TF-32 Add data layer of export attachment for ios platform

lib/features/email/data/datasource/email_datasource.dart

@@ -1,3 +1,4 @@
+import 'package:dio/dio.dart';
 import 'package:jmap_dart_client/jmap/account_id.dart';
 import 'package:jmap_dart_client/jmap/mail/email/email.dart';
 import 'package:model/email/read_actions.dart';
@@ -17,4 +18,12 @@ abstract class EmailDataSource {
     String baseDownloadUrl,
     AccountRequest accountRequest
   );
+
+  Future<String> exportAttachment(
+    Attachment attachment,
+    AccountId accountId,
+    String baseDownloadUrl,
+    AccountRequest accountRequest,
+    CancelToken cancelToken
+  );
 }

lib/features/email/data/datasource_impl/email_datasource_impl.dart

@@ -1,3 +1,4 @@
+import 'package:dio/dio.dart';
 import 'package:jmap_dart_client/jmap/account_id.dart';
 import 'package:jmap_dart_client/jmap/mail/email/email.dart';
 import 'package:model/email/read_actions.dart';
@@ -54,4 +55,19 @@ class EmailDataSourceImpl extends EmailDataSource {
       throw error;
     });
   }
+
+  @override
+  Future<String> exportAttachment(
+      Attachment attachment,
+      AccountId accountId,
+      String baseDownloadUrl,
+      AccountRequest accountRequest,
+      CancelToken cancelToken
+  ) {
+    return Future.sync(() async {
+      return await emailAPI.exportAttachment(attachment, accountId, baseDownloadUrl, accountRequest, cancelToken);
+    }).catchError((error) {
+      throw error;
+    });
+  }
 }

lib/features/email/data/network/email_api.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:core/core.dart';
+import 'package:dio/dio.dart';
 import 'package:external_path/external_path.dart';
 import 'package:flutter_downloader/flutter_downloader.dart';
 import 'package:jmap_dart_client/http/http_client.dart';
@@ -29,14 +30,15 @@ import 'package:model/model.dart';
 
 class EmailAPI {
 
-  final HttpClient httpClient;
+  final HttpClient _httpClient;
+  final DownloadManager _downloadManager;
 
-  EmailAPI(this.httpClient);
+  EmailAPI(this._httpClient, this._downloadManager);
 
   Future<Email> getEmailContent(AccountId accountId, EmailId emailId) async {
     final processingInvocation = ProcessingInvocation();
 
-    final jmapRequestBuilder = JmapRequestBuilder(httpClient, processingInvocation);
+    final jmapRequestBuilder = JmapRequestBuilder(_httpClient, processingInvocation);
 
     final getEmailMethod = GetEmailMethod(accountId)
       ..addIds({emailId.id})
@@ -84,7 +86,7 @@ class EmailAPI {
         })
       });
 
-    final requestBuilder = JmapRequestBuilder(httpClient, ProcessingInvocation());
+    final requestBuilder = JmapRequestBuilder(_httpClient, ProcessingInvocation());
 
     final setEmailInvocation = requestBuilder.invocation(setEmailMethod);
     final setEmailSubmissionInvocation = requestBuilder.invocation(setEmailSubmissionMethod);
@@ -172,4 +174,21 @@ class EmailAPI {
       .map((taskId) => DownloadTaskId(taskId!))
       .toList();
   }
+
+  Future<String> exportAttachment(
+      Attachment attachment,
+      AccountId accountId,
+      String baseDownloadUrl,
+      AccountRequest accountRequest,
+      CancelToken cancelToken
+  ) async {
+    final basicAuth = 'Basic ' + base64Encode(utf8.encode('${accountRequest.userName.userName}:${accountRequest.password.value}'));
+
+    return _downloadManager.downloadFile(
+      attachment.getDownloadUrl(baseDownloadUrl, accountId),
+      getTemporaryDirectory(),
+      attachment.name ?? '',
+      basicAuth,
+      cancelToken: cancelToken);
+  }
 }

lib/features/email/data/repository/email_repository_impl.dart

@@ -1,4 +1,5 @@
 
+import 'package:dio/src/cancel_token.dart';
 import 'package:jmap_dart_client/jmap/account_id.dart';
 import 'package:jmap_dart_client/jmap/mail/email/email.dart';
 import 'package:model/email/read_actions.dart';
@@ -39,4 +40,20 @@ class EmailRepositoryImpl extends EmailRepository {
   ) {
     return emailDataSource.downloadAttachments(attachments, accountId, baseDownloadUrl, accountRequest);
   }
+
+  @override
+  Future<String> exportAttachment(
+      Attachment attachment,
+      AccountId accountId,
+      String baseDownloadUrl,
+      AccountRequest accountRequest,
+      CancelToken cancelToken
+  ) {
+    return emailDataSource.exportAttachment(
+      attachment,
+      accountId,
+      baseDownloadUrl,
+      accountRequest,
+      cancelToken);
+  }
 }