Pads a number/string with "0" to the left.
 *
 * @private
 *
 * @param {string|number} n The number/string to pad.
 * @param {number} min The min size of the padded string.
 * @returns {string}
 */
function padLeft(n: number | string, min: number): string {
  const padding = getPadding(n, min);
  return `${padding}${n}`;
}

/**
 * Pads a number/string with "0" to the right.
 *
 * @private
 *
 * @param {string|number} n The number/string to pad.
 * @param {number} min The min size of the padded string.
 * @returns {string}
 */
function padRight(n: number | string, min: number): string {
  const padding = getPadding(n, min);
  return `${n}${padding}`;
}

/**
 * Creates padding based on current size and min size needed.
 *
 * @private
 *
 * @param {string|number} n The number/string to pad.
 * @param {number} [min=3] The min size of the padded string.
 * @returns {string}
 */
function getPadding(n: number | string, min: number): string {
  const size = Math.max(min - n.toString().length, 0);
  return '0'.repeat(size);
}