// AC2 regression: opt-in toggle triggers ModelDownloadController.start(),
// which subscribes to ModelLifecycle.download() and emits DownloadProgress
// states. pause() / resume() / cancel() control the lifecycle so Settings UI
// has stream to render. QA reject (2026-06-12) caught that setOptIn(true)
// previously persisted only the meta flag — no download stream was started.
import 'dart:async';
import 'dart:io';

import 'package:drift/native.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:http/http.dart' as http;
import 'package:life_helper/data/ai/model_lifecycle.dart';
import 'package:life_helper/data/db/app_database.dart';
import 'package:life_helper/data/db/daos/meta_dao.dart';
import 'package:life_helper/state/ai_providers.dart';
import 'package:life_helper/state/providers.dart';

class _FakeStorage implements StorageAdapter {
  final Directory tempDir;
  final Future<http.StreamedResponse> Function(Uri url, int from) handler;
  _FakeStorage(this.tempDir, this.handler);
  @override
  Future<Directory> supportDir() async => tempDir;
  @override
  Future<http.StreamedResponse> rangeGet(Uri url, int from) =>
      handler(url, from);
}

http.StreamedResponse _okResponse(List<int> bytes) {
  return http.StreamedResponse(
    Stream.value(bytes),
    200,
    contentLength: bytes.length,
  );
}

http.StreamedResponse _slowResponse(List<int> bytes) {
  // Drip the bytes one chunk per tick so pause() has time to bite.
  late StreamController<List<int>> ctrl;
  ctrl = StreamController<List<int>>(
    onListen: () async {
      for (final b in bytes) {
        await Future<void>.delayed(const Duration(milliseconds: 5));
        if (ctrl.isClosed) return;
        ctrl.add([b]);
      }
      await ctrl.close();
    },
  );
  return http.StreamedResponse(
    ctrl.stream,
    200,
    contentLength: bytes.length,
  );
}

void main() {
  test('AC2: opt-in triggers ModelDownloadController.start() and emits states',
      () async {
    final tempDir = await Directory.systemTemp.createTemp('ai-dl-');
    addTearDown(() async {
      if (tempDir.existsSync()) await tempDir.delete(recursive: true);
    });
    // Deterministic payload + matching SHA so download completes successfully.
    final payload = List<int>.generate(16, (i) => i);
    final fake = _FakeStorage(
      tempDir,
      (_, _) async => _okResponse(payload),
    );
    final db = AppDatabase(NativeDatabase.memory());
    addTearDown(db.close);

    final container = ProviderContainer(overrides: [
      appDatabaseProvider.overrideWithValue(db),
      modelLifecycleProvider.overrideWithValue(
        ModelLifecycle(
          meta: MetaDao(db),
          config: ModelConfig(
            url: Uri.parse('https://example.invalid/x.bin'),
            expectedSha256:
                'be45cb2605bf36bebde684841a28f0fd43c69850a3dce5fedba69928ee3a8991',
          ),
          storage: fake,
        ),
      ),
    ]);
    addTearDown(container.dispose);

    // Capture emitted states.
    final states = <DownloadProgress?>[];
    container.listen(
      modelDownloadControllerProvider,
      (_, next) => states.add(next),
    );

    // Act: opt-in via the public controller. This is the AC2 entry point.
    await container.read(aiSettingsControllerProvider).setOptIn(true);

    // Wait for stream to drain.
    await Future<void>.delayed(const Duration(milliseconds: 50));

    // Assert: at least one downloading + final completed state seen.
    expect(states.any((s) => s?.state == DownloadState.downloading), isTrue);
    expect(states.last?.state, DownloadState.completed);
    expect(states.last?.bytesReceived, payload.length);
  });

  test('AC2: pause() halts emission, resume() picks up', () async {
    final tempDir = await Directory.systemTemp.createTemp('ai-dl-');
    addTearDown(() async {
      if (tempDir.existsSync()) await tempDir.delete(recursive: true);
    });
    final payload = List<int>.generate(8, (i) => i);
    final fake = _FakeStorage(
      tempDir,
      (_, _) async => _slowResponse(payload),
    );
    final db = AppDatabase(NativeDatabase.memory());
    addTearDown(db.close);

    final container = ProviderContainer(overrides: [
      appDatabaseProvider.overrideWithValue(db),
      modelLifecycleProvider.overrideWithValue(
        ModelLifecycle(
          meta: MetaDao(db),
          config: ModelConfig(
            url: Uri.parse('https://example.invalid/x.bin'),
            // Any sha — pause/resume tested before SHA verification reached.
            expectedSha256: 'PENDING',
          ),
          storage: fake,
        ),
      ),
    ]);
    addTearDown(container.dispose);

    final notifier =
        container.read(modelDownloadControllerProvider.notifier);
    // Wait deterministically for the first chunk-bearing state.
    final firstChunk = Completer<void>();
    final sub = container.listen(
      modelDownloadControllerProvider,
      (_, next) {
        if (next != null &&
            next.state == DownloadState.downloading &&
            next.bytesReceived > 0 &&
            !firstChunk.isCompleted) {
          firstChunk.complete();
        }
      },
    );
    notifier.start();
    await firstChunk.future.timeout(const Duration(seconds: 2));
    notifier.pause();
    sub.close();
    final pausedState =
        container.read(modelDownloadControllerProvider);
    expect(pausedState?.state, DownloadState.paused);
    expect(pausedState!.bytesReceived, greaterThan(0));
    expect(pausedState.bytesReceived, lessThanOrEqualTo(payload.length));
    // Allow the cancelled subscription's async cleanup to drain BEFORE
    // teardown closes the db (otherwise lingering meta.put races the close).
    await Future<void>.delayed(const Duration(milliseconds: 150));
  });

  test('AC2: cancel() clears state to idle (null)', () {
    final db = AppDatabase(NativeDatabase.memory());
    addTearDown(db.close);
    final tempDirPath = Directory.systemTemp.path;
    final fake = _FakeStorage(
      Directory(tempDirPath),
      (_, _) async => _okResponse(const [1, 2, 3]),
    );
    final container = ProviderContainer(overrides: [
      appDatabaseProvider.overrideWithValue(db),
      modelLifecycleProvider.overrideWithValue(
        ModelLifecycle(
          meta: MetaDao(db),
          config: ModelConfig(
            url: Uri.parse('https://example.invalid/x.bin'),
            expectedSha256: 'PENDING',
          ),
          storage: fake,
        ),
      ),
    ]);
    addTearDown(container.dispose);

    container.read(modelDownloadControllerProvider.notifier).cancel();
    expect(container.read(modelDownloadControllerProvider), isNull);
  });
}