// Global variables
let albumsData = [];
let filteredData = [];
let currentPage = 1;
const itemsPerPage = 50;
let isReversed = false;

// DOM elements
const albumsGrid = document.getElementById('albumsGrid');
const searchInput = document.getElementById('searchInput');
const statusFilter = document.getElementById('statusFilter');
const sortBy = document.getElementById('sortBy');
const reverseButton = document.getElementById('reverseButton');
const jumpToRank = document.getElementById('jumpToRank');
const jumpButton = document.getElementById('jumpButton');
const loading = document.getElementById('loading');
const error = document.getElementById('error');
const stats = document.getElementById('stats');

// Initialize the application
document.addEventListener('DOMContentLoaded', function() {
    loadAlbumsData();
    setupEventListeners();
    handleUrlParams();
});

// Setup event listeners
function setupEventListeners() {
    searchInput.addEventListener('input', debounce(handleSearch, 300));
    statusFilter.addEventListener('change', handleFilter);
    sortBy.addEventListener('change', handleSort);
    reverseButton.addEventListener('click', handleReverse);
    jumpButton.addEventListener('click', handleJumpToRank);
    jumpToRank.addEventListener('keypress', handleRankKeypress);
    
    // Add scroll listener for infinite scroll
    window.addEventListener('scroll', handleScroll);
}

// Load albums data from CSV
async function loadAlbumsData() {
    try {
        const response = await fetch('top_500_albums_2023.csv');
        if (!response.ok) {
            throw new Error('Failed to load data');
        }
        
        const csvText = await response.text();
        albumsData = parseCSV(csvText);
        filteredData = [...albumsData];
        
        hideLoading();
        renderAlbums();
        updateStats();
        
    } catch (err) {
        console.error('Error loading data:', err);
        showError();
    }
}

// Parse CSV data
function parseCSV(csvText) {
    const lines = csvText.split('\n');
    const headers = lines[0].split(',').map(h => h.trim().replace(/"/g, ''));
    const albums = [];
    
    for (let i = 1; i < lines.length; i++) {
        const line = lines[i].trim();
        if (!line) continue;
        
        // Handle CSV parsing with proper quote handling
        const values = parseCSVLine(line);
        if (values.length < headers.length) continue;
        
        const album = {};
        headers.forEach((header, index) => {
            album[header] = values[index] ? values[index].replace(/"/g, '').trim() : '';
        });
        
        // Convert rank to number
        album.Rank = parseInt(album.Rank) || 0;
        
        // Extract year from Info field
        const yearMatch = album.Info ? album.Info.match(/\b(19|20)\d{2}\b/) : null;
        album.Year = yearMatch ? parseInt(yearMatch[0]) : null;
        
        albums.push(album);
    }
    
    return albums;
}

// Parse a single CSV line handling quotes and commas
function parseCSVLine(line) {
    const values = [];
    let current = '';
    let inQuotes = false;
    
    for (let i = 0; i < line.length; i++) {
        const char = line[i];
        
        if (char === '"') {
            inQuotes = !inQuotes;
        } else if (char === ',' && !inQuotes) {
            values.push(current);
            current = '';
        } else {
            current += char;
        }
    }
    
    values.push(current);
    return values;
}

// Render albums
function renderAlbums() {
    const startIndex = (currentPage - 1) * itemsPerPage;
    const endIndex = startIndex + itemsPerPage;
    const albumsToShow = filteredData.slice(0, endIndex);
    
    if (currentPage === 1) {
        albumsGrid.innerHTML = '';
    }
    
    albumsToShow.slice(startIndex).forEach(album => {
        const albumCard = createAlbumCard(album);
        albumsGrid.appendChild(albumCard);
    });
}

// Create album card element
function createAlbumCard(album) {
    const card = document.createElement('div');
    card.className = 'album-card';
    card.setAttribute('data-rank', album.Rank);
    
    const statusClass = getStatusClass(album.Status);
    const statusText = formatStatus(album.Status);
    
    card.innerHTML = `
        <div class="album-rank">#${album.Rank}</div>
        <div class="album-content">
            <div class="album-title">${escapeHtml(album.Album)}</div>
            <div class="album-artist">${escapeHtml(album.Artist)}</div>
            ${album.Info ? `<div class="album-info">${escapeHtml(album.Info)}</div>` : ''}
            <div class="album-status ${statusClass}">${statusText}</div>
            ${album.Description ? `<div class="album-description">${escapeHtml(album.Description)}</div>` : ''}
        </div>
        <div class="album-cover">
            <div class="album-cover-icon">🎵</div>
        </div>
        <button class="album-share" title="Share this album" data-rank="${album.Rank}">🔗</button>
    `;
    
