feat(frontend): analytics shows minutes online by hour of week and by day, sessions with start and end, says when last seen is hidden, chat status is live and in russian

frontend/src/lib/stores/presence.svelte.ts

@@ -0,0 +1,73 @@
+import { getCurrentPresence } from "#lib/api/endpoints.js";
+import type { PresenceSample } from "#lib/api/types.js";
+import { events } from "#lib/stores/events.svelte.js";
+
+const CLOCK_INTERVAL = 30_000;
+
+function createPresence() {
+  let peerId: number | null = null;
+  let key: string | null = null;
+  let sample = $state<PresenceSample | null>(null);
+  let now = $state(Date.now());
+  let clock: ReturnType<typeof setInterval> | undefined;
+  let token = 0;
+
+  async function refresh() {
+    const id = peerId;
+    token += 1;
+    const current = token;
+    if (id === null) {
+      return;
+    }
+    try {
+      const next = await getCurrentPresence(id);
+      if (current === token) {
+        sample = next;
+        now = Date.now();
+      }
+    } catch {
+      if (current === token) {
+        sample = null;
+      }
+    }
+  }
+
+  events.subscribe((event) => {
+    if (event.type === "presence" && event.peer_id === peerId) {
+      token += 1;
+      ({ sample } = event);
+      now = Date.now();
+    }
+  });
+  events.onReconnect(() => {
+    refresh();
+  });
+
+  return {
+    follow(accountId: number | null, id: number | null) {
+      const next =
+        accountId === null || id === null ? null : `${accountId}:${id}`;
+      if (next === key) {
+        return;
+      }
+      key = next;
+      peerId = next === null ? null : id;
+      sample = null;
+      clearInterval(clock);
+      if (peerId !== null) {
+        clock = setInterval(() => {
+          now = Date.now();
+        }, CLOCK_INTERVAL);
+        refresh();
+      }
+    },
+    get now(): number {
+      return now;
+    },
+    get sample(): PresenceSample | null {
+      return sample;
+    },
+  };
+}
+
+export const presence = createPresence();