Move tracking unsaved changes into coordinator

ios/MullvadVPN/Classes/InterceptibleNavigationController.swift

@@ -14,6 +14,7 @@ class InterceptibleNavigationController: CustomNavigationController {
 
     // Called when popping the topmost view controller in the stack, eg. by pressing a navigation
     // bar back button.
+    @discardableResult
     override func popViewController(animated: Bool) -> UIViewController? {
         guard let viewController = viewControllers.last else { return nil }
 
@@ -26,6 +27,7 @@ class InterceptibleNavigationController: CustomNavigationController {
 
     // Called when popping to a specific view controller, eg. by long pressing a navigation bar
     // back button (revealing a navigation menu) and selecting a destination view controller.
+    @discardableResult
     override func popToViewController(_ viewController: UIViewController, animated: Bool) -> [UIViewController]? {
         if shouldPopToViewController?(viewController) ?? true {
             return super.popToViewController(viewController, animated: animated)

ios/MullvadVPN/Coordinators/CustomLists/CustomListViewController.swift

@@ -31,7 +31,7 @@ class CustomListViewController: UIViewController {
         return interactor.fetchAll().first(where: { $0.id == subject.value.id })
     }
 
-    private var hasUnsavedChanges: Bool {
+    var hasUnsavedChanges: Bool {
         persistedCustomList != subject.value.customList
     }
 
@@ -83,12 +83,12 @@ class CustomListViewController: UIViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
 
+        navigationItem.rightBarButtonItem = saveBarButton
         view.directionalLayoutMargins = UIMetrics.contentLayoutMargins
         view.backgroundColor = .secondaryColor
         isModalInPresentation = true
 
         addSubviews()
-        configureNavigationItem()
         configureDataSource()
         configureTableView()
 
@@ -98,39 +98,6 @@ class CustomListViewController: UIViewController {
         }.store(in: &cancellables)
     }
 
-    private func configureNavigationItem() {
-        if let navigationController = navigationController as? InterceptibleNavigationController {
-            interceptNavigation(navigationController)
-        }
-
-        navigationController?.interactivePopGestureRecognizer?.delegate = self
-        navigationItem.rightBarButtonItem = saveBarButton
-    }
-
-    private func interceptNavigation(_ navigationController: InterceptibleNavigationController) {
-        navigationController.shouldPopViewController = { [weak self] viewController in
-            guard
-                let self,
-                viewController is Self,
-                hasUnsavedChanges
-            else { return true }
-
-            self.onUnsavedChanges()
-            return false
-        }
-
-        navigationController.shouldPopToViewController = { [weak self] viewController in
-            guard
-                let self,
-                viewController is ListCustomListViewController,
-                hasUnsavedChanges
-            else { return true }
-
-            self.onUnsavedChanges()
-            return false
-        }
-    }
-
     private func configureTableView() {
         tableView.delegate = dataSourceConfiguration
         tableView.backgroundColor = .secondaryColor
@@ -232,68 +199,4 @@ class CustomListViewController: UIViewController {
 
