import 'dart:async';
import 'dart:typed_data';
import 'dart:ui' as ui;

import 'package:flutter_test/flutter_test.dart';
import 'package:http/http.dart' as http;
import 'package:http/testing.dart';

import 'package:dmc_app/domain/waypoint/flat_waypoint_list.dart';
import 'package:dmc_app/services/terrain/terrain_service.dart';

/// Baut eine 256x256-PNG, deren Pixel alle dieselbe Terrarium-kodierte
/// Hoehe tragen - reicht aus, um die komplette Pipeline (HTTP-Fetch,
/// PNG-Decodierung, Terrarium-Formel, Relativierung) zu pruefen, ohne dass
/// die exakte Pixelposition innerhalb der Kachel eine Rolle spielt.
Future<Uint8List> _uniformElevationPng(int r, int g, int b) async {
  const size = 256;
  final pixels = Uint8List(size * size * 4);
  for (var i = 0; i < size * size; i++) {
    pixels[i * 4] = r;
    pixels[i * 4 + 1] = g;
    pixels[i * 4 + 2] = b;
    pixels[i * 4 + 3] = 255;
  }
  final completer = Completer<ui.Image>();
  ui.decodeImageFromPixels(
    pixels,
    size,
    size,
    ui.PixelFormat.rgba8888,
    completer.complete,
  );
  final image = await completer.future;
  final byteData = await image.toByteData(format: ui.ImageByteFormat.png);
  return byteData!.buffer.asUint8List();
}

void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  const waypoints = [
    Waypoint(lat: 48.1351, lon: 11.5820, altitudeM: 60, speedMs: 15, catchRadiusM: 60),
    Waypoint(lat: 48.1360, lon: 11.5830, altitudeM: 60, speedMs: 15, catchRadiusM: 60),
  ];

  test('fetchProfile decodiert die Terrarium-PNG in relative Hoehen', () async {
    // R=128, G=100, B=0 -> (128*256 + 100 + 0/256) - 32768 = 100.
    final pngBytes = await _uniformElevationPng(128, 100, 0);
    final client = MockClient((request) async => http.Response.bytes(pngBytes, 200));
    final service = TerrainService(client: client);

    final profile = await service.fetchProfile(waypoints);

    expect(profile, isNotNull);
    expect(profile!.points, isNotEmpty);
    // Gleichfoermiges Gelaende: jedes Sample hat dieselbe absolute Hoehe
    // wie das erste gueltige -> relative Hoehe ueberall 0.
    for (final p in profile.points) {
      expect(p.elevationRelM, isNotNull);
      expect(p.elevationRelM, closeTo(0, 0.01));
    }
    expect(profile.points.first.distanceM, 0);
  });

  test('fetchProfile liefert null, wenn keine Kachel geladen werden kann', () async {
    final client = MockClient((request) async => http.Response('', 500));
    final service = TerrainService(client: client);

    expect(await service.fetchProfile(waypoints), isNull);
  });

  test('fetchProfile liefert null fuer eine einzelne Wegpunkt-Route', () async {
    final client = MockClient((request) async => http.Response('', 500));
    final service = TerrainService(client: client);

    expect(await service.fetchProfile([waypoints.first]), isNull);
  });
}