gristlabs_grist-core/app/common/parseDate.ts

330 lines
11 KiB
TypeScript
Raw Normal View History

import escapeRegExp = require('lodash/escapeRegExp');
import memoize = require('lodash/memoize');
import * as moment from 'moment-timezone';
// When using YY format, use a consistent interpretation in datepicker and in moment parsing: add
// 2000 if the result is at most 10 years greater than the current year; otherwise add 1900. See
// https://bootstrap-datepicker.readthedocs.io/en/latest/options.html#assumenearbyyear and
// "Parsing two digit years" in https://momentjs.com/docs/#/parsing/string-format/.
export const TWO_DIGIT_YEAR_THRESHOLD = 10;
const MAX_TWO_DIGIT_YEAR = new Date().getFullYear() + TWO_DIGIT_YEAR_THRESHOLD - 2000;
// Moment suggests that overriding this is fine, but we need to force TypeScript to allow it.
(moment as any).parseTwoDigitYear = function(yearString: string): number {
const year = parseInt(yearString, 10);
return year + (year > MAX_TWO_DIGIT_YEAR ? 1900 : 2000);
};
// Order of formats to try if the date cannot be parsed as the currently set format.
// Formats are parsed in momentjs strict mode, but separator matching and the MM/DD
// two digit requirement are ignored. Also, partial completion is permitted, so formats
// may match even if only beginning elements are provided.
// TODO: These should be affected by the user's locale/settings.
// TODO: We may want to consider adding default time formats as well to support more
// time formats.
const PARSER_FORMATS: string[] = [
'M D YYYY',
'M D YY',
'M D',
'M',
'MMMM D YYYY',
'MMMM D',
'MMMM Do YYYY',
'MMMM Do',
'D MMMM YYYY',
'D MMMM',
'Do MMMM YYYY',
'Do MMMM',
'MMMM',
'MMM D YYYY',
'MMM D',
'MMM Do YYYY',
'MMM Do',
'D MMM YYYY',
'D MMM',
'Do MMM YYYY',
'Do MMM',
'MMM',
'YYYY M D',
'YYYY M',
'YYYY',
'D M YYYY',
'D M YY',
'D M',
'D'
];
const UNAMBIGUOUS_FORMATS = [
'YYYY M D',
...PARSER_FORMATS.filter(f => f.includes("MMM")),
];
const TIME_REGEX = /(?:^|\s+|T)(?:(\d\d?)(?::(\d\d?)(?::(\d\d?))?)?|(\d\d?)(\d\d))\s*([ap]m?)?$/i;
// [^a-zA-Z] because no letters are allowed directly before the abbreviation
const UTC_REGEX = /[^a-zA-Z](UTC?|GMT|Z)$/i;
const NUMERIC_TZ_REGEX = /([+-]\d\d?)(?::?(\d\d))?$/i;
// Not picky about separators, so replace them in the date and format strings to be spaces.
const SEPARATORS = /[\W_]+/g;
const tzAbbreviations = memoize((tzName: string): RegExp => {
// Some abbreviations are just e.g. +05
// and escaping the + seems better than filtering
const abbreviations = new Set(moment.tz.zone(tzName)!.abbrs.map(escapeRegExp));
const union = [...abbreviations].join('|');
// [^a-zA-Z] because no letters are allowed directly before the abbreviation
// so for example CEST won't match even if EST does
return new RegExp(`[^a-zA-Z](${union})$`, 'i');
});
interface ParseOptions {
time?: string;
dateFormat?: string;
timeFormat?: string;
timezone?: string;
}
/**
* parseDate - Attempts to parse a date string using several common formats. Returns the
* timestamp of the parsed date in seconds since epoch, or returns null on failure.
* @param {String} date - The date string to parse.
* @param {String} options.dateFormat - The preferred momentjs format to use to parse the
* date. This is attempted before the default formats.
* @param {String} options.time - The time string to parse.
* @param {String} options.timeFormat - The momentjs format to use to parse the time. This
* must be given if options.time is given.
