Next refactors

lib/data/services/ai_process_manager.dart

@@ -0,0 +1,174 @@
+import 'dart:io';
+
+import 'package:flutter/foundation.dart';
+import 'package:path/path.dart' as p;
+import 'package:path_provider/path_provider.dart';
+import 'package:trainhub_flutter/core/constants/ai_constants.dart';
+
+enum AiServerStatus { offline, starting, ready, error }
+
+/// Manages the two llama.cpp server processes that provide AI features.
+///
+/// Both processes are kept alive for the lifetime of the app and must be
+/// killed on shutdown to prevent zombie processes from consuming RAM.
+///
+/// - Qwen 2.5 7B  → port 8080  (chat / completions)
+/// - Nomic Embed  → port 8081  (embeddings)
+class AiProcessManager extends ChangeNotifier {
+  Process? _qwenProcess;
+  Process? _nomicProcess;
+  AiServerStatus _status = AiServerStatus.offline;
+  String? _lastError;
+
+  // -------------------------------------------------------------------------
+  // Public API
+  // -------------------------------------------------------------------------
+
+  AiServerStatus get status => _status;
+  bool get isRunning => _status == AiServerStatus.ready;
+  String? get errorMessage => _lastError;
+
+  /// Starts both inference servers.  No-ops if already running or starting.
+  Future<void> startServers() async {
+    if (_status == AiServerStatus.starting || _status == AiServerStatus.ready) {
+      return;
+    }
+
+    _updateStatus(AiServerStatus.starting);
+    _lastError = null;
+
+    final dir = await getApplicationDocumentsDirectory();
+    final base = dir.path;
+    final serverBin = p.join(base, AiConstants.serverBinaryName);
+
+    if (!File(serverBin).existsSync()) {
+      _lastError = 'llama-server executable not found.';
+      _updateStatus(AiServerStatus.error);
+      return;
+    }
+
+    try {
+      _qwenProcess = await Process.start(serverBin, [
+        '-m', p.join(base, AiConstants.qwenModelFile),
+        '--port', '${AiConstants.chatServerPort}',
+        '--ctx-size', '${AiConstants.qwenContextSize}',
+        '-ngl', '${AiConstants.gpuLayerOffload}',
+      ], runInShell: false);
+
+      _qwenProcess!.stdout.listen((event) {
+        if (kDebugMode) print('[QWEN STDOUT] ${String.fromCharCodes(event)}');
+      });
+      _qwenProcess!.stderr.listen((event) {
+        if (kDebugMode) print('[QWEN STDERR] ${String.fromCharCodes(event)}');
+      });
+
+      // Monitor for unexpected crash
+      _qwenProcess!.exitCode.then((code) {
+        if (_status == AiServerStatus.ready ||
+            _status == AiServerStatus.starting) {
+          _lastError = 'Qwen Chat Server crashed with code $code';
+          _updateStatus(AiServerStatus.error);
+        }
+      });
+
+      _nomicProcess = await Process.start(serverBin, [
+        '-m', p.join(base, AiConstants.nomicModelFile),
+        '--port', '${AiConstants.embeddingServerPort}',
+        '--ctx-size', '${AiConstants.nomicContextSize}',
+        '--embedding',
+      ], runInShell: false);
+
+      _nomicProcess!.stdout.listen((event) {
+        if (kDebugMode) print('[NOMIC STDOUT] ${String.fromCharCodes(event)}');
+      });
+      _nomicProcess!.stderr.listen((event) {
+        if (kDebugMode) print('[NOMIC STDERR] ${String.fromCharCodes(event)}');
+      });
+
+      // Monitor for unexpected crash
+      _nomicProcess!.exitCode.then((code) {
+        if (_status == AiServerStatus.ready ||
+            _status == AiServerStatus.starting) {
+          _lastError = 'Nomic Embedding Server crashed with code $code';
+          _updateStatus(AiServerStatus.error);
+        }
+      });
+
+      // Wait for servers to bind to their ports and allocate memory.
+      // This is crucial because loading models (especially 7B) takes several
+      // seconds and significant RAM, which might cause the dart process to appear hung.
+      int attempts = 0;
+      bool qwenReady = false;
+      bool nomicReady = false;
+
+      while (attempts < 20 && (!qwenReady || !nomicReady)) {
+        await Future.delayed(const Duration(milliseconds: 500));
+
+        if (!qwenReady) {
+          qwenReady = await _isPortReady(AiConstants.chatServerPort);
+        }
+        if (!nomicReady) {
+          nomicReady = await _isPortReady(AiConstants.embeddingServerPort);
+        }
+
+        attempts++;
+      }
+
+      if (!qwenReady || !nomicReady) {
+        throw Exception('Servers failed to start within 10 seconds.');
+      }
+
+      _updateStatus(AiServerStatus.ready);
+    } catch (e) {
+      // Clean up any partially-started processes before returning error.
+      _qwenProcess?.kill();
+      _nomicProcess?.kill();
+      _qwenProcess = null;
+      _nomicProcess = null;
+      _lastError = e.toString();
+      _updateStatus(AiServerStatus.error);
+    }
+  }
+
+  /// Kills both processes and resets the running flag.
+  /// Safe to call even if servers were never started.
+  Future<void> stopServers() async {
+    _qwenProcess?.kill();
+    _nomicProcess?.kill();
+
+    if (Platform.isWindows) {
+      try {
+        await Process.run('taskkill', ['/F', '/IM', AiConstants.serverBinaryName]);
+      } catch (_) {}
+    } else if (Platform.isMacOS || Platform.isLinux) {
+      try {
+        await Process.run('pkill', ['-f', 'llama-server']);
+      } catch (_) {}
+    }
+
+    _qwenProcess = null;
+    _nomicProcess = null;
+    _updateStatus(AiServerStatus.offline);
+  }
+
+  Future<bool> _isPortReady(int port) async {
+    try {
+      final socket = await Socket.connect(
+        '127.0.0.1',
+        port,
+        timeout: const Duration(seconds: 1),
+      );
+      socket.destroy();
+      return true;
+    } catch (_) {
+      return false;
+    }
+  }
+
+  void _updateStatus(AiServerStatus newStatus) {
+    if (_status != newStatus) {
+      _status = newStatus;
+      notifyListeners();
+    }
+  }
+}