// Raw FFI bindings for the C ABI in native/src/ffi.rs: one lookup per entry
// point, no logic. Handles are opaque pointers at this layer; the typed
// methods accept plain addresses (ints) so they cross isolates freely.
// Every string this ABI returns is freed with smolFreeString — Dart's GC
// runs no Rust destructor.

import "dart:convert";
import "dart:ffi";
import "dart:typed_data";

import "package:ffi/ffi.dart";

import "package:smol_mail/native/library.dart";

// Stable error codes, mirrored from native/src/ffi.rs. The space is split
// like the wire's: 0-10 are protocol status codes, verbatim, and local
// failures live from 64 up, so a recovery path can be picked by range —
// RATE_LIMITED (8) retries on the live session it arrived on, while
// HANDSHAKE_REFUSED (71) means there is no session to retry on.
const smolOk = 0;
const smolMalformed = 1;
const smolBadVersion = 2;
const smolUnknownUser = 3;
const smolAuthRequired = 4;
const smolAuthFailed = 5;
const smolQuotaExceeded = 6;
const smolTooLarge = 7;
const smolRateLimited = 8;
const smolNotPermitted = 9;
const smolInternalError = 10;
/// Unassigned status byte; the raw byte is in the payload's "status".
const smolUnknownStatus = 11;

const smolNotPinned = 64;
const smolPinMismatch = 65;
const smolKeyChanged = 66;
const smolNotRegistered = 67;
const smolChainLimit = 68;
const smolSchemaVersion = 69;
const smolUnreachable = 70;
const smolHandshakeRefused = 71;
const smolStorage = 72;
const smolNoise = 73;
const smolIo = 74;
const smolOther = 75;
const smolPanic = 76;

/// What a failed native call reports: the decision code plus the structured
/// payload the ABI carries (host, known, offered — keys as base32).
class NativeSmolException implements Exception {
  final int code;
  final String message;
  final Map<String, dynamic> details;

  const NativeSmolException(this.code, this.message, this.details);

  @override
  String toString() => message;
}

/// The raw ABI. Opened per isolate — handles are plain addresses, so the
/// same store can be called from any isolate, which is what the async
/// wrapper relies on.
class SmolFfi {
  SmolFfi._(this._lib);

  final DynamicLibrary _lib;

  static SmolFfi? _cached;

  factory SmolFfi.open() => _cached ??= SmolFfi._(openSmolLibrary());

  Pointer<Void> _h(int address) => Pointer<Void>.fromAddress(address);

  late final Pointer<Utf8> Function() _lastError = _lib
      .lookupFunction<Pointer<Utf8> Function(), Pointer<Utf8> Function()>(
          "smol_last_error");
  late final void Function(Pointer<Utf8>) _freeString = _lib.lookupFunction<
      Void Function(Pointer<Utf8>),
      void Function(Pointer<Utf8>)>("smol_free_string");

  late final Pointer<Void> Function(Pointer<Utf8>) _storeOpen = _lib
      .lookupFunction<Pointer<Void> Function(Pointer<Utf8>),
          Pointer<Void> Function(Pointer<Utf8>)>("smol_store_open");
  late final Pointer<Void> Function() _storeMemory = _lib.lookupFunction<
      Pointer<Void> Function(),
      Pointer<Void> Function()>("smol_store_memory");
  late final void Function(Pointer<Void>) _storeFree = _lib.lookupFunction<
      Void Function(Pointer<Void>),
      void Function(Pointer<Void>)>("smol_store_free");
  late final Pointer<Void> Function(Pointer<Uint8>, int) _accountNew = _lib
      .lookupFunction<
          Pointer<Void> Function(Pointer<Uint8>, Uint32),
          Pointer<Void> Function(
              Pointer<Uint8>, int)>("smol_account_new");
  late final void Function(Pointer<Void>) _accountFree = _lib.lookupFunction<
      Void Function(Pointer<Void>),
      void Function(Pointer<Void>)>("smol_account_free");
  late final Pointer<Utf8> Function(Pointer<Void>) _accountPk = _lib
      .lookupFunction<Pointer<Utf8> Function(Pointer<Void>),
          Pointer<Utf8> Function(Pointer<Void>)>("smol_account_pk");
  late final Pointer<Void> Function() _flagNew = _lib.lookupFunction<
      Pointer<Void> Function(),
      Pointer<Void> Function()>("smol_flag_new");
  late final void Function(Pointer<Void>, int) _flagSet = _lib.lookupFunction<
      Void Function(Pointer<Void>, Int32),
      void Function(Pointer<Void>, int)>("smol_flag_set");
  late final void Function(Pointer<Void>) _flagFree = _lib.lookupFunction<
      Void Function(Pointer<Void>),
      void Function(Pointer<Void>)>("smol_flag_free");

