import 'dart:typed_data';

import 'package:flutter_test/flutter_test.dart';
import 'package:fuel_tax_tracker/models/fuel_entry.dart';
import 'package:fuel_tax_tracker/models/vehicle.dart';
import 'package:fuel_tax_tracker/services/fuel_report.dart';
import 'package:fuel_tax_tracker/services/fuel_report_pdf.dart';

/// PDF content isn't practically assertable byte-for-byte, so this is a
/// smoke test: every include-images/include-line-items combination should
/// render without throwing and produce a well-formed (non-trivial, valid
/// header) document — the real coverage of what each section *contains*
/// lives in fuel_report_test.dart (data) and is exercised by hand.
void main() {
  final vehicle = Vehicle(
    id: 'v1',
    vin: '1FMPU18L1TLB51349',
    nickname: 'Truck',
    updatedAt: DateTime.utc(2026, 1, 1),
  );

  final entryA = FuelEntry(
    id: 'e1',
    vehicleId: 'v1',
    date: DateTime(2026, 3, 5),
    gallons: 10,
    pricePerGallon: 3.5,
    totalCost: 35,
    updatedAt: DateTime.utc(2026, 3, 5),
    receiptImagePath: '/local/a.jpg',
  );
  final entryB = FuelEntry(
    id: 'e2',
    vehicleId: 'v1',
    date: DateTime(2026, 3, 12),
    gallons: 12,
    pricePerGallon: 3.6,
    totalCost: 43.2,
    updatedAt: DateTime.utc(2026, 3, 12),
    receiptDriveFileId: 'remote-1',
  );

  final report = FuelReport(
    startDate: DateTime(2026, 3, 1),
    endDate: DateTime(2026, 3, 31),
    rows: [
      VehicleReportRow(
        vehicle: vehicle,
        entries: [entryA, entryB],
        totalGallons: 22,
        totalCost: 78.2,
      ),
    ],
  );

  // A 1x1 red pixel PNG — enough for the pdf package to embed as an image.
  final onePixelPng = Uint8List.fromList([
    0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, 0x00, 0x00, 0x00, 0x0D,
    0x49, 0x48, 0x44, 0x52, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01,
    0x08, 0x02, 0x00, 0x00, 0x00, 0x90, 0x77, 0x53, 0xDE, 0x00, 0x00, 0x00,
    0x0C, 0x49, 0x44, 0x41, 0x54, 0x08, 0xD7, 0x63, 0xF8, 0xCF, 0xC0, 0x00,
    0x00, 0x03, 0x01, 0x01, 0x00, 0x18, 0xDD, 0x8D, 0xB0, 0x00, 0x00, 0x00,
    0x00, 0x49, 0x45, 0x4E, 0x44, 0xAE, 0x42, 0x60, 0x82,
  ]);

  Future<void> expectValidPdf(Uint8List bytes) async {
    expect(bytes.length, greaterThan(100));
    expect(String.fromCharCodes(bytes.take(5)), '%PDF-');
  }

  test('summary only (both toggles off)', () async {
    final bytes = await buildFuelReportPdf(report);
    await expectValidPdf(bytes);
  });

  test('with line items, no images', () async {
    final bytes = await buildFuelReportPdf(report, includeLineItems: true);
    await expectValidPdf(bytes);
  });

  test('with images, no line items', () async {
    final bytes = await buildFuelReportPdf(
      report,
      includeReceiptImages: true,
      receiptImages: {'e1': onePixelPng, 'e2': onePixelPng},
    );
    await expectValidPdf(bytes);
  });

  test('with both — line items and images each get their own section, cross-referenced by number',
      () async {
    final bytes = await buildFuelReportPdf(
      report,
      includeLineItems: true,
      includeReceiptImages: true,
      receiptImages: {'e1': onePixelPng, 'e2': onePixelPng},
    );
    await expectValidPdf(bytes);
  });

  test('a report with enough entries to span multiple pages does not throw', () async {
    // Regression test: the page banner/watermark used to be drawn by
    // wrapping the *entire*, unbounded-height body in a Stack, which
    // doesn't paginate — MultiPage threw "Widget won't fit into the page"
    // for anything long enough to need a page break. Enough months/entries
    // here to force at least one break.
    final vehicle2 = Vehicle(id: 'v2', vin: '1GNWK5EG4DR302326', updatedAt: DateTime.utc(2026, 1, 1));
    final manyEntries = <FuelEntry>[];
    for (var month = 1; month <= 12; month++) {
      for (var day = 2; day <= 26; day += 6) {
        final id = 'm$month-d$day';
        manyEntries.add(FuelEntry(
          id: id,
          vehicleId: month.isEven ? 'v1' : 'v2',
          date: DateTime(2026, month, day),
          gallons: 20,
          pricePerGallon: 3.5,
          totalCost: 70,
          updatedAt: DateTime.utc(2026, month, day),
          receiptDriveFileId: 'remote-$id',
        ));
      }
    }
    final bigReport = buildFuelReport(
      vehicles: [vehicle, vehicle2],
      fuelEntries: manyEntries,
      startDate: DateTime(2026, 1, 1),
      endDate: DateTime(2026, 12, 31),
    );

    final bytes = await buildFuelReportPdf(
      bigReport,
      includeLineItems: true,
      includeReceiptImages: true,
      receiptImages: {for (final e in manyEntries) e.id: onePixelPng},
    );
    await expectValidPdf(bytes);
  });

  test('receiptImages missing an entry does not crash — that photo is just skipped', () async {
    final bytes = await buildFuelReportPdf(
      report,
      includeReceiptImages: true,
      receiptImages: {'e1': onePixelPng}, // e2 deliberately missing
    );
    await expectValidPdf(bytes);
  });

  test('empty report (no rows) with all sections on', () async {
    final empty = FuelReport(startDate: DateTime(2026, 1, 1), endDate: DateTime(2026, 1, 31), rows: []);
    final bytes = await buildFuelReportPdf(empty, includeLineItems: true, includeReceiptImages: true);
    await expectValidPdf(bytes);
  });

  test('fuelReportFileName formats the date range', () {
    expect(fuelReportFileName(report), 'fuel-report-20260301-20260331.pdf');
  });
}