/**
 * Debrid Services Comparison - Modern Refactored Version
 * Optimized for performance, maintainability, and modern web standards
 * @version 2.0.0
 */

/* ============================================================================
   CONFIGURATION & CONSTANTS
   ============================================================================ */
const CONFIG = Object.freeze({
  API: {
    FILE_HOSTS: ['./json/file-hosts-optimized.json', './json/file-hosts.json'],
    ADULT_HOSTS: ['./json/adult-hosts-optimized.json', './json/adult-hosts.json'],
    TIMEOUT: 8000,
    RETRY_ATTEMPTS: 2
  },
  PERFORMANCE: {
    DEBOUNCE_DELAY: 250,
    THROTTLE_DELAY: 100,
    RENDER_CHUNK_SIZE: 40,
    RENDER_IDLE_TIMEOUT: 160,
    SCROLL_THRESHOLD: 300
  },
  INTERSECTION: {
    THRESHOLD: 0.1,
    ROOT_MARGIN: '-40% 0px -50% 0px'
  },
  ANIMATION: {
    DURATION: 250,
    EASING: 'cubic-bezier(0.4, 0, 0.2, 1)'
  }
});

/* ============================================================================
   UTILITIES MODULE
   ============================================================================ */
const Utils = (() => {
  // Performance-optimized debounce with WeakMap cache
  const debounceCache = new WeakMap();
  
  const debounce = (func, wait = CONFIG.PERFORMANCE.DEBOUNCE_DELAY) => {
    if (debounceCache.has(func)) return debounceCache.get(func);
    
    let timeoutId;
    const debounced = function executeDebouncedFunction(...args) {
      clearTimeout(timeoutId);
      timeoutId = setTimeout(() => func.apply(this, args), wait);
    };
    
    debounced.cancel = () => clearTimeout(timeoutId);
    debounceCache.set(func, debounced);
    return debounced;
  };

  // RAF-based throttle for smooth animations
  const throttle = (func, limit = CONFIG.PERFORMANCE.THROTTLE_DELAY) => {
    let waiting = false;
    let lastArgs = null;
    
    return function executeThrottledFunction(...args) {
      if (!waiting) {
        func.apply(this, args);
        waiting = true;
        
        requestAnimationFrame(() => {
          setTimeout(() => {
            waiting = false;
            if (lastArgs) {
              func.apply(this, lastArgs);
              lastArgs = null;
            }
          }, limit);
        });
      } else {
        lastArgs = args;
      }
    };
  };

  // Lazy fetch with timeout and abort controller
  const fetchWithTimeout = async (url, options = {}) => {
    const { timeout = CONFIG.API.TIMEOUT, ...fetchOptions } = options;
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), timeout);
    
    try {
      const response = await fetch(url, {
        ...fetchOptions,
        signal: controller.signal
      });
      
      if (!response.ok) {
        throw new Error(`HTTP ${response.status}: ${response.statusText}`);
      }
      
      return response;
    } finally {
      clearTimeout(timeoutId);
    }
  };

  // Cascade fetch with multiple fallback URLs
  const fetchWithFallback = async (urls, options = {}) => {
    const errors = [];
    
    for (const url of urls) {
      try {
        const response = await fetchWithTimeout(url, options);
        return await response.json();
      } catch (error) {
        errors.push({ url, error: error.message });
        continue;
      }
    }
    
    throw new Error(`All fetch attempts failed: ${JSON.stringify(errors)}`);
  };

  // Efficient DOM element creation with attributes
  const createElement = (tag, attributes = {}, children = []) => {
    const element = document.createElement(tag);
    
    Object.entries(attributes).forEach(([key, value]) => {
      if (key === 'className') {
        element.className = value;
      } else if (key === 'dataset') {
        Object.assign(element.dataset, value);
      } else if (key.startsWith('on') && typeof value === 'function') {
        element.addEventListener(key.slice(2).toLowerCase(), value);
      } else {
        element.setAttribute(key, value);
      }
    });
    
    children.forEach(child => {
      if (typeof child === 'string') {
        element.appendChild(document.createTextNode(child));
      } else if (child instanceof Node) {
        element.appendChild(child);
      }
    });
    
    return element;
  };

  // Schedule work during idle time
  const scheduleIdleWork = (callback, options = {}) => {
    if ('requestIdleCallback' in window) {
      return requestIdleCallback(callback, {
        timeout: CONFIG.PERFORMANCE.RENDER_IDLE_TIMEOUT,
        ...options
      });
    }
    return requestAnimationFrame(callback);
  };

