Sets up global cache and uses it to fetch sessions

src/context/cache/CacheContext.tsx

@@ -0,0 +1,74 @@
+import { createContext, use, useContext, useMemo, useRef } from "react";
+import type { ReactNode } from "react";
+import { RecordCache } from "@/lib/recordCache";
+import { pb } from "@/lib/pocketbase";
+import { type DocumentId, type AnyDocument, CollectionIds } from "@/lib/types";
+import { useQueryClient } from "@tanstack/react-query";
+
+/**
+ * Context value for the record cache singleton.
+ */
+export type CacheContextValue = RecordCache;
+
+const CacheContext = createContext<CacheContextValue | undefined>(undefined);
+
+/**
+ * Provider for the record cache context. Provides a singleton RecordCache instance to children.
+ */
+export function CacheProvider({ children }: { children: ReactNode }) {
+  const cacheRef = useRef<RecordCache | undefined>(undefined);
+  if (!cacheRef.current) {
+    cacheRef.current = new RecordCache();
+  }
+  return (
+    <CacheContext.Provider value={cacheRef.current}>
+      {children}
+    </CacheContext.Provider>
+  );
+}
+
+/**
+ * Hook to access the record cache context. Throws if used outside of CacheProvider.
+ */
+export function useCache(): CacheContextValue {
+  const ctx = useContext(CacheContext);
+  if (!ctx) throw new Error("useCache must be used within a CacheProvider");
+  return ctx;
+}
+
+export function useDocument(documentId: DocumentId): AnyDocument {
+  const cache = useCache();
+  const queryClient = useQueryClient();
+
+  async function fetchItems() {
+    const cacheValue = cache.getDocument(documentId);
+
+    if (cacheValue) {
+      console.info(`Serving ${documentId} from cache.`);
+      return cacheValue;
+    }
+
+    const { doc } = await queryClient.fetchQuery({
+      queryKey: [CollectionIds.Documents, documentId],
+      queryFn: async () => {
+        const doc: AnyDocument = await pb
+          .collection("documents")
+          .getOne(documentId, {
+            expand:
+              "relationships_via_primary,relationships_via_primary.secondary",
+          });
+
+        console.info(`Saving ${documentId} to cache.`);
+        cache.set(doc);
+
+        return { doc };
+      },
+    });
+
+    return doc;
+  }
+
+  const items = useMemo(fetchItems, [documentId, cache, queryClient]);
+
+  return use(items);
+}