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Marc-André Bombeck
4ba600d908
The card and the table carried byte-identical copies of the day-label arithmetic. Two copies is how they drift, and neither was reachable from a test, which is why the double conversion in both survived review. Lift it into resolveNextDueDayLabel, which returns a discriminated label the callers map onto their own strings, and cover the case the old code could not get right: a browser zone that differs from the profile zone. Those tests pin the host zone explicitly — the defect was invisible whenever host and profile agree, which is the only configuration a UTC-only suite runs in. Also pin that the window-status verdict is identical from every host zone, including one whose spring-forward gap swallows the profile wall clock.
56 lines
2.2 KiB
TypeScript
56 lines
2.2 KiB
TypeScript
/**
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* Which day label the next-intake line carries — "today", "tomorrow", a
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* weekday name, or a full date.
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*
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* Lifted out of `<MedicationCard>` and `<MedicationTable>`, which carried
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* byte-identical copies of this arithmetic. Both surfaces must agree; two
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* copies is how they drift.
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*
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* The caller maps the result onto its own i18n strings, so this module
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* stays free of translation plumbing and is directly testable.
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*/
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import { localDayIndex, wallClockInTz } from "@/lib/tz/wall-clock";
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export type NextDueDayLabel =
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| { kind: "today" }
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| { kind: "tomorrow" }
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/** 0 = Sunday … 6 = Saturday, read in the PROFILE zone. */
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| { kind: "weekday"; weekday: number }
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/**
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* Far enough out to want a full date. Carries the RAW instant — the
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* formatter applies the profile zone itself, so handing it a
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* zone-shifted `Date` would convert twice.
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*/
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| { kind: "date"; instant: Date };
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/**
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* Resolve the label for a next-due instant relative to `now`, both read in
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* `tz` (the user's PROFILE timezone — never the browser's).
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*
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* Two properties this function exists to guarantee:
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*
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* - The distance is a CALENDAR-day difference, not an hour count. A
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* `(next - now) / 86_400_000` round admits the 23 h / 25 h length of a
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* DST-transition day and can round "tomorrow" into "today".
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* - Every field is read through `wallClockInTz` in the profile zone, and
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* the `date` case hands back the untouched instant. The previous
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* implementation pre-shifted the instant into the profile zone and then
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* passed that shifted value to a formatter that applies the zone AGAIN,
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* so the rendered day was wrong for any user whose browser zone differs
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* from their profile zone — invisible whenever the two agree.
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*/
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export function resolveNextDueDayLabel(
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nextAt: Date,
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now: Date,
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tz: string,
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): NextDueDayLabel {
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const nextParts = wallClockInTz(nextAt, tz);
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const dayDelta =
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localDayIndex(nextParts) - localDayIndex(wallClockInTz(now, tz));
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if (dayDelta === 0) return { kind: "today" };
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if (dayDelta === 1) return { kind: "tomorrow" };
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if (dayDelta <= 5) return { kind: "weekday", weekday: nextParts.weekday };
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return { kind: "date", instant: nextAt };
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}
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