  // Cancel scheduled idle work
  const cancelIdleWork = (id) => {
    if ('cancelIdleCallback' in window) {
      cancelIdleCallback(id);
    } else {
      cancelAnimationFrame(id);
    }
  };

  return Object.freeze({
    debounce,
    throttle,
    fetchWithTimeout,
    fetchWithFallback,
    createElement,
    scheduleIdleWork,
    cancelIdleWork
  });
})();

/* ============================================================================
   STATE MANAGEMENT
   ============================================================================ */
class StateManager {
  #state = {};
  #listeners = new Map();
  
  constructor(initialState = {}) {
    this.#state = { ...initialState };
  }
  
  get(key) {
    return key ? this.#state[key] : { ...this.#state };
  }
  
  set(key, value) {
    const oldValue = this.#state[key];
    this.#state[key] = value;
    
    if (this.#listeners.has(key)) {
      this.#listeners.get(key).forEach(callback => {
        callback(value, oldValue);
      });
    }
    
    return this;
  }
  
  update(updates) {
    Object.entries(updates).forEach(([key, value]) => {
      this.set(key, value);
    });
    return this;
  }
  
  subscribe(key, callback) {
    if (!this.#listeners.has(key)) {
      this.#listeners.set(key, new Set());
    }
    this.#listeners.get(key).add(callback);
    
    return () => this.#listeners.get(key)?.delete(callback);
  }
  
  reset() {
    this.#state = {};
    this.#listeners.clear();
  }
}

/* ============================================================================
   LOADING MANAGER
   ============================================================================ */
class LoadingManager {
  #loaders = new Map();
  #template = null;
  
  constructor() {
    this.#template = this.#createTemplate();
  }
  
  #createTemplate() {
    const template = document.createElement('template');
    template.innerHTML = `
      <div class="loading-overlay" role="status" aria-live="polite">
        <div class="loading-content">
          <div class="loading-spinner" aria-hidden="true">
            <div class="spinner-ring"></div>
            <div class="spinner-ring"></div>
            <div class="spinner-ring"></div>
          </div>
          <p class="loading-text"></p>
        </div>
      </div>
    `;
    return template;
  }
  
  show(target, text = 'Loading...') {
    const element = typeof target === 'string' 
      ? document.querySelector(target) 
      : target;
    
    if (!element) return null;
    
    const loaderId = `loader-${Date.now()}-${Math.random().toString(36).slice(2, 11)}`;
    const loader = this.#template.content.cloneNode(true).firstElementChild;
    
    loader.dataset.loaderId = loaderId;
    loader.querySelector('.loading-text').textContent = text;
    
    // Ensure parent has positioning context
    if (getComputedStyle(element).position === 'static') {
      element.style.position = 'relative';
    }
    
    element.appendChild(loader);
    this.#loaders.set(loaderId, { element: loader, parent: element });
    
    // Trigger animation
    requestAnimationFrame(() => {
      loader.classList.add('loading-overlay--visible');
    });
    
    return loaderId;
  }
  
  hide(loaderId) {
    const loaderData = this.#loaders.get(loaderId);
    if (!loaderData) return;
    
    const { element } = loaderData;
    element.classList.remove('loading-overlay--visible');
    element.classList.add('loading-overlay--hiding');
    
    setTimeout(() => {
      element.remove();
      this.#loaders.delete(loaderId);
    }, CONFIG.ANIMATION.DURATION);
  }
  
  hideAll() {
    this.#loaders.forEach((_, loaderId) => this.hide(loaderId));
  }
}

/* ============================================================================
   DATA TRANSFORMER
   ============================================================================ */
class DataTransformer {
  static transformIndexedData(data) {
    if (!data?.services || !data?.supported) {
      return { isIndexed: false, data };
    }
    
    const { services, supported } = data;
    const transformed = {};
    
    Object.entries(supported).forEach(([host, indices]) => {
      transformed[host] = Object.fromEntries(
        services.map((service, idx) => [
          service,
          indices.includes(idx) ? '✅' : '❌'
        ])
      );
    });
    
    return {
      isIndexed: true,
      data: transformed,
      services
    };
  }
  
  static extractServices(data) {
    const firstHost = Object.values(data)[0];
    return firstHost ? Object.keys(firstHost) : [];
  }
}

