using System.Globalization;
using Elternbeirat.Contracts;

namespace Elternbeirat.Web.Shared;

/// <summary>
/// Formats an <see cref="Event"/>'s date range for display in German. Shared by
/// the full event list and the home-page events embed so both render dates the
/// same way.
/// </summary>
public static class EventFormat
{
    private static readonly CultureInfo German = CultureInfo.GetCultureInfo("de-DE");

    // An event counts as all-day when its start carries no wall-clock time
    // (00:00); PocketBase has no separate flag.
    private static bool HasTime(Event ev) => ev.Start.TimeOfDay != TimeSpan.Zero;

    /// <summary>
    /// Formats the entry's date range: a single day, a date with a time, or a
    /// span across days.
    /// </summary>
    public static string Range(Event ev)
    {
        var start = HasTime(ev)
            ? ev.Start.ToString("dddd, d. MMMM yyyy, HH:mm", German) + " Uhr"
            : ev.Start.ToString("dddd, d. MMMM yyyy", German);

        if (ev.End is not { } end)
        {
            return start;
        }

        // Same day: append just the end time. Different days: append the full
        // end date.
        if (end.Date == ev.Start.Date)
        {
            return HasTime(ev)
                ? start + "–" + end.ToString("HH:mm", German) + " Uhr"
                : start;
        }

        var endText = HasTime(ev)
            ? end.ToString("d. MMMM yyyy, HH:mm", German) + " Uhr"
            : end.ToString("d. MMMM yyyy", German);
        return start + " – " + endText;
    }
}