* @param {String} options.timezone - The timezone string for the date/time, which affects
* the resulting timestamp.
*/
export function parseDate(date: string, options: ParseOptions = {}): number | null {
// If no date, return null.
if (!date) {
return null;
}
const dateFormats = PARSER_FORMATS.slice();
// If a preferred parse format is given, set that to be the first parser used.
if (options.dateFormat) {
dateFormats.unshift(..._buildVariations(options.dateFormat, date));
}
const cleanDate = date.replace(SEPARATORS, ' ');
let datetime = cleanDate.trim();
let timeformat = '';
let time = options.time;
if (time) {
const parsedTimeZone = parseTimeZone(time, options.timezone!);
const parsedTime = standardizeTime(parsedTimeZone.remaining);
if (!parsedTime || parsedTime.remaining) {
return null;
}
time = parsedTime.time;
const {tzOffset} = parsedTimeZone;
datetime += ' ' + time + tzOffset;
timeformat = ' HH:mm:ss' + (tzOffset ? 'Z' : '');
}
for (const f of dateFormats) {
const fullFormat = f + timeformat;
const m = moment.tz(datetime, fullFormat, true, options.timezone || 'UTC');
if (m.isValid()) {
return m.valueOf() / 1000;
}
}
return null;
}
/**
* Similar to parseDate, with these differences:
* - Only for a date (no time part)
* - Only falls back to UNAMBIGUOUS_FORMATS, not the full PARSER_FORMATS
* - Optionally adds all dates which match some format to `results`, otherwise returns first match.
* This is safer so it can be used for parsing when pasting a large number of dates
* and won't silently swap around day and month.
*/
export function parseDateStrict(
date: string, dateFormat: string | null, results?: Set<number>, timezone: string = 'UTC'
): number | undefined {
if (!date) {
return;
}
const dateFormats = [];
if (dateFormat) {
dateFormats.push(..._buildVariations(dateFormat, date));
}
dateFormats.push(...UNAMBIGUOUS_FORMATS);
const cleanDate = date.replace(SEPARATORS, ' ').trim();
for (const format of dateFormats) {
const m = moment.tz(cleanDate, format, true, timezone);
if (m.isValid()) {
const value = m.valueOf() / 1000;
if (results) {
results.add(value);
} else {
return value;
}
}
}
}
export function parseDateTime(dateTime: string, options: ParseOptions): number | undefined {
dateTime = dateTime.trim();
if (!dateTime) {
return;
}
const dateFormat = options.dateFormat || null;
const timezone = options.timezone || "UTC";
const dateOnly = parseDateStrict(dateTime, dateFormat, undefined, timezone);
if (dateOnly) {
return dateOnly;
}
const parsedTimeZone = parseTimeZone(dateTime, timezone);
let tzOffset = '';
if (parsedTimeZone) {
tzOffset = parsedTimeZone.tzOffset;
dateTime = parsedTimeZone.remaining;
}
const parsedTime = standardizeTime(dateTime);
if (!parsedTime) {
return;
}
dateTime = parsedTime.remaining;
const date = parseDateStrict(dateTime, dateFormat);
if (!date) {
return;
}
// date is a timestamp of midnight in UTC, so to get a formatted representation (for parsing
// together with time), take care to interpret it in UTC.
const dateString = moment.unix(date).utc().format("YYYY-MM-DD");
dateTime = dateString + ' ' + parsedTime.time + tzOffset;
const fullFormat = "YYYY-MM-DD HH:mm:ss" + (tzOffset ? 'Z' : '');
return moment.tz(dateTime, fullFormat, true, timezone).valueOf() / 1000;
}
// Helper function to get the partial format string based on the input. Momentjs has a feature
// which allows defaulting to the current year, month and/or day if not accounted for in the
// parser. We remove any parts of the parser not given in the input to take advantage of this
// feature.
function _getPartialFormat(input: string, format: string): string {
// Define a regular expression to match contiguous non-separators.
const re = /Y+|M+o?|D+o?|[a-zA-Z0-9]+/ig;
// Count the number of meaningful parts in the input.