    // Add click handler to expand description
    const description = card.querySelector('.album-description');
    if (description) {
        description.addEventListener('click', function() {
            this.classList.toggle('expanded');
        });
    }
    
    // Add click handler for share button
    const shareBtn = card.querySelector('.album-share');
    shareBtn.addEventListener('click', function(e) {
        e.stopPropagation(); // Prevent card click
        const rank = this.getAttribute('data-rank');
        handleAlbumShare(rank, this);
    });
    
    return card;
}

// Get CSS class for status
function getStatusClass(status) {
    if (status === 'New in 2023') return 'status-new';
    if (status === 'No change') return 'status-no-change';
    if (status.startsWith('+')) return 'status-improved';
    if (status.startsWith('-')) return 'status-dropped';
    return 'status-no-change';
}

// Format status text
function formatStatus(status) {
    if (status === 'New in 2023') return 'New in 2023';
    if (status === 'No change') return 'No Change';
    if (status.startsWith('+')) return `↗ ${status}`;
    if (status.startsWith('-')) return `↘ ${status}`;
    return status;
}

// Handle search
function handleSearch(event) {
    const query = event.target.value.toLowerCase().trim();
    
    if (!query) {
        filteredData = [...albumsData];
    } else {
        filteredData = albumsData.filter(album => 
            album.Artist.toLowerCase().includes(query) ||
            album.Album.toLowerCase().includes(query) ||
            (album.Description && album.Description.toLowerCase().includes(query))
        );
    }
    
    // Reset reverse state when searching
    resetReverse();
    
    currentPage = 1;
    renderAlbums();
    updateStats();
}

// Handle filter
function handleFilter(event) {
    const filterValue = event.target.value;
    
    if (!filterValue) {
        filteredData = [...albumsData];
    } else if (filterValue === 'improved') {
        filteredData = albumsData.filter(album => album.Status.startsWith('+'));
    } else if (filterValue === 'dropped') {
        filteredData = albumsData.filter(album => album.Status.startsWith('-'));
    } else {
        filteredData = albumsData.filter(album => album.Status === filterValue);
    }
    
    // Reset reverse state when filtering
    resetReverse();
    
    currentPage = 1;
    renderAlbums();
    updateStats();
}

// Handle sort
function handleSort(event) {
    const sortValue = event.target.value;
    
    filteredData.sort((a, b) => {
        let result;
        switch (sortValue) {
            case 'rank':
                result = a.Rank - b.Rank;
                break;
            case 'artist':
                result = a.Artist.localeCompare(b.Artist);
                break;
            case 'album':
                result = a.Album.localeCompare(b.Album);
                break;
            case 'year':
                const yearA = a.Year || 0;
                const yearB = b.Year || 0;
                result = yearB - yearA; // Most recent first
                break;
            default:
                result = 0;
        }
        
        // Apply reverse if needed
        return isReversed ? -result : result;
    });
    
    currentPage = 1;
    renderAlbums();
}

// Handle reverse
function handleReverse() {
    isReversed = !isReversed;
    
    // Update button appearance
    reverseButton.classList.toggle('reversed', isReversed);
    
    // Reverse the current filtered data
    filteredData.reverse();
    
    currentPage = 1;
    renderAlbums();
}

// Reset reverse state
function resetReverse() {
    if (isReversed) {
        isReversed = false;
        reverseButton.classList.remove('reversed');
    }
}

// Handle infinite scroll
function handleScroll() {
    if (window.innerHeight + window.scrollY >= document.body.offsetHeight - 1000) {
        if (currentPage * itemsPerPage < filteredData.length) {
            currentPage++;
            renderAlbums();
        }
    }
}

// Update statistics
function updateStats() {
    const total = filteredData.length;
    const newAlbums = filteredData.filter(album => album.Status === 'New in 2023').length;
    const improved = filteredData.filter(album => album.Status.startsWith('+')).length;
    const dropped = filteredData.filter(album => album.Status.startsWith('-')).length;
    
    document.getElementById('totalAlbums').textContent = total;
    document.getElementById('newAlbums').textContent = newAlbums;
    document.getElementById('improvedAlbums').textContent = improved;
    document.getElementById('droppedAlbums').textContent = dropped;
}

