import 'package:test/test.dart';

void main() {
  group('URL Extraction from HTML', () {

    test('should extract URL from HTML anchor tag', () {
      // Access the private method through reflection or create a test helper
      // For now, let's test the functionality indirectly by testing the regex pattern
      final input = '<a href="https://www.youtube.com/watch?v=dpx6L15oA4k">https://www.youtube.com/watch?v=dpx6L15oA4k</a>';
      final aTagRegex = RegExp(r'<a\s+href="([^"]+)"[^>]*>.*?</a>', caseSensitive: false);
      final match = aTagRegex.firstMatch(input);
      
      expect(match, isNotNull);
      expect(match!.group(1), equals('https://www.youtube.com/watch?v=dpx6L15oA4k'));
    });

    test('should return original string if not HTML anchor tag', () {
      final input = 'https://www.youtube.com/watch?v=dpx6L15oA4k';
      final aTagRegex = RegExp(r'<a\s+href="([^"]+)"[^>]*>.*?</a>', caseSensitive: false);
      final match = aTagRegex.firstMatch(input);
      
      expect(match, isNull);
    });

    test('should handle various HTML anchor tag formats', () {
      final testCases = [
        '<a href="https://example.com">Link</a>',
        '<a href="https://example.com" target="_blank">Link</a>',
        '<A HREF="https://example.com">Link</A>',
        '<a href="https://example.com" class="link">Link Text</a>',
      ];

      final aTagRegex = RegExp(r'<a\s+href="([^"]+)"[^>]*>.*?</a>', caseSensitive: false);

      for (final testCase in testCases) {
        final match = aTagRegex.firstMatch(testCase);
        expect(match, isNotNull, reason: 'Failed to match: $testCase');
        expect(match!.group(1), equals('https://example.com'));
      }
    });

    test('should handle empty or whitespace input', () {
      final testCases = ['', '   ', '\t\n'];
      final aTagRegex = RegExp(r'<a\s+href="([^"]+)"[^>]*>.*?</a>', caseSensitive: false);

      for (final testCase in testCases) {
        final match = aTagRegex.firstMatch(testCase.trim());
        expect(match, isNull, reason: 'Should not match empty/whitespace: "$testCase"');
      }
    });
  });
}