continue refactor of backend to utilize ts, deprecate js

server/src/stores/documentCacheStore.ts

@@ -0,0 +1,67 @@
+'use strict';
+
+interface Source {
+  id: string;
+}
+
+interface CacheEntry {
+  document: unknown;
+  sourceHash: string;
+  createdAt: number;
+}
+
+const cache = new Map<string, CacheEntry | boolean>();
+
+function buildSourceHash(sources: Source[]): string {
+  return sources
+    .map((s) => s.id)
+    .sort()
+    .join('|');
+}
+
+export function getCachedDocument(notebookId: string, type: string): CacheEntry | null {
+  const entry = cache.get(`${notebookId}:${type}`);
+  if (!entry || typeof entry === 'boolean') return null;
+  return entry;
+}
+
+export function setCachedDocument(
+  notebookId: string,
+  type: string,
+  document: unknown,
+  sources: Source[]
+): void {
+  const key = `${notebookId}:${type}`;
+  cache.set(key, {
+    document,
+    sourceHash: buildSourceHash(sources),
+    createdAt: Date.now(),
+  });
+}
+
+export function isFresh(notebookId: string, type: string, currentSources: Source[]): boolean {
+  const entry = cache.get(`${notebookId}:${type}`);
+  if (!entry || typeof entry === 'boolean') return false;
+  return entry.sourceHash === buildSourceHash(currentSources);
+}
+
+export function invalidate(notebookId: string): void {
+  for (const key of cache.keys()) {
+    if (key.startsWith(`${notebookId}:`)) {
+      cache.delete(key);
+    }
+  }
+}
+
+export function markGenerating(notebookId: string): void {
+  const key = `${notebookId}:__generating`;
+  cache.set(key, true);
+}
+
+export function clearGenerating(notebookId: string): void {
+  cache.delete(`${notebookId}:__generating`);
+}
+
+export function isGenerating(notebookId: string): boolean {
+  return cache.get(`${notebookId}:__generating`) === true;
+}