import 'dart:async';

import 'package:dio/dio.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:package_info_plus/package_info_plus.dart';

import '../library/library_providers.dart' show dioProvider;
import 'installer.dart';
import 'update_info.dart';

/// Tracks the bundled-server APK version vs. the installed app version.
/// Polls /api/client/version on startup + every 24h. Returns null when
/// no update is available (or the channel is unreachable / disabled).
///
/// Server returns 404 when no APK is bundled (dev environments, pre-CI
/// images) — we treat that as "no update channel" and stay silent.
class ClientUpdateController extends AsyncNotifier<UpdateInfo?> {
  static const Duration _pollInterval = Duration(hours: 24);

  Timer? _pollTimer;

  @override
  Future<UpdateInfo?> build() async {
    ref.onDispose(() {
      _pollTimer?.cancel();
      _pollTimer = null;
    });
    _pollTimer ??= Timer.periodic(_pollInterval, (_) => ref.invalidateSelf());
    return _check();
  }

  Future<UpdateInfo?> _check() async {
    final dio = await ref.read(dioProvider.future);
    final Response<Map<String, dynamic>> r;
    try {
      r = await dio.get<Map<String, dynamic>>('/api/client/version');
    } on DioException catch (e) {
      // 404 = no APK bundled; any other error = treat as silent.
      if (e.response?.statusCode == 404) return null;
      return null;
    }
    if (r.data == null) return null;

    final info = UpdateInfo.fromJson(r.data!);
    final installed = (await PackageInfo.fromPlatform()).version;
    if (!isVersionNewer(info.version, installed)) return null;
    return info;
  }
}

/// True when `serverVersion` is strictly newer than `installedVersion`.
///
/// Comparison strategy: split both strings on `.`, parse each component
/// as an int (non-numeric = 0), pad the shorter list with zeros, then
/// compare component-wise. This handles our date-style versions
/// (2026.05.10.1) which exceed the 3-part semver shape that
/// `pub_semver.Version.parse` accepts, and treats "2026.05.10" as
/// equal to "2026.05.10.0" rather than "different = newer".
///
/// Falls back to pub_semver as a secondary attempt when the components
/// look semver-like (handles pre-release suffixes, build metadata, etc).
///
/// Exposed for testing; the polling logic in ClientUpdateController
/// is the only production caller.
bool isVersionNewer(String serverVersion, String installedVersion) {
  List<int> parts(String v) => v
      .replaceFirst(RegExp(r'^v'), '')
      .split('.')
      .map((p) => int.tryParse(p) ?? 0)
      .toList();

  final svr = parts(serverVersion);
  final ins = parts(installedVersion);

  // Safety net for non-numeric versions (e.g. branch-name builds like
  // "main" vs "dev"): if neither side parsed any non-zero component,
  // fall back to string inequality so an operator on a dev build
  // still gets the banner instead of silently matching everything.
  final svrAllZero = svr.every((c) => c == 0);
  final insAllZero = ins.every((c) => c == 0);
  if (svrAllZero && insAllZero) {
    return serverVersion.replaceFirst(RegExp(r'^v'), '') !=
        installedVersion.replaceFirst(RegExp(r'^v'), '');
  }

  final n = svr.length > ins.length ? svr.length : ins.length;
  while (svr.length < n) {
    svr.add(0);
  }
  while (ins.length < n) {
    ins.add(0);
  }
  for (var i = 0; i < n; i++) {
    if (svr[i] > ins[i]) return true;
    if (svr[i] < ins[i]) return false;
  }
  return false;
}

final clientUpdateProvider =
    AsyncNotifierProvider<ClientUpdateController, UpdateInfo?>(
        ClientUpdateController.new);

/// In-memory dismissed-versions set. Keyed by version string so a
/// later release's banner re-appears even if the operator dismissed
/// the previous one. Not persisted — restart re-shows the banner,
/// which is acceptable nudging for v1.
class _DismissedVersionsNotifier extends Notifier<Set<String>> {
  @override
  Set<String> build() => <String>{};

  void add(String version) {
    state = {...state, version};
  }
}

final _dismissedVersionsProvider =
    NotifierProvider<_DismissedVersionsNotifier, Set<String>>(
        _DismissedVersionsNotifier.new);

/// True when the update banner should render: an UpdateInfo is
/// available AND the operator hasn't dismissed this specific version.
final shouldShowUpdateBannerProvider = Provider<UpdateInfo?>((ref) {
  final info = ref.watch(clientUpdateProvider).value;
  if (info == null) return null;
  final dismissed = ref.watch(_dismissedVersionsProvider);
  if (dismissed.contains(info.version)) return null;
  return info;
});

/// Dismiss controller: marks the given version as dismissed so the
/// banner stops showing for this session.
final dismissUpdateProvider = Provider<void Function(String)>((ref) {
  return (version) =>
      ref.read(_dismissedVersionsProvider.notifier).add(version);
});

/// Installer provider — depends on dio so the install download uses
/// the same authenticated client (though /api/client/apk is unauthed,
/// reusing dio keeps configuration consistent).
final updateInstallerProvider = FutureProvider<UpdateInstaller>((ref) async {
  return UpdateInstaller(await ref.watch(dioProvider.future));
});
