import 'dart:io';

import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';

/// 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 {
  Process? _qwenProcess;
  Process? _nomicProcess;
  bool _running = false;

  // -------------------------------------------------------------------------
  // Public API
  // -------------------------------------------------------------------------

  bool get isRunning => _running;

  /// Starts both inference servers.  No-ops if already running or if the
  /// llama-server binary is not present on disk.
  Future<void> startServers() async {
    if (_running) return;

    final dir = await getApplicationDocumentsDirectory();
    final base = dir.path;
    final serverBin = p.join(
      base,
      Platform.isWindows ? 'llama-server.exe' : 'llama-server',
    );

    if (!File(serverBin).existsSync()) return;

    try {
      // ── Qwen 2.5 7B chat server ──────────────────────────────────────────
      _qwenProcess = await Process.start(
        serverBin,
        [
          '-m', p.join(base, 'qwen2.5-7b-instruct-q4_k_m.gguf'),
          '--port', '8080',
          '--ctx-size', '4096',
          '-ngl', '99', // offload all layers to GPU
        ],
        runInShell: false,
      );
      // Drain pipes so the process is never blocked by a full buffer.
      _qwenProcess!.stdout.drain<List<int>>();
      _qwenProcess!.stderr.drain<List<int>>();

      // ── Nomic embedding server ───────────────────────────────────────────
      _nomicProcess = await Process.start(
        serverBin,
        [
          '-m', p.join(base, 'nomic-embed-text-v1.5.Q4_K_M.gguf'),
          '--port', '8081',
          '--ctx-size', '8192',
          '--embedding',
        ],
        runInShell: false,
      );
      _nomicProcess!.stdout.drain<List<int>>();
      _nomicProcess!.stderr.drain<List<int>>();

      _running = true;
    } catch (_) {
      // Clean up any partially-started processes before rethrowing.
      _qwenProcess?.kill();
      _nomicProcess?.kill();
      _qwenProcess = null;
      _nomicProcess = null;
      rethrow;
    }
  }

  /// 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();
    _qwenProcess = null;
    _nomicProcess = null;
    _running = false;
  }
}