Fix #6: Display relative timestamps

src/lib/relativeTime.ts

@@ -0,0 +1,40 @@
+import { derived, readable, type Readable } from 'svelte/store';
+
+export const time = readable(new Date(), function start(set) {
+  const interval = setInterval(() => {
+    set(new Date());
+  }, 10000); //Every 10sec is enough, we don't need that much granularity
+
+  return function stop() {
+    clearInterval(interval);
+  };
+});
+
+export function secondsSince(date: Date): Readable<number> {
+  return derived(
+    time,
+    $time => Math.round(($time.getTime() - date.getTime()) / 1000)
+  );
+}
+
+export function relativeTime(seconds: number): string | null {
+  const min = 60;
+  if (seconds < min) {
+    return 'just now';
+  }
+
+  const hour = 60 * min;
+  if (seconds < hour) {
+    return `${Math.floor(seconds / min)}min`;
+  }
+
+  const day = hour * 24;
+  if (seconds < day) {
+    return `${(Math.floor(seconds / hour))}h`;
+  }
+  const maxRelative = day * 31;
+  if (seconds < maxRelative) {
+    return `${seconds % day}d`;
+  }
+  return null;
+}