// Scriptable HubService fake — the hermeticity backbone of the
// widget suites. Injected via HubService.debugSetInstance so the
// pages under test never open a real gRPC channel: test results
// must not depend on whether a hub happens to listen on the
// operator's machine (the a11y suite's old flake came exactly
// from that coupling).
//
// Behaviour model:
//   * Default: a healthy, empty hub — every read succeeds with
//     zero modules / flows / events / approvals / runs.
//   * `failWith(error, only: {...})` scripts per-RPC failures —
//     e.g. UNIMPLEMENTED for one method to simulate an older hub,
//     or `failAll` for a hub that is gone entirely.
//   * `FakeGrpcError` mirrors package:grpc's GrpcError shape
//     (`.code` / `.message`) because production code duck-types
//     on those fields (friendly_error.dart, runs classification).
//
// Any HubService member the fake does not implement lands in
// noSuchMethod, which records the name in [missing] and throws —
// so a sweep test can fail with the exact list of members that
// still need a default instead of silently rendering error states.

import 'dart:ui';

import 'package:flutter_test/flutter_test.dart';

import 'package:chain_client_sdk/chain_client_sdk.dart'
    show HubEndpoint, HubProbeResult, StoreSource;
import 'package:chain_studio/data/hub.dart';

/// Duck-typed stand-in for `GrpcError`: production code reads
/// `.code` (int) and `.message` (String?) off thrown objects.
class FakeGrpcError implements Exception {
  final int code;
  final String? message;
  const FakeGrpcError(this.code, [this.message]);

  @override
  String toString() => 'gRPC Error (code: $code, message: $message)';
}

/// Shorthands for the codes the scenarios use.
const kUnimplemented = FakeGrpcError(12, 'method not implemented');
const kUnavailable = FakeGrpcError(14, 'connection refused');
const kDetachedOff = FakeGrpcError(
  9,
  'detached invocations are not enabled — set detached.enabled: true '
  'in the operator config',
);

class FakeHubService extends Fake implements HubService {
  /// Error thrown by every RPC-backed method when set.
  Object? failAll;

  /// Per-method errors, keyed by method name (e.g.
  /// 'listDetachedRuns'). Wins over [failAll] absence; [failAll]
  /// wins overall when both are set? No — per-method is checked
  /// first so a scenario can single out one RPC.
  final Map<String, Object> failures = {};

  /// Members hit without an implementation (see header).
  final Set<String> missing = {};

  /// Scriptable bits of otherwise-default answers.
  bool detachedEnabled = false;
  bool probeServing = true;

  /// Approvals returned by [listApprovalsRecords], filtered by the
  /// requested statuses so the pending / history tabs each see the
  /// right slice. Empty by default (healthy-empty inbox).
  List<ApprovalRecord> approvals = const [];

  void failWith(Object error, {Set<String>? only}) {
    if (only == null) {
      failAll = error;
    } else {
      for (final m in only) {
        failures[m] = error;
      }
    }
  }

  T _guard<T>(String method, T Function() value) {
    final err = failures[method] ?? failAll;
    if (err != null) throw err;
    return value();
  }

  Future<T> _async<T>(String method, T Function() value) async =>
      _guard(method, value);

  @override
  dynamic noSuchMethod(Invocation invocation) {
    missing.add(invocation.memberName.toString());
    return super.noSuchMethod(invocation);
  }

  // ── Connection / endpoint plumbing (never fails) ─────────────

  @override
  String get endpointLabel => 'http://127.0.0.1:65535';

  @override
  HubEndpoint get currentEndpoint =>
      HubEndpoint(host: '127.0.0.1', port: 65535, secure: false);

  @override
  Future<void> loadPersistedEndpoint() async {}

  @override
  Future<void> reconnect(
    HubEndpoint endpoint, {
    Object? authToken = const Object(),
    bool persist = true,
  }) async {}

  @override
  Future<void> reloadAuthToken() async {}

  @override
  Future<bool> reloadAuthTokenIfChanged() async => false;

  @override
  void debugResetChannel() {}

  @override
  Future<ThemeModeValue> loadThemeMode() async => ThemeModeValue.system;

  @override
  Future<void> saveThemeMode(ThemeModeValue mode) async {}

  @override
  Future<Locale> loadLocale() async => const Locale('de');

  @override
  Future<void> saveLocale(Locale locale) async {}

  @override
  String? get connectedChannelName => 'local';

  // ── Health ───────────────────────────────────────────────────

  @override
  Future<bool> healthy() =>
      _async('healthy', () => probeServing && failAll == null);

