streamMessages method

Stream<String> streamMessages(String message)

Implementation

Stream<String> streamMessages(String message) async* {
  final url = Uri.parse('https://api.openai.com/v1/chat/completions');
  final headers = {
    'Content-Type': 'application/json',
    'Authorization': 'Bearer $apiKey',
  };

  final userContent = message +
      '\n\nPlease respond in simple plain text. Avoid using any bold, italics, headings, or special formatting. Make sure to use proper line breaks and include bullet points where necessary for lists.';

  final body = jsonEncode({
    'model': model,
    'messages': [
      {
        'role': 'user',
        'content': userContent,
      },
      {'role': 'system', 'content': systemPrompt},
    ],
    'temperature': temperature,
    'max_tokens': maxTokens,
    'stream': true, // Enable streaming
  });

  final request = http.Request('POST', url)
    ..headers.addAll(headers)
    ..body = body;

  try {
    final streamedResponse = await request.send();

    if (streamedResponse.statusCode == 200) {
      String buffer = ''; // Buffer to store parts of the message

      await for (var chunk in streamedResponse.stream) {
        final chunkString = utf8.decode(chunk);
        final lines = chunkString.split('\n');

        for (var line in lines) {
          if (line.isNotEmpty && line.startsWith('data: ')) {
            final jsonLine = line.substring(6); // Remove 'data: '
            if (jsonLine == '[DONE]') {
              yield buffer; // Yield the full message
              return; // End the stream
            }

            try {
              final parsed = jsonDecode(jsonLine);
              if (parsed['choices'] != null && parsed['choices'].isNotEmpty) {
                final content =
                    parsed['choices'][0]['delta']['content'] ?? '';

                buffer += content; // Add new content to the buffer

                if (content.contains('\n')) {
                  yield buffer; // Yield full message if it contains a newline
                  buffer = ''; // Clear the buffer after yielding
                }
              }
            } catch (e) {
              throw Exception('Streaming error: ${e.toString()}');
            }
          }
        }
      }
    } else {
      throw Exception('Error: ${streamedResponse.reasonPhrase}');
    }
  } catch (e) {
    throw Exception('Streaming error: ${e.toString()}');
  }
}