import 'dart:convert';
import 'package:flutter_test/flutter_test.dart';

String? extractAudioUrl(String responseBody) {
  try {
    final List<dynamic> entries = jsonDecode(responseBody) as List<dynamic>;
    for (final entry in entries) {
      if (entry is Map<String, dynamic>) {
        final phonetics = entry['phonetics'];
        if (phonetics is List<dynamic>) {
          for (final phonetic in phonetics) {
            if (phonetic is Map<String, dynamic>) {
              final String? audio = phonetic['audio'] as String?;
              if (audio != null && audio.isNotEmpty) {
                if (audio.startsWith('//')) {
                  return 'https:$audio';
                }
                return audio;
              }
            }
          }
        }
      }
    }
  } catch (_) {}
  return null;
}

void main() {
  group('Dictionary Audio Parser Tests', () {
    test('extracts standard audio URL', () {
      const jsonStr = '''
      [
        {
          "word": "hello",
          "phonetics": [
            {
              "text": "/həˈləʊ/",
              "audio": "https://api.dictionaryapi.dev/media/pronunciations/en/hello-uk.mp3"
            }
          ]
        }
      ]
      ''';
      expect(
        extractAudioUrl(jsonStr),
        'https://api.dictionaryapi.dev/media/pronunciations/en/hello-uk.mp3',
      );
    });

    test('handles protocol-relative URL starting with //', () {
      const jsonStr = '''
      [
        {
          "word": "test",
          "phonetics": [
            {
              "audio": "//ssl.gstatic.com/dictionary/static/sounds/20201201/test--us.mp3"
            }
          ]
        }
      ]
      ''';
      expect(
        extractAudioUrl(jsonStr),
        'https://ssl.gstatic.com/dictionary/static/sounds/20201201/test--us.mp3',
      );
    });

    test('skips empty audio fields and selects first valid audio URL', () {
      const jsonStr = '''
      [
        {
          "word": "multiple",
          "phonetics": [
            {
              "text": "/mʌl.tɪ.pl̩/",
              "audio": ""
            },
            {
              "audio": "https://example.com/valid.mp3"
            }
          ]
        }
      ]
      ''';
      expect(
        extractAudioUrl(jsonStr),
        'https://example.com/valid.mp3',
      );
    });

    test('returns null for empty json or missing audio', () {
      expect(extractAudioUrl('[]'), isNull);
      expect(extractAudioUrl('invalid json'), isNull);
      
      const missingAudioJson = '''
      [
        {
          "word": "missing",
          "phonetics": [
            {
              "text": "/mɪs.ɪŋ/"
            }
          ]
        }
      ]
      ''';
      expect(extractAudioUrl(missingAudioJson), isNull);
    });
  });
}