import { fontKeys } from '$shared/api/queryKeys';
import { BaseQueryStore } from '$shared/lib/helpers/BaseQueryStore.svelte';
import {
    fetchFontsByIds,
    seedFontCache,
} from '../../api/proxy/proxyFonts';
import {
    FontNetworkError,
    FontResponseError,
} from '../../lib/errors/errors';
import type { UnifiedFont } from '../../model/types';

/**
 * Internal fetcher that seeds the cache and handles error wrapping.
 * Standalone function to avoid 'this' issues during construction.
 */
async function fetchAndSeed(ids: string[]): Promise<UnifiedFont[]> {
    if (ids.length === 0) return [];

    let response: UnifiedFont[];
    try {
        response = await fetchFontsByIds(ids);
    } catch (cause) {
        throw new FontNetworkError(cause);
    }

    if (!response || !Array.isArray(response)) {
        throw new FontResponseError('batchResponse', response);
    }

    seedFontCache(response);
    return response;
}

/**
 * Reactive store for fetching and caching batches of fonts by ID.
 * Integrates with TanStack Query via BaseQueryStore and handles
 * normalized cache seeding.
 */
export class BatchFontStore extends BaseQueryStore<UnifiedFont[]> {
    constructor(initialIds: string[] = []) {
        super({
            queryKey: fontKeys.batch(initialIds),
            queryFn: () => fetchAndSeed(initialIds),
            enabled: initialIds.length > 0,
            retry: false,
        });
    }

    /**
     * Updates the IDs to fetch. Triggers a new query.
     *
     * @param ids - Array of font IDs
     */
    setIds(ids: string[]): void {
        this.updateOptions({
            queryKey: fontKeys.batch(ids),
            queryFn: () => fetchAndSeed(ids),
            enabled: ids.length > 0,
            retry: false,
        });
    }

    /**
     * Array of fetched fonts
     */
    get fonts(): UnifiedFont[] {
        return this.result.data ?? [];
    }

    /**
     * Whether the query is currently loading
     */
    get isLoading(): boolean {
        return this.result.isLoading;
    }

    /**
     * Whether the query encountered an error
     */
    get isError(): boolean {
        return this.result.isError;
    }

    /**
     * The error object if the query failed
     */
    get error(): Error | null {
        return (this.result.error as Error) ?? null;
    }
}