import 'dart:convert';
import 'dart:io';

import 'package:crypto/crypto.dart' show sha256;
import 'package:flutter_test/flutter_test.dart';
import 'package:http/http.dart' as http;
import 'package:http/testing.dart';
import 'package:observer/models/model_manager.dart';

const _modelBytes = [1, 2, 3, 4, 5, 6, 7, 8];

String _shaHex(List<int> bytes) => sha256.convert(bytes).toString();

/// 分两段到达的下载流（中间 50ms 停顿，供取消测试在下载中触发）
Stream<List<int>> _delayedChunks() async* {
  yield [1, 2, 3, 4];
  await Future<void>.delayed(const Duration(milliseconds: 50));
  yield [5, 6, 7, 8];
}

Map<String, dynamic> _catalog(List<Map<String, dynamic>> models) => {
      'code': 0,
      'message': 'ok',
      'data': {'version': '0.0.2', 'notes': '', 'models': models}
    };

Map<String, dynamic> _item({
  int datasetId = 7,
  String variant = kVariantS,
  String name = '数据集A',
  String version = 'v1.0.0',
  String sha = '',
}) =>
    {
      'datasetId': datasetId,
      'datasetName': name,
      if (variant.isNotEmpty) 'variant': variant,
      'version': version,
      'labels': ['target', 'suspect'],
      'sizeBytes': _modelBytes.length,
      'sha256': sha.isEmpty ? _shaHex(_modelBytes) : sha,
      'downloadUrl': '/download/models/$datasetId/$variant.tflite',
      'coverUrl': '/api/v1/app/cover?namePrefix=DS001',
    };

void main() {
  late Directory root;
  late int downloadHits;

  setUp(() async {
    root = await Directory.systemTemp.createTemp('model-manager-test');
    downloadHits = 0;
  });

  tearDown(() async {
    // refresh 末尾的 autoUpdate 为不阻塞目录刷新的 fire-and-forget：其真实
    // 文件 IO 可能晚于 test body 结束，delete 撞上迟到写入会 Directory not
    // empty → 等待后重试清根（迟到链结束后即可删净）
    for (var i = 0; i < 40; i++) {
      try {
        await root.delete(recursive: true);
        return;
      } on FileSystemException {
        await Future<void>.delayed(const Duration(milliseconds: 10));
      }
    }
    await root.delete(recursive: true);
  });

  ModelManager manager(MockClient client) => ModelManager(
        baseUrl: 'http://test.local',
        client: client,
        rootDir: () async => root,
      );

  MockClient client(List<Map<String, dynamic>> models) =>
      MockClient((req) async {
        if (req.url.path == '/api/v1/app/update') {
          // Response(String) 默认 latin1 编码，中文数据集名会抛异常 → 用 bytes
          return http.Response.bytes(
              utf8.encode(jsonEncode(_catalog(models))), 200);
        }
        if (req.url.path.startsWith('/download/models/')) {
          downloadHits++;
          return http.Response.bytes(_modelBytes, 200);
        }
        return http.Response('not found', 404);
      });

  test('refresh 只拉目录：不下载任何模型，coverUrl 解析正确', () async {
    final m = manager(client([_item()]));
    await m.refresh();

    expect(m.ready, isTrue);
    expect(m.error, isNull);
    expect(downloadHits, 0, reason: 'refresh 不应触发下载');
    expect(m.models, isEmpty, reason: '未激活的模型不应出现在 models');
    expect(m.catalog.length, 1);
    expect(m.catalog.first.coverUrl, '/api/v1/app/cover?namePrefix=DS001');
    expect(m.catalog.first.variant, kVariantS,
        reason: '旧目录无 variant 字段（单档 s）应归为 s');
  });

  test('downloadModel：下载+校验+落盘+自动激活+进度回调', () async {
    final m = manager(client([_item()]));
    await m.refresh();

    final progresses = <double>[];
    final ok = await m.downloadModel(m.catalog.first, onProgress: (r, t) {
      progresses.add(t == 0 ? 0 : r / t);
    });

    expect(ok, isTrue);
    expect(downloadHits, 1);
    expect(m.isDownloaded(7, kVariantS), isTrue);
    expect(m.isActive(7, kVariantS), isTrue, reason: '下载完成应自动使用');
    expect(progresses.last, 1.0);
    expect(m.models.length, 1);
    expect(m.models.first.datasetName, '数据集A');
    expect(m.models.first.variant, kVariantS);

