/// PhotoThumbnail widget 测试（UI-01 Task 3）。
///
/// 覆盖：无 URL 常驻中性占位（固定宽高比）、加载中立即显示占位（非
/// 转圈，网格布局稳定）、失败替代图（中性块 + 小图标，不显示破图）、
/// 加载成功显示图片（HttpOverrides 注入 1x1 PNG）。
library;

import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:photo_live/app/theme.dart';
import 'package:photo_live/ui/components/photo_thumbnail.dart';

/// 1x1 透明 PNG（真实可解码字节）。
final Uint8List kPngBytes = base64Decode(
  'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJ'
  'AAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg==',
);

void main() {
  Future<void> pumpThumb(
    WidgetTester tester, {
    String? url,
    double aspectRatio = 16 / 9,
  }) {
    return tester.pumpWidget(
      MaterialApp(
        theme: AppTheme.light,
        home: Scaffold(
          body: Center(
            child: PhotoThumbnail(url: url, aspectRatio: aspectRatio),
          ),
        ),
      ),
    );
  }

  testWidgets('url 为 null → 常驻中性占位（固定宽高比）', (tester) async {
    await pumpThumb(tester);
    await tester.pumpAndSettle();

    expect(find.byIcon(Icons.image_outlined), findsOneWidget);
    expect(find.byIcon(Icons.broken_image_outlined), findsNothing);

    // 固定宽高比：视口 800x600 → 800 x 450。
    final size = tester.getSize(find.byType(PhotoThumbnail));
    expect(size.width, 800);
    expect(size.height, 450);
  });

  testWidgets('加载中 → 立即占位；失败 → 中性块 + 小图标（不显示破图）', (tester) async {
    // 测试环境默认 HttpClient 一律 400 → NetworkImage 失败路径。
    await pumpThumb(tester, url: 'http://test.local/cover.jpg');

    // 首帧立即显示占位（非转圈；布局稳定）。
    expect(find.byIcon(Icons.image_outlined), findsOneWidget);

    await tester.pumpAndSettle();
    expect(find.byIcon(Icons.broken_image_outlined), findsOneWidget);
    expect(find.byIcon(Icons.image_outlined), findsNothing);
    expect(find.byType(CircularProgressIndicator), findsNothing);
  });

  testWidgets('加载成功 → 图片显示、占位消失', (tester) async {
    // debug 钩子注入假 HttpClient：以真实 1x1 PNG 字节应答全部 GET
    // （覆盖 flutter_test 默认的网络 400 mock）。测试体内复位——painting
    // 调试变量须在框架不变量校验前归位（addTearDown 时机过晚）。
    debugNetworkImageHttpClientProvider = _FakeHttpClient.new;
    try {
      await pumpThumb(tester, url: 'http://test.local/cover.png');

      // 立即占位（帧未 ready）。
      expect(find.byIcon(Icons.image_outlined), findsOneWidget);

      // 真实网络字节 + dart:ui 解码在真实事件循环中完成（fake-async 需要
      // runAsync 放行）。
      await tester.runAsync(
        () => Future<void>.delayed(const Duration(milliseconds: 200)),
      );
      await tester.pumpAndSettle();

      expect(
        find.byIcon(Icons.image_outlined),
        findsNothing,
        reason: '加载完成后占位消失',
      );
      expect(find.byIcon(Icons.broken_image_outlined), findsNothing);
      final image = tester.widget<Image>(find.byType(Image));
      expect(image.image, isA<NetworkImage>());
    } finally {
      debugNetworkImageHttpClientProvider = null;
    }
  });
}

/// 以真实 1x1 PNG 字节应答全部 GET 的 HttpClient 替身。
class _FakeHttpClient implements HttpClient {
  @override
  bool autoUncompress = true;

  @override
  Future<HttpClientRequest> getUrl(Uri url) async => _FakeHttpClientRequest();

  @override
  dynamic noSuchMethod(Invocation invocation) =>
      throw UnimplementedError('${invocation.memberName}');
}

class _FakeHttpClientRequest implements HttpClientRequest {
  final _FakeHttpHeaders _headers = _FakeHttpHeaders();

  @override
  HttpHeaders get headers => _headers;

  @override
  String get method => 'GET';

  @override
  Future<HttpClientResponse> close() async => _FakeHttpClientResponse();

  @override
  dynamic noSuchMethod(Invocation invocation) =>
      throw UnimplementedError('${invocation.memberName}');
}

class _FakeHttpClientResponse extends Stream<List<int>>
    implements HttpClientResponse {
  late final Stream<List<int>> _stream = Stream<List<int>>.value(kPngBytes);

  @override
  StreamSubscription<List<int>> listen(
    void Function(List<int> event)? onData, {
    Function? onError,
    void Function()? onDone,
    bool? cancelOnError,
  }) => _stream.listen(
    onData,
    onError: onError,
    onDone: onDone,
    cancelOnError: cancelOnError,
  );

  @override
  int get statusCode => HttpStatus.ok;

  @override
  int get contentLength => kPngBytes.length;

  @override
  bool get isRedirect => false;

  @override
  bool get persistentConnection => true;

  @override
  String get reasonPhrase => 'OK';

  @override
  HttpHeaders get headers => _FakeHttpHeaders();

  @override
  HttpClientResponseCompressionState get compressionState =>
      HttpClientResponseCompressionState.notCompressed;

  @override
  List<Cookie> get cookies => <Cookie>[];

  @override
  dynamic noSuchMethod(Invocation invocation) =>
      throw UnimplementedError('${invocation.memberName}');
}

class _FakeHttpHeaders implements HttpHeaders {
  final Map<String, String> _values = <String, String>{};

  @override
  String? value(String field) => _values[field.toLowerCase()];

  @override
  void add(String name, Object value, {bool preserveHeaderCase = false}) {
    _values[name.toLowerCase()] = value.toString();
  }

  @override
  void set(String name, Object value, {bool preserveHeaderCase = false}) {
    _values[name.toLowerCase()] = value.toString();
  }

  @override
  dynamic noSuchMethod(Invocation invocation) =>
      throw UnimplementedError('${invocation.memberName}');
}