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/report_screen.dart';
import 'package:fuel_tax_tracker/services/app_state.dart';

/// Covers the per-vehicle selection cards on the Reports tab: once a date
/// range is picked, every vehicle with a receipted entry in range starts
/// selected (colored like the "Share" button), tapping one to deselect it
/// drops it from the total (and, by extension, the generated report) and
/// reverts its coloring to a plain unselected card, and deselecting every
/// vehicle shows a distinct "nothing selected" message rather than "no
/// entries in range". There's deliberately no checkbox — selection state is
/// conveyed by color alone.
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));

  // showDatePicker's initial date (when none is set yet) defaults to
  // "now" — dating these entries to "now" too, rather than a fixed date,
  // means just accepting that default on both pickers (below) already
  // covers them, without needing to drive the calendar UI to a specific day.
  final now = DateTime.now();

  FuelEntry entryFor(String vehicleId, String id, double gallons, double cost) => FuelEntry(
        id: id,
        vehicleId: vehicleId,
        date: now,
        gallons: gallons,
        pricePerGallon: cost / gallons,
        totalCost: cost,
        updatedAt: now.toUtc(),
        receiptDriveFileId: 'remote-$id',
      );

  Future<void> pickRange(WidgetTester tester) async {
    await tester.tap(find.text('Start date'));
    await tester.pumpAndSettle();
    await tester.tap(find.text('OK'));
    await tester.pumpAndSettle();

    await tester.tap(find.text('End date'));
    await tester.pumpAndSettle();
    await tester.tap(find.text('OK'));
    await tester.pumpAndSettle();
  }

  Future<AppState> pumpReport(WidgetTester tester) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA, vehicleB]
      ..fuelEntries = [
        entryFor('a', 'e1', 10, 35),
        entryFor('b', 'e2', 20, 70),
      ];

    await tester.pumpWidget(
      ChangeNotifierProvider.value(
        value: appState,
        child: const MaterialApp(home: ReportScreen()),
      ),
    );
    return appState;
  }

  Card cardFor(WidgetTester tester, String vehicleLabel) => tester.widget<Card>(
        find.ancestor(of: find.text(vehicleLabel), matching: find.byType(Card)),
      );

  testWidgets('both vehicles start colored as selected once a range with entries for both is picked',
      (tester) async {
    await pumpReport(tester);
    await pickRange(tester);

    final colorScheme = Theme.of(tester.element(find.text('Truck'))).colorScheme;

    expect(cardFor(tester, 'Truck').color, colorScheme.primary);
    expect(cardFor(tester, 'Van').color, colorScheme.primary);
    expect(find.text('30.000 gal · \$105.00'), findsOneWidget, reason: 'combined total');
  });

  testWidgets('tapping a selected vehicle deselects it (reverts its coloring) and drops it from the total',
      (tester) async {
    await pumpReport(tester);
    await pickRange(tester);

    final colorScheme = Theme.of(tester.element(find.text('Truck'))).colorScheme;

    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();

    expect(find.text('20.000 gal · \$70.00'), findsOneWidget, reason: "only Van's total remains");
    expect(cardFor(tester, 'Truck').color, isNot(colorScheme.primary), reason: 'deselected');
    expect(cardFor(tester, 'Van').color, colorScheme.primary, reason: 'still selected');
  });

  testWidgets('tapping a deselected vehicle again reselects it (restores its coloring)',
      (tester) async {
    await pumpReport(tester);
    await pickRange(tester);

    final colorScheme = Theme.of(tester.element(find.text('Truck'))).colorScheme;

    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();
    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();

    expect(cardFor(tester, 'Truck').color, colorScheme.primary);
    expect(find.text('30.000 gal · \$105.00'), findsOneWidget, reason: 'both counted again');
  });

  testWidgets('deselecting every vehicle shows a distinct "nothing selected" message',
      (tester) async {
    await pumpReport(tester);
    await pickRange(tester);

    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();
    await tester.tap(find.text('Van'));
    await tester.pumpAndSettle();

    expect(
      find.text('No vehicles selected — tap at least one above to build a report.'),
      findsOneWidget,
    );
    expect(find.text('Share'), findsNothing);
    expect(find.text('Print'), findsNothing);
    // The cards themselves stay visible so the user can tap one again.
    expect(find.text('Truck'), findsOneWidget);
    expect(find.text('Van'), findsOneWidget);
  });
}