    final dir = Directory('${root.path}/7');
    expect(await File('${dir.path}/model.tflite').exists(), isTrue);
    expect(await File('${dir.path}/labels.json').exists(), isTrue);
    expect(await File('${dir.path}/meta.json').exists(), isTrue);
  });

  test('已下载未激活：setActive 直接使用，不触发下载', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    await m.downloadModel(m.catalog.first);
    await m.setActive(7, kVariantS, false);
    expect(m.isActive(7, kVariantS), isFalse);
    expect(m.models, isEmpty);

    final before = downloadHits;
    await m.setActive(7, kVariantS, true);
    expect(m.isActive(7, kVariantS), isTrue);
    expect(downloadHits, before, reason: '已下载直接使用不应重新下载');
    expect(m.models.length, 1);
  });

  test('版本更新：downloadModel 重新下载', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    await m.downloadModel(m.catalog.first);
    expect(downloadHits, 1);

    final m2 = manager(client([_item(version: 'v2.0.0')]));
    await m2.refresh();
    await m2.downloadModel(m2.catalog.first);
    expect(downloadHits, 2);
    expect(m2.models.first.version, 'v2.0.0');
  });

  test('autoUpdate：已下载模型出新版本，自动补齐文件但不改变激活状态', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    await m.downloadModel(m.catalog.first); // (7, s) v1 下载并激活
    expect(downloadHits, 1);

    // 模拟新会话（新实例 + 服务器目录出 v2）：文件仍在 → autoUpdate 只补文件
    final m2 = manager(client([_item(version: 'v2.0.0')]));
    await m2.refresh();
    for (var i = 0; i < 50 && downloadHits < 2; i++) {
      await Future<void>.delayed(const Duration(milliseconds: 20));
    }

    expect(downloadHits, 2, reason: '新版本应自动补齐（只更新文件不激活）');
    expect(m2.isDownloaded(7, kVariantS), isTrue);
    expect(m2.isActive(7, kVariantS), isFalse,
        reason: '会话制：自动补齐不激活任何模型');
    expect(m2.models, isEmpty, reason: '新会话从仅预览开始');

    // 手动启用后跑的是新版本
    await m2.setActive(7, kVariantS, true);
    expect(m2.models.first.version, 'v2.0.0');
    expect(m2.models.first.bytes, _modelBytes);
  });

  test('sha256 不匹配：重试后失败、不激活、错误可见', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    final bad = _item(version: 'v3.0.0');
    bad['sha256'] = _shaHex([9, 9, 9]);
    final m2 = manager(client([bad]));
    await m2.refresh();

    final ok = await m2.downloadModel(m2.catalog.first);
    expect(ok, isFalse);
    expect(downloadHits, 2, reason: '校验失败应重试一次');
    expect(m2.isDownloaded(7, kVariantS), isFalse);
    expect(m2.isActive(7, kVariantS), isFalse);
    expect(m2.errorOf(7, kVariantS), isNotNull);
  });

  test('会话制：进入新会话清空激活，文件保留，再启用不重新下载', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    await m.downloadModel(m.catalog.first);
    expect(m.isActive(7, kVariantS), isTrue);

    // 每次进入视野页 = 新会话：清空激活与已加载模型（不恢复上次使用的模型）
    m.resetForSession();
    expect(m.isActive(7, kVariantS), isFalse,
        reason: '新会话不自动恢复上次使用的模型');
    expect(m.models, isEmpty);
    expect(m.isDownloaded(7, kVariantS), isTrue, reason: '文件保留：清单显示已下载');