         alertPresenter.showAlert(presentation: presentation, animated: true)
     }
-
-    @objc private func onUnsavedChanges() {
-        let message = NSMutableAttributedString(
-            markdownString: NSLocalizedString(
-                "CUSTOM_LISTS_UNSAVED_CHANGES_PROMPT",
-                tableName: "CustomLists",
-                value: "You have unsaved changes.",
-                comment: ""
-            ),
-            options: MarkdownStylingOptions(font: .preferredFont(forTextStyle: .body))
-        )
-
-        let presentation = AlertPresentation(
-            id: "api-custom-lists-unsaved-changes-alert",
-            icon: .alert,
-            attributedMessage: message,
-            buttons: [
-                AlertAction(
-                    title: NSLocalizedString(
-                        "CUSTOM_LISTS_DISCARD_CHANGES_BUTTON",
-                        tableName: "CustomLists",
-                        value: "Discard changes",
-                        comment: ""
-                    ),
-                    style: .destructive,
-                    handler: {
-                        // Reset subject/view model to no longer having unsaved changes.
-                        if let persistedCustomList = self.persistedCustomList {
-                            self.subject.value.update(with: persistedCustomList)
-                        }
-                        self.delegate?.customListDidSave(self.subject.value.customList)
-                    }
-                ),
-                AlertAction(
-                    title: NSLocalizedString(
-                        "CUSTOM_LISTS_BACK_TO_EDITING_BUTTON",
-                        tableName: "CustomLists",
-                        value: "Back to editing",
-                        comment: ""
-                    ),
-                    style: .default
-                ),
-            ]
-        )
-
-        alertPresenter.showAlert(presentation: presentation, animated: true)
-    }
-}
-
-extension CustomListViewController: UIGestureRecognizerDelegate {
-    // For some reason, intercepting `popViewController(animated: Bool)` in `InterceptibleNavigationController`
-    // by SWIPING back leads to weird behaviour where subsequent navigation seem to happen systemwise but not
-    // UI-wise. This leads to the UI freezing up, and the only remedy is to restart the app.
-    //
-    // To get around this issue we can intercept the back swipe gesture and manually perform the transition
-    // instead, thereby bypassing the inner mechanisms that seem to go out of sync.
-    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
-        guard gestureRecognizer == navigationController?.interactivePopGestureRecognizer else {
-            return true
-        }
-
-        navigationController?.popViewController(animated: true)
-        return false
-    }
 }

ios/MullvadVPN/Coordinators/CustomLists/EditCustomListCoordinator.swift

@@ -21,12 +21,16 @@ class EditCustomListCoordinator: Coordinator, Presentable, Presenting {
     let customList: CustomList
     let nodes: [LocationNode]
     let subject: CurrentValueSubject<CustomListViewModel, Never>
+    private lazy var alertPresenter: AlertPresenter = {
+        AlertPresenter(context: self)
+    }()
 
     var presentedViewController: UIViewController {
         navigationController
     }
 
     var didFinish: ((EditCustomListCoordinator, FinishAction, CustomList) -> Void)?
+    var didCancel: ((EditCustomListCoordinator) -> Void)?
 
     init(
         navigationController: UINavigationController,
@@ -50,7 +54,7 @@ class EditCustomListCoordinator: Coordinator, Presentable, Presenting {
         let controller = CustomListViewController(
             interactor: customListInteractor,
             subject: subject,
-            alertPresenter: AlertPresenter(context: self)
+            alertPresenter: alertPresenter
         )
         controller.delegate = self
 
@@ -61,7 +65,77 @@ class EditCustomListCoordinator: Coordinator, Presentable, Presenting {
             comment: ""
         )
 