// Utility functions
function debounce(func, wait) {
    let timeout;
    return function executedFunction(...args) {
        const later = () => {
            clearTimeout(timeout);
            func(...args);
        };
        clearTimeout(timeout);
        timeout = setTimeout(later, wait);
    };
}

function escapeHtml(text) {
    if (!text) return '';
    const div = document.createElement('div');
    div.textContent = text;
    return div.innerHTML;
}

function hideLoading() {
    loading.style.display = 'none';
    albumsGrid.style.display = 'grid';
}

function showError() {
    loading.style.display = 'none';
    error.style.display = 'block';
}

// Bookmark and navigation functions
function handleUrlParams() {
    const urlParams = new URLSearchParams(window.location.search);
    const hash = window.location.hash.slice(1);
    
    // Handle rank from hash (#rank123) or query parameter (?rank=123)
    const rankFromHash = hash.match(/^rank(\d+)$/);
    const rankFromQuery = urlParams.get('rank');
    const targetRank = rankFromHash ? parseInt(rankFromHash[1]) : 
                      rankFromQuery ? parseInt(rankFromQuery) : null;
    
    // Handle other URL parameters for filters/search first
    const search = urlParams.get('search');
    const status = urlParams.get('status');
    const sort = urlParams.get('sort');
    const reversed = urlParams.get('reversed') === 'true';
    
    // Set up the state based on URL parameters
    let delay = 1000;
    
    if (search) {
        searchInput.value = search;
        setTimeout(() => handleSearch({target: searchInput}), delay);
        delay += 100;
    }
    
    if (status) {
        statusFilter.value = status;
        setTimeout(() => handleFilter({target: statusFilter}), delay);
        delay += 100;
    }
    
    if (sort) {
        sortBy.value = sort;
        setTimeout(() => handleSort({target: sortBy}), delay);
        delay += 100;
    }
    
    if (reversed) {
        setTimeout(() => handleReverse(), delay);
        delay += 100;
    }
    
    // Finally, jump to the rank if specified
    if (targetRank) {
        setTimeout(() => jumpToRankWithCurrentState(targetRank), delay);
    }
}

function handleJumpToRank() {
    const inputValue = jumpToRank.value.trim();
    let rank;
    
    if (inputValue === '') {
        // Default to rank 1 if no input
        rank = 1;
        jumpToRank.value = '1';
    } else {
        rank = parseInt(inputValue);
        if (isNaN(rank) || rank < 1 || rank > 500) {
            alert('Please enter a valid rank between 1 and 500');
            return;
        }
    }
    
    jumpToRankNumber(rank);
}

function handleRankKeypress(event) {
    if (event.key === 'Enter') {
        handleJumpToRank();
    }
}

function jumpToRankNumber(rank) {
    if (!albumsData.length) return;
    
    // Reset filters to show all albums by rank
    searchInput.value = '';
    statusFilter.value = '';
    sortBy.value = 'rank';
    isReversed = false;
    reverseButton.classList.remove('reversed');
    
    // Reset data and apply rank sorting
    filteredData = [...albumsData];
    filteredData.sort((a, b) => a.Rank - b.Rank);
    
    // Update URL - clear all params if jumping to rank 1, otherwise set rank
    if (rank === 1) {
        clearUrl();
    } else {
        updateUrl({rank});
    }
    
    // Find the album card and scroll to it
    currentPage = Math.ceil(rank / itemsPerPage);
    renderAlbums();
    
    // Wait for render then scroll
    setTimeout(() => scrollToRank(rank), 100);
    
    updateStats();
}

function jumpToRankWithCurrentState(rank) {
    if (!albumsData.length) return;
    
    // Don't reset filters - preserve current state
    // Just ensure the target album is visible in current filtered data
    
    // Find the album card and scroll to it
    // First, make sure enough albums are loaded
    const albumInFiltered = filteredData.find(album => album.Rank === rank);
    if (albumInFiltered) {
        const indexInFiltered = filteredData.indexOf(albumInFiltered);
        currentPage = Math.ceil((indexInFiltered + 1) / itemsPerPage);
        renderAlbums();
    }
    
    // Wait for render then scroll
    setTimeout(() => scrollToRank(rank), 100);
    
    updateStats();
}

function scrollToRank(rank) {
    const albumCard = document.querySelector(`[data-rank="${rank}"]`);
    if (albumCard) {
        albumCard.scrollIntoView({
            behavior: 'smooth',
            block: 'center'
        });
        