/* ============================================================================
   TABLE MANAGER
   ============================================================================ */
class TableManager {
  #elements = {};
  #state = null;
  #renderToken = null;
  #idleCallbackId = null;
  
  constructor(containerId, searchInputId, clearIconId, options = {}) {
    this.#elements = {
      container: document.getElementById(containerId),
      searchInput: document.getElementById(searchInputId),
      clearIcon: document.getElementById(clearIconId)
    };
    
    this.options = {
      sortable: true,
      chunkSize: CONFIG.PERFORMANCE.RENDER_CHUNK_SIZE,
      ...options
    };
    
    this.#state = new StateManager({
      currentData: {},
      filteredData: {},
      sort: { column: null, direction: 'asc' },
      services: [],
      columns: []
    });
    
    this.#init();
  }
  
  #init() {
    if (!this.#elements.container) return;
    
    // Bind event handlers
    if (this.#elements.searchInput) {
      const debouncedSearch = Utils.debounce(() => this.#performSearch());
      this.#elements.searchInput.addEventListener('input', debouncedSearch);
      this.#elements.searchInput.addEventListener('keydown', (e) => {
        if (e.key === 'Escape') this.#clearSearch();
      });
    }
    
    if (this.#elements.clearIcon) {
      this.#elements.clearIcon.addEventListener('click', () => this.#clearSearch());
    }
  }
  
  generateTable(rawData) {
    if (!this.#elements.container || !rawData) {
      this.#showEmptyState('No data available');
      return;
    }
    
    // Transform data if needed
    const { data, services } = DataTransformer.transformIndexedData(rawData);
    
    if (!Object.keys(data).length) {
      this.#showEmptyState('No data available');
      return;
    }
    
    // Update state
    this.#state.update({
      currentData: data,
      filteredData: { ...data },
      services: services || DataTransformer.extractServices(data),
      columns: DataTransformer.extractServices(data)
    });
    
    this.#renderTable();
  }
  
  #renderTable() {
    const { columns } = this.#state.get();
    const tableId = this.#elements.container.id.replace('-container', '');
    
    // Create table structure
    const table = Utils.createElement('table', {
      id: tableId,
      className: 'enhanced-table',
      role: 'table',
      'aria-label': 'Service Comparison Table'
    });
    
    // Create header
    const thead = Utils.createElement('thead');
    thead.innerHTML = this.#generateHeaderHTML(columns);
    table.appendChild(thead);
    
    // Create body
    const tbody = Utils.createElement('tbody');
    table.appendChild(tbody);
    
    // Create wrapper
    const wrapper = Utils.createElement('div', { className: 'table-wrapper' }, [table]);
    
    // Replace container content
    this.#elements.container.innerHTML = '';
    this.#elements.container.appendChild(wrapper);
    
    // Attach event handlers
    this.#attachTableEvents();
    
    // Render rows
    this.#renderTableBody();
  }
  
  #generateHeaderHTML(columns) {
    const generateHeaderCell = (label, dataColumn) => `
      <th class="sortable" 
          data-column="${dataColumn}" 
          tabindex="0" 
          role="columnheader" 
          aria-sort="none">
        <span>${label}</span>
        <svg class="sort-icon" width="12" height="12" viewBox="0 0 24 24" 
             fill="none" stroke="currentColor" stroke-width="2" aria-hidden="true">
          <path d="M12 5v14M5 12l7-7 7 7"/>
        </svg>
      </th>
    `;
    
    const columnHeaders = columns
      .map(col => generateHeaderCell(col, col))
      .join('');
    
    return `
      <tr>
        ${generateHeaderCell('Service Name', 'service')}
        ${columnHeaders}
      </tr>
    `;
  }
  
  #renderTableBody() {
    const table = this.#elements.container?.querySelector('table');
    const tbody = table?.querySelector('tbody');
    if (!tbody) return;
    
    const { filteredData, columns } = this.#state.get();
    const entries = Object.entries(filteredData);
    
    // Cancel any pending render
    if (this.#idleCallbackId) {
      Utils.cancelIdleWork(this.#idleCallbackId);
    }
    
    // Generate unique render token
    const token = Symbol('render');
    this.#renderToken = token;
    
    // Clear tbody
    tbody.textContent = '';
    
    if (!entries.length) {
      this.#renderEmptyRow(tbody, columns.length + 1);
      return;
    }
    
