import '../audio/runtime_audio_manager.dart';
import '../models/game_diff.dart';
import '../resources/game_resource_manager.dart';
import '../scripting/script_engine.dart';
import 'game_package.dart';
import 'game_package_repository.dart';
import 'package_verifier.dart';
import 'stable_package_store.dart';

class PackageActivationController {
  const PackageActivationController({
    required this.repository,
    required this.resources,
    required this.scriptEngine,
    this.audio,
    this.runtimeApiVersion = 1,
    this.store = const StablePackageStore(),
    this.assetFallback = const AssetGamePackageRepository(),
    this.resourceManagerFactory,
    this.audioManagerFactory,
    this.scriptEngineFactory,
  });

  final GamePackageRepository repository;
  final GameResourceManager resources;
  final ScriptEngine scriptEngine;
  final RuntimeAudioManager? audio;
  final int runtimeApiVersion;
  final StablePackageStore store;
  final GamePackageRepository assetFallback;
  final GameResourceManager Function()? resourceManagerFactory;
  final RuntimeAudioManager Function()? audioManagerFactory;
  final ScriptEngine Function()? scriptEngineFactory;

  Future<PackageActivationResult> activate({
    required String gameId,
    required Map<String, Object?> Function(GamePackage package) contextBuilder,
    bool Function()? shouldContinue,
  }) async {
    final plan = await prepare(
      gameId: gameId,
      contextBuilder: contextBuilder,
      shouldContinue: shouldContinue,
    );
    await commit(plan, shouldContinue: shouldContinue);
    return PackageActivationResult.fromPlan(plan);
  }

  Future<PackageActivationPlan> prepare({
    required String gameId,
    required Map<String, Object?> Function(GamePackage package) contextBuilder,
    bool Function()? shouldContinue,
  }) async {
    final verifier = PackageVerifier(runtimeApiVersion: runtimeApiVersion);
    final candidates = await _candidatePackages(gameId, shouldContinue);

    Object? lastError;
    for (final candidate in candidates) {
      try {
        _ensureContinue(shouldContinue);
        final plan = await _prepareCandidate(
          candidate: candidate,
          verifier: verifier,
          contextBuilder: contextBuilder,
          shouldContinue: shouldContinue,
        );
        return plan;
      } catch (error) {
        if (shouldContinue != null && !shouldContinue()) {
          rethrow;
        }
        lastError = error;
      }
    }

    throw StateError(
      'No activatable package for $gameId. Last error: $lastError',
    );
  }

  Future<void> commit(
    PackageActivationPlan plan, {
    bool Function()? shouldContinue,
  }) async {
    _ensureContinue(shouldContinue);
    await store.markStable(plan.package);
    _ensureContinue(shouldContinue);
  }

  Future<List<GamePackage>> _candidatePackages(
    String gameId,
    bool Function()? shouldContinue,
  ) async {
    final candidates = <GamePackage>[];

    try {
      final package = await repository.load(gameId);
      _ensureContinue(shouldContinue);
      candidates.add(package);
    } catch (_) {
      // Continue with stable/fallback candidates.
    }
    _ensureContinue(shouldContinue);

    final stable = await store.stablePackage(gameId);
    if (stable != null && !_containsPackage(candidates, stable)) {
      candidates.add(stable);
    }

    _ensureContinue(shouldContinue);

    final previous = await store.previousStablePackage(gameId);
    if (previous != null && !_containsPackage(candidates, previous)) {
      candidates.add(previous);
    }

    _ensureContinue(shouldContinue);

    final fallback = await assetFallback.load(gameId);
    if (!_containsPackage(candidates, fallback)) {
      candidates.add(fallback);
    }
    _ensureContinue(shouldContinue);

    return candidates;
  }

  Future<PackageActivationPlan> _prepareCandidate({
    required GamePackage candidate,
    required PackageVerifier verifier,
    required Map<String, Object?> Function(GamePackage package) contextBuilder,
    required bool Function()? shouldContinue,
  }) async {
    final preparedResources = resourceManagerFactory?.call() ?? resources;
    final preparedAudio = audioManagerFactory?.call() ?? audio;
    final preparedScriptEngine = scriptEngineFactory?.call() ?? scriptEngine;
    final ownsPreparedResources = preparedResources != resources;
    final ownsPreparedAudio = preparedAudio != null && preparedAudio != audio;

    try {
      await verifier.verify(candidate);
      _ensureContinue(shouldContinue);
      await preparedResources.mount(candidate);
      _ensureContinue(shouldContinue);
      await preparedAudio?.mount(candidate);
      _ensureContinue(shouldContinue);
      await preparedScriptEngine.loadPackage(candidate);
      _ensureContinue(shouldContinue);

      final context = contextBuilder(candidate);
      _ensureContinue(shouldContinue);
      if (!preparedScriptEngine.smokeTest(context)) {
        throw StateError('Lua package smoke_test returned false');
      }

      _ensureContinue(shouldContinue);
      final diff = preparedScriptEngine.init(context);
      _ensureContinue(shouldContinue);
      return PackageActivationPlan(
        package: candidate,
        initialDiff: diff,
        resources: preparedResources,
        scriptEngine: preparedScriptEngine,
        audio: preparedAudio,
      );
    } catch (_) {
      if (ownsPreparedResources) {
        preparedResources.dispose();
      }
      if (ownsPreparedAudio) {
        preparedAudio.dispose();
      }
      rethrow;
    }
  }

  void _ensureContinue(bool Function()? shouldContinue) {
    if (shouldContinue != null && !shouldContinue()) {
      throw StateError('Package activation cancelled');
    }
  }

  bool _containsPackage(List<GamePackage> packages, GamePackage package) {
    return packages.any(
      (item) =>
          item.source == package.source && item.rootPath == package.rootPath,
    );
  }
}

class PackageActivationPlan {
  const PackageActivationPlan({
    required this.package,
    required this.initialDiff,
    required this.resources,
    required this.scriptEngine,
    this.audio,
  });

  final GamePackage package;
  final GameDiff initialDiff;
  final GameResourceManager resources;
  final ScriptEngine scriptEngine;
  final RuntimeAudioManager? audio;
}

class PackageActivationResult {
  const PackageActivationResult({
    required this.package,
    required this.initialDiff,
    required this.resources,
    required this.scriptEngine,
    this.audio,
  });

  factory PackageActivationResult.fromPlan(PackageActivationPlan plan) {
    return PackageActivationResult(
      package: plan.package,
      initialDiff: plan.initialDiff,
      resources: plan.resources,
      scriptEngine: plan.scriptEngine,
      audio: plan.audio,
    );
  }

  final GamePackage package;
  final GameDiff initialDiff;
  final GameResourceManager resources;
  final ScriptEngine scriptEngine;
  final RuntimeAudioManager? audio;
}