feat: create conversation import use case - WPB-14599

wire-ios-data-model/Source/Model/UserClient/UserClient.swift

@@ -157,6 +157,12 @@ public class UserClient: ZMManagedObject, UserClientType {
         return userClient
     }
 
+    public func markAsSelfClient() {
+        guard let context = managedObjectContext else { return }
+        context.setPersistentStoreMetadata(remoteIdentifier, key: ZMPersistedClientIdKey)
+        _ = context.makeMetadataPersistent()
+    }
+
     public static func fetchUserClient(
         withRemoteId remoteIdentifier: String,
         forUser user: ZMUser,

wire-ios-sync-engine/Source/SessionManager/SessionManager+Backup.swift

@@ -107,6 +107,8 @@ extension SessionManager {
 
     // MARK: - Import
 
+    // TODO: [WPB-14616] delete import related code when the restore button from the authentication flow is removed
+
     /// Restores the account database from the Wire iOS database back up file.
     /// @param completion called when the restoration is ended. If success, Result.success with the new restored account
     /// is called.
@@ -256,7 +258,7 @@ private extension BackupMetadata {
 
 // MARK: - Zip Helper
 
-extension URL {
+private extension URL {
     func zipDirectory(to url: URL) -> Bool {
         SSZipArchive.createZipFile(atPath: url.path, withContentsOfDirectory: path)
     }

wire-ios-sync-engine/Source/SessionManager/SessionManager.swift

@@ -747,8 +747,7 @@ public final class SessionManager: NSObject, SessionManagerType {
                 account,
                 from: selectedAccount,
                 userSessionCanBeTornDown: { [weak self] in
-                    self?.activeUserSession = nil
-                    tearDownCompletion?()
+                    self?.tearDownActiveSession(completion: tearDownCompletion)
                     guard let self else {
                         completion?(nil)
                         return
@@ -1008,6 +1007,16 @@ public final class SessionManager: NSObject, SessionManagerType {
         delegate?.sessionManagerAsksToRetryStart()
     }
 
+    // TODO: [WPB-14616] use this method for restoring a backup from the settings
+    /// The active user session will be torn down and the app goes into migration state.
+    public func prepareForRestoreWithMigration(completion: @escaping () -> Void) {
+        guard let delegate else { return completion() }
+
+        delegate.sessionManagerWillMigrateAccount {
+            self.tearDownActiveSession(completion: completion)
+        }
+    }
+
     private func setupUserSession(
         account: Account,
         onCompletion: @escaping (ZMUserSession?) -> Void
@@ -1183,6 +1192,11 @@ public final class SessionManager: NSObject, SessionManagerType {
         }
     }
 
+    private func tearDownActiveSession(completion: (() -> Void)?) {
+        activeUserSession = nil
+        completion?()
+    }
+
     // Creates the user session for @c account given, calls @c completion when done.
     private func startBackgroundSession(
         for account: Account,

wire-ios-sync-engine/Source/Use cases/ImportBackupUseCase/BackupRestoreError.swift

@@ -0,0 +1,26 @@
+//
+// Wire
+// Copyright (C) 2025 Wire Swiss GmbH
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see http://www.gnu.org/licenses/.
+//
+
+enum BackupRestoreError: Error {
+    case noActiveAccount
+    case compressionError
+    case invalidFileExtension
+    case keyCreationFailed
+    case decryptionError
+    case unknown
+}

wire-ios-sync-engine/Source/Use cases/ImportBackupUseCase/ImportBackupEntityStorage.swift

@@ -0,0 +1,79 @@
+//
+// Wire
+// Copyright (C) 2025 Wire Swiss GmbH
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see http://www.gnu.org/licenses/.
+//
+
+import Foundation
+
+struct ImportBackupEntityStorage: ImportBackupEntityStorageProtocol {
+
+    var importsDirectory: URL {
+        CoreDataStack.importsDirectory
+    }
+
+    @MainActor
+    func replacePersistentStore(
+        accountIdentifier: UUID,
+        from backupDirectory: URL,
+        applicationContainer: URL,
+        dispatchGroup: ZMSDispatchGroup
+    ) async throws -> URL {
+
+        try await withCheckedThrowingContinuation { continuation in
+
+            CoreDataStack.importLocalStorage(
+                accountIdentifier: accountIdentifier,
+                from: backupDirectory,
+                applicationContainer: applicationContainer,
+                dispatchGroup: dispatchGroup
+            ) { result in
+                continuation.resume(with: result)
+            }
+
+        }
+
+    }
+
+    @MainActor
+    func createContextProvider(
+        account: Account,
+        applicationContainer: URL,
+        dispatchGroup: ZMSDispatchGroup?
+    ) async throws -> any ContextProvider {
+
+        let stack = CoreDataStack(
+            account: account,
+            applicationContainer: applicationContainer,
+            dispatchGroup: dispatchGroup
+        )
+
+        try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Void, Error>) in
+
+            stack.loadStores { error in
+                if let error {
+                    continuation.resume(throwing: error)
+                } else {
+                    continuation.resume()
+                }
+            }
+
+        }
+
+        return stack
+
+    }
+
+}

wire-ios-sync-engine/Source/Use cases/ImportBackupUseCase/ImportBackupFileArchiver.swift

@@ -0,0 +1,35 @@
+//
+// Wire
+// Copyright (C) 2025 Wire Swiss GmbH
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see http://www.gnu.org/licenses/.
+//
+
+import ZipArchive
+
+struct ImportBackupFileArchiver: ImportBackupFileArchiverProtocol {
+
+    func unzipFile(at sourceURL: URL, to destinationURL: URL) throws {
+
+        let success = SSZipArchive.unzipFile(
+            atPath: sourceURL.path,
+            toDestination: destinationURL.path
+        )
+
+        guard success else {
+            throw BackupRestoreError.compressionError
+        }
+
+    }
+}

wire-ios-sync-engine/Source/Use cases/ImportBackupUseCase/ImportBackupStreamDecryptor.swift

@@ -0,0 +1,53 @@
+//
+// Wire
+// Copyright (C) 2025 Wire Swiss GmbH
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see http://www.gnu.org/licenses/.
+//
+
+import Foundation
+import WireCrypto
+
+struct ImportBackupStreamDecryptor: ImportBackupStreamDecryptorProtocol {
+
+    func decrypt(
+        input: InputStream,
+        output: OutputStream,
+        accountID: UUID,
+        password: String
+    ) throws {
+
+        do {
+
+            let passphrase = ChaCha20Poly1305.StreamEncryption.Passphrase(
+                password: password,
+                uuid: accountID
+            )
+
+            try ChaCha20Poly1305.StreamEncryption.decrypt(
+                input: input,
+                output: output,
+                passphrase: passphrase
+            )
+
+        } catch ChaCha20Poly1305.StreamEncryption.EncryptionError.decryptionFailed {
+            throw BackupRestoreError.decryptionError
+
+        } catch ChaCha20Poly1305.StreamEncryption.EncryptionError.keyGenerationFailed {
+            throw BackupRestoreError.keyCreationFailed
+        }
+
+    }
+
+}