Sets up global cache and uses it to fetch sessions

src/lib/recordCache.ts

@@ -0,0 +1,81 @@
+import {
+  type CollectionId,
+  type AnyDocument,
+  CollectionIds,
+  type Relationship,
+  type DocumentId,
+  type RelationshipId,
+} from "./types";
+
+type CacheKey<C extends CollectionId = CollectionId> = `${C}:${string}`;
+type DocumentKey = CacheKey<typeof CollectionIds.Documents>;
+type RelationshipKey = CacheKey<typeof CollectionIds.Relationships>;
+
+export class RecordCache {
+  private cache: Record<
+    `${CollectionId}:${string}`,
+    {
+      record: AnyDocument | Relationship;
+      subscriptions: ((record: AnyDocument | Relationship | null) => void)[];
+    }
+  > = {};
+
+  private makeKey<C extends CollectionId>(
+    collectionId: C,
+    id: string,
+  ): CacheKey<C> {
+    return `${collectionId}:${id}`;
+  }
+
+  private docKey = (id: DocumentId): DocumentKey =>
+    this.makeKey(CollectionIds.Documents, id);
+
+  private relationKey = (id: RelationshipId): RelationshipKey =>
+    this.makeKey(CollectionIds.Relationships, id);
+
+  get = (key: CacheKey): AnyDocument | Relationship | undefined =>
+    this.cache[key]?.record;
+
+  set = (record: AnyDocument | Relationship) => {
+    const key = this.makeKey(record.collectionName, record.id);
+    if (this.cache[key] === undefined) {
+      this.cache[key] = {
+        record,
+        subscriptions: [],
+      };
+    }
+    const entry = this.cache[key];
+
+    entry.record = record;
+
+    for (const subscription of entry.subscriptions) {
+      subscription(record);
+    }
+
+    for (const doc of record.expand?.secondary ?? []) {
+      this.set(doc);
+    }
+    for (const rel of record.expand?.relationships_via_primary ?? []) {
+      this.set(rel);
+    }
+  };
+
+  remove = (key: CacheKey) => {
+    const entry = this.cache[key];
+    delete this.cache[key];
+    for (const subscription of entry.subscriptions) {
+      subscription(null);
+    }
+  };
+
+  getDocument = (id: DocumentId): AnyDocument | undefined =>
+    this.get(this.docKey(id)) as AnyDocument | undefined;
+
+  getRelationship = (id: RelationshipId): Relationship | undefined =>
+    this.get(this.relationKey(id)) as Relationship | undefined;
+
+  removeDocument = (id: DocumentId) => this.remove(this.docKey(id));
+
+  removeRelationship = (id: RelationshipId) =>
+    this.remove(this.relationKey(id));
+}