since3-portal/modules/shared/lib/info-format.ts

import type { TaskStatus } from "@/modules/shared/schemas/info";

const TIME_ZONE = "Europe/Berlin";
const DAY_MS = 24 * 60 * 60 * 1000;

// Server läuft in UTC; "heute" soll aber der Kalendertag in Deutschland sein.
export function berlinToday() {
    return new Intl.DateTimeFormat("en-CA", { timeZone: TIME_ZONE }).format(new Date());
}

function daysBetween(fromIso: string, toIso: string) {
    return Math.round((Date.parse(toIso) - Date.parse(fromIso)) / DAY_MS);
}

const shortDate = new Intl.DateTimeFormat("de-DE", { day: "numeric", month: "short", timeZone: "UTC" });

export function formatTaskTiming(status: TaskStatus, since: string, today = berlinToday()) {
    const days = daysBetween(since, today);

    if (status === "planned" || days < 0) {
        return `ab ${shortDate.format(new Date(`${since}T00:00:00Z`))}`;
    }
    if (days === 0) return "seit heute";
    if (days === 1) return "seit gestern";
    return `seit ${days} Tagen`;
}

const dateTime = new Intl.DateTimeFormat("de-DE", {
    day: "2-digit",
    month: "2-digit",
    year: "numeric",
    hour: "2-digit",
    minute: "2-digit",
    timeZone: TIME_ZONE,
});

export function formatDateTime(timestamp: string) {
    return `${dateTime.format(new Date(timestamp))} Uhr`;
}

const percent = new Intl.NumberFormat("de-DE", { minimumFractionDigits: 2, maximumFractionDigits: 2 });

export function formatUptime(value: number) {
    return `${percent.format(value)} %`;
}