import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../llm/llm_service.dart';
import '../llm/mediapipe_llm_service.dart';

// ── Service singleton ─────────────────────────────────────────────────────────

final llmServiceProvider = Provider<LlmService>((ref) {
  final service = MediapipeLlmService();
  ref.onDispose(service.dispose);
  return service;
});

// ── Model initialisation state ────────────────────────────────────────────────

final llmReadyProvider = FutureProvider<void>((ref) async {
  await ref.watch(llmServiceProvider).initialise();
});

// ── Streaming response notifier ───────────────────────────────────────────────

class LlmResponseNotifier extends Notifier<AsyncValue<String>> {
  bool _cancelled = false;

  @override
  AsyncValue<String> build() => const AsyncData('');

  Future<void> generate(String prompt) async {
    _cancelled = false;
    state = const AsyncLoading();

    final service = ref.read(llmServiceProvider);
    final buffer = StringBuffer();

    try {
      await for (final token in service.generateStream(prompt)) {
        if (_cancelled || !ref.mounted) break;
        buffer.write(token);
        state = AsyncData(buffer.toString());
      }
    } catch (e, st) {
      if (!ref.mounted) return;
      state = AsyncError(e, st);
    }
  }

  void cancel() {
    _cancelled = true;
    state = const AsyncData('');
  }

  void clear() => state = const AsyncData('');
}

final llmResponseNotifierProvider =
    NotifierProvider.autoDispose<LlmResponseNotifier, AsyncValue<String>>(
        LlmResponseNotifier.new);