ET-2530 Make migration work seamlessly while offline

Modules/App/Sources/App/ProtonMailApp.swift

@@ -119,6 +119,11 @@ private struct RootView: View {
 
                 case .activeSessionTransition:
                     EmptyView()
+                case .waitingForSessionInitialization:
+                    OperationInProgressView(
+                        text: nil,
+                        toast: .error(message: L10n.Session.initializationDifficulties.string)
+                    )
                 }
             }
             .transition(.opacity)
@@ -132,7 +137,7 @@ private struct RootView: View {
         case .checkingIfMigrationIsNeeded:
             EmptyView()
         case .inProgress:
-            MigrationInProgressView()
+            OperationInProgressView(text: L10n.LegacyMigration.migrationInProgress, toast: nil)
         case .pinRequired(let errorFromLatestAttempt):
             PINLockScreen(error: .constant(errorFromLatestAttempt)) { output in
                 switch output {
@@ -154,13 +159,26 @@ private struct RootView: View {
     }
 }
 
-private struct MigrationInProgressView: View {
+private struct OperationInProgressView: View {
+    let text: LocalizedStringResource?
+    let toast: Toast?
+
     var body: some View {
         ZStack(alignment: .center) {
             Color.clear
 
             ProgressView() {
-                Text(L10n.LegacyMigration.migrationInProgress)
+                if let text {
+                    Text(text)
+                }
+            }
+
+            if let toast {
+                VStack {
+                    Spacer()
+
+                    ToastView(model: toast) {}
+                }
             }
         }
     }

Modules/App/Sources/Resources/Localizable.xcstrings

@@ -2605,6 +2605,9 @@
     "Protection" : {
       "comment" : "Protection setting title in app settings."
     },
+    "Proton Mail needs to connect to the server to finish initialization. Please ensure you have a good internet connection." : {
+      "comment" : "Error when the connection fails during session initialization."
+    },
     "Provided value is not a valid PIN" : {
       "comment" : "Error message when setting up PIN"
     },

Modules/App/Sources/Services/ApplicationServices.swift

@@ -23,6 +23,7 @@ struct ApplicationServices {
     var enterBackgroundServices: [ApplicationServiceDidEnterBackground] = []
     var terminateServices: [ApplicationServiceTerminate] = []
 
+    @MainActor
     func setUp() {
         setUpServices.forEach { $0.setUpService() }
     }
@@ -41,6 +42,7 @@ struct ApplicationServices {
 }
 
 protocol ApplicationServiceSetUp {
+    @MainActor
     func setUpService()
 }
 

Modules/App/Sources/State/AppContext.swift

@@ -69,6 +69,7 @@ final class AppContext: Sendable, ObservableObject {
         self.dependencies = dependencies
     }
 
+    @MainActor
     private func start() throws {
         AppLogger.log(message: "AppContext.start", category: .appLifeCycle)
 
@@ -87,12 +88,7 @@ final class AppContext: Sendable, ObservableObject {
         setupAccountBindings()
 
         if let currentSession = accountAuthCoordinator.primaryAccountSignedInSession() {
-            switch mailSession.userContextFromSession(session: currentSession) {
-            case .ok(let newUserSession):
-                withAnimation { sessionState = .activeSession(session: newUserSession) }
-            case .error(let error):
-                throw error
-            }
+            setupActiveUserSession(session: currentSession)
         }
     }
 }
@@ -127,9 +123,26 @@ extension AppContext: AccountAuthDelegate {
 
     @MainActor
     private func setupActiveUserSession(session: StoredSession) {
+        let start = ContinuousClock.now
+
         switch mailSession.userContextFromSession(session: session) {
         case .ok(let newUserSession):
             withAnimation { self.sessionState = .activeSession(session: newUserSession) }
+        case .error(.other(.network)):
+            AppLogger.log(
+                message: "Failed to initialize session due to network error, will retry...",
+                category: .userSessions,
+                isError: true
+            )
+
+            withAnimation { sessionState = .waitingForSessionInitialization }
+
+            Task {
+                let minimumTimeBetweenRetries = Duration.seconds(5)
+                let earliestNextAttemptTime = start + minimumTimeBetweenRetries
+                try! await Task.sleep(until: earliestNextAttemptTime)
+                setupActiveUserSession(session: session)
+            }
         case .error(let error):
             AppLogger.log(error: error, category: .userSessions)
         }

Modules/App/Sources/State/SessionState.swift

@@ -22,6 +22,7 @@ enum SessionState: Equatable {
     case noSession
     case activeSession(session: MailUserSession)
     case activeSessionTransition
+    case waitingForSessionInitialization
 
     var userSession: MailUserSession? {
         guard case .activeSession(let session) = self else { return nil }
@@ -34,6 +35,8 @@ enum SessionState: Equatable {
             return true
         case (.activeSessionTransition, .activeSessionTransition):
             return true
+        case (.waitingForSessionInitialization, .waitingForSessionInitialization):
+            return true
         case (.activeSession(let lhsSession), .activeSession(let rhsSession)):
             return lhsSession.sessionId() == rhsSession.sessionId()
         default:

Modules/App/Sources/Utils/EmailsPrefetching/SessionState+IsAuthorized.swift

@@ -22,7 +22,7 @@ extension SessionState {
         switch self {
         case .activeSession:
             true
-        case .noSession, .activeSessionTransition:
+        case .noSession, .activeSessionTransition, .waitingForSessionInitialization:
             false
         }
     }

Modules/App/Sources/Utils/L10n.swift

@@ -665,6 +665,13 @@ enum L10n {
         )
     }
 
+    enum Session {
+        static let initializationDifficulties = LocalizedStringResource(
+            "Proton Mail needs to connect to the server to finish initialization. Please ensure you have a good internet connection.",
+            comment: "Error when the connection fails during session initialization."
+        )
+    }
+
     enum Settings {
         enum App {
             static let title = LocalizedStringResource(

Modules/App/Tests/Tests/Unit/App/UserNotificationCenterDelegateTests.swift

@@ -61,7 +61,7 @@ final class UserNotificationCenterDelegateTests {
         mailSession.onPrimaryAccountChanged = nil
     }
 
-    @Test
+    @MainActor @Test
     func whenServicesAreSetUp_assignsItselfAsUserNotificationCenterDelegate() {
         sut.setUpService()