Reorganise colouring of schedule times, add 'delay' column (E, RT, D). Including reusable function to assist.

src/lib/utils/time.ts

@@ -1,3 +1,4 @@
+import type { ApiTrainsTrainDetails } from '@owlboard/owlboard-ts';
 /**
  * Converts ISO/JSON time to UK-formatted HH:MM string.
  * Ensures Europe/London timezone irrespective of browser timezone.
@@ -15,3 +16,34 @@ export function formatUkTime(dateStr: string | Date | undefined): string {
 		timeZone: 'Europe/London'
 	});
 }
+
+/**
+ * Calculates a 'delay' value, in the formats:
+ * RT, 1E, 7L, etc.
+ * @param 'Schedule Location' object
+ * @returns Delay string for departure boards
+ */
+export function calculateDelay(loc: ApiTrainsTrainDetails.ServiceLocation): {val: string, type: string} {
+const pairs = [
+        { actual: loc.atd, sched: loc.ptd ?? loc.wtd },
+        { actual: loc.ata, sched: loc.pta ?? loc.wta },
+        { actual: loc.atp, sched: loc.wtp }
+    ];
+
+    const match = pairs.find(p => p.actual && p.sched);
+
+    if (!match || !match.actual || !match.sched) return {val: '', type: 'none'};
+
+    const diffMinutes = Math.round(
+        (Date.parse(match.actual) - Date.parse(match.sched)) / 60000
+    );
+
+    if (diffMinutes === 0) return {val: 'RT', type: 'ontime'};
+
+    const absDiff = Math.abs(diffMinutes);
+    if (diffMinutes > 0) {
+        return { val: `${absDiff}L`, type: 'late' };
+    } else {
+        return { val: `${absDiff}E`, type: 'early' };
+    }
+}