Calendar: edit and delete a single occurrence

Closes #132.

Stalwart 0.16.20 accepts a synthetic id on `CalendarEvent/set`, writing a
`recurrenceOverrides` entry rather than touching the series, so editing
one date of a recurring event is now something the server does and this
does too.

Editing asks the scope *before* the form opens, because it decides which
event the form is even about: a form populated from the master shows the
series' start date, so editing Wednesday's standup would have offered to
move Monday's. Deleting asks in place of the old confirm.

The patch is narrowed rather than posted hopefully. 0.16.20 sorts
per-occurrence properties into three groups and only one is honest: ten
are refused with `invalidProperties`, twelve more are dropped from the
patch while the response still reports success, and the rest are applied.
That silent middle group is how #26 reached a live server - a successful
response is not evidence anything was written - so `occurrencePatch`
throws on the first group, reports the second to the caller, and the
editor leaves out the five it always sends. A patch that would be
entirely dropped is not sent at all.

The refusal for an occurrence of a this-and-future change offers the
series instead of a bare error toast. Nothing here writes one of those,
but an event synced from another client can carry one.

Two things the scope prompt cost, both worth knowing. A dialog is queued
in a store the moment it is asked for, so it outlives the effect that
asked: without a ref guard a remount queues a second prompt the first
answer cannot retract. And gating the *answer* on the effect's cleanup
flag is worse - StrictMode runs mount, cleanup, mount, so the flag is
already set by the time anyone clicks and the editor never opens.