    // Render in chunks
    this.#renderChunked(tbody, entries, columns, token);
  }
  
  #renderChunked(tbody, entries, columns, token) {
    let index = 0;
    const chunkSize = this.options.chunkSize;
    
    const renderNextChunk = () => {
      // Check if render was cancelled
      if (this.#renderToken !== token) return;
      
      const fragment = document.createDocumentFragment();
      const limit = Math.min(entries.length, index + chunkSize);
      
      for (; index < limit; index++) {
        const [host, hostData] = entries[index];
        const row = this.#createTableRow(host, hostData, columns);
        fragment.appendChild(row);
      }
      
      tbody.appendChild(fragment);
      
      // Continue rendering if more entries exist
      if (index < entries.length) {
        this.#idleCallbackId = Utils.scheduleIdleWork(renderNextChunk);
      }
    };
    
    this.#idleCallbackId = Utils.scheduleIdleWork(renderNextChunk);
  }
  
  #createTableRow(host, hostData, columns) {
    const row = Utils.createElement('tr', {
      role: 'row',
      dataset: { host: host.toLowerCase() }
    });
    
    // Service name cell
    const serviceCell = this.#createServiceCell(host);
    row.appendChild(serviceCell);
    
    // Status cells
    columns.forEach(column => {
      const statusCell = this.#createStatusCell(hostData[column]);
      row.appendChild(statusCell);
    });
    
    return row;
  }
  
  #createServiceCell(serviceName) {
    const cell = Utils.createElement('td', {
      className: 'service-cell',
      role: 'gridcell'
    });
    
    const serviceInfo = Utils.createElement('div', { className: 'service-info' });
    const nameSpan = Utils.createElement('span', { className: 'service-name' }, [serviceName]);
    
    serviceInfo.appendChild(nameSpan);
    cell.appendChild(serviceInfo);
    
    return cell;
  }
  
  #createStatusCell(status) {
    const isSupported = status === '✅';
    const cell = Utils.createElement('td', {
      className: 'status-cell',
      role: 'gridcell',
      dataset: {
        status: status || '',
        supported: isSupported ? 'true' : 'false'
      }
    });
    
    const indicator = Utils.createElement('span', {
      className: 'status-indicator',
      'aria-hidden': 'true',
      dataset: { supported: isSupported ? 'true' : 'false' }
    }, [isSupported ? '✅' : '❌']);
    
    const srText = Utils.createElement('span', {
      className: 'visually-hidden'
    }, [isSupported ? 'Supported' : 'Not supported']);
    
    cell.appendChild(indicator);
    cell.appendChild(srText);
    
    return cell;
  }
  
  #renderEmptyRow(tbody, colSpan) {
    const row = Utils.createElement('tr');
    const cell = Utils.createElement('td', {
      className: 'empty-state-row',
      colSpan
    }, ['No services match your current filters.']);
    
    row.appendChild(cell);
    tbody.appendChild(row);
  }
  
  #attachTableEvents() {
    if (!this.options.sortable) return;
    
    const thead = this.#elements.container.querySelector('thead');
    if (!thead) return;
    
    thead.addEventListener('click', (e) => this.#handleSort(e));
    thead.addEventListener('keydown', (e) => {
      const sortableHeader = e.target.closest('.sortable');
      if (sortableHeader && (e.key === 'Enter' || e.key === ' ')) {
        e.preventDefault();
        this.#handleSort({ target: sortableHeader });
      }
    });
  }
  
  #handleSort(event) {
    const header = event.target.closest('.sortable');
    if (!header) return;
    
    const column = header.dataset.column;
    const { sort, currentData } = this.#state.get();
    
    // Determine sort direction
    const direction = sort.column === column && sort.direction === 'asc' 
      ? 'desc' 
      : 'asc';
    
    // Update state
    this.#state.set('sort', { column, direction });
    
    // Update ARIA attributes
    const allHeaders = this.#elements.container.querySelectorAll('[role="columnheader"]');
    allHeaders.forEach(h => h.setAttribute('aria-sort', 'none'));
    header.setAttribute('aria-sort', direction === 'asc' ? 'ascending' : 'descending');
    
    // Sort data
    const sortedData = this.#sortData(currentData, column, direction);
    this.#state.set('filteredData', sortedData);
    
