ente/lib/ui/settings/data/export_widget.dart

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

import 'package:ente_auth/core/configuration.dart';
import 'package:ente_auth/l10n/l10n.dart';
import 'package:ente_auth/models/export/ente.dart';
import 'package:ente_auth/services/local_authentication_service.dart';
import 'package:ente_auth/store/code_store.dart';
import 'package:ente_auth/ui/components/buttons/button_widget.dart';
import 'package:ente_auth/ui/components/dialog_widget.dart';
import 'package:ente_auth/ui/components/models/button_type.dart';
import 'package:ente_auth/utils/crypto_util.dart';
import 'package:ente_auth/utils/dialog_util.dart';
import 'package:ente_auth/utils/toast_util.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_sodium/flutter_sodium.dart';
import 'package:logging/logging.dart';
import 'package:share_plus/share_plus.dart';

Future<void> handleExportClick(BuildContext context) async {
  final result = await showDialogWidget(
    context: context,
    title: "Select export format",
    body: "Encrypted exports will be protected by a password of your choice.",
    buttons: [
      const ButtonWidget(
        buttonType: ButtonType.primary,
        labelText: "Encrypted",
        isInAlert: true,
        buttonSize: ButtonSize.large,
        buttonAction: ButtonAction.first,
      ),
      const ButtonWidget(
        buttonType: ButtonType.secondary,
        labelText: "Plain text",
        buttonSize: ButtonSize.large,
        isInAlert: true,
        buttonAction: ButtonAction.second,
      ),
    ],
  );
  if (result?.action != null && result!.action != ButtonAction.cancel) {
    if (result.action == ButtonAction.first) {
      await _requestForEncryptionPassword(context);
    } else {
      await _showExportWarningDialog(context);
    }
  }
}

Future<void> _requestForEncryptionPassword(BuildContext context,
    {String? password,}) async {
  await showTextInputDialog(
    context,
    title: "Password to encrypt export",
    submitButtonLabel: "Export",
    hintText: "Enter password",
    isPasswordInput: true,
    alwaysShowSuccessState: false,
    onSubmit: (String password) async {
      if (password.isEmpty || password.length < 4) {
        showToast(context, "Password must be at least 4 characters long.");
        Future.delayed(const Duration(seconds: 0), () {
          _requestForEncryptionPassword(context, password: password);
        });
        return;
      }
      if (password.isNotEmpty) {
        try {
          final kekSalt = CryptoUtil.getSaltToDeriveKey();
          final derivedKeyResult = await CryptoUtil.deriveSensitiveKey(
            utf8.encode(password) as Uint8List,
            kekSalt,
          );
          String exportPlainText = await _getAuthDataForExport();
          // Encrypt the key with this derived key
          final encResult = await CryptoUtil.encryptChaCha(
            utf8.encode(exportPlainText) as Uint8List, derivedKeyResult.key,);
          final encContent = Sodium.bin2base64(encResult.encryptedData!);
          final encNonce = Sodium.bin2base64(encResult.header!);
          final EnteAuthExport data = EnteAuthExport(
            version: 1,
            encryptedData: encContent,
            encryptionNonce: encNonce,
            kdfParams: KDFParams(
              memLimit: derivedKeyResult.memLimit,
              opsLimit: derivedKeyResult.opsLimit,
              salt: Sodium.bin2base64(kekSalt),),
          );
          // get json value of data
          _exportCodes(context, jsonEncode(data.toJson()));
        } catch(e,s) {
          Logger("ExportWidget").severe(e, s);
          showToast(context, "Error while exporting codes.");
        }
      }
    },
  );
}

Future<void> _showExportWarningDialog(BuildContext context) async {
  await showChoiceActionSheet(
    context,
    title: context.l10n.warning,
    body: context.l10n.exportWarningDesc,
    isCritical: true,
    firstButtonOnTap: () async {
      final data = await _getAuthDataForExport();
      await _exportCodes(context, data);
    },
    secondButtonLabel: context.l10n.cancel,
    firstButtonLabel: context.l10n.iUnderStand,
  );
}

Future<void> _exportCodes(BuildContext context, String fileContent) async {
  final _codeFile = File(
    Configuration.instance.getTempDirectory() + "ente-authenticator-codes.txt",
  );
  final hasAuthenticated = await LocalAuthenticationService.instance
      .requestLocalAuthentication(context, context.l10n.authToExportCodes);
  if (!hasAuthenticated) {
    return;
  }
  if (_codeFile.existsSync()) {
    await _codeFile.delete();
  }
  _codeFile.writeAsStringSync(fileContent);
  await Share.shareFiles([_codeFile.path]);
  Future.delayed(const Duration(seconds: 15), () async {
    if (_codeFile.existsSync()) {
      _codeFile.deleteSync();
    }
  });
}

Future<String> _getAuthDataForExport() async {
  final codes = await CodeStore.instance.getAllCodes();
  String data = "";
  for (final code in codes) {
    data += code.rawData + "\n";
  }
  return data;
}