import 'dart:convert';

import '../../app_info.dart';
import '../../domain/mission/drone_profile.dart';

/// Baut die Export-Datei fuer ein Drohnenprofil (Doku 3.5, analog
/// buildDroneExportObject()/shareDrone() im HTML-Demonstrator). Die id wird
/// bewusst nicht mitexportiert - beim Import entsteht immer ein neues,
/// eigenstaendiges Profil (siehe parseDroneImportJson()).
String buildDroneExportJson(DroneProfile profile) {
  final map = {
    'appVersion': kAppVersion,
    'exportedAt': DateTime.now().toUtc().toIso8601String(),
    'drone': {
      'name': profile.name,
      'minSpeed': profile.minSpeed,
      'cruiseSpeed': profile.cruiseSpeed,
      'maxSpeed': profile.maxSpeed,
      'minTurnRadius': profile.minTurnRadius,
      'loiterRadius': profile.loiterRadius,
      'catchRadius': profile.catchRadius,
      'maxClimbRate': profile.maxClimbRate,
      'maxDescentRate': profile.maxDescentRate,
      'maxRangeM': profile.maxRangeM,
      'maxEnduranceMin': profile.maxEnduranceMin,
      'maxAltitudeM': profile.maxAltitudeM,
    },
  };
  return const JsonEncoder.withIndent('  ').convert(map);
}

/// Vorschlagsname fuer die geteilte Datei (Doku 3.5, analog
/// `'drone-' + safeName + '.json'` im HTML-Demonstrator).
String droneExportFilename(String name) {
  final safeName = name.replaceAll(RegExp(r'[^a-zA-Z0-9]'), '_');
  return 'drone-$safeName.json';
}

class ParsedDroneImport {
  const ParsedDroneImport({required this.profile, this.versionMismatch});

  final DroneProfile profile;

  /// Enthaelt die appVersion der Datei, falls sie sich von [kAppVersion] in
  /// der Hauptversionsnummer unterscheidet - sonst null.
  final String? versionMismatch;
}

const _requiredNumericFields = [
  'minSpeed',
  'cruiseSpeed',
  'maxSpeed',
  'minTurnRadius',
  'loiterRadius',
  'catchRadius',
  'maxClimbRate',
  'maxDescentRate',
  'maxRangeM',
  'maxEnduranceMin',
  'maxAltitudeM',
];

/// Parst eine importierte Drohnenprofil-Datei - wirft [FormatException] bei
/// ungueltigem JSON oder fehlenden Pflichtfeldern (Doku 3.5, analog dem
/// `change`-Handler von importDroneInput im HTML-Demonstrator).
ParsedDroneImport parseDroneImportJson(String jsonText) {
  final Object? decoded;
  try {
    decoded = jsonDecode(jsonText);
  } on FormatException {
    throw const FormatException('Invalid drone profile file');
  }
  if (decoded is! Map<String, dynamic>) {
    throw const FormatException('Invalid drone profile file');
  }
  final droneData = decoded['drone'] ?? decoded;
  if (droneData is! Map<String, dynamic>) {
    throw const FormatException('Invalid drone profile file');
  }

  final name = droneData['name'];
  if (name is! String || name.isEmpty) {
    throw const FormatException('File is not a valid drone profile');
  }
  for (final field in _requiredNumericFields) {
    if (droneData[field] is! num) {
      throw const FormatException('File is not a valid drone profile');
    }
  }

  final profile = DroneProfile(
    name: name,
    minSpeed: (droneData['minSpeed'] as num).toDouble(),
    cruiseSpeed: (droneData['cruiseSpeed'] as num).toDouble(),
    maxSpeed: (droneData['maxSpeed'] as num).toDouble(),
    minTurnRadius: (droneData['minTurnRadius'] as num).toDouble(),
    loiterRadius: (droneData['loiterRadius'] as num).toDouble(),
    catchRadius: (droneData['catchRadius'] as num).toDouble(),
    maxClimbRate: (droneData['maxClimbRate'] as num).toDouble(),
    maxDescentRate: (droneData['maxDescentRate'] as num).toDouble(),
    maxRangeM: (droneData['maxRangeM'] as num).toDouble(),
    maxEnduranceMin: (droneData['maxEnduranceMin'] as num).toDouble(),
    maxAltitudeM: (droneData['maxAltitudeM'] as num).toDouble(),
  );

  final appVersion = decoded['appVersion'] as String?;
  final mismatch = appVersion != null &&
          appVersion.split('.').first != kAppVersion.split('.').first
      ? appVersion
      : null;

  return ParsedDroneImport(profile: profile, versionMismatch: mismatch);
}