// Utility Functions for SkyArtShop
// Centralized helper functions used across the application

/**
 * API Request Handler with Error Management
 * @param {string} url - API endpoint
 * @param {object} options - Fetch options
 * @returns {Promise} - Response data
 */
async function apiRequest(url, options = {}) {
  const defaultOptions = {
    credentials: "include",
    headers: {
      "Content-Type": "application/json",
      ...options.headers,
    },
  };

  try {
    const response = await fetch(url, { ...defaultOptions, ...options });

    if (!response.ok) {
      const error = await response.json().catch(() => ({
        message: `HTTP ${response.status}: ${response.statusText}`,
      }));
      throw new Error(error.message || "Request failed");
    }

    return await response.json();
  } catch (error) {
    if (process.env.NODE_ENV !== "production") {
      console.error(`API Request Failed [${url}]:`, error);
    }
    throw error;
  }
}

/**
 * Debounce function to limit execution rate
 * @param {Function} func - Function to debounce
 * @param {number} wait - Wait time in milliseconds
 * @returns {Function} - Debounced function
 */
function debounce(func, wait = 300) {
  let timeout;
  return function executedFunction(...args) {
    const later = () => {
      clearTimeout(timeout);
      func(...args);
    };
    clearTimeout(timeout);
    timeout = setTimeout(later, wait);
  };
}

/**
 * Throttle function to limit execution frequency
 * @param {Function} func - Function to throttle
 * @param {number} limit - Limit in milliseconds
 * @returns {Function} - Throttled function
 */
function throttle(func, limit = 300) {
  let inThrottle;
  return function executedFunction(...args) {
    if (!inThrottle) {
      func.apply(this, args);
      inThrottle = true;
      setTimeout(() => (inThrottle = false), limit);
    }
  };
}

/**
 * Escape HTML to prevent XSS
 * @param {string} text - Text to escape
 * @returns {string} - Escaped text
 */
function escapeHtml(text) {
  const div = document.createElement("div");
  div.textContent = text;
  return div.innerHTML;
}

/**
 * Format date to readable string
 * @param {string} dateString - Date string to format
 * @returns {string} - Formatted date
 */
function formatDate(dateString) {
  if (!dateString) return "N/A";

  const date = new Date(dateString);
  if (isNaN(date.getTime())) return "Invalid Date";

  return new Intl.DateTimeFormat("en-US", {
    year: "numeric",
    month: "short",
    day: "numeric",
  }).format(date);
}

/**
 * Format currency
 * @param {number} amount - Amount to format
 * @param {string} currency - Currency code
 * @returns {string} - Formatted currency
 */
function formatCurrency(amount, currency = "USD") {
  return new Intl.NumberFormat("en-US", {
    style: "currency",
    currency: currency,
  }).format(amount);
}

/**
 * Show toast notification
 * @param {string} message - Message to display
 * @param {string} type - Type of notification (success, error, warning, info)
 * @param {number} duration - Duration in milliseconds
 */
function showToast(message, type = "info", duration = 3000) {
  // Remove existing toasts
  const existingToast = document.querySelector(".toast-notification");
  if (existingToast) {
    existingToast.remove();
  }

  const toast = document.createElement("div");
  toast.className = `toast-notification toast-${type}`;
  toast.setAttribute("role", "alert");
  toast.setAttribute("aria-live", "polite");

  const icons = {
    success: "✓",
    error: "✗",
    warning: "⚠",
    info: "ℹ",
  };

  toast.innerHTML = `
    <span class="toast-icon" aria-hidden="true">${
      icons[type] || icons.info
    }</span>
    <span class="toast-message">${escapeHtml(message)}</span>
    <button class="toast-close" onclick="this.parentElement.remove()" aria-label="Close notification">×</button>
  `;

  document.body.appendChild(toast);

  // Trigger animation
  setTimeout(() => toast.classList.add("show"), 10);

  // Auto remove
  setTimeout(() => {
    toast.classList.remove("show");
    setTimeout(() => toast.remove(), 300);
  }, duration);
}