    // Re-render
    this.#renderTableBody();
  }
  
  #sortData(data, column, direction) {
    const entries = Object.entries(data);
    
    entries.sort(([hostA, dataA], [hostB, dataB]) => {
      let valueA, valueB;
      
      if (column === 'service') {
        valueA = hostA.toLowerCase();
        valueB = hostB.toLowerCase();
      } else {
        valueA = dataA[column] === '✅' ? 1 : 0;
        valueB = dataB[column] === '✅' ? 1 : 0;
      }
      
      if (valueA < valueB) return direction === 'asc' ? -1 : 1;
      if (valueA > valueB) return direction === 'asc' ? 1 : -1;
      return 0;
    });
    
    return Object.fromEntries(entries);
  }
  
  #performSearch() {
    const searchTerm = (this.#elements.searchInput?.value || '').toLowerCase().trim();
    const { currentData } = this.#state.get();
    
    if (searchTerm) {
      const filtered = Object.fromEntries(
        Object.entries(currentData).filter(([host]) =>
          host.toLowerCase().includes(searchTerm)
        )
      );
      
      this.#state.set('filteredData', filtered);
      
      if (this.#elements.clearIcon) {
        this.#elements.clearIcon.style.display = 'block';
      }
      
      this.#updateSearchResults(searchTerm, Object.keys(filtered).length, Object.keys(currentData).length);
    } else {
      this.#clearSearch();
    }
    
    this.#renderTableBody();
  }
  
  #clearSearch() {
    if (this.#elements.searchInput) {
      this.#elements.searchInput.value = '';
    }
    
    const { currentData } = this.#state.get();
    this.#state.set('filteredData', { ...currentData });
    
    if (this.#elements.clearIcon) {
      this.#elements.clearIcon.style.display = 'none';
    }
    
    this.#updateSearchResults('', 0, 0);
    this.#renderTableBody();
  }
  
  #updateSearchResults(searchTerm, filteredCount, totalCount) {
    if (!this.#elements.container) return;
    
    let resultsElement = this.#elements.container.querySelector('.search-results');
    
    if (searchTerm) {
      if (!resultsElement) {
        resultsElement = Utils.createElement('div', {
          className: 'search-results',
          role: 'status',
          'aria-live': 'polite'
        });
        this.#elements.container.insertBefore(resultsElement, this.#elements.container.firstChild);
      }
      
      resultsElement.textContent = `Showing ${filteredCount} of ${totalCount} services`;
      resultsElement.style.display = 'block';
    } else if (resultsElement) {
      resultsElement.style.display = 'none';
    }
  }
  
  #showEmptyState(message) {
    if (!this.#elements.container) return;
    
    const emptyState = Utils.createElement('div', {
      className: 'empty-state'
    });
    
    const emptyMessage = Utils.createElement('p', {}, [message]);
    emptyState.appendChild(emptyMessage);
    
    this.#elements.container.innerHTML = '';
    this.#elements.container.appendChild(emptyState);
  }
}

/* ============================================================================
   COMPARISON MANAGER
   ============================================================================ */
class ComparisonManager {
  #elements = {};
  #data = null;
  #services = [];
  
  constructor(containerId, select1Id, select2Id, data) {
    this.#elements = {
      container: document.getElementById(containerId),
      select1: document.getElementById(select1Id),
      select2: document.getElementById(select2Id)
    };
    
    const transformed = DataTransformer.transformIndexedData(data);
    this.#data = transformed.data;
    this.#services = transformed.services || DataTransformer.extractServices(transformed.data);
    
    this.#init();
  }
  
  #init() {
    if (!this.#elements.select1 || !this.#elements.select2) return;
    
    this.#elements.select1.addEventListener('change', () => this.#handleCompare());
    this.#elements.select2.addEventListener('change', () => this.#handleCompare());
  }
  
  #handleCompare() {
    const service1 = this.#elements.select1.value;
    const service2 = this.#elements.select2.value;
    
    if (!service1 || !service2) {
      this.#showEmptyState();
      return;
    }
    
    if (service1 === service2) {
      this.#showSameProviderWarning();
      return;
    }
    
    this.#renderComparison(service1, service2);
  }
  
  #renderComparison(service1, service2) {
    const hosts = Object.keys(this.#data);
    const stats = this.#calculateStats(service1, service2, hosts);
    
    const table = this.#createComparisonTable(service1, service2, hosts);
    const header = this.#createComparisonHeader(service1, service2, stats);
    
    this.#elements.container.innerHTML = '';
    this.#elements.container.appendChild(header);
    this.#elements.container.appendChild(table);
    this.#elements.container.style.display = 'block';
  }
  