  late final int Function(Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, int)
      _pinServer = _lib.lookupFunction<
          Int32 Function(Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, Uint16),
          int Function(Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>,
              int)>("smol_pin_server");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>, int)
      _serverPin = _lib.lookupFunction<
              Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>, Uint16),
              Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>, int)>(
          "smol_server_pin");
  late final Pointer<Utf8> Function(Pointer<Void>) _storeAccount = _lib
      .lookupFunction<Pointer<Utf8> Function(Pointer<Void>),
          Pointer<Utf8> Function(Pointer<Void>)>("smol_store_account");
  late final int Function(Pointer<Void>) _rotations = _lib.lookupFunction<
      Int32 Function(Pointer<Void>),
      int Function(Pointer<Void>)>("smol_rotations");
  late final int Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
      Pointer<Utf8>, Pointer<Utf8>, int) _register = _lib.lookupFunction<
    Int32 Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>,
        Pointer<Utf8>, Uint64),
    int Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>,
        Pointer<Utf8>, int)
  >("smol_register");
  late final int Function(Pointer<Void>, Pointer<Uint8>, Pointer<Utf8>,
      Pointer<Utf8>, int) _restore = _lib.lookupFunction<
          Int32 Function(Pointer<Void>, Pointer<Uint8>, Pointer<Utf8>,
              Pointer<Utf8>, Uint64),
          int Function(Pointer<Void>, Pointer<Uint8>, Pointer<Utf8>,
              Pointer<Utf8>, int)>("smol_restore");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>,
      Pointer<Utf8>, int) _rotate = _lib.lookupFunction<
          Pointer<Utf8> Function(
              Pointer<Void>, Pointer<Void>, Pointer<Utf8>, Uint64),
          Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
              int)>("smol_rotate");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>, int, int,
      Pointer<Utf8>, int, Pointer<Void>) _fetch = _lib.lookupFunction<
          Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>, Int32, Int32,
              Pointer<Utf8>, Uint64, Pointer<Void>),
          Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>, int, int,
              Pointer<Utf8>, int, Pointer<Void>)>("smol_fetch");
  late final Pointer<Utf8> Function(
      Pointer<Void>,
      Pointer<Void>,
      Pointer<Utf8>,
      Pointer<Utf8>,
      Pointer<Utf8>,
      Pointer<Utf8>,
      int,
      int,
      Pointer<Utf8>,
      int) _send = _lib.lookupFunction<
          Pointer<Utf8> Function(
              Pointer<Void>,
              Pointer<Void>,
              Pointer<Utf8>,
              Pointer<Utf8>,
              Pointer<Utf8>,
              Pointer<Utf8>,
              Int32,
              Int32,
              Pointer<Utf8>,
              Uint64),
          Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
              Pointer<Utf8>, Pointer<Utf8>, Pointer<Utf8>, int, int,
              Pointer<Utf8>, int)>("smol_send");
  late final int Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
      Pointer<Utf8>, int) _delete = _lib.lookupFunction<
          Int32 Function(
              Pointer<Void>, Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, Uint64),
          int Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
              Pointer<Utf8>, int)>("smol_delete");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>) _mail = _lib
      .lookupFunction<Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>),
          Pointer<Utf8> Function(
              Pointer<Void>, Pointer<Utf8>)>("smol_mail");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>,
      Pointer<Utf8>) _describe = _lib.lookupFunction<
          Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>),
          Pointer<Utf8> Function(
              Pointer<Void>, Pointer<Void>, Pointer<Utf8>)>("smol_describe");
  late final Pointer<Utf8> Function(Pointer<Void>) _contacts = _lib