    // 手动启用：直接用本地文件，不重新下载
    final before = downloadHits;
    await m.setActive(7, kVariantS, true);
    expect(m.isActive(7, kVariantS), isTrue);
    expect(m.models.length, 1);
    expect(downloadHits, before, reason: '已下载启用不应重新下载');
  });

  test('目录下线：清理本地并移除激活', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    await m.downloadModel(m.catalog.first);
    expect(await Directory('${root.path}/7').exists(), isTrue);

    final m2 = manager(client([]));
    await m2.refresh();
    expect(m2.models, isEmpty);
    expect(m2.isActive(7, kVariantS), isFalse, reason: '下线的模型应移出激活集');
    expect(await Directory('${root.path}/7').exists(), isFalse,
        reason: '下线的数据集模型目录应被清理');
  });

  test('多模型：只激活其一则只加载其一', () async {
    final m = manager(
        client([_item(datasetId: 7, name: '数据集A'), _item(datasetId: 8, name: '数据集B')]));
    await m.refresh();
    await m.downloadModel(m.catalog.first); // 只下载并激活 7
    expect(m.models.length, 1);
    expect(m.models.first.datasetId, 7);

    await m.downloadModel(m.catalog.last); // 下载 8 自动激活
    expect(m.models.length, 2);
  });

  test('目录接口异常：不覆盖已有就绪状态', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    await m.downloadModel(m.catalog.first);
    expect(m.ready, isTrue);

    final broken = manager(MockClient((_) async => http.Response('boom', 500)));
    await broken.refresh();
    expect(broken.ready, isFalse);
    expect(broken.error, isNotNull);
  });

  test('取消下载：中断后恢复未下载、不记错误', () async {
    final m = manager(MockClient((req) async {
      if (req.url.path == '/api/v1/app/update') {
        return http.Response.bytes(
            utf8.encode(jsonEncode(_catalog([_item()]))), 200);
      }
      if (req.url.path.startsWith('/download/models/')) {
        downloadHits++;
        return http.Response.fromStream(http.StreamedResponse(
            _delayedChunks(), 200,
            contentLength: _modelBytes.length));
      }
      return http.Response('not found', 404);
    }));
    await m.refresh();

    final fut = m.downloadModel(m.catalog.first);
    // 首个分块到达后取消（模拟用户在下载中点取消）
    await Future<void>.delayed(const Duration(milliseconds: 20));
    m.cancelDownload(7, kVariantS);
    final ok = await fut;

    expect(ok, isFalse);
    expect(downloadHits, 1);
    expect(m.isDownloaded(7, kVariantS), isFalse);
    expect(m.isActive(7, kVariantS), isFalse);
    expect(m.progressOf(7, kVariantS), isNull);
    expect(m.errorOf(7, kVariantS), isNull, reason: '取消不记错误');
    expect(await File('${root.path}/7/model.tflite.part').exists(), isFalse,
        reason: '取消后 .part 残留应被清理');
  });

  test('双档位：n 档独立目录 models/7/n/，同物种只运行目标档', () async {
    final m = manager(client(
        [_item(), _item(variant: kVariantN, name: '数据集A', version: 'v1.0.0')]));
    await m.refresh();
    expect(m.catalog.length, 2);

    // 默认目标档 s：下载 s 自动激活并加载
    await m.downloadModel(m.catalog.first); // (7, s)
    expect(m.models.length, 1);
    expect(m.models.first.variant, kVariantS);

    // 同物种已有 s 在使用时下载 n：备好不启用（同物种一次只运行一档）
    final nItem = m.catalog.last;
    expect(nItem.variant, kVariantN);
    await m.downloadModel(nItem);
    expect(m.isDownloaded(7, kVariantN), isTrue);
    expect(m.isActive(7, kVariantN), isFalse, reason: '同物种运行中不叠加启用');
    expect(m.models.length, 1, reason: '备好的 n 档不进加载列表');
    expect(m.models.first.variant, kVariantS);

    // n 档文件在独立子目录（目录键 = 档位），s 档仍为同级文件
    expect(await File('${root.path}/7/n/model.tflite').exists(), isTrue);
    expect(await File('${root.path}/7/n/meta.json').exists(), isTrue);
    expect(await File('${root.path}/7/model.tflite').exists(), isTrue,
        reason: 's 档 legacy 同级布局保持不变');

    // 切目标档：只改偏好，不切换运行中的模型
    final before = downloadHits;
    await m.setMode(kVariantN);
    expect(m.mode, kVariantN);
    expect(downloadHits, before, reason: '切目标档不应触发下载');
    expect(m.isActive(7, kVariantS), isTrue, reason: '切档不改运行状态');
    expect(m.models.length, 1);
    expect(m.models.first.variant, kVariantS);