const numInputParts = input.match(re)?.length || 0;
// Count the number of parts in the format string.
let numFormatParts = format.match(re)?.length || 0;
if (numFormatParts > numInputParts) {
// Remove year from format first, to default to current year.
if (/Y+/.test(format)) {
format = format.replace(/Y+/, ' ').trim();
numFormatParts -= 1;
}
if (numFormatParts > numInputParts) {
// Remove month from format next.
format = format.replace(/M+/, ' ').trim();
}
}
return format;
}
// Moment non-strict mode is considered bad, as it's far too lax. But moment's strict mode is too
// strict. We want to allow YY|YYYY for either year specifier, as well as M for MMM or MMMM month
// specifiers. It's silly that we need to create multiple format variations to support this.
function _buildVariations(dateFormat: string, date: string) {
// Momentjs has an undesirable feature in strict mode where MM and DD
// matches require two digit numbers. Change MM, DD to M, D.
let format = dateFormat.replace(/MM+/g, m => (m === 'MM' ? 'M' : m))
.replace(/DD+/g, m => (m === 'DD' ? 'D' : m))
.replace(SEPARATORS, ' ')
.trim();
// Allow the input date to end with a 4-digit year even if the format doesn't mention the year
if (
format.includes("M") &&
format.includes("D") &&
!format.includes("Y")
) {
format += " YYYY";
}
format = _getPartialFormat(date, format);
// Consider some alternatives to the preferred format.
const variations = new Set<string>([format]);
const otherYear = format.replace(/Y{2,4}/, (m) => (m === 'YY' ? 'YYYY' : (m === 'YYYY' ? 'YY' : m)));
variations.add(otherYear);
variations.add(format.replace(/MMM+/, 'M'));
if (otherYear !== format) {
variations.add(otherYear.replace(/MMM+/, 'M'));
}
return variations;
}
// Based on private calculateOffset in moment source code.
function calculateOffset(tzMatch: string[]): string {
const [, hhOffset, mmOffset] = tzMatch;
const sign = hhOffset.slice(0, 1);
return sign + hhOffset.slice(1).padStart(2, '0') + ':' + (mmOffset || '0').padStart(2, '0');
}
function parseTimeZone(str: string, timezone: string): { remaining: string, tzOffset: string } {
str = str.trim();
let tzMatch = UTC_REGEX.exec(str);
let matchStart = 0;
let tzOffset = '';
if (tzMatch) {
tzOffset = '+00:00';
matchStart = tzMatch.index + 1; // skip [^a-zA-Z] at regex start
} else {
tzMatch = NUMERIC_TZ_REGEX.exec(str);
if (tzMatch) {
tzOffset = calculateOffset(tzMatch);
matchStart = tzMatch.index;
} else if (timezone) {
// Abbreviations are simply stripped and ignored, so tzOffset is not set in this case
tzMatch = tzAbbreviations(timezone).exec(str);
if (tzMatch) {
matchStart = tzMatch.index + 1; // skip [^a-zA-Z] at regex start
}
}
}
if (tzMatch) {
str = str.slice(0, matchStart).trim();
}
return {remaining: str, tzOffset};
}
// Parses time of the form, roughly, HH[:MM[:SS]][am|pm]. Returns the time in the
// standardized HH:mm:ss format.
// This turns out easier than coaxing moment to parse time sensibly and flexibly.
function standardizeTime(timeString: string): { remaining: string, time: string } | undefined {
const match = TIME_REGEX.exec(timeString);
if (!match) {
return;
}
let hours = parseInt(match[1] || match[4], 10);
const mm = (match[2] || match[5] || '0').padStart(2, '0');
const ss = (match[3] || '0').padStart(2, '0');
const ampm = (match[6] || '').toLowerCase();
if (hours < 12 && hours > 0 && ampm.startsWith('p')) {
hours += 12;
} else if (hours === 12 && ampm.startsWith('a')) {
hours = 0;
}
const hh = String(hours).padStart(2, '0');
return {remaining: timeString.slice(0, match.index).trim(), time: `${hh}:${mm}:${ss}`};
}