  #createComparisonHeader(service1, service2, stats) {
    const header = Utils.createElement('div', { className: 'comparison-header' });
    
    const title = Utils.createElement('h3', {}, [`Comparing ${service1} vs ${service2}`]);
    header.appendChild(title);
    
    const statsDiv = Utils.createElement('div', { className: 'comparison-stats' });
    
    const createStatItem = (label, value) => {
      const stat = Utils.createElement('div', { className: 'stat' });
      const statLabel = Utils.createElement('span', { className: 'stat-label' }, [label]);
      const statValue = Utils.createElement('span', { className: 'stat-value' }, [String(value)]);
      stat.appendChild(statLabel);
      stat.appendChild(statValue);
      return stat;
    };
    
    statsDiv.appendChild(createStatItem('Shared', stats.shared));
    statsDiv.appendChild(createStatItem(`${service1} Only`, stats.service1Only));
    statsDiv.appendChild(createStatItem(`${service2} Only`, stats.service2Only));
    
    header.appendChild(statsDiv);
    
    return header;
  }
  
  #createComparisonTable(service1, service2, hosts) {
    const wrapper = Utils.createElement('div', { className: 'table-wrapper' });
    const table = Utils.createElement('table', { className: 'comparison-table' });
    
    // Header
    const thead = Utils.createElement('thead');
    thead.innerHTML = `
      <tr>
        <th>Host</th>
        <th>${service1}</th>
        <th>${service2}</th>
        <th>Status</th>
      </tr>
    `;
    table.appendChild(thead);
    
    // Body
    const tbody = Utils.createElement('tbody');
    hosts.forEach(host => {
      const row = this.#createComparisonRow(host, service1, service2);
      tbody.appendChild(row);
    });
    table.appendChild(tbody);
    
    wrapper.appendChild(table);
    return wrapper;
  }
  
  #createComparisonRow(host, service1, service2) {
    const hostData = this.#data[host];
    const supported1 = hostData[service1] === '✅';
    const supported2 = hostData[service2] === '✅';
    
    let statusClass = 'neither-supported';
    let statusText = 'Neither';
    
    if (supported1 && supported2) {
      statusClass = 'both-supported';
      statusText = 'Both';
    } else if (supported1) {
      statusClass = 'service1-only';
      statusText = `${service1} only`;
    } else if (supported2) {
      statusClass = 'service2-only';
      statusText = `${service2} only`;
    }
    
    const row = Utils.createElement('tr', {
      className: `comparison-row ${statusClass}`,
      dataset: { status: statusClass }
    });
    
    // Host name
    const hostCell = Utils.createElement('td', { className: 'service-name' }, [host]);
    row.appendChild(hostCell);
    
    // Service 1 status
    const status1Cell = this.#createStatusCell(supported1);
    row.appendChild(status1Cell);
    
    // Service 2 status
    const status2Cell = this.#createStatusCell(supported2);
    row.appendChild(status2Cell);
    
    // Status text
    const statusTextCell = Utils.createElement('td', { className: 'status-text' });
    const badge = Utils.createElement('span', {
      className: `status-badge ${statusClass}`
    }, [statusText]);
    statusTextCell.appendChild(badge);
    row.appendChild(statusTextCell);
    
    return row;
  }
  
  #createStatusCell(isSupported) {
    const cell = Utils.createElement('td', {
      className: `support-status ${isSupported ? 'supported' : 'not-supported'}`,
      dataset: { supported: isSupported ? 'true' : 'false' }
    });
    
    const indicator = Utils.createElement('span', {
      className: 'status-indicator',
      'aria-hidden': 'true',
      dataset: { supported: isSupported ? 'true' : 'false' }
    }, [isSupported ? '✅' : '❌']);
    
    const srText = Utils.createElement('span', {
      className: 'visually-hidden'
    }, [isSupported ? 'Supported' : 'Not supported']);
    
    cell.appendChild(indicator);
    cell.appendChild(srText);
    
    return cell;
  }
  
  #calculateStats(service1, service2, hosts) {
    let shared = 0;
    let service1Only = 0;
    let service2Only = 0;
    
    hosts.forEach(host => {
      const hostData = this.#data[host];
      const supported1 = hostData[service1] === '✅';
      const supported2 = hostData[service2] === '✅';
      
      if (supported1 && supported2) shared++;
      else if (supported1) service1Only++;
      else if (supported2) service2Only++;
    });
    
    return { shared, service1Only, service2Only };
  }
  
  #showEmptyState() {
    this.#elements.container.innerHTML = `
      <div class="empty-state">
        <h3>Select Two Services to Compare</h3>
        <p>Choose services from the dropdowns above to see a detailed comparison.</p>
      </div>
    `;
    this.#elements.container.style.display = 'block';
  }
  
