feat(EntityStore): create a helper for creation of an Entity Store to store and operate over values that have ids

src/shared/lib/helpers/createEntityStore/createEntityStore.svelte.ts

@@ -0,0 +1,80 @@
+import { SvelteMap } from 'svelte/reactivity';
+
+export interface Entity {
+    id: string;
+}
+
+/**
+ * Svelte 5 Entity Store
+ * Uses SvelteMap for O(1) lookups and granular reactivity.
+ */
+export class EntityStore<T extends Entity> {
+    // SvelteMap is a reactive version of the native Map
+    #entities = new SvelteMap<string, T>();
+
+    constructor(initialEntities: T[] = []) {
+        this.setAll(initialEntities);
+    }
+
+    // --- Selectors (Equivalent to Selectors) ---
+
+    /** Get all entities as an array */
+    get all() {
+        return Array.from(this.#entities.values());
+    }
+
+    /** Select a single entity by ID */
+    getById(id: string) {
+        return this.#entities.get(id);
+    }
+
+    /** Select multiple entities by IDs */
+    getByIds(ids: string[]) {
+        return ids.map(id => this.#entities.get(id)).filter((e): e is T => !!e);
+    }
+
+    // --- Actions (CRUD) ---
+
+    addOne(entity: T) {
+        this.#entities.set(entity.id, entity);
+    }
+
+    addMany(entities: T[]) {
+        entities.forEach(e => this.addOne(e));
+    }
+
+    updateOne(id: string, changes: Partial<T>) {
+        const entity = this.#entities.get(id);
+        if (entity) {
+            // In Svelte 5, updating the object property directly is reactive
+            // if the object itself was made reactive, but here we replace
+            // the reference to ensure top-level map triggers.
+            this.#entities.set(id, { ...entity, ...changes });
+        }
+    }
+
+    removeOne(id: string) {
+        this.#entities.delete(id);
+    }
+
+    removeMany(ids: string[]) {
+        ids.forEach(id => this.#entities.delete(id));
+    }
+
+    setAll(entities: T[]) {
+        this.#entities.clear();
+        this.addMany(entities);
+    }
+
+    has(id: string) {
+        return this.#entities.has(id);
+    }
+
+    clear() {
+        this.#entities.clear();
+    }
+}
+
+export function createEntityStore<T extends Entity>(initialEntities: T[] = []) {
+    return new EntityStore<T>(initialEntities);
+}