/**
 * Proxy für newsdata.io API.
 * Endpoint: https://newsdata.io/api/1/news?apikey=...&language=...&category=...
 * Pagination: counter = wievieltes Widget dieser Art (0 = erste Seite, 1 = zweite, …), damit News nicht doppelt gezeigt werden.
 */

const NEWS_BASE = 'https://newsdata.io/api/1/news';

/**
 * @param {object} options
 * @param {number} options.counter - 0 = erste Seite, 1 = zweite, … (für Pagination/nextPage)
 * @param {string} [options.language] - z. B. de, en
 * @param {string} [options.category] - z. B. top, technology
 * @returns {Promise<{ results: Array, nextPage: string|null }>}
 */
async function fetchNewsPage({ counter, language = 'de', category = 'top', nextPageToken = null }) {
    const apiKey = process.env.NEWSDATA_IO_API_KEY;
    if (!apiKey || !apiKey.trim()) {
        throw new Error('NEWSDATA_IO_API_KEY is not set in .env');
    }
    const params = new URLSearchParams();
    params.set('apikey', apiKey.trim());
    params.set('language', String(language));
    params.set('category', String(category));
    if (nextPageToken) params.set('page', nextPageToken);

    const url = `${NEWS_BASE}?${params.toString()}`;
    const res = await fetch(url);
    if (!res.ok) {
        const text = await res.text();
        throw new Error(`newsdata.io: ${res.status} ${text.slice(0, 200)}`);
    }
    const data = await res.json();
    return {
        results: data.results ?? [],
        nextPage: data.nextPage ?? null
    };
}

/**
 * Liefert den N-ten Artikel (counter = 0, 1, 2, …) für das N-te News-Widget.
 * Lädt ggf. mehrere Seiten, bis genug Artikel vorhanden sind; jede Widget-Instanz bekommt einen anderen Artikel.
 *
 * @param {object} options
 * @param {number} options.counter - Index des Artikels (0 = erster, 1 = zweiter, …)
 * @param {string} [options.language]
 * @param {string} [options.category]
 * @returns {Promise<{ results: Array, nextPage: string|null }>}
 */
async function getNews({ counter = 0, language = 'de', category = 'top' }) {
    const neededIndex = Math.max(0, counter);
    const collected = [];
    let nextPageToken = null;

    while (collected.length <= neededIndex) {
        const page = await fetchNewsPage({
            language,
            category,
            nextPageToken: nextPageToken || undefined
        });
        const items = page.results ?? [];
        collected.push(...items);
        nextPageToken = page.nextPage ?? null;
        if (items.length === 0 || !nextPageToken) break;
    }

    const single = collected[neededIndex] ? [collected[neededIndex]] : [];
    return { results: single, nextPage: null };
}

export default { getNews };