  @override
  Future<HubProbeResult> probeHealth() async {
    if (failAll != null) return HubProbeResult.unreachable;
    return probeServing ? HubProbeResult.serving : HubProbeResult.notServing;
  }

  // ── Read paths the pages hit (healthy-empty defaults) ────────

  @override
  Future<String> hubVersion() => _async('hubVersion', () => '0.0.0-fake');

  @override
  Future<List<ModuleSummary>> listModules() =>
      _async('listModules', () => const []);

  @override
  Future<List<CapabilityInfo>> allCapabilities() =>
      _async('allCapabilities', () => const []);

  @override
  Future<List<StoreSource>> listStores() =>
      _async('listStores', () => const []);

  @override
  Future<List<StoreItem>> searchStore({
    String query = '',
    String category = '',
    String tag = '',
    String status = '',
    int limit = 50,
  }) => _async('searchStore', () => const []);

  @override
  Future<List<String>> installedVersions(String moduleName) =>
      _async('installedVersions', () => const []);

  @override
  Future<List<SavedFlow>> listFlows() => _async('listFlows', () => const []);

  @override
  Future<List<ProjectRef>> listProjects() =>
      _async('listProjects', () => const []);

  @override
  Stream<AuditEvent> streamEvents({
    int backfill = 0,
    List<String> types = const [],
    String project = '',
  }) {
    final err = failures['streamEvents'] ?? failAll;
    if (err != null) return Stream.error(err);
    return const Stream.empty();
  }

  @override
  Future<List<AuditEvent>> recentEvents({
    int limit = 50,
    List<String> types = const [],
    String project = '',
  }) => _async('recentEvents', () => const []);

  @override
  Future<List<PendingApproval>> pendingApprovals({String project = ''}) =>
      _async('pendingApprovals', () => const []);

  @override
  Future<List<ApprovalRecord>> listApprovalsRecords({
    List<String> statuses = const [],
    int limit = 200,
    String project = '',
  }) => _async(
    'listApprovalsRecords',
    () => statuses.isEmpty
        ? approvals
        : approvals.where((a) => statuses.contains(a.status)).toList(),
  );

  @override
  Future<({List<DetachedRun> runs, bool enabled})> listDetachedRuns({
    String project = '',
  }) => _async('listDetachedRuns', () => (runs: const <DetachedRun>[], enabled: detachedEnabled));

  @override
  Future<List<Satellite>> listSatellites() =>
      _async('listSatellites', () => const []);

  @override
  Future<SystemAiStatus> systemAiStatus() => _async(
    'systemAiStatus',
    () => const SystemAiStatus(
      enabled: false,
      provider: '',
      endpoint: '',
      model: '',
      privacyMode: 'off',
      apiKeyEnv: '',
    ),
  );

  @override
  Future<ChannelStatusSnapshot> channelStatus() => _async(
    'channelStatus',
    () => const ChannelStatusSnapshot(
      active: 'local',
      channels: [
        ChannelInfo(
          name: 'local',
          port: 65535,
          running: true,
          endpoint: 'http://127.0.0.1:65535',
        ),
      ],
    ),
  );

  @override
  Future<List<McpClientInfo>> listMcpClients() =>
      _async('listMcpClients', () => const []);

  @override
  Future<List<N8nEndpointInfo>> listN8nEndpoints() =>
      _async('listN8nEndpoints', () => const []);

  /// Scriptable update hint for the shell banner test.
  UpdateStatus? updateHint;

  @override
  Future<UpdateStatus?> checkHubUpdate() async => updateHint;

  @override
  Future<bool> declareService({
    required String name,
    required String endpoint,
    String healthPath = '',
    List<String> tags = const [],
  }) => _async('declareService', () => true);

  @override
  Future<DoctorSnapshot> doctor() => _async(
    'doctor',
    () => const DoctorSnapshot(
      moduleCount: 0,
      capabilityCount: 0,
      pendingApprovals: 0,
      eventChainTotal: 0,
      eventChainVerified: 0,
      eventChainTamperedAt: null,
      services: [],
      update: UpdateStatus(
        channel: 'stable',
        localVersion: '0.0.0-fake',
        latestVersion: '0.0.0-fake',
        updateAvailable: false,
        manifestReachable: true,
      ),
      paths: DaemonPathsSnapshot(
        logPath: '',
        dbPath: '',
        modulesDir: '',
        flowsDir: '',
        configPath: '',
        pidPath: '',
      ),
    ),
  );
}

/// Install a [FakeHubService] for the duration of the current
/// test and restore a real instance afterwards.
FakeHubService installFakeHub() {
  final fake = FakeHubService();
  HubService.debugSetInstance(fake);
  addTearDown(() => HubService.debugSetInstance(null));
  return fake;
}