import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:provider/provider.dart';

import 'package:fuel_tax_tracker/models/fuel_entry.dart';
import 'package:fuel_tax_tracker/models/vehicle.dart';
import 'package:fuel_tax_tracker/screens/vehicle_detail_screen.dart';
import 'package:fuel_tax_tracker/services/app_state.dart';

/// Covers the "modern navigation" swipe added to the single-vehicle
/// receipt page: it's a PageView over every vehicle, starting on whichever
/// one was tapped — sliding left/right moves to the next/previous vehicle,
/// same as swiping between MainShell's bottom-nav tabs.
void main() {
  final vehicleA = Vehicle(id: 'a', vin: 'VINAAAAAAAAAAAAAA', nickname: 'Truck', updatedAt: DateTime.utc(2026, 1, 1));
  final vehicleB = Vehicle(id: 'b', vin: 'VINBBBBBBBBBBBBBB', nickname: 'Van', updatedAt: DateTime.utc(2026, 1, 1));
  final vehicleC = Vehicle(id: 'c', vin: 'VINCCCCCCCCCCCCCC', nickname: 'Sedan', updatedAt: DateTime.utc(2026, 1, 1));

  Future<void> pumpDetail(WidgetTester tester, AppState appState, String vehicleId) async {
    await tester.pumpWidget(
      ChangeNotifierProvider.value(
        value: appState,
        child: MaterialApp(home: VehicleDetailScreen(vehicleId: vehicleId)),
      ),
    );
  }

  testWidgets('starts on the requested vehicle, not necessarily the first in the list',
      (tester) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA, vehicleB, vehicleC];

    await pumpDetail(tester, appState, 'b');

    expect(find.widgetWithText(AppBar, 'Van'), findsOneWidget);
  });

  testWidgets('a right-to-left swipe advances to the next vehicle', (tester) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA, vehicleB, vehicleC];

    await pumpDetail(tester, appState, 'a');
    expect(find.widgetWithText(AppBar, 'Truck'), findsOneWidget);

    await tester.fling(find.byType(PageView), const Offset(-400, 0), 1000);
    await tester.pumpAndSettle();

    expect(find.widgetWithText(AppBar, 'Van'), findsOneWidget);
  });

  testWidgets('a left-to-right swipe goes back to the previous vehicle', (tester) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA, vehicleB, vehicleC];

    await pumpDetail(tester, appState, 'c');
    expect(find.widgetWithText(AppBar, 'Sedan'), findsOneWidget);

    await tester.fling(find.byType(PageView), const Offset(400, 0), 1000);
    await tester.pumpAndSettle();

    expect(find.widgetWithText(AppBar, 'Van'), findsOneWidget);
  });

  testWidgets('swiping does not go past the last vehicle', (tester) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA, vehicleB];

    await pumpDetail(tester, appState, 'b');

    await tester.fling(find.byType(PageView), const Offset(-400, 0), 1000);
    await tester.pumpAndSettle();

    expect(find.widgetWithText(AppBar, 'Van'), findsOneWidget, reason: 'stayed on the last page');
  });

  testWidgets('a single vehicle has nothing to swipe to and just shows itself', (tester) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA];

    await pumpDetail(tester, appState, 'a');

    expect(find.widgetWithText(AppBar, 'Truck'), findsOneWidget);
  });

  testWidgets('shows an estimated fuel refund next to price/gal when the setting is on',
      (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'a',
      date: DateTime(2026, 5, 14, 9, 30),
      gallons: 10,
      pricePerGallon: 3.5,
      totalCost: 35,
      updatedAt: DateTime.utc(2026, 5, 14),
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA]
      ..fuelEntries = [entry]
      ..showEstimatedFuelRefund = true;

    await pumpDetail(tester, appState, 'a');

    // 10 gal * $0.125/gal = $1.25.
    expect(find.textContaining('\$3.50/gal  ·  Est. \$1.25'), findsOneWidget);
  });

  testWidgets('shows no estimated fuel refund when the setting is off (default)', (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'a',
      date: DateTime(2026, 5, 14, 9, 30),
      gallons: 10,
      pricePerGallon: 3.5,
      totalCost: 35,
      updatedAt: DateTime.utc(2026, 5, 14),
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA]
      ..fuelEntries = [entry];

    await pumpDetail(tester, appState, 'a');

    expect(find.textContaining('Est. \$'), findsNothing);
  });
}