gristlabs_grist-core/app/common/parseDate.ts
Paul Fitzpatrick 5ef889addd (core) move home server into core
Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552
2020-07-21 20:39:10 -04:00

108 lines
4.0 KiB
TypeScript

import * as moment from 'moment-timezone';
// 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',
'MMMM',
'MMM D YYYY',
'MMM D',
'D MMM YYYY',
'D MMM',
'MMM',
'YYYY M D',
'YYYY M',
'YYYY',
'D M YYYY',
'D M YY',
'D M',
'D'
];
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;
}
// Not picky about separators, so replace them in the date and format strings to be spaces.
const separators = /\W+/g;
const dateFormats = PARSER_FORMATS.slice();
// If a preferred parse format is given, set that to be the first parser used.
if (options.dateFormat) {
// Momentjs has an undesirable feature in strict mode where MM and DD
// matches require two digit numbers. Change MM, DD to M, D.
const format = options.dateFormat.replace(/\bMM\b/g, 'M')
.replace(/\bDD\b/g, 'D')
.replace(separators, ' ');
dateFormats.unshift(_getPartialFormat(date, format));
}
const cleanDate = date.replace(separators, ' ');
const datetime = (options.time ? `${cleanDate} ${options.time}` : cleanDate).trim();
for (const f of dateFormats) {
// Momentjs has an undesirable feature in strict mode where HH, mm, and ss
// matches require two digit numbers. Change HH, mm, and ss to H, m, and s.
const timeFormat = options.timeFormat ? options.timeFormat.replace(/\bHH\b/g, 'H')
.replace(/\bmm\b/g, 'm')
.replace(/\bss\b/g, 's') : null;
const fullFormat = options.time && timeFormat ? `${f} ${timeFormat}` : f;
const m = moment.tz(datetime, fullFormat, true, options.timezone || 'UTC');
if (m.isValid()) {
return m.valueOf() / 1000;
}
}
return null;
}
// 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 separators.
const re = /\W+/g;
// Clean off any whitespace from the ends, and count the number of separators.
const inputMatch = input.trim().match(re);
const numInputSeps = inputMatch ? inputMatch.length : 0;
// Find the separator matches in the format string.
let formatMatch;
for (let i = 0; i < numInputSeps + 1; i++) {
formatMatch = re.exec(format);
if (!formatMatch) {
break;
}
}
// Get the format string up until the corresponding input ends.
return formatMatch ? format.slice(0, formatMatch.index) : format;
}