import 'fetch_chat_page.dart';
import 'get_chat_params.dart';
import 'get_chat_response.dart';

/// Long-poll variant of GetChat (`lookIntoFuture=1`); HTTP 304 is the normal
/// "no new messages" outcome (see [fetchChatPage]). `setReadMarker=on` lets
/// the server move the read cursor whenever the call returns messages.
class LongPollChat {
  final String chatToken;
  final int lastKnownMessageId;
  final int timeoutSeconds;

  LongPollChat({
    required this.chatToken,
    required this.lastKnownMessageId,
    this.timeoutSeconds = 30,
  });

  /// Returns the response, or `null` on HTTP 304 (server timeout, nothing new).
  Future<GetChatResponse?> run() => fetchChatPage(
    label: 'LongPollChat',
    chatToken: chatToken,
    params: GetChatParams(
      lookIntoFuture: GetChatParamsSwitch.on,
      timeout: timeoutSeconds,
      lastKnownMessageId: lastKnownMessageId,
      includeLastKnown: GetChatParamsSwitch.off,
      setReadMarker: GetChatParamsSwitch.on,
      limit: 100,
    ),
    timeout: Duration(seconds: timeoutSeconds + 15),
  );
}