/**
 * 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 die Seite für das „counter.“-te Widget (0 = erste Seite, 1 = zweite, …).
 * Ruft die API ggf. mehrfach auf (nextPage), damit jede Widget-Instanz andere Artikel bekommt.
 *
 * @param {object} options
 * @param {number} options.counter
 * @param {string} [options.language]
 * @param {string} [options.category]
 * @returns {Promise<{ results: Array, nextPage: string|null }>}
 */
async function getNews({ counter = 0, language = 'de', category = 'top' }) {
    let nextPageToken = null;
    let lastResult = { results: [], nextPage: null };

    for (let i = 0; i <= counter; i++) {
        lastResult = await fetchNewsPage({
            counter: i,
            language,
            category,
            nextPageToken: nextPageToken || undefined
        });
        nextPageToken = lastResult.nextPage;
        if (!nextPageToken && i < counter) {
            break;
        }
    }

    return lastResult;
}

export default { getNews };