const bookId = window.location.pathname.split('/').pop();
let allChapters = []; // Stores all fetched chapters
let filteredChapters = []; // Stores currently displayed chapters (filtered)
let currentPage = 1;
const itemsPerPage = 12;

async function init() {
    try {
        // 1. Load Metadata
        const res = await fetch(`/api/book/${bookId}`);
        const data = await res.json();

        if (data.error) {
            const titleEl = document.getElementById('title');
            if (titleEl) titleEl.innerText = "Book Not Found";
            return;
        }

        // Populate Hero Elements
        const title = data.title.english || data.title.romaji;
        document.title = `${title} | WaifuBoard Books`;
        
        const titleEl = document.getElementById('title');
        if (titleEl) titleEl.innerText = title;

        const descEl = document.getElementById('description');
        if (descEl) descEl.innerHTML = data.description || "No description available.";

        const scoreEl = document.getElementById('score');
        if (scoreEl) scoreEl.innerText = (data.averageScore || '?') + '% Score';

        const pubEl = document.getElementById('published-date');
        if (pubEl) {
            if (data.startDate && data.startDate.year) {
                const y = data.startDate.year;
                const m = data.startDate.month ? `-${data.startDate.month.toString().padStart(2, '0')}` : '';
                const d = data.startDate.day ? `-${data.startDate.day.toString().padStart(2, '0')}` : '';
                pubEl.innerText = `${y}${m}${d}`;
            } else {
                pubEl.innerText = '????';
            }
        }

        const statusEl = document.getElementById('status');
        if (statusEl) statusEl.innerText = data.status || 'Unknown';

        const formatEl = document.getElementById('format');
        if (formatEl) formatEl.innerText = data.format || 'MANGA';

        const chaptersEl = document.getElementById('chapters');
        if (chaptersEl) chaptersEl.innerText = data.chapters || '?';
        
        const genresEl = document.getElementById('genres');
        if(genresEl && data.genres) {
            genresEl.innerText = data.genres.slice(0, 3).join(' • ');
        }

        const img = data.coverImage.extraLarge || data.coverImage.large;
        
        const posterEl = document.getElementById('poster');
        if (posterEl) posterEl.src = img;

        const heroBgEl = document.getElementById('hero-bg');
        if (heroBgEl) heroBgEl.src = data.bannerImage || img;

        // 2. Load Chapters
        loadChapters();

    } catch (err) {
        console.error("Metadata Error:", err);
    }
}

async function loadChapters() {
    const tbody = document.getElementById('chapters-body');
    if (!tbody) return;
    
    tbody.innerHTML = '<tr><td colspan="4" style="text-align:center; padding: 2rem;">Searching extensions for chapters...</td></tr>';

    try {
        const res = await fetch(`/api/book/${bookId}/chapters`);
        const data = await res.json();
        
        allChapters = data.chapters || [];
        filteredChapters = [...allChapters]; // Initially, show all
        
        const totalEl = document.getElementById('total-chapters');
        
        if (allChapters.length === 0) {
            tbody.innerHTML = '<tr><td colspan="4" style="text-align:center; padding: 2rem;">No chapters found on loaded extensions.</td></tr>';
            if (totalEl) totalEl.innerText = "0 Found";
            return;
        }

        if (totalEl) totalEl.innerText = `${allChapters.length} Found`;
        
        // Populate Provider Filter
        populateProviderFilter();

        // Read Button Action (Start at filtered Ch 1)
        const readBtn = document.getElementById('read-start-btn');
        if (readBtn && filteredChapters.length > 0) {
            readBtn.onclick = () => openReader(filteredChapters[0].id);
        }

        renderTable();

    } catch (err) {
        tbody.innerHTML = '<tr><td colspan="4" style="text-align:center; color: #ef4444;">Error loading chapters.</td></tr>';
        console.error(err);
    }
}

function populateProviderFilter() {
    const select = document.getElementById('provider-filter');
    if (!select) return;

    // Extract unique providers
    const providers = [...new Set(allChapters.map(ch => ch.provider))];
    
    // Only show filter if there are actual providers found
    if (providers.length > 0) {
        select.style.display = 'inline-block';
        
        // Clear existing options except "All"
        select.innerHTML = '<option value="all">All Providers</option>';
        
        providers.forEach(prov => {
            const opt = document.createElement('option');
            opt.value = prov;
            opt.innerText = prov;
            select.appendChild(opt);
        });

        // Attach Event Listener
        select.onchange = (e) => {
            const selected = e.target.value;
            if (selected === 'all') {
                filteredChapters = [...allChapters];
            } else {
                filteredChapters = allChapters.filter(ch => ch.provider === selected);
            }
            currentPage = 1; // Reset to page 1 on filter change
            renderTable();
        };
    }
}

function renderTable() {
    const tbody = document.getElementById('chapters-body');
    if (!tbody) return;

    tbody.innerHTML = '';

    if (filteredChapters.length === 0) {
        tbody.innerHTML = '<tr><td colspan="4" style="text-align:center; padding: 2rem;">No chapters match this filter.</td></tr>';
        updatePagination();
        return;
    }

    const start = (currentPage - 1) * itemsPerPage;
    const end = start + itemsPerPage;
    const pageItems = filteredChapters.slice(start, end);

    pageItems.forEach((ch, idx) => {
        const realIndex = start + idx;

        const row = document.createElement('tr');

        row.innerHTML = `
            <td>${ch.number}</td>
            <td>${ch.title || 'Chapter ' + ch.number}</td>
            <td><span class="pill" style="font-size:0.75rem;">${ch.provider}</span></td>
            <td>
                <button class="read-btn-small" onclick="openReader('${bookId}', '${realIndex}', '${ch.provider}')">
                    Read
                </button>
            </td>
        `;
        tbody.appendChild(row);
    });

    updatePagination();
}

function updatePagination() {
    const totalPages = Math.ceil(filteredChapters.length / itemsPerPage);
    const pagination = document.getElementById('pagination');
    
    if (!pagination) return;

    if (totalPages <= 1) {
        pagination.style.display = 'none';
        return;
    }
    
    pagination.style.display = 'flex';
    document.getElementById('page-info').innerText = `Page ${currentPage} of ${totalPages}`;
    
    const prevBtn = document.getElementById('prev-page');
    const nextBtn = document.getElementById('next-page');
    
    prevBtn.disabled = currentPage === 1;
    nextBtn.disabled = currentPage >= totalPages;

    prevBtn.onclick = () => { currentPage--; renderTable(); };
    nextBtn.onclick = () => { currentPage++; renderTable(); };
}

function openReader(bookId, chapterId, provider) {
    localStorage.setItem('reader_prev_url', window.location.href);
    const c = encodeURIComponent(chapterId);
    const p = encodeURIComponent(provider);
    window.location.href = `/read/${bookId}/${c}/${p}`;
}

init();