/**
 * LocalStorage with error handling
 */
const storage = {
  get(key, defaultValue = null) {
    try {
      const item = localStorage.getItem(key);
      return item ? JSON.parse(item) : defaultValue;
    } catch (error) {
      if (process.env.NODE_ENV !== "production") {
        console.error("Storage get error:", error);
      }
      return defaultValue;
    }
  },

  set(key, value) {
    try {
      localStorage.setItem(key, JSON.stringify(value));
      return true;
    } catch (error) {
      if (process.env.NODE_ENV !== "production") {
        console.error("Storage set error:", error);
      }
      return false;
    }
  },

  remove(key) {
    try {
      localStorage.removeItem(key);
      return true;
    } catch (error) {
      if (process.env.NODE_ENV !== "production") {
        console.error("Storage remove error:", error);
      }
      return false;
    }
  },

  clear() {
    try {
      localStorage.clear();
      return true;
    } catch (error) {
      if (process.env.NODE_ENV !== "production") {
        console.error("Storage clear error:", error);
      }
      return false;
    }
  },
};

/**
 * Validate email format
 * @param {string} email - Email to validate
 * @returns {boolean} - Valid or not
 */
function isValidEmail(email) {
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
  return emailRegex.test(email);
}

/**
 * Get image URL with fallback
 * @param {string} imagePath - Image path from server
 * @param {string} fallback - Fallback image path
 * @returns {string} - Full image URL
 */
function getImageUrl(imagePath, fallback = "/assets/images/placeholder.png") {
  if (!imagePath) return fallback;

  // If already a full URL, return as is
  if (imagePath.startsWith("http://") || imagePath.startsWith("https://")) {
    return imagePath;
  }

  // Handle relative paths
  return imagePath.startsWith("/") ? imagePath : `/${imagePath}`;
}

/**
 * Create accessible image element
 * @param {string} src - Image source
 * @param {string} alt - Alt text
 * @param {string} className - CSS classes
 * @returns {HTMLImageElement} - Image element
 */
function createImage(src, alt, className = "") {
  const img = document.createElement("img");
  img.src = getImageUrl(src);
  img.alt = alt || "Image";
  img.className = className;
  img.loading = "lazy";

  // Add error handler with fallback
  img.onerror = function () {
    this.src = "/assets/images/placeholder.png";
    this.onerror = null; // Prevent infinite loop
  };

  return img;
}

/**
 * Trap focus within modal for accessibility
 * @param {HTMLElement} element - Element to trap focus in
 */
function trapFocus(element) {
  const focusableElements = element.querySelectorAll(
    'a[href], button:not([disabled]), textarea:not([disabled]), input:not([disabled]), select:not([disabled]), [tabindex]:not([tabindex="-1"])'
  );

  const firstFocusable = focusableElements[0];
  const lastFocusable = focusableElements[focusableElements.length - 1];

  element.addEventListener("keydown", function (e) {
    if (e.key !== "Tab") return;

    if (e.shiftKey) {
      if (document.activeElement === firstFocusable) {
        lastFocusable.focus();
        e.preventDefault();
      }
    } else {
      if (document.activeElement === lastFocusable) {
        firstFocusable.focus();
        e.preventDefault();
      }
    }
  });

  // Focus first element
  firstFocusable?.focus();
}

/**
 * Announce to screen readers
 * @param {string} message - Message to announce
 * @param {string} priority - Priority level (polite, assertive)
 */
function announceToScreenReader(message, priority = "polite") {
  const announcement = document.createElement("div");
  announcement.setAttribute("role", "status");
  announcement.setAttribute("aria-live", priority);
  announcement.className = "sr-only";
  announcement.textContent = message;

  document.body.appendChild(announcement);

  setTimeout(() => announcement.remove(), 1000);
}

// Export for use in other scripts
if (typeof module !== "undefined" && module.exports) {
  module.exports = {
    apiRequest,
    debounce,
    throttle,
    escapeHtml,
    formatDate,
    formatCurrency,
    showToast,
    storage,
    isValidEmail,
    getImageUrl,
    createImage,
    trapFocus,
    announceToScreenReader,
  };
}