completeStream method

Implementation

@override
Stream<AIStreamChunk> completeStream(
  List<AIMessage> messages, {
  int? maxTokens,
  double? temperature,
  List<AITool>? tools,
}) async* {
  final body =
      _buildRequestBody(messages, maxTokens, temperature, stream: true);

  final request = http.Request('POST', Uri.parse('$_baseUrl/messages'));
  request.headers.addAll(_headers());
  request.body = jsonEncode(body);

  final streamedResponse = await _httpClient.send(request);

  if (streamedResponse.statusCode != 200) {
    final responseBody = await streamedResponse.stream.bytesToString();
    final json = jsonDecode(responseBody) as Map<String, dynamic>;
    throw _parseError(streamedResponse.statusCode, json);
  }

  String currentEvent = '';

  await for (final line in streamedResponse.stream
      .transform(utf8.decoder)
      .transform(const LineSplitter())) {
    if (line.startsWith('event: ')) {
      currentEvent = line.substring(7);
      continue;
    }

    if (!line.startsWith('data: ')) continue;

    final jsonStr = line.substring(6);
    try {
      final json = jsonDecode(jsonStr) as Map<String, dynamic>;

      switch (currentEvent) {
        case 'content_block_delta':
          final delta = json['delta'] as Map<String, dynamic>?;
          if (delta?['type'] == 'text_delta') {
            final text = delta?['text'] as String? ?? '';
            if (text.isNotEmpty) {
              yield AIStreamChunk(
                text: text,
                provider: name,
                model: config.model,
              );
            }
          }
          break;

        case 'message_delta':
          final usage = json['usage'] as Map<String, dynamic>?;
          yield AIStreamChunk(
            text: '',
            isComplete: true,
            finishReason: json['delta']?['stop_reason'] as String?,
            usage: usage != null
                ? AIUsage(
                    promptTokens: 0,
                    completionTokens: usage['output_tokens'] as int? ?? 0,
                  )
                : null,
            provider: name,
            model: config.model,
          );
          break;
      }
    } on FormatException catch (_) {
      // Skip malformed JSON chunks
    }
  }
}