import 'dart:io';

import 'package:dio/dio.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:open_file/open_file.dart';
import 'package:package_info_plus/package_info_plus.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';

enum UpdateStatus {
  idle,
  checking,
  downloading,
  readyToInstall,
  upToDate,
  error,
}

class UpdateState {
  final UpdateStatus status;
  final String? currentVersion;
  final String? latestVersion;
  final String? downloadUrl;
  final double downloadProgress;
  final String? errorMessage;
  final String? apkPath;

  const UpdateState({
    this.status = UpdateStatus.idle,
    this.currentVersion,
    this.latestVersion,
    this.downloadUrl,
    this.downloadProgress = 0.0,
    this.errorMessage,
    this.apkPath,
  });

  UpdateState copyWith({
    UpdateStatus? status,
    String? currentVersion,
    String? latestVersion,
    String? downloadUrl,
    double? downloadProgress,
    String? errorMessage,
    String? apkPath,
  }) =>
      UpdateState(
        status: status ?? this.status,
        currentVersion: currentVersion ?? this.currentVersion,
        latestVersion: latestVersion ?? this.latestVersion,
        downloadUrl: downloadUrl ?? this.downloadUrl,
        downloadProgress: downloadProgress ?? this.downloadProgress,
        errorMessage: errorMessage ?? this.errorMessage,
        apkPath: apkPath ?? this.apkPath,
      );
}

class UpdateNotifier extends Notifier<UpdateState> {
  @override
  UpdateState build() => const UpdateState();

  Future<void> check(String repoUrl) async {
    state = state.copyWith(status: UpdateStatus.checking);
    try {
      final packageInfo = await PackageInfo.fromPlatform();
      final currentVersion =
          '${packageInfo.version}.${packageInfo.buildNumber}';

      final uri = Uri.parse(repoUrl);
      final parts = uri.pathSegments.where((s) => s.isNotEmpty).toList();
      if (parts.length < 2) throw 'Invalid repository URL (need /owner/repo)';
      final apiUrl =
          '${uri.scheme}://${uri.authority}/api/v1/repos/${parts[0]}/${parts[1]}/releases/latest';

      final response = await Dio().get(apiUrl);
      final tagName = (response.data['tag_name'] as String? ?? '').trim();
      final latestVersion =
          tagName.startsWith('v') ? tagName.substring(1) : tagName;

      if (_isNewer(latestVersion, currentVersion)) {
        final assets = (response.data['assets'] as List<dynamic>? ?? [])
            .cast<Map<String, dynamic>>();
        final apk = assets.firstWhere(
          (a) => (a['name'] as String? ?? '').endsWith('.apk'),
          orElse: () => {},
        );
        if (apk.isNotEmpty) {
          final downloadUrl = apk['browser_download_url'] as String?;
          state = state.copyWith(
            currentVersion: currentVersion,
            latestVersion: latestVersion,
            downloadUrl: downloadUrl,
          );
          await _downloadInBackground();
          return;
        }
      }

      state = state.copyWith(
        status: UpdateStatus.upToDate,
        currentVersion: currentVersion,
        latestVersion: latestVersion,
      );
    } catch (e) {
      state = state.copyWith(
        status: UpdateStatus.error,
        errorMessage: e.toString(),
      );
    }
  }

  Future<void> _downloadInBackground() async {
    if (state.downloadUrl == null) return;
    state = state.copyWith(status: UpdateStatus.downloading, downloadProgress: 0);

    try {
      final dir = await _apkDir();
      await _cleanupApks(dir);

      final path = '${dir.path}/fabled_${state.latestVersion}.apk';

      await Dio().download(
        state.downloadUrl!,
        path,
        onReceiveProgress: (received, total) {
          if (total > 0) {
            state = state.copyWith(downloadProgress: received / total);
          }
        },
      );

      final file = File(path);
      if (!await file.exists() || await file.length() == 0) {
        state = state.copyWith(
          status: UpdateStatus.error,
          errorMessage: 'Download failed — file is empty',
        );
        return;
      }

      state = state.copyWith(
        status: UpdateStatus.readyToInstall,
        apkPath: path,
        downloadProgress: 1.0,
      );
    } catch (e) {
      state = state.copyWith(
        status: UpdateStatus.error,
        errorMessage: e.toString(),
      );
    }
  }

  Future<void> install() async {
    final path = state.apkPath;
    if (path == null) return;

    final installPermission = await Permission.requestInstallPackages.status;
    if (!installPermission.isGranted) {
      final result = await Permission.requestInstallPackages.request();
      if (!result.isGranted) {
        state = state.copyWith(
          status: UpdateStatus.error,
          errorMessage:
              'Grant "Install unknown apps" permission for Fabled in Settings, then try again.',
        );
        return;
      }
    }

    try {
      final result = await OpenFile.open(
        path,
        type: 'application/vnd.android.package-archive',
      );

      if (result.type == ResultType.done) {
        state = const UpdateState();
      } else {
        state = state.copyWith(
          status: UpdateStatus.error,
          errorMessage: 'Could not open installer: ${result.message}',
        );
      }
    } catch (e) {
      state = state.copyWith(
        status: UpdateStatus.error,
        errorMessage: e.toString(),
      );
    }
  }

  /// Remove any previously cached APKs.
  Future<void> cleanup() async {
    final dir = await _apkDir();
    await _cleanupApks(dir);
  }

  void dismiss() => state = const UpdateState();

  Future<Directory> _apkDir() async {
    return await getExternalStorageDirectory() ??
        await getTemporaryDirectory();
  }

  Future<void> _cleanupApks(Directory dir) async {
    try {
      final entries = dir.listSync();
      for (final entry in entries) {
        if (entry is File && entry.path.endsWith('.apk')) {
          await entry.delete();
        }
      }
    } catch (_) {}
  }

  bool _isNewer(String latest, String current) {
    try {
      final l = latest.split('.').map(int.parse).toList();
      final c = current.split('.').map(int.parse).toList();
      for (var i = 0; i < l.length && i < c.length; i++) {
        if (l[i] > c[i]) return true;
        if (l[i] < c[i]) return false;
      }
      return l.length > c.length;
    } catch (_) {
      return false;
    }
  }
}

final updateProvider =
    NotifierProvider<UpdateNotifier, UpdateState>(UpdateNotifier.new);