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

import 'features/connection/startup_screen.dart';
import 'features/connection/server_discovery_screen.dart';
import 'features/connection/login_screen.dart';
import 'features/onboarding/onboarding_screen.dart';
import 'features/shell/main_shell.dart';
import 'features/floorplan/floor_plan_screen.dart';
import 'features/sensors/sensor_list_screen.dart';
import 'features/tags/tag_list_screen.dart';
import 'features/settings/settings_screen.dart';
import 'providers.dart';

// Routes that manage their own auth state — no redirect applied.
const _unauthenticated = {'/', '/connect', '/login', '/onboarding'};

final routerProvider = Provider<GoRouter>((ref) {
  return GoRouter(
    initialLocation: '/',
    redirect: (context, state) {
      final loc = state.matchedLocation;
      if (_unauthenticated.contains(loc)) return null;

      final hasConfig = ref.read(serverConfigProvider) != null;
      final hasToken = ref.read(authTokenProvider) != null;

      if (!hasConfig) return '/connect';
      if (!hasToken) return '/login';
      return null;
    },
    routes: [
      GoRoute(
        path: '/',
        builder: (context, state) => const StartupScreen(),
      ),
      GoRoute(
        path: '/connect',
        builder: (context, state) => const ServerDiscoveryScreen(),
      ),
      GoRoute(
        path: '/login',
        builder: (context, state) => const LoginScreen(),
      ),
      GoRoute(
        path: '/onboarding',
        builder: (context, state) => const OnboardingScreen(),
      ),
      StatefulShellRoute(
        builder: (context, state, shell) => MainShell(shell: shell),
        navigatorContainerBuilder: (context, shell, children) =>
            _SlidingTabSwitcher(index: shell.currentIndex, children: children),
        branches: [
          StatefulShellBranch(routes: [
            GoRoute(
              path: '/floorplan',
              builder: (context, state) => const FloorPlanScreen(),
            ),
          ]),
          StatefulShellBranch(routes: [
            GoRoute(
              path: '/sensors',
              builder: (context, state) => const SensorListScreen(),
            ),
          ]),
          StatefulShellBranch(routes: [
            GoRoute(
              path: '/tags',
              builder: (context, state) => const TagListScreen(),
            ),
          ]),
          StatefulShellBranch(routes: [
            GoRoute(
              path: '/settings',
              builder: (context, state) => const SettingsScreen(),
            ),
          ]),
        ],
      ),
    ],
  );
});

class _SlidingTabSwitcher extends StatefulWidget {
  const _SlidingTabSwitcher({required this.index, required this.children});

  final int index;
  final List<Widget> children;

  @override
  State<_SlidingTabSwitcher> createState() => _SlidingTabSwitcherState();
}

class _SlidingTabSwitcherState extends State<_SlidingTabSwitcher>
    with SingleTickerProviderStateMixin {
  late AnimationController _controller;
  late Animation<double> _animation;
  late int _current;
  int _previous = -1;
  bool _forward = true;

  @override
  void initState() {
    super.initState();
    _current = widget.index;
    _controller = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 220),
      value: 1.0,
    );
    _animation = CurvedAnimation(parent: _controller, curve: Curves.easeInOut);
  }

  @override
  void didUpdateWidget(_SlidingTabSwitcher old) {
    super.didUpdateWidget(old);
    if (widget.index != _current) {
      _previous = _current;
      _forward = widget.index > _current;
      setState(() => _current = widget.index);
      _controller.forward(from: 0);
    }
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _animation,
      builder: (context, _) {
        return Stack(
          fit: StackFit.expand,
          children: List.generate(widget.children.length, (i) {
            if (i == _current) {
              final begin = Offset(_forward ? 1.0 : -1.0, 0);
              final offset = Offset.lerp(begin, Offset.zero, _animation.value)!;
              return FractionalTranslation(
                translation: offset,
                child: TickerMode(enabled: true, child: widget.children[i]),
              );
            }
            if (i == _previous) {
              final end = Offset(_forward ? -1.0 : 1.0, 0);
              final offset = Offset.lerp(Offset.zero, end, _animation.value)!;
              return FractionalTranslation(
                translation: offset,
                child: IgnorePointer(
                  child: TickerMode(enabled: false, child: widget.children[i]),
                ),
              );
            }
            return Offstage(
              offstage: true,
              child: TickerMode(enabled: false, child: widget.children[i]),
            );
          }),
        );
      },
    );
  }
}