import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../../main.dart';
import 'package:go_router/go_router.dart';

class SplashScreen extends ConsumerStatefulWidget {
  const SplashScreen({super.key});
  @override
  ConsumerState<SplashScreen> createState() => _SplashState();
}

class _SplashState extends ConsumerState<SplashScreen>
    with SingleTickerProviderStateMixin {
  late final AnimationController _ac = AnimationController(
      vsync: this, duration: const Duration(milliseconds: 600))
    ..forward();

  @override
  void initState() {
    super.initState();
    _boot();
  }

  Future<void> _boot() async {
    final tokens = ref.read(tokenStorageProvider);
    final access = await tokens.access;
    var authed = _isJwtValid(access);
    if (!authed) {
      await tokens.refreshAccess();
      authed = _isJwtValid(await tokens.access);
    }
    if (!mounted) return;
    await Future.delayed(
        const Duration(milliseconds: 300)); // kleines Fade-Finish
    if (!mounted) return;
    context.go(authed ? '/igel' : '/login');
  }

  bool _isJwtValid(String? jwt) {
    if (jwt == null || jwt.isEmpty) return false;
    try {
      final parts = jwt.split('.');
      if (parts.length != 3) return false;
      final payload = jsonDecode(
              utf8.decode(base64Url.decode(base64Url.normalize(parts[1]))))
          as Map<String, dynamic>;
      final exp = (payload['exp'] as num?)?.toInt();
      final now = DateTime.now().millisecondsSinceEpoch ~/ 1000;
      return exp == null ? true : now < exp - 15;
    } catch (_) {
      return false;
    }
  }

  @override
  void dispose() {
    _ac.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final t = CurvedAnimation(parent: _ac, curve: Curves.easeOut);
    return Scaffold(
      body: FadeTransition(
        opacity: t,
        child: const Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Icon(Icons.pets, size: 96),
              SizedBox(height: 12),
              CircularProgressIndicator(),
            ],
          ),
        ),
      ),
    );
  }
}