    // 改用 n：同物种 s 自动停用，n 启用（无需重新下载）
    await m.setActive(7, kVariantN, true);
    expect(m.isActive(7, kVariantS), isFalse, reason: '改用自动停用另一档');
    expect(m.isActive(7, kVariantN), isTrue);
    expect(m.models.length, 1);
    expect(m.models.first.variant, kVariantN);
    expect(m.models.first.datasetName, '数据集A');

    // 切回 s 档恢复 s 模型
    await m.setActive(7, kVariantS, true);
    expect(m.models.length, 1);
    expect(m.models.first.variant, kVariantS);
    expect(m.isActive(7, kVariantN), isFalse);
  });

  test('识别目标档位偏好持久化；激活集为会话态不跨重启', () async {
    final m = manager(client(
        [_item(), _item(variant: kVariantN, name: '数据集A', version: 'v1.0.0')]));
    await m.refresh();
    await m.downloadModel(m.catalog.first); // (7, s) 下载自动激活
    await m.downloadModel(m.catalog.last); // (7, n) 备好不启用
    await m.setMode(kVariantN);

    // 同一 root 新建 manager 模拟重启：目标档偏好持久化，激活集不恢复
    final m2 = manager(client(
        [_item(), _item(variant: kVariantN, name: '数据集A', version: 'v1.0.0')]));
    await m2.refresh();
    expect(m2.mode, kVariantN, reason: '识别目标档位是用户偏好，应持久化');
    expect(m2.isActive(7, kVariantS), isFalse, reason: '激活集不跨会话恢复');
    expect(m2.isActive(7, kVariantN), isFalse);
    expect(m2.models, isEmpty, reason: '重启/新会话从仅预览开始');
    expect(m2.isDownloaded(7, kVariantS), isTrue, reason: '文件保留可即点即用');
    expect(m2.isDownloaded(7, kVariantN), isTrue);
    expect(downloadHits, 2, reason: '重启不应触发下载');
  });

  test('多物种混合档位：改用一物种不影响其它物种的档位', () async {
    final m = manager(client([
      _item(datasetId: 7, name: '数据集A'),
      _item(datasetId: 7, variant: kVariantN, name: '数据集A'),
      _item(datasetId: 8, name: '数据集B'),
      _item(datasetId: 8, variant: kVariantN, name: '数据集B'),
    ]));
    await m.refresh();
    for (final it in m.catalog) {
      await m.downloadModel(it);
    }
    expect(m.models.length, 2);
    expect(m.isActive(7, kVariantS), isTrue);
    expect(m.isActive(8, kVariantS), isTrue);

    // 只把 7 改到 n：8 保持 s —— 两物种不同档位并行运行
    await m.setActive(7, kVariantN, true);
    expect(m.models.length, 2);
    final byId = {for (final b in m.models) b.datasetId: b.variant};
    expect(byId, {7: kVariantN, 8: kVariantS});
    expect(m.isActive(7, kVariantS), isFalse);
    expect(m.isActive(8, kVariantS), isTrue);
    expect(m.isActive(8, kVariantN), isFalse);

    // 7 改回 s
    await m.setActive(7, kVariantS, true);
    expect(m.models.length, 2);
    expect(m.models.firstWhere((b) => b.datasetId == 7).variant, kVariantS);
  });

  test('目标档决定首次下载自动启用：非目标档先落地不启用，目标档落地启用', () async {
    final m = manager(client(
        [_item(), _item(variant: kVariantN, name: '数据集A', version: 'v1.0.0')]));
    await m.refresh();
    await m.setMode(kVariantN); // 目标高性能

    // 先下 s（非目标档）：数据集尚无档位在使用，但不应启用 s
    await m.downloadModel(m.catalog.first);
    expect(m.isDownloaded(7, kVariantS), isTrue);
    expect(m.isActive(7, kVariantS), isFalse, reason: '非目标档落地不自动启用');
    expect(m.models, isEmpty);

