const readable = (iso?: string) => {
    if (!iso) return undefined;
    const at = new Date(iso);
    return Number.isNaN(at.getTime()) ? undefined : at;
};

const clock = (at: Date) => at.toLocaleTimeString("en-US", { hour: "numeric", minute: "2-digit" });

const daysBefore = (at: Date) => {
    const midnight = (day: Date) => new Date(day.getFullYear(), day.getMonth(), day.getDate()).getTime();
    return Math.round((midnight(new Date()) - midnight(at)) / 86_400_000);
};

/** "today, 8:05 AM", "yesterday, 4:20 PM" or "9/24/2026, 8:05 AM". */
export const dayAndTime = (iso?: string): string | undefined => {
    const at = readable(iso);
    if (!at) return undefined;
    const ago = daysBefore(at);
    const day = ago === 0 ? "today" : ago === 1 ? "yesterday" : at.toLocaleDateString("en-US");
    return `${day}, ${clock(at)}`;
};

/** A row on the bench is today's work, so today reads as the time alone. */
export const benchTime = (iso?: string): string | undefined => {
    const at = readable(iso);
    if (!at) return undefined;
    return daysBefore(at) === 0 ? clock(at) : dayAndTime(iso);
};

export const capitalized = (text: string) => text.charAt(0).toUpperCase() + text.slice(1);