rarare

webui/src/hooks/useDriverVideoModePolicy.js

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+import { useEffect, useMemo, useState } from 'react';
+import { useSessionSelector } from '../context/SessionContext.jsx';
+
+export function useDriverVideoModePolicy(roverId) {
+  const mode = useSessionSelector((state) => state.session?.mode || null);
+  const roster = useSessionSelector((state) => state.session?.roster ?? []);
+  const users = useSessionSelector((state) => state.session?.users ?? []);
+  const turnQueues = useSessionSelector((state) => state.session?.turnQueues ?? {});
+  const socketId = useSessionSelector((state) => state.session?.socketId || null);
+  const activeDrivers = useSessionSelector((state) => state.session?.activeDrivers ?? {});
+  const [now, setNow] = useState(() => Date.now());
+
+  const turnInfo = roverId ? turnQueues?.[roverId] || null : null;
+  const activeDriverId = roverId ? activeDrivers?.[roverId] || null : null;
+  const isActiveDriver = Boolean(socketId && activeDriverId === socketId);
+  const nextDriverId = useMemo(() => {
+    const queue = turnInfo?.queue || [];
+    if (!queue.length || !turnInfo?.current || queue.length <= 1) return null;
+    const idx = queue.findIndex((id) => id === turnInfo.current);
+    if (idx === -1) return queue[0] || null;
+    return queue[(idx + 1) % queue.length] || null;
+  }, [turnInfo?.queue, turnInfo?.current]);
+  const isNextDriver = Boolean(socketId && nextDriverId === socketId);
+  const deadline = turnInfo?.deadline || null;
+  const msUntilTurn = deadline ? deadline - now : null;
+  const isTurnsMode = mode === 'turns';
+  const totalRovers = roster.length;
+  const totalDrivers = useMemo(() => {
+    const unique = new Set();
+    users.forEach((entry) => {
+      const role = String(entry?.role || '');
+      if (role === 'spectator') return;
+      const turnRoverId = String(entry?.roverId || '').trim();
+      const turnSocketId = String(entry?.socketId || '').trim();
+      if (!turnRoverId || !turnSocketId) return;
+      unique.add(turnSocketId);
+    });
+    return unique.size;
+  }, [users]);
+  const shouldUsePreviewByLoad = isTurnsMode && totalDrivers > totalRovers;
+  const isPreSwitchWindow =
+    isTurnsMode && isNextDriver && msUntilTurn != null && msUntilTurn <= 5000 && msUntilTurn > 0;
+  const showNotTurnNotice = isTurnsMode && !isActiveDriver;
+  const forceSnapshotByTurnPolicy = showNotTurnNotice && !isPreSwitchWindow && shouldUsePreviewByLoad;
+
+  useEffect(() => {
+    if (mode !== 'turns') return undefined;
+    const timer = setInterval(() => setNow(Date.now()), 250);
+    return () => clearInterval(timer);
+  }, [mode]);
+
+  return forceSnapshotByTurnPolicy ? 'snapshot' : null;
+}