  #showSameProviderWarning() {
    this.#elements.container.innerHTML = `
      <div class="warning-state">
        <div class="warning-icon">⚠️</div>
        <h3>Same Service Selected</h3>
        <p>Please select two different services to compare</p>
      </div>
    `;
    this.#elements.container.style.display = 'block';
  }
}

/* ============================================================================
   UI FEATURES
   ============================================================================ */
const UIFeatures = (() => {
  // Intersection Observer for scroll animations
  const setupScrollAnimations = () => {
    if (!('IntersectionObserver' in window)) return;
    
    const elements = document.querySelectorAll('.section, .status-card, .referral-card');
    if (!elements.length) return;
    
    const observer = new IntersectionObserver((entries) => {
      entries.forEach(entry => {
        if (entry.isIntersecting) {
          entry.target.classList.add('animate-in');
          observer.unobserve(entry.target);
        }
      });
    }, {
      threshold: CONFIG.INTERSECTION.THRESHOLD,
      rootMargin: '0px 0px -50px 0px'
    });
    
    elements.forEach(el => observer.observe(el));
  };

  // Header elevation on scroll
  const setupHeaderElevation = () => {
    const header = document.querySelector('.site-header');
    if (!header) return;
    
    const updateHeader = () => {
      header.classList.toggle('is-scrolled', window.scrollY > 8);
    };
    
    updateHeader();
    
    const throttledUpdate = Utils.throttle(updateHeader);
    window.addEventListener('scroll', throttledUpdate, { passive: true });
  };

  // Back to top button
  const setupBackToTop = () => {
    const btn = document.getElementById('backToTop');
    if (!btn) return;
    
    const updateVisibility = () => {
      btn.classList.toggle('visible', window.pageYOffset > CONFIG.PERFORMANCE.SCROLL_THRESHOLD);
    };
    
    const throttledUpdate = Utils.throttle(updateVisibility, 150);
    window.addEventListener('scroll', throttledUpdate, { passive: true });
    
    btn.addEventListener('click', () => {
      window.scrollTo({ top: 0, behavior: 'smooth' });
    });
  };

  // Navigation highlight
  const setupNavHighlight = () => {
    if (!('IntersectionObserver' in window)) return;
    
    const links = Array.from(document.querySelectorAll('.header-nav .nav-link[href^="#"]'));
    if (!links.length) return;
    
    const sections = links
      .map(link => document.querySelector(link.getAttribute('href')))
      .filter(Boolean);
    
    const linkMap = new Map(
      links.map(link => [link.getAttribute('href'), link])
    );
    
    const observer = new IntersectionObserver((entries) => {
      entries.forEach(entry => {
        const id = `#${entry.target.id}`;
        const link = linkMap.get(id);
        
        if (link && entry.isIntersecting) {
          links.forEach(l => l.removeAttribute('aria-current'));
          link.setAttribute('aria-current', 'page');
        }
      });
    }, {
      threshold: CONFIG.INTERSECTION.THRESHOLD,
      rootMargin: CONFIG.INTERSECTION.ROOT_MARGIN
    });
    
    sections.forEach(section => observer.observe(section));
  };

  // URL-based comparison
  const setupURLComparison = () => {
    const params = new URLSearchParams(window.location.search);
    const provider1 = params.get('compare');
    const provider2 = params.get('with');
    
    if (provider1 && provider2) {
      requestAnimationFrame(() => {
        const select1 = document.getElementById('provider1');
        const select2 = document.getElementById('provider2');
        
        if (select1 && select2) {
          select1.value = provider1;
          select2.value = provider2;
          select1.dispatchEvent(new Event('change'));
        }
      });
    }
  };

