Preserve leaderboard context in player profiles

src/lib/leaderboard-navigation.ts

@@ -0,0 +1,44 @@
+import { leaderboardMetrics } from './leaderboard.js';
+
+const origin = 'https://electric-cherry.invalid';
+const contextKeys = ['game', 'map', 'metric', 'q', 'offset'] as const;
+
+/** Only retain a local leaderboard destination and its supported view state. */
+export function leaderboardReturnHref(value: string | null | undefined): string {
+    if (!value?.startsWith('/leaderboard')) return '/leaderboard';
+    try {
+        const url = new URL(value, origin);
+        if (url.origin !== origin || url.pathname !== '/leaderboard') return '/leaderboard';
+        const params = new URLSearchParams();
+        for (const key of contextKeys) {
+            const entry = url.searchParams.get(key);
+            if (entry) params.set(key, entry);
+        }
+        return `/leaderboard${params.size ? `?${params}` : ''}`;
+    } catch { return '/leaderboard'; }
+}
+
+export function playerContextHref(guid: string, source: string): string {
+    const returnTo = leaderboardReturnHref(source);
+    const original = new URL(returnTo, origin).searchParams;
+    const params = new URLSearchParams({ returnTo });
+    // History pagination is independent of the originating leaderboard page.
+    const game = original.get('game');
+    const map = original.get('map');
+    const metric = original.get('metric');
+    // Match the leaderboard's displayed defaults for older or hand-edited URLs.
+    if (game === 't5' || game === 't6') params.set('game', game);
+    if (map && map.length <= 1024) params.set('map', map);
+    if (metric && leaderboardMetrics.some(item => item.key === metric)) params.set('metric', metric);
+    return `/leaderboard/players/${encodeURIComponent(guid)}?${params}`;
+}
+
+export function profileViewHref(current: URL, changes: Record<string, string>): string {
+    const params = new URLSearchParams(current.search);
+    params.delete('offset');
+    for (const [key, value] of Object.entries(changes)) {
+        if (value) params.set(key, value);
+        else params.delete(key);
+    }
+    return `${current.pathname}${params.size ? `?${params}` : ''}`;
+}