The mock expands recurrences for the first time, which is what makes any
of this developable. It hands out synthetic ids for everything including
one-offs, gives occurrences a `recurrenceId` and no rule, and reproduces
the refusals - including the silent drops, since a mock that applied them
would let a client that sends them look correct everywhere but a real
server.
This commit is contained in:
2026-08-30 21:35:01 -07:00
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/**
* Enough recurrence expansion for the mock to behave like Stalwart 0.16.20.
*
* The mock used to hand a recurring event back once, as its stored self. Three
* things that only a live server showed were therefore impossible to develop
* against, and all three had already cost a debugging session:
*
* - an expanded query gives *everything* a synthetic id over a `baseEventId`,
* a one-off included, so `baseEventId` is no evidence of a series;
* - an occurrence carries a `recurrenceId` and no rule of its own;
* - 0.16.20 takes a write aimed at a synthetic id and turns it into a
* `recurrenceOverrides` entry rather than touching the series.
*
* A mock that agrees with the client rather than with the server is how #26 and
* #30 reached a live instance, so the refusals matter as much as the successes:
* what Stalwart rejects is rejected here, and what it drops in silence is
* dropped here, in silence, on purpose.
*/
export type Obj = Record<string, unknown>;
/** How far the expander will walk before giving up on a rule. */
const MAX_ITERATIONS = 750;
const DAYS = ["su", "mo", "tu", "we", "th", "fr", "sa"];
/**
* The id an occurrence is addressed by.
*
* Stalwart's are opaque; the mock's are parseable because it has to resolve
* them, and nothing in ihasmail may read either. The index counts from the
* start of the series and survives an excluded date, so an id keeps meaning the
* same occurrence after one of its neighbours is deleted.
*/
export const syntheticId = (baseId: string, index: number): string => `${baseId}-o${index}`;
export function parseSyntheticId(id: string): { baseId: string; index: number } | null {
const m = /^(.+)-o(\d+)$/.exec(id);
return m ? { baseId: m[1]!, index: Number(m[2]) } : null;
}
/** `2026-08-31T09:00:00` — the naive local form the mock stores `start` in. */
export function localDateTime(d: Date): string {
const p = (n: number) => String(n).padStart(2, "0");
return `${d.getFullYear()}-${p(d.getMonth() + 1)}-${p(d.getDate())}T${p(d.getHours())}:${p(d.getMinutes())}:${p(d.getSeconds())}`;
}
const parseLocal = (s: string): Date => new Date(s);
export interface Occurrence {
index: number;
/** The slot in the series this instance fills, which keys any override. */
recurrenceId: string;
start: string;
/** Set when a `recurrenceOverrides` entry applies to this date. */
override?: Obj;
}
interface Rule {
frequency?: string;
interval?: number;
count?: number;
until?: string;
byDay?: { day: string }[];
}
/**
* Every occurrence of `base` between `from` and `to`, in series order.
*
* An event with no rule has exactly one, at index 0 — which is what gives a
* one-off the synthetic id a real server would give it.
*/
export function expandOccurrences(base: Obj, from: Date, to: Date): Occurrence[] {
const overrides = (base.recurrenceOverrides as Record<string, Obj> | undefined) ?? {};
const startStr = base.start as string;
if (!startStr) return [];
const first = parseLocal(startStr);
const rule = base.recurrenceRule as Rule | undefined;
const out: Occurrence[] = [];
const emit = (index: number, at: Date): boolean => {
const recurrenceId = localDateTime(at);
const override = overrides[recurrenceId];
// An excluded date still consumes its index: ids have to stay stable when a
// neighbour is deleted, or every occurrence after it silently renumbers.
if (override?.excluded === true) return true;
if (at >= from && at < to) {
out.push({ index, recurrenceId, start: recurrenceId, ...(override ? { override } : {}) });
}
return at < to;
};
if (!rule?.frequency) {
emit(0, first);
return out;
}
const interval = Math.max(1, rule.interval ?? 1);
const until = rule.until ? parseLocal(rule.until) : null;
const byDay = rule.byDay?.length ? new Set(rule.byDay.map((d) => d.day.toLowerCase())) : null;
let index = 0;
let emitted = 0;
const cursor = new Date(first);
for (let step = 0; step < MAX_ITERATIONS; step++) {
if (until && cursor > until) break;
if (rule.count != null && emitted >= rule.count) break;
const matches = !byDay || byDay.has(DAYS[cursor.getDay()]!);
if (matches) {
emitted++;
const keepGoing = emit(index, new Date(cursor));
index++;
if (!keepGoing) break;
}
// A rule with byDay walks day by day and keeps the days it names; without
// one it steps by its own frequency.
if (byDay) cursor.setDate(cursor.getDate() + 1);
else if (rule.frequency === "daily") cursor.setDate(cursor.getDate() + interval);
else if (rule.frequency === "weekly") cursor.setDate(cursor.getDate() + 7 * interval);
else if (rule.frequency === "monthly") cursor.setMonth(cursor.getMonth() + interval);
else if (rule.frequency === "yearly") cursor.setFullYear(cursor.getFullYear() + interval);
else break;
}
return out;
}
/** Fields that describe the series and never travel down to one instance. */
const SERIES_ONLY = ["recurrenceRule", "recurrenceRules", "excludedRecurrenceRules", "recurrenceOverrides"];
/**
* The object a `CalendarEvent/get` returns for one occurrence.
*
* The rule is stripped, `recurrenceId` is set, and `baseEventId` points at the
* master — so an occurrence is recognisable by its `recurrenceId` and by
* nothing else, which is the shape `isRecurring` was written against.
*/
export function occurrenceView(base: Obj, occ: Occurrence): Obj {
const view: Obj = { ...base };
for (const k of SERIES_ONLY) delete view[k];
Object.assign(view, occ.override ?? {});
view.id = syntheticId(base.id as string, occ.index);
view.baseEventId = base.id;
view.start = occ.start;
// Only a genuine instance of a series carries one. A one-off expanded into
// its single occurrence does not, or every one-off would look recurring.
if (base.recurrenceRule) view.recurrenceId = occ.recurrenceId;
delete view.excluded;
return view;
}
/* ---------- what a single occurrence will not take ---------- */
/** Refused outright, with `invalidProperties`. */
export const OCCURRENCE_REJECTED = new Set([
"baseEventId", "calendarIds", "isDraft", "isOrigin", "utcStart", "utcEnd",
"useDefaultAlerts", "mayInviteSelf", "mayInviteOthers", "hideAttendees",
]);
/**
* Dropped from the patch, with the response still reporting success.
*
* This is the half that has to be reproduced most carefully. A mock that
* *applied* these would agree with a client that sends them, and the belief
* would ship — which is exactly the road #26 took to a live server.
*/
export const OCCURRENCE_INHERITED = new Set([
"@type", "method", "organizerCalendarAddress", "privacy", "prodId",
"recurrenceId", "recurrenceIdTimeZone", "sentBy", "uid",
"recurrenceOverrides", "recurrenceRule", "relatedTo",
]);
/**
* Split a per-occurrence patch the way the server's validator does.
*
* `rejected` is the first property that would be refused, if any; `applied` is
* what actually lands on the override. Everything else vanishes without a word.
*/
export function splitOccurrencePatch(patch: Obj): { rejected?: string; applied: Obj } {
const applied: Obj = {};
for (const [key, value] of Object.entries(patch)) {
const [head, , third] = key.split("/");
const root = head ?? key;
if (OCCURRENCE_REJECTED.has(root)) return { rejected: root, applied };
if (OCCURRENCE_INHERITED.has(root)) continue;
if (root === "participants" && third === "calendarAddress") continue;
if (root === "id") continue;
applied[key] = value;
}
return { applied };
}
/** One occurrence by its index, wherever in the series it falls. */
export function occurrenceAt(base: Obj, index: number): Occurrence | null {
const all = expandOccurrences(base, new Date(-8640000000000), new Date(8640000000000));
return all.find((o) => o.index === index) ?? null;
}