/// UI-01: a persistent 4-tab shell (`StatefulShellRoute`), replacing the push/pop stack
/// rooted at Record that this app used through v3. Each branch keeps its own navigator,
/// so pushing Trip Detail from Rides -- or the route planner from Plan -- doesn't
/// disturb the other tabs' state or the active tab index.
library;

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

import 'app_shell.dart';
import 'detail/trip_detail_screen.dart';
import 'record/record_screen.dart';
import 'routes/route_planner_screen.dart';
import 'routes/routes_list_screen.dart';
import 'settings/settings_screen.dart';
import 'trips/trips_screen.dart';

abstract final class Routes {
  static const record = '/';
  static const trips = '/rides';
  static const tripDetail = '/rides/:tripId';
  static const settings = '/settings';
  static const routes = '/plan';
  static const routePlanner = '/plan/:routeId';

  static String detailFor(int tripId) => '/rides/$tripId';
  static String plannerFor(int routeId) => '/plan/$routeId';
}

GoRouter buildRouter() => GoRouter(
  initialLocation: Routes.record,
  routes: [
    StatefulShellRoute.indexedStack(
      builder: (context, state, navigationShell) =>
          AppShell(navigationShell: navigationShell),
      branches: [
        // Branch 0: Map. The Record screen, headerless -- see AppShell's doc comment.
        StatefulShellBranch(
          routes: [
            GoRoute(path: Routes.record, builder: (context, state) => const RecordScreen()),
          ],
        ),
        // Branch 1: Rides. Trip Detail pushes within this branch's own navigator.
        StatefulShellBranch(
          routes: [
            GoRoute(
              path: Routes.trips,
              builder: (context, state) => TripsScreen(
                onOpenTrip: (id) => context.push(Routes.detailFor(id)),
              ),
              routes: [
                GoRoute(
                  path: ':tripId',
                  builder: (context, state) {
                    final id = int.tryParse(state.pathParameters['tripId'] ?? '');
                    if (id == null) return const _NotFound();
                    return TripDetailScreen(tripId: id, onBack: () => context.pop());
                  },
                ),
              ],
            ),
          ],
        ),
        // Branch 2: Plan. The route planner pushes within this branch's own navigator.
        StatefulShellBranch(
          routes: [
            GoRoute(
              path: Routes.routes,
              builder: (context, state) => RoutesListScreen(
                onOpenRoute: (id) => context.push(Routes.plannerFor(id)),
              ),
              routes: [
                GoRoute(
                  path: ':routeId',
                  builder: (context, state) {
                    final id = int.tryParse(state.pathParameters['routeId'] ?? '');
                    if (id == null) return const _NotFound();
                    return RoutePlannerScreen(routeId: id, onBack: () => context.pop());
                  },
                ),
              ],
            ),
          ],
        ),
        // Branch 3: Settings.
        StatefulShellBranch(
          routes: [
            GoRoute(
              path: Routes.settings,
              builder: (context, state) => const SettingsScreen(),
            ),
          ],
        ),
      ],
    ),
  ],
  errorBuilder: (context, state) => const _NotFound(),
);

class _NotFound extends StatelessWidget {
  const _NotFound();

  @override
  Widget build(BuildContext context) => Scaffold(
    body: Center(
      child: TextButton(
        onPressed: () => context.canPop() ? context.pop() : context.go(Routes.record),
        child: const Text('That ride could not be found. Back'),
      ),
    ),
  );
}