// HubClient — typed Dart wrapper around the F∆I gRPC surface.
//
// Holds a single grpc.ClientChannel keyed by [HubEndpoint]. Each
// public method maps onto exactly one RPC on Hub or HubAdmin, so
// callers don't have to know which service hosts which call.

import 'package:grpc/grpc.dart';

import 'generated/fai/v1/hub.pb.dart' as pb;
import 'generated/fai/v1/hub.pbgrpc.dart' as grpc_hub;
import 'generated/google/protobuf/empty.pb.dart' show Empty;

/// Connection coordinates for a hub endpoint.
class HubEndpoint {
  /// Hostname or IP. Defaults to localhost for the canonical
  /// `fai serve` setup.
  final String host;

  /// gRPC port. Defaults to 50051.
  final int port;

  /// When true, use TLS. Phase 1+ will add credential support.
  final bool secure;

  const HubEndpoint({
    this.host = '127.0.0.1',
    this.port = 50051,
    this.secure = false,
  });

  @override
  String toString() => '${secure ? "https" : "http"}://$host:$port';
}

/// Re-exports of generated protobuf types so callers don't have
/// to import the `generated/` directory directly.
typedef CapabilityEntry = pb.CapabilityEntry;
typedef CapabilityList = pb.CapabilityList;
typedef LoggedEvent = pb.LoggedEvent;
typedef PendingApprovalEntry = pb.PendingApprovalEntry;
typedef DeclaredService = pb.DeclaredService;
typedef VerifyEventChainResponse = pb.VerifyEventChainResponse;

/// Typed client for the F∆I Hub gRPC surface. Construct once,
/// reuse for the process lifetime, call [close] on shutdown.
class HubClient {
  final HubEndpoint endpoint;
  final ClientChannel _channel;
  final grpc_hub.HubClient _hub;
  final grpc_hub.HubAdminClient _admin;

  HubClient({this.endpoint = const HubEndpoint()})
      : _channel = ClientChannel(
          endpoint.host,
          port: endpoint.port,
          options: ChannelOptions(
            credentials: endpoint.secure
                ? const ChannelCredentials.secure()
                : const ChannelCredentials.insecure(),
          ),
        ),
        _hub = grpc_hub.HubClient(
          ClientChannel(
            endpoint.host,
            port: endpoint.port,
            options: ChannelOptions(
              credentials: endpoint.secure
                  ? const ChannelCredentials.secure()
                  : const ChannelCredentials.insecure(),
            ),
          ),
        ),
        _admin = grpc_hub.HubAdminClient(
          ClientChannel(
            endpoint.host,
            port: endpoint.port,
            options: ChannelOptions(
              credentials: endpoint.secure
                  ? const ChannelCredentials.secure()
                  : const ChannelCredentials.insecure(),
            ),
          ),
        );

  /// Liveness probe. Returns true when the hub responds with
  /// SERVING. False on any failure (includes connection refused).
  Future<bool> healthy() async {
    try {
      final r = await _hub.health(Empty());
      return r.state == pb.HealthStatus_State.SERVING;
    } catch (_) {
      return false;
    }
  }

  /// All capabilities provided by installed modules.
  Future<List<CapabilityEntry>> listCapabilities() async {
    final r = await _admin.listCapabilities(Empty());
    return r.capabilities;
  }

  /// Recent events from the audit log, newest-first. Pass an
  /// empty `types` list for all event types.
  Future<List<LoggedEvent>> eventLog({
    int limit = 100,
    List<String> types = const [],
  }) async {
    final req = pb.EventLogRequest()
      ..limit = limit
      ..eventTypes.addAll(types);
    final r = await _admin.eventLog(req);
    return r.events;
  }

  /// Pending approvals filtered by status. Defaults to all.
  Future<List<PendingApprovalEntry>> listApprovals({
    List<String> statuses = const [],
    int limit = 100,
  }) async {
    final req = pb.ListApprovalsRequest()
      ..limit = limit
      ..statuses.addAll(statuses);
    final r = await _admin.listApprovals(req);
    return r.entries;
  }

  /// Approve a pending approval. The flow that posted it resumes
  /// on its next polling tick.
  Future<void> approve({
    required String approvalId,
    required String reviewer,
  }) async {
    final req = pb.DecideApprovalRequest()
      ..approvalId = approvalId
      ..reviewer = reviewer
      ..decision = pb.DecideApprovalRequest_Decision.APPROVE;
    await _admin.decideApproval(req);
  }

  /// Reject a pending approval. The flow fails with the supplied
  /// reason on its next polling tick.
  Future<void> reject({
    required String approvalId,
    required String reviewer,
    required String reason,
  }) async {
    final req = pb.DecideApprovalRequest()
      ..approvalId = approvalId
      ..reviewer = reviewer
      ..reason = reason
      ..decision = pb.DecideApprovalRequest_Decision.REJECT;
    await _admin.decideApproval(req);
  }

  /// Walk the event-log hash chain on the hub. Returns total /
  /// verified counts and an `tamperedAt` id (empty when clean).
  Future<VerifyEventChainResponse> verifyEventChain() {
    return _admin.verifyEventChain(Empty());
  }

  /// Host services declared in the operator config. Each entry
  /// is a name + endpoint + tags; reachability is up to the
  /// caller (typically a follow-up HTTP probe).
  Future<List<DeclaredService>> listServices() async {
    final r = await _admin.listServices(Empty());
    return r.services;
  }

  /// Closes the gRPC channel. Idempotent.
  Future<void> close() async {
    await _channel.shutdown();
  }
}