      .lookupFunction<Pointer<Utf8> Function(Pointer<Void>),
          Pointer<Utf8> Function(Pointer<Void>)>("smol_contacts");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>) _contact =
      _lib.lookupFunction<
              Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>),
              Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>)>(
          "smol_contact");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>,
      Pointer<Utf8>, Pointer<Utf8>, int) _accept = _lib.lookupFunction<
          Pointer<Utf8> Function(
              Pointer<Void>, Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, Uint64),
          Pointer<Utf8> Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
              Pointer<Utf8>, int)>("smol_accept");
  late final int Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
      Pointer<Utf8>, int) _block = _lib.lookupFunction<
          Int32 Function(
              Pointer<Void>, Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, Uint64),
          int Function(Pointer<Void>, Pointer<Void>, Pointer<Utf8>,
              Pointer<Utf8>, int)>("smol_block");
  late final Pointer<Utf8> Function(
      Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, int) _resolve = _lib
          .lookupFunction<
              Pointer<Utf8> Function(
                  Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, Uint64),
              Pointer<Utf8> Function(Pointer<Void>, Pointer<Utf8>,
                  Pointer<Utf8>, int)>("smol_resolve");
  late final int Function(Pointer<Void>, Pointer<Utf8>) _accountSet = _lib
      .lookupFunction<Int32 Function(Pointer<Void>, Pointer<Utf8>),
          int Function(Pointer<Void>, Pointer<Utf8>)>("smol_account_set");
  late final int Function(Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, int)
      _contactSave = _lib.lookupFunction<
          Int32 Function(
              Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>, Int32),
          int Function(Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>,
              int)>("smol_contact_save");
  late final int Function(Pointer<Void>, Pointer<Utf8>, int) _unpinServer =
      _lib.lookupFunction<
          Int32 Function(Pointer<Void>, Pointer<Utf8>, Uint16),
          int Function(
              Pointer<Void>, Pointer<Utf8>, int)>("smol_unpin_server");
  late final Pointer<Utf8> Function(Pointer<Void>) _pins = _lib.lookupFunction<
      Pointer<Utf8> Function(Pointer<Void>),
      Pointer<Utf8> Function(Pointer<Void>)>("smol_pins");
  late final int Function(Pointer<Void>) _syncOk = _lib.lookupFunction<
      Int32 Function(Pointer<Void>),
      int Function(Pointer<Void>)>("smol_sync_ok");
  late final int Function(Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>)
      _deleteLocal = _lib.lookupFunction<
          Int32 Function(Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>),
          int Function(
              Pointer<Void>, Pointer<Utf8>, Pointer<Utf8>)>("smol_delete_local");
  late final Pointer<Utf8> Function(Pointer<Utf8>) _parseAddress = _lib
      .lookupFunction<Pointer<Utf8> Function(Pointer<Utf8>),
          Pointer<Utf8> Function(Pointer<Utf8>)>("smol_parse_address");
  late final int Function(Pointer<Void>, Pointer<Utf8>) _importContact = _lib
      .lookupFunction<Int32 Function(Pointer<Void>, Pointer<Utf8>),
          int Function(Pointer<Void>, Pointer<Utf8>)>("smol_import_contact");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Uint8>)
      _exportBackup = _lib.lookupFunction<
          Pointer<Utf8> Function(Pointer<Void>, Pointer<Uint8>),
          Pointer<Utf8> Function(
              Pointer<Void>, Pointer<Uint8>)>("smol_export_backup");
  late final Pointer<Utf8> Function(Pointer<Void>, Pointer<Uint8>,
      Pointer<Utf8>) _importBackup = _lib.lookupFunction<
          Pointer<Utf8> Function(
              Pointer<Void>, Pointer<Uint8>, Pointer<Utf8>),
          Pointer<Utf8> Function(
              Pointer<Void>, Pointer<Uint8>, Pointer<Utf8>)>(
      "smol_import_backup");

