frontend/js/main.js

/**
 * Main JavaScript file for AI Document Analyzer
 */

document.addEventListener('DOMContentLoaded', () => {
  // Initialize tabs
  initTabs();
  
  // Initialize animations
  initAnimations();
});

/**
 * Initialize tab functionality
 */
function initTabs() {
  const tabBtns = document.querySelectorAll('.tab-btn');
  const tabContents = document.querySelectorAll('.tab-content');
  
  tabBtns.forEach(btn => {
    btn.addEventListener('click', () => {
      // Remove active class from all buttons and contents
      tabBtns.forEach(b => b.classList.remove('active'));
      tabContents.forEach(c => c.classList.remove('active'));
      
      // Add active class to clicked button and corresponding content
      btn.classList.add('active');
      const tabId = `${btn.dataset.tab}-tab`;
      document.getElementById(tabId).classList.add('active');
    });
  });
}

/**
 * Initialize animations
 */
function initAnimations() {
  // Intersection Observer for scroll animations
  const observer = new IntersectionObserver((entries) => {
    entries.forEach(entry => {
      if (entry.isIntersecting) {
        entry.target.classList.add('appear');
      }
    });
  }, {
    threshold: 0.2
  });
  
  // Observe elements that should animate on scroll
  const animatedElements = document.querySelectorAll('.section-title, .feature-card, .about-content p');
  animatedElements.forEach(element => {
    observer.observe(element);
  });
}

/**
 * Show loading overlay
 */
function showLoading() {
  const loadingOverlay = document.getElementById('loading-overlay');
  loadingOverlay.style.display = 'flex';
}

/**
 * Hide loading overlay
 */
function hideLoading() {
  const loadingOverlay = document.getElementById('loading-overlay');
  loadingOverlay.style.display = 'none';
}

/**
 * Display error message
 * @param {string} message - The error message to display
 */
function showError(message) {
  // Create error notification
  const notification = document.createElement('div');
  notification.className = 'error-notification fade-in';
  notification.innerHTML = `
    <div class="error-icon"><i class="fas fa-exclamation-circle"></i></div>
    <div class="error-message">${message}</div>
  `;
  
  // Add to DOM
  document.body.appendChild(notification);
  
  // Remove after delay
  setTimeout(() => {
    notification.classList.add('fade-out');
    setTimeout(() => {
      document.body.removeChild(notification);
    }, 500);
  }, 4000);
}

/**
 * Format file size in human-readable format
 * @param {number} bytes - File size in bytes
 * @returns {string} Formatted file size
 */
function formatFileSize(bytes) {
  if (bytes === 0) return '0 Bytes';
  
  const k = 1024;
  const sizes = ['Bytes', 'KB', 'MB', 'GB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  
  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i];
}

/**
 * Get file extension from filename
 * @param {string} filename - The name of the file
 * @returns {string} The file extension
 */
function getFileExtension(filename) {
  return filename.slice((filename.lastIndexOf('.') - 1 >>> 0) + 2).toLowerCase();
}

/**
 * Check if file type is allowed
 * @param {string} fileType - The type of file
 * @param {string} allowedTypes - Comma-separated list of allowed types
 * @returns {boolean} Whether the file type is allowed
 */
function isFileTypeAllowed(filename, allowedTypes) {
  const extension = getFileExtension(filename);
  const allowedExtensions = allowedTypes.split(',').map(type => type.trim().replace('.', '').toLowerCase());
  
  return allowedExtensions.includes(extension);
}