/**
 * Übernimmt Filterung (Kategorie), Sortierung und Pagination der
 * Suchergebnisse vollständig clientseitig, ohne Neuladen der Seite.
 *
 * Voraussetzung: Im HTML liegt ein <script type="application/json" id="s-res-data">
 * mit allen Treffern der aktuellen Suche (siehe content/search-results.php).
 *
 * Ist kein JavaScript aktiv, bleibt die serverseitig gerenderte Ausgabe
 * (inkl. echter Pagination-Links und Formular-Submit) unverändert nutzbar.
 */
(function () {
    const DEFAULT_PER_PAGE = 10;

    const state = {
        all: [],
        filtered: [],
        category: 'all',
        sort: 'alphabet',
        perPage: DEFAULT_PER_PAGE,
        page: 1,
    };

    const els = {};

    function init() {
        const dataScript = document.getElementById('s-res-data');
        const listContainer = document.querySelector('.s-res-list');
        if (!dataScript || !listContainer) {
            return; // keine Ergebnisliste auf dieser Seite vorhanden
        }

        try {
            state.all = JSON.parse(dataScript.textContent);
        } catch (e) {
            console.error('Suchergebnis-Daten konnten nicht gelesen werden.', e);
            return;
        }

        els.list = listContainer;
        els.categorySelect = document.getElementById('category-filter');
        els.perPageSelect = document.getElementById('s-res-per-page');
        els.sortRadios = document.querySelectorAll('.sort-radio');
        els.pagerContainer = document.querySelector('.s-res-page-navigation');
        els.metaCount = document.querySelector('.s-res-meta');

        // Ausgangszustand aus dem serverseitig gerenderten Markup übernehmen,
        // damit Browser-zurück / geteilte Links konsistent bleiben.
        if (els.categorySelect) state.category = els.categorySelect.value || 'all';
        if (els.perPageSelect) state.perPage = parseInt(els.perPageSelect.value, 10) || DEFAULT_PER_PAGE;
        const checkedSort = document.querySelector('.sort-radio:checked');
        if (checkedSort) state.sort = checkedSort.value;

        // Ab hier übernimmt JS: Formular-Steuerelemente lösen keinen
        // Seiten-Reload mehr aus, sondern rendern direkt neu.
        if (els.categorySelect) {
            els.categorySelect.addEventListener('change', function () {
                state.category = this.value;
                state.page = 1;
                render();
            });
        }
        if (els.perPageSelect) {
            els.perPageSelect.addEventListener('change', function () {
                state.perPage = parseInt(this.value, 10) || DEFAULT_PER_PAGE;
                state.page = 1;
                render();
            });
        }
        els.sortRadios.forEach(function (radio) {
            radio.addEventListener('change', function () {
                state.sort = this.value;
                state.page = 1;
                render();
            });
        });

        render();
    }

    function sortItems(items, sortValue) {
        const copy = items.slice();
        switch (sortValue) {
            case 'likes':
                copy.sort(function (a, b) { return (b.likes || 0) - (a.likes || 0); });
                break;
            case 'newest':
                copy.sort(function (a, b) { return (b.creationDate || '').localeCompare(a.creationDate || ''); });
                break;
            case 'oldest':
                copy.sort(function (a, b) { return (a.creationDate || '').localeCompare(b.creationDate || ''); });
                break;
            case 'alphabet':
            default:
                copy.sort(function (a, b) { return a.title.localeCompare(b.title, 'de', { sensitivity: 'base' }); });
                break;
        }
        return copy;
    }

    function render() {
        let items = state.all;
        if (state.category && state.category !== 'all') {
            items = items.filter(function (it) {
                return (it.category || '').toLowerCase() === state.category.toLowerCase();
            });
        }
        state.filtered = sortItems(items, state.sort);

        const totalResults = state.filtered.length;
        const totalPages = Math.max(1, Math.ceil(totalResults / state.perPage));
        if (state.page > totalPages) state.page = totalPages;
        if (state.page < 1) state.page = 1;

        const start = (state.page - 1) * state.perPage;
        const pageItems = state.filtered.slice(start, start + state.perPage);

        renderList(pageItems);
        renderPager(totalPages);
        renderMeta(totalResults);
    }

    function renderList(items) {
        els.list.innerHTML = '';

        if (items.length === 0) {
            const p = document.createElement('p');
            p.textContent = 'Keine Beiträge zu diesem Suchbegriff gefunden.';
            els.list.appendChild(p);
            return;
        }

        items.forEach(function (item) {
            const div = document.createElement('div');
            div.className = 's-res-item';
            div.setAttribute('data-likes', item.likes || 0);
            div.setAttribute('data-category', (item.category || '').toLowerCase());

            div.innerHTML =
                '<div class="s-res-content">' +
                '<h2 class="s-res-item-title">' +
                '<a class="s-res-link"></a>' +
                '</h2>' +
                '<div class="s-res-meta-row">' +
                '<p class="s-res-author">Von: <span class="s-res-author-name"></span></p>' +
                '<span class="s-res-likes"></span>' +
                '</div>' +
                '</div>' +
                '<div class="s-res-arrow">&rarr;</div>';

            const link = div.querySelector('.s-res-link');
            link.href = 'index.php?pfad=showArticle&id=' + encodeURIComponent(item.id);
            link.textContent = item.title;
            div.querySelector('.s-res-author-name').textContent = item.author;
            div.querySelector('.s-res-likes').textContent = item.likes || 0;

            els.list.appendChild(div);
        });
    }

    function renderPager(totalPages) {
        if (!els.pagerContainer) return;
        els.pagerContainer.innerHTML = '';

        const prevBtn = document.createElement('button');
        prevBtn.type = 'button';
        prevBtn.className = 's-res-page-btn';
        prevBtn.textContent = '\u00AB';
        prevBtn.disabled = state.page <= 1;
        prevBtn.addEventListener('click', function () { goToPage(state.page - 1); });
        els.pagerContainer.appendChild(prevBtn);

        const span = document.createElement('span');
        span.id = 'dynamic-page-numbers';
        span.textContent = 'Seite ' + state.page + ' von ' + totalPages;
        els.pagerContainer.appendChild(span);

        const nextBtn = document.createElement('button');
        nextBtn.type = 'button';
        nextBtn.className = 's-res-page-btn';
        nextBtn.textContent = '\u00BB';
        nextBtn.disabled = state.page >= totalPages;
        nextBtn.addEventListener('click', function () { goToPage(state.page + 1); });
        els.pagerContainer.appendChild(nextBtn);
    }

    function renderMeta(totalResults) {
        if (!els.metaCount) return;
        const query = els.metaCount.getAttribute('data-query') || '';
        els.metaCount.textContent = totalResults + ' Treffer für Ihre Suchanfrage "' + query + '"';
    }

    function goToPage(page) {
        state.page = page;
        render();
        els.list.scrollIntoView({ behavior: 'smooth', block: 'start' });
    }

    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', init);
    } else {
        init();
    }
})();