import 'dart:convert';
import 'dart:io';

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:http/http.dart' as http;
import 'package:package_info_plus/package_info_plus.dart';
import 'package:shared_preferences/shared_preferences.dart';

// ─── Configuration ────────────────────────────────────────────────────────────

const _kGiteaBase = 'https://git.steggi-matrix.work';
const _kGiteaRepo = 'steggi/pyramid';
const _kCheckIntervalHours = 4;
const _kPrefLastCheck = 'update_last_check_ms';
const _kPrefSkippedTag = 'update_skipped_tag';

// ─── Data model ───────────────────────────────────────────────────────────────

class UpdateInfo {
  final String tagName;
  final String releaseName;
  final String body;
  final String htmlUrl;
  final String? downloadUrl;
  final (int, int, int) remoteVersion;

  const UpdateInfo({
    required this.tagName,
    required this.releaseName,
    required this.body,
    required this.htmlUrl,
    required this.remoteVersion,
    this.downloadUrl,
  });

  bool get canDownload => downloadUrl != null;
}

// ─── Version helpers ──────────────────────────────────────────────────────────

(int, int, int)? _parseVersion(String raw) {
  final clean = raw.trim().replaceFirst(RegExp(r'^v'), '').split('+').first;
  final parts = clean.split('.');
  if (parts.length < 3) return null;
  try {
    return (int.parse(parts[0]), int.parse(parts[1]), int.parse(parts[2]));
  } catch (_) {
    return null;
  }
}

bool _isNewer((int, int, int) remote, (int, int, int) local) {
  if (remote.$1 != local.$1) return remote.$1 > local.$1;
  if (remote.$2 != local.$2) return remote.$2 > local.$2;
  return remote.$3 > local.$3;
}

String? _findDownloadUrl(List<dynamic> assets) {
  if (assets.isEmpty) return null;
  final list = assets.cast<Map<String, dynamic>>();

  String? pick(bool Function(String name) test) {
    for (final a in list) {
      final name = (a['name'] as String? ?? '').toLowerCase();
      if (test(name)) return a['browser_download_url'] as String?;
    }
    return null;
  }

  if (Platform.isWindows) {
    return pick((n) => n.endsWith('.exe')) ?? pick((n) => n.endsWith('.msix'));
  }
  if (Platform.isAndroid) {
    return pick((n) => n.endsWith('.apk'));
  }
  return null;
}

// ─── Fetch ────────────────────────────────────────────────────────────────────

Future<UpdateInfo?> _fetchLatestRelease() async {
  try {
    final uri = Uri.parse(
      '$_kGiteaBase/api/v1/repos/$_kGiteaRepo/releases?limit=1',
    );
    final response = await http
        .get(uri, headers: {'Accept': 'application/json'})
        .timeout(const Duration(seconds: 10));

    if (response.statusCode != 200) return null;

    final list = json.decode(response.body) as List<dynamic>;
    if (list.isEmpty) return null;
    final data = list.first as Map<String, dynamic>;

    final tagName = data['tag_name'] as String? ?? '';
    if (tagName.isEmpty) return null;

    final remoteVer = _parseVersion(tagName);
    if (remoteVer == null) return null;

    final assets = (data['assets'] as List<dynamic>?) ?? [];
    final downloadUrl = _findDownloadUrl(assets);

    return UpdateInfo(
      tagName: tagName,
      releaseName: data['name'] as String? ?? tagName,
      body: data['body'] as String? ?? '',
      htmlUrl: '$_kGiteaBase/$_kGiteaRepo/releases/tag/$tagName',
      remoteVersion: remoteVer,
      downloadUrl: downloadUrl,
    );
  } catch (_) {
    return null;
  }
}

// ─── Provider ─────────────────────────────────────────────────────────────────

final updateInfoProvider = FutureProvider<UpdateInfo?>((ref) async {
  // iOS: can't sideload, skip
  if (Platform.isIOS || Platform.isMacOS || Platform.isLinux) return null;

  final prefs = await SharedPreferences.getInstance();
  final lastCheckMs = prefs.getInt(_kPrefLastCheck) ?? 0;
  final elapsed = DateTime.now().millisecondsSinceEpoch - lastCheckMs;
  if (elapsed < _kCheckIntervalHours * 3600 * 1000) return null;

  await prefs.setInt(_kPrefLastCheck, DateTime.now().millisecondsSinceEpoch);

  final remote = await _fetchLatestRelease();
  if (remote == null) return null;

  final info = await PackageInfo.fromPlatform();
  final localVer = _parseVersion(info.version);
  if (localVer == null) return null;

  if (!_isNewer(remote.remoteVersion, localVer)) return null;

  final skipped = prefs.getString(_kPrefSkippedTag);
  if (skipped == remote.tagName) return null;

  return remote;
});

// ─── Actions ──────────────────────────────────────────────────────────────────

Future<void> skipUpdateVersion(String tagName) async {
  final prefs = await SharedPreferences.getInstance();
  await prefs.setString(_kPrefSkippedTag, tagName);
}

Future<void> resetUpdateCheckTimer() async {
  final prefs = await SharedPreferences.getInstance();
  await prefs.remove(_kPrefLastCheck);
}