Define the all-day rule once as Event.HasTime

Elternbeirat.Web/Shared/EventFormat.cs

@@ -4,45 +4,80 @@ 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.
+///     Formats the date range of an <see cref="Event"/> for display in German.
 /// </summary>
+/// <remarks>
+///     Shared by the full event list and the home-page events embed, so both render
+///     dates the same way.
+/// </remarks>
 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>
+    ///     Date format for the start, and for a single-day event.
+    /// </summary>
+    private const string LongDate = "dddd, d. MMMM yyyy";
 
     /// <summary>
-    /// Formats the entry's date range: a single day, a date with a time, or a
-    /// span across days.
+    ///     Date format for the end of a multi-day event; the weekday is omitted.
     /// </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);
+    private const string ShortDate = "d. MMMM yyyy";
 
-        if (ev.End is not { } end)
+    /// <summary>
+    ///     The culture used for month and weekday names.
+    /// </summary>
+    private static readonly CultureInfo German = CultureInfo.GetCultureInfo("de-DE");
+
+    /// <summary>
+    ///     Formats the date range of an event.
+    /// </summary>
+    /// <param name="event">
+    ///     The event to format.
+    /// </param>
+    /// <returns>
+    ///     The formatted range, depending on <see cref="Event.End"/> and <see cref="Event.HasTime"/>:
+    ///     <list type="bullet">
+    ///         <item>
+    ///             <description>No end: <c>Donnerstag, 8. Oktober 2026, 19:30 Uhr</c></description>
+    ///         </item>
+    ///         <item>
+    ///             <description>Same day: <c>Donnerstag, 8. Oktober 2026, 19:30–21:00 Uhr</c></description>
+    ///         </item>
+    ///         <item>
+    ///             <description>Several days: <c>Freitag, 9. Oktober 2026 – 11. Oktober 2026</c></description>
+    ///         </item>
+    ///     </list>
+    ///     Without a time, the time parts are omitted.
+    /// </returns>
+    public static string Range(Event @event)
+        => (@event.Start, @event.End, @event.HasTime) switch
         {
-            return start;
-        }
+            (var start, null, var hasTime)
+                => Stamp(start, LongDate, hasTime),
+            (var start, { } end, true) when end.Date == start.Date
+                => $"{start.ToString(LongDate, German)}, {start.ToString("HH:mm", German)}–{end.ToString("HH:mm", German)} Uhr",
+            (var start, { } end, false) when end.Date == start.Date
+                => Stamp(start, LongDate, withTime: false),
+            (var start, { } end, var hasTime)
+                => $"{Stamp(start, LongDate, hasTime)} – {Stamp(end, ShortDate, hasTime)}",
+        };
 
-        // 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;
-    }
+    /// <summary>
+    ///     Formats a single point in time as a date with an optional time.
+    /// </summary>
+    /// <param name="value">
+    ///     The date and time to format.
+    /// </param>
+    /// <param name="dateFormat">
+    ///     The date format, e.g. <see cref="LongDate"/>.
+    /// </param>
+    /// <param name="withTime">
+    ///     <see langword="true"/> to append the time, e.g. <c>, 19:30 Uhr</c>.
+    /// </param>
+    /// <returns>
+    ///     The formatted date, with the time if requested.
+    /// </returns>
+    private static string Stamp(DateTime value, string dateFormat, bool withTime)
+        => withTime
+            ? value.ToString(dateFormat + ", HH:mm", German) + " Uhr"
+            : value.ToString(dateFormat, German);
 }