feat: add shared recurrence helpers

This commit is contained in:
2026-04-09 17:41:04 -04:00
parent 95bc5db9a8
commit 911e5735a4
6 changed files with 454 additions and 388 deletions

238
src/lib/recurrence.ts Normal file
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import { format, parseISO } from "date-fns";
import { RRule, rrulestr } from "rrule";
import type { Frequency, Weekday } from "@/lib/rfc5545-types";
export type SupportedRecurrenceFrequency = "NONE" | "DAILY" | "WEEKLY" | "MONTHLY";
export interface RecurrenceFormValue {
freq: SupportedRecurrenceFrequency;
interval: number;
byDay: Weekday[];
count?: number;
until?: string;
}
export interface RecurrenceValidationResult {
isValid: boolean;
errors: Partial<Record<"count" | "until" | "rule", string>>;
}
const EMPTY_RECURRENCE: RecurrenceFormValue = {
freq: "NONE",
interval: 1,
byDay: [],
};
const RULE_FREQUENCIES: Record<Exclude<SupportedRecurrenceFrequency, "NONE">, number> = {
DAILY: RRule.DAILY,
WEEKLY: RRule.WEEKLY,
MONTHLY: RRule.MONTHLY,
};
const WEEKDAY_ORDER: Weekday[] = ["MO", "TU", "WE", "TH", "FR", "SA", "SU"];
const RULE_WEEKDAYS = {
MO: RRule.MO,
TU: RRule.TU,
WE: RRule.WE,
TH: RRule.TH,
FR: RRule.FR,
SA: RRule.SA,
SU: RRule.SU,
};
const FREQUENCY_LABELS: Record<number, SupportedRecurrenceFrequency> = {
[RRule.DAILY]: "DAILY",
[RRule.WEEKLY]: "WEEKLY",
[RRule.MONTHLY]: "MONTHLY",
};
const SUPPORTED_FREQUENCIES = new Set<SupportedRecurrenceFrequency>([
"NONE",
"DAILY",
"WEEKLY",
"MONTHLY",
]);
const sortWeekdays = (days: string[] | undefined): Weekday[] => {
if (!days?.length) return [];
return [...days]
.filter((day): day is Weekday => WEEKDAY_ORDER.includes(day as Weekday))
.sort((left, right) => WEEKDAY_ORDER.indexOf(left) - WEEKDAY_ORDER.indexOf(right));
};
const toUntilDate = (until: string): Date => {
const parsed = parseISO(`${until}T23:59:59`);
return parsed;
};
const toRRuleOptions = (value: RecurrenceFormValue, dtstart?: string) => {
if (value.freq === "NONE") return null;
const options: ConstructorParameters<typeof RRule>[0] = {
freq: RULE_FREQUENCIES[value.freq],
interval: value.interval,
};
if (dtstart) {
options.dtstart = parseISO(dtstart);
}
if (value.freq === "WEEKLY" && value.byDay.length > 0) {
options.byweekday = value.byDay.map((day) => RULE_WEEKDAYS[day]);
}
if (value.count) options.count = value.count;
if (value.until) options.until = toUntilDate(value.until);
return options;
};
export const getDefaultRecurrence = (): RecurrenceFormValue => ({
...EMPTY_RECURRENCE,
});
export const validateRecurrence = (
value: RecurrenceFormValue,
): RecurrenceValidationResult => {
const errors: RecurrenceValidationResult["errors"] = {};
if (!SUPPORTED_FREQUENCIES.has(value.freq)) {
errors.rule = "Unsupported recurrence frequency.";
}
if (!Number.isInteger(value.interval) || value.interval < 1) {
errors.rule = "Interval must be at least 1.";
}
if (value.count !== undefined && (!Number.isInteger(value.count) || value.count < 1)) {
errors.count = "Count must be a whole number greater than 0.";
}
if (value.until) {
const parsed = parseISO(value.until);
if (Number.isNaN(parsed.getTime())) {
errors.until = "Until must be a valid date.";
}
}
if (value.count !== undefined && value.until) {
errors.rule = "Choose either count or until, not both.";
}
if (value.freq === "WEEKLY" && value.byDay.length === 0) {
