import 'dart:async';
import 'dart:io';

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

import 'app_paths.dart';
import 'local_node_service.dart';

class LinuxLocalNodeService implements LocalNodeService {
  LinuxLocalNodeService({required Logger logger}) : _logger = logger;

  final Logger _logger;
  Future<bool>? _startFuture;
  LocalNodeConfig? _lastConfig;

  @override
  Future<bool> isRunning({LocalNodeConfig? config}) async {
    final resolved = _resolveConfig(config);
    return _isRpcAvailable(resolved);
  }

  @override
  Future<bool> ensureRunning({LocalNodeConfig? config}) async {
    final effective = _resolveConfig(config);
    if (await _isRpcAvailable(effective)) {
      return true;
    }
    return _startNode(effective);
  }

  @override
  Future<bool> start({LocalNodeConfig? config}) async {
    final effective = _resolveConfig(config);
    return _startNode(effective);
  }

  @override
  Future<bool> stop() async {
    final effective = _resolveConfig(null);
    final pidFile = File(await _pidFilePath());
    if (!await pidFile.exists()) {
      _logger.w('Local node pidfile not found at ${pidFile.path}');
      return false;
    }
    final rawPid = await pidFile.readAsString();
    final pid = int.tryParse(rawPid.trim());
    if (pid == null) {
      _logger.w('Local node pidfile invalid: $rawPid');
      return false;
    }
    final killed = Process.killPid(pid);
    if (!killed) {
      _logger.w('Failed to terminate local node process ($pid)');
      return false;
    }
    return _waitForStop(effective);
  }

  @override
  Future<bool> restart({LocalNodeConfig? config}) async {
    final effective = _resolveConfig(config);
    await stop();
    return _startNode(effective);
  }

  Future<bool> _startNode(LocalNodeConfig config) async {
    if (_startFuture != null) {
      return _startFuture!;
    }
    _startFuture = _startNodeInternal(config);
    try {
      return await _startFuture!;
    } finally {
      _startFuture = null;
    }
  }

  Future<bool> _startNodeInternal(LocalNodeConfig config) async {
    _lastConfig = config;
    final binary = await _locateBinary();
    if (binary == null) {
      _logger.w('Local node binary not found. Expected external/daemon/peyad');
      return false;
    }
    final pidFile = await _pidFilePath();
    final args = <String>[
      '--detach',
      '--non-interactive',
      '--rpc-bind-ip',
      config.rpcHost,
      '--rpc-bind-port',
      config.rpcPort.toString(),
      '--pidfile',
      pidFile,
      ...config.extraArgs,
    ];
    try {
      await Process.start(
        binary,
        args,
        workingDirectory: Directory.current.path,
        mode: ProcessStartMode.detached,
      );
    } catch (error) {
      _logger.w('Failed to start local node: $error');
      return false;
    }
    return _waitForRpc(config);
  }

  Future<bool> _waitForRpc(LocalNodeConfig config) async {
    const attempts = 20;
    for (var i = 0; i < attempts; i++) {
      if (await _isRpcAvailable(config)) {
        return true;
      }
      await Future.delayed(const Duration(seconds: 1));
    }
    _logger.w('Local node did not become available after ${attempts}s.');
    return false;
  }

  Future<bool> _waitForStop(LocalNodeConfig config) async {
    const attempts = 15;
    for (var i = 0; i < attempts; i++) {
      if (!await _isRpcAvailable(config)) {
        return true;
      }
      await Future.delayed(const Duration(seconds: 1));
    }
    return false;
  }

  Future<bool> _isRpcAvailable(LocalNodeConfig config) async {
    try {
      final socket = await Socket.connect(
        config.rpcHost,
        config.rpcPort,
        timeout: const Duration(seconds: 1),
      );
      socket.destroy();
      return true;
    } catch (_) {
      return false;
    }
  }

  LocalNodeConfig _resolveConfig(LocalNodeConfig? config) {
    final base = config ?? _lastConfig ?? const LocalNodeConfig();
    return _applyOverrides(base);
  }

  LocalNodeConfig _applyOverrides(LocalNodeConfig config) {
    var host = config.rpcHost;
    var port = config.rpcPort;
    final args = config.extraArgs;
    for (var i = 0; i < args.length; i++) {
      final arg = args[i];
      if (arg.startsWith('--rpc-bind-ip=')) {
        host = arg.split('=').last.trim();
        continue;
      }
      if (arg == '--rpc-bind-ip' && i + 1 < args.length) {
        host = args[i + 1].trim();
        continue;
      }
      if (arg.startsWith('--rpc-bind-port=')) {
        final parsed = int.tryParse(arg.split('=').last.trim());
        if (parsed != null) {
          port = parsed;
        }
        continue;
      }
      if (arg == '--rpc-bind-port' && i + 1 < args.length) {
        final parsed = int.tryParse(args[i + 1].trim());
        if (parsed != null) {
          port = parsed;
        }
      }
    }
    return config.copyWith(rpcHost: host, rpcPort: port);
  }

  Future<String?> _locateBinary() async {
    final cwd = Directory.current.path;
    final executableDir = p.dirname(Platform.resolvedExecutable);
    final candidates = [
      p.join(executableDir, 'external', 'daemon', 'peyad'),
      p.join(cwd, 'external', 'daemon', 'peyad'),
      p.join(cwd, '..', 'external', 'daemon', 'peyad'),
    ];
    for (final candidate in candidates) {
      final file = File(candidate);
      if (await file.exists()) {
        return file.path;
      }
    }
    return null;
  }

  Future<String> _pidFilePath() async {
    return (await AppPaths.localNodePidFile()).path;
  }
}