  // Online/offline detection
  const setupOfflineDetection = () => {
    const showStatus = (isOnline) => {
      console.log(isOnline ? '✅ Connection restored' : '⚠️ You are offline');
    };
    
    window.addEventListener('online', () => showStatus(true));
    window.addEventListener('offline', () => showStatus(false));
  };

  return Object.freeze({
    setupScrollAnimations,
    setupHeaderElevation,
    setupBackToTop,
    setupNavHighlight,
    setupURLComparison,
    setupOfflineDetection
  });
})();

/* ============================================================================
   PERFORMANCE MONITOR
   ============================================================================ */
class PerformanceMonitor {
  #marks = new Map();
  
  constructor() {
    this.mark('start');
  }
  
  mark(name) {
    this.#marks.set(name, performance.now());
  }
  
  measure(name, startMark = 'start') {
    const start = this.#marks.get(startMark) || 0;
    const end = performance.now();
    return end - start;
  }
  
  log(name, startMark = 'start') {
    const duration = this.measure(name, startMark);
    console.log(`⏱️ ${name}: ${duration.toFixed(2)}ms`);
  }
}

/* ============================================================================
   APPLICATION BOOTSTRAP
   ============================================================================ */
class App {
  #loadingManager = null;
  #performanceMonitor = null;
  
  constructor() {
    this.#loadingManager = new LoadingManager();
    this.#performanceMonitor = new PerformanceMonitor();
  }
  
  async init() {
    try {
      this.#performanceMonitor.mark('dom-ready');
      
      // Initialize tables
      const fileHostsTable = new TableManager(
        'file-hosts-table-container',
        'host-search-input',
        'clear-host-search'
      );
      
      const adultHostsTable = new TableManager(
        'adult-hosts-table-container',
        'adult-host-search-input',
        'clear-adult-host-search'
      );
      
      // Show loaders
      const loaders = [
        this.#loadingManager.show('#file-hosts-table-container', 'Loading file hosts...'),
        this.#loadingManager.show('#adult-hosts-table-container', 'Loading adult hosts...')
      ];
      
      // Fetch data
      const dataPromises = [
        Utils.fetchWithFallback(CONFIG.API.FILE_HOSTS),
        Utils.fetchWithFallback(CONFIG.API.ADULT_HOSTS)
      ];
      
      const results = await Promise.allSettled(dataPromises);
      
      // Process results
      results.forEach((result, index) => {
        this.#loadingManager.hide(loaders[index]);
        
        if (result.status === 'fulfilled') {
          if (index === 0) {
            fileHostsTable.generateTable(result.value);
            new ComparisonManager('compare-table-container', 'provider1', 'provider2', result.value);
          } else {
            adultHostsTable.generateTable(result.value);
          }
        } else {
          console.error(`Failed to load dataset ${index}:`, result.reason);
          const containerId = index === 0 
            ? '#file-hosts-table-container' 
            : '#adult-hosts-table-container';
          const container = document.querySelector(containerId);
          if (container) {
            container.innerHTML = `
              <div class="error-state">
                <p>Failed to load data. Please check your connection and refresh.</p>
              </div>
            `;
          }
        }
      });
      
      // Setup UI features
      UIFeatures.setupScrollAnimations();
      UIFeatures.setupHeaderElevation();
      UIFeatures.setupBackToTop();
      UIFeatures.setupNavHighlight();
      UIFeatures.setupURLComparison();
      UIFeatures.setupOfflineDetection();
      
      this.#performanceMonitor.mark('fully-loaded');
      this.#performanceMonitor.log('Application initialized', 'dom-ready');
      
    } catch (error) {
      console.error('❌ Critical application error:', error);
      this.#loadingManager.hideAll();
    }
  }
}

/* ============================================================================
   GLOBAL ERROR HANDLING
   ============================================================================ */
window.addEventListener('error', (event) => {
  console.error('❌ Global error:', event.error || event.message);
}, { passive: true });

window.addEventListener('unhandledrejection', (event) => {
  console.error('❌ Unhandled promise rejection:', event.reason);
});

/* ============================================================================
   SERVICE WORKER REGISTRATION
   ============================================================================ */
if ('serviceWorker' in navigator) {
  window.addEventListener('load', () => {
    navigator.serviceWorker
      .register('/sw.js')
      .then(() => console.log('✅ Service worker registered'))
      .catch((error) => console.warn('⚠️ Service worker registration failed:', error));
  });
}

/* ============================================================================
   INITIALIZE APPLICATION
   ============================================================================ */
document.addEventListener('DOMContentLoaded', () => {
  const app = new App();
  app.init();
});