Add consented social milestone posting

src/lib/social-milestones.ts

@@ -0,0 +1,69 @@
+export const DEFAULT_SOCIAL_MILESTONE_THRESHOLDS = [1000, 10000] as const;
+
+export type SocialMilestoneKind = `unique_scans_${number}`;
+
+/**
+ * Staging can set SOCIAL_MILESTONE_THRESHOLDS=1 (or e.g. 1,2) so the complete
+ * flow is testable without fabricating thousands of scans. Production keeps
+ * the conservative defaults unless its environment explicitly changes them.
+ */
+export function getSocialMilestoneThresholds(): number[] {
+  const configured = process.env.SOCIAL_MILESTONE_THRESHOLDS;
+  if (!configured) return [...DEFAULT_SOCIAL_MILESTONE_THRESHOLDS];
+
+  const thresholds = Array.from(new Set(
+    configured.split(',')
+      .map(value => Number(value.trim()))
+      .filter(value => Number.isInteger(value) && value > 0 && value <= 1_000_000)
+  )).sort((a, b) => a - b);
+
+  return thresholds.length ? thresholds : [...DEFAULT_SOCIAL_MILESTONE_THRESHOLDS];
+}
+
+const useCaseLabels: Record<string, string> = {
+  menu_pdf: 'menu QR code',
+  marketing_campaign: 'campaign QR code',
+  vcard: 'digital business-card QR code',
+  event: 'event QR code',
+  feedback: 'feedback QR code',
+};
+
+export function milestoneKind(threshold: number): SocialMilestoneKind {
+  return `unique_scans_${threshold}` as SocialMilestoneKind;
+}
+
+export function milestoneThreshold(kind: string): number | null {
+  const result = /^unique_scans_(\d+)$/.exec(kind);
+  return result ? Number(result[1]) : null;
+}
+
+export type SocialLocale = 'en' | 'de';
+
+export function socialLocale(value?: string | null): SocialLocale {
+  return value === 'de' ? 'de' : 'en';
+}
+
+export function usageLabel(primaryUseCase: string | null, locale: SocialLocale = 'en'): string {
+  if (locale === 'de') {
+    const german: Record<string, string> = { menu_pdf: 'Speisekarten-QR-Code', marketing_campaign: 'Kampagnen-QR-Code', vcard: 'Visitenkarten-QR-Code', event: 'Event-QR-Code', feedback: 'Feedback-QR-Code' };
+    return (primaryUseCase && german[primaryUseCase]) || 'QR-Code';
+  }
+  return (primaryUseCase && useCaseLabels[primaryUseCase]) || 'QR code';
+}
+
+export function buildMilestonePost(primaryUseCase: string | null, threshold: number, xHandle?: string | null, locale: SocialLocale = 'en'): string {
+  const count = threshold.toLocaleString(locale === 'de' ? 'de-DE' : 'en-US');
+  const base = locale === 'de'
+    ? `Ein ${usageLabel(primaryUseCase, locale)} hat gerade ${count} eindeutige Scans erreicht. 🎉`
+    : `A ${usageLabel(primaryUseCase, locale)} just reached ${count} unique scans. 🎉`;
+  return xHandle ? `${base} By @${xHandle.replace(/^@/, '')}.` : base;
+}
+
+export function buildMilestoneCard(primaryUseCase: string | null, threshold: number, locale: SocialLocale) {
+  return { version: 'milestone-card-v1', language: locale, threshold, label: usageLabel(primaryUseCase, locale), title: locale === 'de' ? 'Erfolgsmeilenstein' : 'Success milestone' };
+}
+
+export function normalizeXHandle(value: string): string | null {
+  const handle = value.trim().replace(/^@/, '');
+  return /^[A-Za-z0-9_]{1,15}$/.test(handle) ? handle : null;
+}