Carlos Florêncio
67 lines
2.9 KiB
TypeScript
67 lines
2.9 KiB
TypeScript
// Strict wire format: full RFC3339 with an explicit offset or UTC marker.
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// Date.parse is permissive, so shape validation must happen before any date
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// formatting or malformed values can be normalized into a different instant.
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const RFC3339_PATTERN =
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/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(?:\.(\d+))?(Z|[+-](\d{2}):(\d{2}))$/;
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const DAYS_IN_MONTH = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
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/** Whether the year is a leap year in the proleptic Gregorian calendar. */
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function isLeapYear(year: number): boolean {
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return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
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}
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/** Whether the day exists in the month, including leap-day validation. */
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function validDayForMonth(year: number, month: number, day: number): boolean {
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if (day < 1) return false;
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const maxDay = month === 2 && isLeapYear(year) ? 29 : DAYS_IN_MONTH[month - 1];
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return day <= maxDay;
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}
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/** Returns the UTC offset in seconds for a matched RFC3339 zone. */
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function parseOffsetSeconds(
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zone: string,
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offsetHourText: string | undefined,
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offsetMinuteText: string | undefined,
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): number | null {
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if (zone === "Z") return 0;
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const hour = Number(offsetHourText);
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const minute = Number(offsetMinuteText);
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if (hour > 23 || minute > 59) return null;
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return (zone.startsWith("-") ? -1 : 1) * (hour * 60 + minute) * 60;
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}
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/**
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* Parses an RFC3339/RFC3339Nano timestamp into epoch nanoseconds.
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*
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* Missing, empty, malformed, and semantically invalid values return `null`.
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* Calendar and time components are validated explicitly because Date.parse
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* normalizes values such as February 30th instead of rejecting them.
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*/
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export function parseStrictRfc3339Timestamp(value: string | undefined): bigint | null {
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if (!value) return null;
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const match = RFC3339_PATTERN.exec(value);
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if (!match) return null;
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const year = Number(match[1]);
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const month = Number(match[2]);
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if (month < 1 || month > 12) return null;
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if (!validDayForMonth(year, month, Number(match[3]))) return null;
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if (Number(match[4]) > 23 || Number(match[5]) > 59 || Number(match[6]) > 59) {
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return null;
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}
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const offsetSeconds = parseOffsetSeconds(match[8], match[9], match[10]);
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if (offsetSeconds === null) return null;
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// RFC3339Nano caps the fraction at 9 digits; longer fractions would
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// overflow into the seconds component when padded.
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if (match[7] !== undefined && match[7].length > 9) return null;
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// setUTCFullYear handles years 0-99 correctly; Date.UTC maps them to
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// 1900-1999 and would therefore normalize an otherwise valid timestamp.
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const utc = new Date(0);
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utc.setUTCFullYear(year, month - 1, Number(match[3]));
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utc.setUTCHours(Number(match[4]), Number(match[5]), Number(match[6]), 0);
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const wholeSeconds = BigInt(Math.floor(utc.getTime() / 1000)) - BigInt(offsetSeconds);
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const fractionNs = BigInt((match[7] ?? "").padEnd(9, "0"));
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return wholeSeconds * BigInt(1_000_000_000) + fractionNs;
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}
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