Rechtliches: Fristen- und Versionslogik mit Tests

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/lib/legal.js

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+// Reine Logik fuer den Bereich Rechtliches: Kuendigungsfristen der Anbieter-Vertraege
+// und die Versionsgeschichte der Rechtstexte. Datumswerte sind immer 'YYYY-MM-DD'.
+
+const DAY = 24 * 60 * 60 * 1000
+
+function toUtc(date) {
+  const [y, m, d] = date.split('-').map(Number)
+  return Date.UTC(y, m - 1, d)
+}
+
+function fromUtc(ms) {
+  return new Date(ms).toISOString().slice(0, 10)
+}
+
+function addDays(date, n) {
+  return fromUtc(toUtc(date) + n * DAY)
+}
+
+function daysBetween(from, to) {
+  return Math.round((toUtc(to) - toUtc(from)) / DAY)
+}
+
+function isSet(value) {
+  return value !== null && value !== undefined && value !== ''
+}
+
+/** Monate addieren; der Tag wird auf das Monatsende geklemmt (31.01. + 1 = 28./29.02.). */
+export function addMonthsClamped(date, n) {
+  const [y, m, d] = date.split('-').map(Number)
+  const index = y * 12 + (m - 1) + n
+  const year = Math.floor(index / 12)
+  const month = index - year * 12
+  const lastDay = new Date(Date.UTC(year, month + 1, 0)).getUTCDate()
+  return fromUtc(Date.UTC(year, month, Math.min(d, lastDay)))
+}
+
+function noticeDate(periodEnd, contract) {
+  const value = Number(contract.noticeValue)
+  return contract.noticeUnit === 'days'
+    ? addDays(periodEnd, -value)
+    : addMonthsClamped(periodEnd, -value)
+}
+
+/**
+ * Naechster Kuendigungstermin eines Anbieter-Vertrags.
+ * state: active (noticeBy = spaetester Kuendigungstag), anytime (jederzeit kuendbar),
+ * ends (laeuft ohne Verlaengerung aus), ended, cancelled, incomplete (Angaben fehlen).
+ */
+export function nextCancellationDate(contract, today) {
+  if (isSet(contract.cancelledAt)) {
+    return { state: 'cancelled', periodEnd: contract.endsAt || null, noticeBy: null }
+  }
+  if (!isSet(contract.startDate) || !isSet(contract.termMonths)) {
+    return { state: 'incomplete', periodEnd: null, noticeBy: null }
+  }
+  const term = Number(contract.termMonths)
+  if (term === 0) return { state: 'anytime', periodEnd: null, noticeBy: null }
+
+  const renewal = Number(contract.renewalMonths) || 0
+  let periodEnd = addMonthsClamped(contract.startDate, term)
+  if (renewal === 0) {
+    return { state: periodEnd < today ? 'ended' : 'ends', periodEnd, noticeBy: null }
+  }
+  if (!isSet(contract.noticeValue) || !isSet(contract.noticeUnit)) {
+    return { state: 'incomplete', periodEnd: null, noticeBy: null }
+  }
+  while (noticeDate(periodEnd, contract) < today) {
+    periodEnd = addMonthsClamped(periodEnd, renewal)
+  }
+  return { state: 'active', periodEnd, noticeBy: noticeDate(periodEnd, contract) }
+}
+
+/** Farbe in der Vertragsliste: rot <= 30 Tage, orange <= 90 Tage bis zum Kuendigungstermin. */
+export function deadlineTone(result, today) {
+  if (result.state === 'cancelled' || result.state === 'ended') return 'grey'
+  if (result.state === 'incomplete') return 'missing'
+  if (result.state !== 'active' || !result.noticeBy) return 'normal'
+  const days = daysBetween(today, result.noticeBy)
+  if (days <= 30) return 'red'
+  if (days <= 90) return 'orange'
+  return 'normal'
+}
+
+/** Aktuell gueltige Version; bei mehreren (z. B. halb gescheiterte Abloesung) die juengste. */
+export function currentVersion(versions) {
+  return versions
+    .filter((v) => v.status === 'current')
+    .reduce((best, v) => (!best || v.validFrom > best.validFrom ? v : best), null)
+}
+
+/**
+ * Was beim Anlegen einer Version zu tun ist: das neue Dokument und die Aenderungen an
+ * bestehenden Versionen. Eine juengere gueltige Version loest die aktuelle ab; eine
+ * nachgetragene aeltere Fassung wird direkt als abgeloest einsortiert.
+ */
+export function planNewVersion(versions, input) {
+  const siblings = versions.filter(
+    (v) => v.documentKey === input.documentKey && v.$id !== input.$id
+  )
+  if (input.status !== 'current') {
+    return { create: { ...input, validTo: null }, updates: [] }
+  }
+  const current = currentVersion(siblings)
+  if (!current || input.validFrom >= current.validFrom) {
+    const updates = current
+      ? [{ id: current.$id, patch: { status: 'superseded', validTo: addDays(input.validFrom, -1) } }]
+      : []
+    return { create: { ...input, validTo: null }, updates }
+  }
+  const nextFrom = siblings
+    .filter((v) => v.status !== 'draft' && v.validFrom > input.validFrom)
+    .map((v) => v.validFrom)
+    .sort()[0]
+  return {
+    create: { ...input, status: 'superseded', validTo: addDays(nextFrom, -1) },
+    updates: [],
+  }
+}
+
+/** 'YYYY-MM-DD' -> 'dd.mm.yyyy' */
+export function formatDate(date) {
+  if (!date) return '–'
+  const [y, m, d] = date.slice(0, 10).split('-')
+  return `${d}.${m}.${y}`
+}