  // --- helpers over the raw surface ------------------------------------------

  /// Throws when a status call returned non-zero, decoding the error slot.
  /// The slot is thread-local: this only works because it runs inside the
  /// same Isolate.run closure that made the failing call — after the
  /// closure returns, the slot on that thread is gone.
  Never _fail() {
    final slot = _lastError();
    if (slot == nullptr) {
      throw const NativeSmolException(smolOther, "the native call failed", {});
    }
    final text = take(slot);
    final Map<String, dynamic> details;
    try {
      details = jsonDecode(text) as Map<String, dynamic>;
    } on FormatException {
      throw NativeSmolException(smolOther, text, {});
    }
    throw NativeSmolException(
        details["code"] as int? ?? smolOther,
        details["message"] as String? ?? "the native call failed",
        details);
  }

  /// Reads one returned buffer into a String and frees the buffer — the
  /// ownership rule every caller owes a returned pointer.
  String take(Pointer<Utf8> ptr) {
    if (ptr == nullptr) _fail();
    final text = ptr.toDartString();
    _freeString(ptr);
    return text;
  }

  Pointer<Utf8> _text(String text) => text.toNativeUtf8();

  Pointer<Uint8> _bytes(Uint8List bytes) {
    final buf = malloc<Uint8>(32);
    buf.asTypedList(32).setAll(0, bytes);
    return buf;
  }

  // --- typed surface: handles cross as ints ----------------------------------

  int openStore(String path) {
    final ptr = _storeOpen(_text(path));
    if (ptr == nullptr) _fail();
    return ptr.address;
  }

  int openMemoryStore() {
    final ptr = _storeMemory();
    if (ptr == nullptr) _fail();
    return ptr.address;
  }

  void closeStore(int store) => _storeFree(_h(store));

  int newAccount(Uint8List master, int index) {
    final buf = _bytes(master);
    final ptr = _accountNew(buf, index);
    malloc.free(buf);
    if (ptr == nullptr) _fail();
    return ptr.address;
  }

  void freeAccount(int account) => _accountFree(_h(account));

  String accountPk(int account) => take(_accountPk(_h(account)));

  int newFlag() => _flagNew().address;

  void setFlag(int flag, bool value) => _flagSet(_h(flag), value ? 1 : 0);

  void freeFlag(int flag) => _flagFree(_h(flag));

  void pinServer(int store, String host, String keyB32, int port) {
    if (_pinServer(_h(store), _text(host), _text(keyB32), port) != smolOk) {
      _fail();
    }
  }

  void unpinServer(int store, String host, int port) {
    if (_unpinServer(_h(store), _text(host), port) != smolOk) _fail();
  }

  /// Every pin: [{host, key}] with keys as base32.
  List<dynamic> pins(int store) =>
      jsonDecode(take(_pins(_h(store)))) as List<dynamic>;

  /// Whether the local accept-token set may replace the server's (sec 4).
  bool syncOk(int store) => _syncOk(_h(store)) == 1;

  void saveContact(int store, String address, String keyB32,
          {required bool verified}) =>
      _contactSave(
          _h(store), _text(address), _text(keyB32), verified ? 1 : 0);

  /// Null when nothing is pinned.
  String? serverPin(int store, String host, int port) {
    final text = take(_serverPin(_h(store), _text(host), port));
    return text.isEmpty ? null : text;
  }

  /// Null when not registered.
  String? accountAddress(int store) {
    final text = take(_storeAccount(_h(store)));
    return text.isEmpty ? null : text;
  }

  int rotations(int store) => _rotations(_h(store));

  /// Binds the account locally, as register and restore do at their end.
  void setAccount(int store, String address) {
    if (_accountSet(_h(store), _text(address)) != smolOk) _fail();
  }

  void register(int store, int account, String address,
      {String? invite, String? dial, int timeout = 30}) {
    if (_register(
            _h(store),
            _h(account),
            _text(address),
            invite == null ? nullptr : _text(invite),
            dial == null ? nullptr : _text(dial),
            timeout) !=
        smolOk) {
      _fail();
    }
  }

  void restore(int store, Uint8List master, String address,
      {String? dial, int timeout = 30}) {
    final buf = _bytes(master);
    final code = _restore(_h(store), buf, _text(address),
        dial == null ? nullptr : _text(dial), timeout);
    malloc.free(buf);
    if (code != smolOk) _fail();
  }

