Review fixes: a missed passphrase change follows at the next backup, a key from before 1.1.0 counts as used, schedules edited in their own time zone

- A location that a passphrase change could not reach gets it at its next backup
- A key from before 1.1.0 is never replaced as an unused one
- An unreadable settings file on a location is told apart from a missing one
- A schedule is shown and saved in the zone it was saved in
- Saving an unchanged schedule keeps its moment; --timezone needs a schedule
- Schedule coverage uses the time the backup began reading its data
- Tests: catch-up scenario, upgrade test restores the new file, autumn clock change

src/components/LocationScheduleRow.vue

@@ -6,7 +6,7 @@
 	<div class="ngb-row">
 		<strong class="ngb-name">{{ target.name }}</strong>
 		<NcSelect v-model="kind" :options="kinds" label="label" :input-label="t('ng_backup', 'Schedule')" :clearable="false" />
-		<NcTextField v-if="kind.id !== 'off'" v-model="time" class="ngb-time" :label="kind.id === 'daily' ? t('ng_backup', 'At (HH:MM, {zone})', { zone: browserZone }) : t('ng_backup', 'From (HH:MM, {zone})', { zone: browserZone })" />
+		<NcTextField v-if="kind.id !== 'off'" v-model="time" class="ngb-time" :label="kind.id === 'daily' ? t('ng_backup', 'At (HH:MM, {zone})', { zone }) : t('ng_backup', 'From (HH:MM, {zone})', { zone })" />
 		<NcTextField v-if="kind.id === 'hours'" v-model="hours" class="ngb-hours" type="number" min="1" max="23" :label="t('ng_backup', 'Every … hours')" />
 		<NcButton :disabled="busy || wanted === current" @click="save">{{ t('ng_backup', 'Save') }}</NcButton>
 	</div>
@@ -19,7 +19,6 @@ import NcButton from '@nextcloud/vue/components/NcButton'
 import NcSelect from '@nextcloud/vue/components/NcSelect'
 import NcTextField from '@nextcloud/vue/components/NcTextField'
 import api from '../api.js'
-import { toZone } from '../format.js'
 
 const props = defineProps({ target: { type: Object, required: true } })
 const emit = defineEmits(['changed', 'error'])
@@ -29,9 +28,11 @@ const kinds = [
 	{ id: 'daily', label: t('ng_backup', 'Once a day') },
 	{ id: 'hours', label: t('ng_backup', 'Every few hours') },
 ]
-// The time is saved in the administrator's own zone (the browser's); a schedule saved in another
-// zone is shown in this one, so it reads as the moment it runs here.
+// A schedule is shown and edited in the zone it was saved in, named next to the time: "every 6
+// hours from 02:00" runs until midnight of that zone, so moving it to another zone would change
+// how often it runs. A location without a schedule gets the administrator's own zone (the browser's).
 const browserZone = Intl.DateTimeFormat().resolvedOptions().timeZone || 'UTC'
+const zone = computed(() => props.target.schedule !== '' && props.target.scheduleZone ? props.target.scheduleZone : browserZone)
 const kind = ref(kinds[0])
 const time = ref('02:00')
 const hours = ref('6')
@@ -39,7 +40,7 @@ const busy = ref(false)
 
 const current = computed(() => {
 	const [at, every] = props.target.schedule.split('/')
-	return at === '' ? '' : (props.target.scheduleZone !== browserZone ? toZone(at, props.target.scheduleZone, browserZone) : at) + (every ? '/' + every : '')
+	return at === '' ? '' : at + (every ? '/' + every : '')
 })
 const wanted = computed(() => {
 	if (kind.value.id === 'off') {
@@ -59,7 +60,7 @@ async function save() {
 	busy.value = true
 	emit('error', '')
 	try {
-		await api.setTargetSchedule(props.target.id, wanted.value, browserZone)
+		await api.setTargetSchedule(props.target.id, wanted.value, zone.value)
 		emit('changed')
 	} catch (e) {
 		emit('error', e.message)

src/format.js

@@ -26,30 +26,3 @@ export function formatSize(bytes) {
 	}
 	return i === 0 ? `${b} B` : `${b.toFixed(1)} ${units[i]}`
 }
-
-/**
- * A time of day "HH:MM" in zone `from`, as "HH:MM" in zone `to`, at today's offsets.
- *
- * @param {string} hhmm the time
- * @param {string} from IANA zone it is in
- * @param {string} to IANA zone to show it in
- * @param {Date} now the day to convert on (today)
- * @return {string}
- */
-export function toZone(hhmm, from, to, now = new Date()) {
-	const [h, m] = hhmm.split(':').map(Number)
-	const parts = (zone, date) => Object.fromEntries(new Intl.DateTimeFormat('en-GB', {
-		timeZone: zone, hourCycle: 'h23', year: 'numeric', month: '2-digit', day: '2-digit', hour: '2-digit', minute: '2-digit',
-	}).formatToParts(date).map((p) => [p.type, p.value]))
-	const offsetAt = (at) => {
-		const seen = parts(from, new Date(at))
-		return Date.UTC(+seen.year, +seen.month - 1, +seen.day, +seen.hour, +seen.minute) - at
-	}
-	const today = parts(from, now)
-	const wall = Date.UTC(+today.year, +today.month - 1, +today.day, h, m)
-	// the offset at the wall time itself: on a day the clocks change it differs from the one at
-	// midnight, so it is looked up a second time at the moment found first
-	const at = wall - offsetAt(wall - offsetAt(wall))
-	const there = parts(to, new Date(at))
-	return `${there.hour}:${there.minute}`
-}