        // Highlight the album briefly
        albumCard.style.boxShadow = '0 0 20px rgba(102, 126, 234, 0.5)';
        albumCard.style.transform = 'scale(1.02)';
        
        setTimeout(() => {
            albumCard.style.boxShadow = '';
            albumCard.style.transform = '';
        }, 2000);
    }
}

function handleAlbumShare(rank, buttonElement) {
    const albumUrl = generateAlbumUrl(rank);
    
    // Copy to clipboard
    if (navigator.clipboard) {
        navigator.clipboard.writeText(albumUrl).then(() => {
            showAlbumShareFeedback(buttonElement);
        }).catch(() => {
            fallbackCopyToClipboard(albumUrl, buttonElement);
        });
    } else {
        fallbackCopyToClipboard(albumUrl, buttonElement);
    }
}

function generateAlbumUrl(rank) {
    const baseUrl = window.location.origin + window.location.pathname;
    const params = new URLSearchParams();
    
    // Add current state parameters
    if (statusFilter.value) {
        params.set('status', statusFilter.value);
    }
    
    if (sortBy.value !== 'rank') {
        params.set('sort', sortBy.value);
    }
    
    if (isReversed) {
        params.set('reversed', 'true');
    }
    
    // Add search if present
    if (searchInput.value.trim()) {
        params.set('search', searchInput.value.trim());
    }
    
    // Always add the rank for direct navigation
    params.set('rank', rank);
    
    const queryString = params.toString();
    return queryString ? `${baseUrl}?${queryString}` : `${baseUrl}#rank${rank}`;
}

function generateShareableUrl() {
    const baseUrl = window.location.origin + window.location.pathname;
    const params = new URLSearchParams();
    
    // Add current filters/search
    if (searchInput.value.trim()) {
        params.set('search', searchInput.value.trim());
    }
    
    if (statusFilter.value) {
        params.set('status', statusFilter.value);
    }
    
    if (sortBy.value !== 'rank') {
        params.set('sort', sortBy.value);
    }
    
    if (isReversed) {
        params.set('reversed', 'true');
    }
    
    // If we're viewing a specific rank area, add it
    const visibleCards = document.querySelectorAll('.album-card');
    if (visibleCards.length > 0 && sortBy.value === 'rank' && !isReversed) {
        const firstVisibleRank = visibleCards[0].getAttribute('data-rank');
        if (firstVisibleRank) {
            params.set('rank', firstVisibleRank);
        }
    }
    
    const queryString = params.toString();
    return queryString ? `${baseUrl}?${queryString}` : baseUrl;
}

function updateUrl(options = {}) {
    const params = new URLSearchParams();
    
    if (options.rank) {
        window.location.hash = `rank${options.rank}`;
        return;
    }
    
    // Update query parameters based on current state
    if (searchInput.value.trim()) {
        params.set('search', searchInput.value.trim());
    }
    
    if (statusFilter.value) {
        params.set('status', statusFilter.value);
    }
    
    if (sortBy.value !== 'rank') {
        params.set('sort', sortBy.value);
    }
    
    if (isReversed) {
        params.set('reversed', 'true');
    }
    
    const queryString = params.toString();
    const newUrl = queryString ? 
        `${window.location.pathname}?${queryString}` : 
        window.location.pathname;
    
    window.history.replaceState({}, '', newUrl);
}

function clearUrl() {
    // Clear both query parameters and hash
    window.history.replaceState({}, '', window.location.pathname);
}

function showAlbumShareFeedback(buttonElement) {
    const originalText = buttonElement.innerHTML;
    buttonElement.innerHTML = '✓';
    buttonElement.classList.add('copied');
    
    setTimeout(() => {
        buttonElement.innerHTML = originalText;
        buttonElement.classList.remove('copied');
    }, 2000);
}

function fallbackCopyToClipboard(text, buttonElement) {
    const textArea = document.createElement('textarea');
    textArea.value = text;
    document.body.appendChild(textArea);
    textArea.focus();
    textArea.select();
    
    try {
        document.execCommand('copy');
        if (buttonElement) {
            showAlbumShareFeedback(buttonElement);
        }
    } catch (err) {
        alert('Unable to copy to clipboard. URL: ' + text);
    }
    
    document.body.removeChild(textArea);
}