import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import './usa-header.ts';
import type { USAHeader } from './usa-header.js';
import { testComponentAccessibility, USWDS_A11Y_CONFIG } from './accessibility-utils.js';

/**
 * USAHeader USWDS Integration Validation
 *
 * Risk Level: HIGH
 * Risk Factors: navigation-transformation, mobile-menu-behavior, responsive-changes, complex-structure
 * USWDS Module: usa-header
 *
 * Generated based on tooltip troubleshooting patterns to prevent:
 * - dom transformation
 * - light dom-slots
 * - module optimization
 */

describe('USAHeader USWDS Integration Validation', () => {
  let element: USAHeader;
  let testContainer: HTMLElement;

  beforeEach(() => {
    testContainer = document.createElement('div');
    testContainer.id = 'header-test-container';
    document.body.appendChild(testContainer);

    element = document.createElement('usa-header') as USAHeader;
    testContainer.appendChild(element);
  });

  afterEach(() => {
    testContainer.remove();
  });

  describe('DOM Transformation Validation', () => {
    it('should handle USWDS DOM transformation correctly', async () => {
      // Add test content that USWDS will transform
      const testContent = document.createElement('nav');
      testContent.classList.add('usa-header');
      testContent.textContent = 'Test header';
      element.appendChild(testContent);

      await element.updateComplete;

      // Simulate USWDS transformation (header specific)
      const preTransformElement = element.querySelector('.usa-header');
      expect(preTransformElement).toBeTruthy();

      // Simulate USWDS changing class structure
      preTransformElement?.classList.remove('usa-header');
      preTransformElement?.classList.add('usa-header__trigger');

      // Component should handle both pre and post-transformation states
      const postTransformElement = element.querySelector('.usa-header__trigger');
      expect(postTransformElement).toBeTruthy();
      expect(postTransformElement).toBe(preTransformElement);
    });

    it('should apply attributes before USWDS initialization', async () => {
      const testElement = document.createElement('nav');
      testElement.classList.add('usa-header');
      element.appendChild(testElement);

      // Apply component properties
      // No specific properties to test

      await element.updateComplete;

      // Attributes should be applied to element
      expect(testElement.getAttribute("class")).toBeTruthy();
    });
  });

  describe('Light DOM Slot Behavior', () => {
    it('should access slot content correctly in light DOM', () => {
      // Add complex slot content
      const slotContent = `
        <nav class="direct-child">Direct content</nav>
        <slot>
          <span class="slotted-content">Slotted content</span>
        </slot>
      `;
      element.innerHTML = slotContent;

      // Strategy 1: Direct children access
      const directChildren = Array.from(element.children).filter(
        child => child.nodeType === Node.ELEMENT_NODE && child.tagName !== 'SLOT'
      );
      expect(directChildren.length).toBeGreaterThan(0);

      // Strategy 2: Slot children access
      const slotElement = element.querySelector('slot');
      const slotChildren = slotElement ? Array.from(slotElement.children) : [];

      // Should find content using light DOM patterns
      const totalElements = directChildren.length + slotChildren.length;
      expect(totalElements).toBeGreaterThan(0);
    });

    it('should handle content updates dynamically', () => {
      // Count initial children (header may have default content)
      const initialChildCount = element.children.length;

      // Add initial content
      const initialContent = document.createElement('nav');
      initialContent.textContent = 'Initial';
      element.appendChild(initialContent);

      expect(element.children.length).toBe(initialChildCount + 1);

      // Add new content
      const newContent = document.createElement('span');
      newContent.textContent = 'New content';
      element.appendChild(newContent);

      expect(element.children.length).toBe(initialChildCount + 2);

      // Remove content
      initialContent.remove();
      expect(element.children.length).toBe(initialChildCount + 1);
    });
  });

  describe('USWDS Module Optimization', () => {
    it('should handle USWDS module loading', async () => {
      
      // Test USWDS module import pattern
      try {
        // This is the pattern used in components:
        // const module = await import('@uswds/uswds/js/usa-header');

        // For test, simulate the module structure
        const mockModule = {
          default: {
            on: (element: HTMLElement) => {
              element.setAttribute('data-uswds-initialized', 'true');
            },
            off: (element: HTMLElement) => {
              element.removeAttribute('data-uswds-initialized');
            }
          }
        };

        // Test module functionality
        mockModule.default.on(element);
        expect(element.getAttribute('data-uswds-initialized')).toBe('true');

        mockModule.default.off(element);
        expect(element.getAttribute('data-uswds-initialized')).toBeNull();

      } catch (error) {
        // Module loading may fail in test environment
        console.warn('USWDS module test failed in test environment:', error);
      }
      
    });

    it('should handle module loading failures gracefully', async () => {
      const mockFailingImport = async () => {
        throw new Error('Module not found');
      };

      try {
        await mockFailingImport();
        expect(true).toBe(false); // Should not reach here
      } catch (error) {
        // Should handle gracefully
        expect(error).toBeInstanceOf(Error);
      }
    });
  });
});