errors.rule = "Choose at least one weekday for weekly recurrence.";
}
return {
isValid: Object.keys(errors).length === 0,
errors,
};
};
export const parseRecurrenceRule = (rule?: string): RecurrenceFormValue => {
if (!rule) return getDefaultRecurrence();
const parsed = rrulestr(`RRULE:${rule}`) as RRule;
const options = parsed.origOptions;
const frequency = FREQUENCY_LABELS[options.freq ?? -1] ?? "NONE";
if (!SUPPORTED_FREQUENCIES.has(frequency)) {
return getDefaultRecurrence();
}
const byweekday = Array.isArray(options.byweekday)
? options.byweekday.map((weekday) => weekday.toString())
: options.byweekday
? [options.byweekday.toString()]
: [];
return {
freq: frequency,
interval: options.interval ?? 1,
byDay: sortWeekdays(byweekday),
count: options.count ?? undefined,
until: options.until ? format(options.until, "yyyy-MM-dd") : undefined,
};
};
export const serializeRecurrenceRule = (
value: RecurrenceFormValue,
dtstart?: string,
): string | undefined => {
if (value.freq === "NONE") return undefined;
const validation = validateRecurrence(value);
if (!validation.isValid) {
throw new Error(validation.errors.rule || validation.errors.count || validation.errors.until || "Invalid recurrence.");
}
const options = toRRuleOptions(value, dtstart);
if (!options) return undefined;
const rule = new RRule(options);
const ruleLine = rule.toString().split("\n").find((line) => line.startsWith("RRULE:"));
if (!ruleLine) return undefined;
const entries = ruleLine.replace(/^RRULE:/, "").split(";");
const orderedKeys = ["FREQ", "INTERVAL", "UNTIL", "COUNT", "BYDAY"];
const sorted = [...entries].sort((left, right) => {
const leftKey = left.split("=")[0] ?? "";
const rightKey = right.split("=")[0] ?? "";
const leftIndex = orderedKeys.indexOf(leftKey);
const rightIndex = orderedKeys.indexOf(rightKey);
const normalizedLeftIndex = leftIndex === -1 ? Number.MAX_SAFE_INTEGER : leftIndex;
const normalizedRightIndex = rightIndex === -1 ? Number.MAX_SAFE_INTEGER : rightIndex;
return normalizedLeftIndex - normalizedRightIndex || leftKey.localeCompare(rightKey);
});
return sorted.join(";");
};
export const getRecurrencePreview = (
value: RecurrenceFormValue,
dtstart?: string,
limit = 3,
): string[] => {
if (!dtstart || value.freq === "NONE") return [];
const options = toRRuleOptions(value, dtstart);
if (!options) return [];
const validation = validateRecurrence(value);
if (!validation.isValid) return [];
const rule = new RRule(options);
return rule
.all((_, index) => index < limit)
.map((date) => date.toISOString());
};
export const formatRecurrenceText = (rule?: string): string | null => {
if (!rule) return null;
return rrulestr(`RRULE:${rule}`).toText();
};
export const getWeekdayOptions = (): Array<{ value: Weekday; label: string }> => [
{ value: "MO", label: "Mon" },
{ value: "TU", label: "Tue" },
{ value: "WE", label: "Wed" },
{ value: "TH", label: "Thu" },
{ value: "FR", label: "Fri" },
{ value: "SA", label: "Sat" },
{ value: "SU", label: "Sun" },
];
export const isWeekdayPreset = (value: RecurrenceFormValue): boolean =>
value.freq === "WEEKLY" &&
value.interval === 1 &&
value.byDay.join(",") === ["MO", "TU", "WE", "TH", "FR"].join(",");
export const recurrenceFrequencyLabels: Record<SupportedRecurrenceFrequency, string> = {
NONE: "Does not repeat",
DAILY: "Daily",
WEEKLY: "Weekly",
MONTHLY: "Monthly",
};
export type { Frequency, Weekday };