  Map<String, dynamic> rotate(int store, int account,
          {String? dial, int timeout = 30}) =>
      jsonDecode(take(_rotate(_h(store), _h(account),
          dial == null ? nullptr : _text(dial), timeout)))
          as Map<String, dynamic>;

  Map<String, dynamic> fetch(int store, int account,
      {bool keep = false,
      bool reset = false,
      String? dial,
      int timeout = 30,
      int? cancel}) {
    final text = take(_fetch(_h(store), _h(account), keep ? 1 : 0, reset ? 1 : 0,
        dial == null ? nullptr : _text(dial), timeout,
        cancel == null ? nullptr : _h(cancel)));
    return jsonDecode(text) as Map<String, dynamic>;
  }

  Map<String, dynamic> send(int store, int account, String to, String body,
      {String? subject,
      String? replyTo,
      bool anonymous = false,
      bool noPad = false,
      String? dial,
      int timeout = 30}) {
    final text = take(_send(
        _h(store),
        _h(account),
        _text(to),
        subject == null ? nullptr : _text(subject),
        _text(body),
        replyTo == null ? nullptr : _text(replyTo),
        anonymous ? 1 : 0,
        noPad ? 1 : 0,
        dial == null ? nullptr : _text(dial),
        timeout));
    return jsonDecode(text) as Map<String, dynamic>;
  }

  /// Ids are 64 hex characters everywhere — the same shape `mail` and
  /// `describe` return, so no caller hex-decodes solely to delete.
  void delete(int store, int account, List<String> ids,
      {String? dial, int timeout = 30}) {
    if (_delete(_h(store), _h(account), _text(jsonEncode(ids)),
            dial == null ? nullptr : _text(dial), timeout) !=
        smolOk) {
      _fail();
    }
  }

  List<dynamic> mail(int store, String folder) =>
      jsonDecode(take(_mail(_h(store), _text(folder)))) as List<dynamic>;

  Map<String, dynamic> describe(int store, int account, String idHex) =>
      jsonDecode(take(_describe(_h(store), _h(account), _text(idHex))))
          as Map<String, dynamic>;

  List<dynamic> contacts(int store) =>
      jsonDecode(take(_contacts(_h(store)))) as List<dynamic>;

  Map<String, dynamic> contact(int store, String address) =>
      jsonDecode(take(_contact(_h(store), _text(address))))
          as Map<String, dynamic>;

  int accept(int store, int account, String address,
          {String? dial, int timeout = 30}) =>
      (jsonDecode(take(_accept(_h(store), _h(account), _text(address),
              dial == null ? nullptr : _text(dial), timeout)))
          as Map<String, dynamic>)["held"] as int;

  void block(int store, int account, String address,
      {String? dial, int timeout = 30}) {
    if (_block(_h(store), _h(account), _text(address),
            dial == null ? nullptr : _text(dial), timeout) !=
        smolOk) {
      _fail();
    }
  }

  Map<String, dynamic> resolve(int store, String address,
      {String? dial, int timeout = 30}) {
    final text = take(_resolve(_h(store), _text(address),
        dial == null ? nullptr : _text(dial), timeout));
    return jsonDecode(text) as Map<String, dynamic>;
  }

  /// The reader's delete: removes locally and marks seen, so a kept
  /// server copy is not re-stored by the next fetch.
  void deleteLocal(int store, String folder, List<String> ids) {
    if (_deleteLocal(_h(store), _text(folder), _text(jsonEncode(ids))) !=
        smolOk) {
      _fail();
    }
  }

  /// One address for the UI: {user, host, port, short, scheme}, or a
  /// NativeSmolException when it does not parse.
  Map<String, dynamic> parseAddress(String text) {
    return jsonDecode(take(_parseAddress(_text(text))))
        as Map<String, dynamic>;
  }

  void importContact(int store, String uri) {
    if (_importContact(_h(store), _text(uri)) != smolOk) _fail();
  }

  String exportBackup(int store, Uint8List master) {
    final buf = _bytes(master);
    final text = take(_exportBackup(_h(store), buf));
    malloc.free(buf);
    return text;
  }

  String importBackup(int store, Uint8List master, String text) {
    final buf = _bytes(master);
    final summary = take(_importBackup(_h(store), buf, _text(text)));
    malloc.free(buf);
    return summary;
  }
}