    // 目标档 n 落地：自动启用（s 保持备好）
    await m.downloadModel(m.catalog.last);
    expect(m.isActive(7, kVariantN), isTrue);
    expect(m.isActive(7, kVariantS), isFalse);
    expect(m.models.length, 1);
    expect(m.models.first.variant, kVariantN);
  });

  test('单档目录（无目标档条目）：下载即自动启用仅有的档', () async {
    final m = manager(client([_item()])); // 目录只有 s
    await m.refresh();
    await m.setMode(kVariantN); // 目标高性能但目录没有 n
    await m.downloadModel(m.catalog.first);
    expect(m.isActive(7, kVariantS), isTrue, reason: '无目标档时启用仅有的档');
    expect(m.models.length, 1);
  });

  test('数据集仍在但 n 档下线：清理 n 档子目录，保留数据集目录', () async {
    final m = manager(client([_item(variant: kVariantN)]));
    await m.refresh();
    await m.downloadModel(m.catalog.first); // (7, n)
    expect(await File('${root.path}/7/n/model.tflite').exists(), isTrue);

    final m2 = manager(client([_item()])); // 目录只剩 s 档
    await m2.refresh();
    expect(await File('${root.path}/7/n/model.tflite').exists(), isFalse,
        reason: '数据集仍在但 n 档下线：应清理 n 档子目录');
    expect(await Directory('${root.path}/7').exists(), isTrue,
        reason: '数据集仍在（s 档）：不应删整目录');
  });

  test('目录缓存：断网重启后展示上次目录、标出已下载、保留文件且不恢复激活', () async {
    final m = manager(client([_item()]));
    await m.refresh();
    await m.downloadModel(m.catalog.first); // (7, s) 下载并激活
    expect(m.isDownloaded(7, kVariantS), isTrue);

    // 模拟重启 + 断网：同 root 新实例、目录接口失败
    final offline =
        manager(MockClient((_) async => http.Response('boom', 500)));
    await offline.refresh();

    expect(offline.catalog.length, 1, reason: '无网络也应以缓存目录展示模型清单');
    expect(offline.catalog.first.datasetId, 7);
    expect(offline.error, isNotNull, reason: '未拉取成功过仍提示目录刷新失败');
    expect(offline.ready, isFalse);
    expect(offline.isDownloaded(7, kVariantS), isTrue,
        reason: '缓存目录同样扫描本地文件：按钮不误导为未下载');
    expect(offline.isActive(7, kVariantS), isFalse, reason: '会话制：不恢复激活');
    expect(offline.models, isEmpty);
    expect(await Directory('${root.path}/7').exists(), isTrue,
        reason: '离线降级（非权威目录）不得清理本地模型');
  });

  test('目录缓存：网络成功覆盖缓存，再离线读到最近一次目录', () async {
    final m = manager(client([_item(datasetId: 7, name: '数据集A')]));
    await m.refresh(); // 缓存 v1：只有数据集 7 的 s 档

    final m2 = manager(client([
      _item(datasetId: 7, name: '数据集A'),
      _item(datasetId: 7, variant: kVariantN, name: '数据集A'),
      _item(datasetId: 8, name: '数据集B'),
    ]));
    await m2.refresh();
    expect(m2.catalog.length, 3);

    final offline =
        manager(MockClient((_) async => http.Response('boom', 500)));
    await offline.refresh();
    expect(offline.catalog.length, 3, reason: '缓存应为最近一次成功拉取的目录');
    expect(offline.catalog.map((c) => c.datasetId).toSet(), {7, 8});
    expect(
        offline.catalog
            .where((c) => c.datasetId == 7)
            .map((c) => c.variant)
            .toSet(),
        {kVariantS, kVariantN});
  });

  test('升级后断网首启（无缓存文件）：拉取失败不执行任何清理', () async {
    // 旧版本下载的文件直接落盘（无 catalog.json）：升级首启即断网的最坏情况
    final dir = Directory('${root.path}/9');
    await dir.create(recursive: true);
    await File('${dir.path}/model.tflite').writeAsBytes(_modelBytes);
    await File('${dir.path}/meta.json')
        .writeAsString(jsonEncode({'version': 'v1.0.0'}));

    final offline =
        manager(MockClient((_) async => http.Response('boom', 500)));
    await offline.refresh();

    expect(offline.error, isNotNull);
    expect(offline.catalog, isEmpty, reason: '无缓存可兜底：无可展示目录');
    expect(await dir.exists(), isTrue,
        reason: '清理只在网络拉取成功后执行，离线首启不得误删已下载模型');
  });
}