feature: Create BaseFontStore class with Tanstack query logic and FontshareStore, GoogleFontsStore based on it

src/entities/Font/model/store/baseFontStore.svelte.ts

@@ -0,0 +1,156 @@
+import { queryClient } from '$shared/api/queryClient';
+import {
+    type QueryKey,
+    QueryObserver,
+    type QueryObserverOptions,
+    type QueryObserverResult,
+} from '@tanstack/query-core';
+import type { UnifiedFont } from '../types';
+
+/** */
+export abstract class BaseFontStore<TParams extends Record<string, any>> {
+    // params = $state<TParams>({} as TParams);
+    cleanup: () => void;
+
+    #bindings = $state<(() => Partial<TParams>)[]>([]);
+    #internalParams = $state<TParams>({} as TParams);
+
+    params = $derived.by(() => {
+        let merged = { ...this.#internalParams };
+
+        // Loop through every "Cable" plugged into the store
+        for (const getter of this.#bindings) {
+            merged = { ...merged, ...getter() };
+        }
+
+        return merged as TParams;
+    });
+
+    protected result = $state<QueryObserverResult<UnifiedFont[], Error>>({} as any);
+    protected observer: QueryObserver<UnifiedFont[], Error>;
+    protected qc = queryClient;
+
+    constructor(initialParams: TParams) {
+        this.#internalParams = initialParams;
+
+        this.observer = new QueryObserver(this.qc, this.getOptions());
+
+        // Sync TanStack -> Svelte State
+        this.observer.subscribe(r => {
+            this.result = r;
+        });
+
+        // Sync Svelte State -> TanStack Options
+        this.cleanup = $effect.root(() => {
+            $effect(() => {
+                this.observer.setOptions(this.getOptions());
+            });
+        });
+    }
+
+    /**
+     * Mandatory: Child must define how to fetch data and what the key is.
+     */
+    protected abstract getQueryKey(params: TParams): QueryKey;
+    protected abstract fetchFn(params: TParams): Promise<UnifiedFont[]>;
+
+    private getOptions(params = this.params): QueryObserverOptions<UnifiedFont[], Error> {
+        return {
+            queryKey: this.getQueryKey(params),
+            queryFn: () => this.fetchFn(params),
+            staleTime: 5 * 60 * 1000,
+        };
+    }
+
+    // --- Common Getters ---
+    get fonts() {
+        return this.result.data ?? [];
+    }
+    get isLoading() {
+        return this.result.isLoading;
+    }
+    get isFetching() {
+        return this.result.isFetching;
+    }
+    get isError() {
+        return this.result.isError;
+    }
+    get isEmpty() {
+        return !this.isLoading && this.fonts.length === 0;
+    }
+
+    // --- Common Actions ---
+
+    addBinding(getter: () => Partial<TParams>) {
+        this.#bindings.push(getter);
+
+        return () => {
+            this.#bindings = this.#bindings.filter(b => b !== getter);
+        };
+    }
+
+    setParams(newParams: Partial<TParams>) {
+        this.#internalParams = { ...this.params, ...newParams };
+    }
+    /**
+     * Invalidate cache and refetch
+     */
+    invalidate() {
+        this.qc.invalidateQueries({ queryKey: this.getQueryKey(this.params) });
+    }
+
+    destroy() {
+        this.cleanup();
+    }
+
+    /**
+     * Manually refetch
+     */
+    async refetch() {
+        await this.observer.refetch();
+    }
+
+    /**
+     * Prefetch with different params (for hover states, pagination, etc.)
+     */
+    async prefetch(params: TParams) {
+        await this.qc.prefetchQuery(this.getOptions(params));
+    }
+
+    /**
+     * Cancel ongoing queries
+     */
+    cancel() {
+        this.qc.cancelQueries({
+            queryKey: this.getQueryKey(this.params),
+        });
+    }
+
+    /**
+     * Clear cache for current params
+     */
+    clearCache() {
+        this.qc.removeQueries({
+            queryKey: this.getQueryKey(this.params),
+        });
+    }
+
+    /**
+     * Get cached data without triggering fetch
+     */
+    getCachedData() {
+        return this.qc.getQueryData<UnifiedFont[]>(
+            this.getQueryKey(this.params),
+        );
+    }
+
+    /**
+     * Set data manually (optimistic updates)
+     */
+    setQueryData(updater: (old: UnifiedFont[] | undefined) => UnifiedFont[]) {
+        this.qc.setQueryData(
+            this.getQueryKey(this.params),
+            updater,
+        );
+    }
+}