+        navigationController.interactivePopGestureRecognizer?.delegate = self
         navigationController.pushViewController(controller, animated: true)
+
+        guard let interceptibleNavigationController = navigationController as? InterceptibleNavigationController else {
+            return
+        }
+
+        interceptibleNavigationController.shouldPopViewController = { [weak self] viewController in
+            guard
+                let self,
+                let customListViewController = viewController as? CustomListViewController,
+                customListViewController.hasUnsavedChanges
+            else { return true }
+
+            presentUnsavedChangesDialog()
+            return false
+        }
+
+        interceptibleNavigationController.shouldPopToViewController = { [weak self] viewController in
+            guard
+                let self,
+                let customListViewController = viewController as? CustomListViewController,
+                customListViewController.hasUnsavedChanges
+            else { return true }
+
+            presentUnsavedChangesDialog()
+            return false
+        }
+    }
+
+    private func presentUnsavedChangesDialog() {
+        let message = NSMutableAttributedString(
+            markdownString: NSLocalizedString(
+                "CUSTOM_LISTS_UNSAVED_CHANGES_PROMPT",
+                tableName: "CustomLists",
+                value: "You have unsaved changes.",
+                comment: ""
+            ),
+            options: MarkdownStylingOptions(font: .preferredFont(forTextStyle: .body))
+        )
+
+        let presentation = AlertPresentation(
+            id: "api-custom-lists-unsaved-changes-alert",
+            icon: .alert,
+            attributedMessage: message,
+            buttons: [
+                AlertAction(
+                    title: NSLocalizedString(
+                        "CUSTOM_LISTS_DISCARD_CHANGES_BUTTON",
+                        tableName: "CustomLists",
+                        value: "Discard changes",
+                        comment: ""
+                    ),
+                    style: .destructive,
+                    handler: {
+                        self.didCancel?(self)
+                    }
+                ),
+                AlertAction(
+                    title: NSLocalizedString(
+                        "CUSTOM_LISTS_BACK_TO_EDITING_BUTTON",
+                        tableName: "CustomLists",
+                        value: "Back to editing",
+                        comment: ""
+                    ),
+                    style: .default
+                ),
+            ]
+        )
+
+        alertPresenter.showAlert(presentation: presentation, animated: true)
     }
 }
 
@@ -90,3 +164,19 @@ extension EditCustomListCoordinator: CustomListViewControllerDelegate {
         addChild(coordinator)
     }
 }
+
+extension EditCustomListCoordinator: UIGestureRecognizerDelegate {
+    // For some reason, intercepting `popViewController(animated: Bool)` in `InterceptibleNavigationController`
+    // by SWIPING back leads to weird behaviour where subsequent navigation seem to happen systemwise but not
+    // UI-wise. This leads to the UI freezing up, and the only remedy is to restart the app.
+    //
+    // To get around this issue we can intercept the back swipe gesture and manually perform the transition
+    // instead, thereby bypassing the inner mechanisms that seem to go out of sync.
+    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+        guard gestureRecognizer == navigationController.interactivePopGestureRecognizer else {
+            return true
+        }
+        navigationController.popViewController(animated: true)
+        return false
+    }
+}

ios/MullvadVPN/Coordinators/CustomLists/ListCustomListCoordinator.swift

@@ -65,6 +65,12 @@ class ListCustomListCoordinator: Coordinator, Presentable, Presenting {
             self.updateRelayConstraints(for: action, in: list)
         }
 
+        coordinator.didCancel = { [weak self] editCustomListCoordinator in
+            guard let self else { return }
+            popToList()
+            editCustomListCoordinator.removeFromParent()
+        }
+
         coordinator.start()
         addChild(coordinator)
     }
@@ -84,6 +90,14 @@ class ListCustomListCoordinator: Coordinator, Presentable, Presenting {
                     customListSelection: UserSelectedRelays.CustomListSelection(listId: list.id, isList: true)
                 )
                 relayConstraints.locations = .only(selectedRelays)
+            } else {
+                let selectedConstraintIsRemovedFromList = list.locations.filter {
+                    relayConstraints.locations.value?.locations.contains($0) ?? false
+                }.isEmpty
+
+                if selectedConstraintIsRemovedFromList {
+                    relayConstraints.locations = .only(UserSelectedRelays(locations: []))
+                }
             }
         case .delete:
             relayConstraints.locations = .only(UserSelectedRelays(locations: []))

ios/MullvadVPN/View controllers/SelectLocation/LocationCellViewModel.swift

@@ -15,13 +15,16 @@ struct LocationCellViewModel: Hashable {
     var isSelected = false
 
     func hash(into hasher: inout Hasher) {
-        hasher.combine(section)
         hasher.combine(node)
+        hasher.combine(node.children.count)
+        hasher.combine(section)
+        hasher.combine(isSelected)
         hasher.combine(indentationLevel)
     }
 
     static func == (lhs: Self, rhs: Self) -> Bool {
         lhs.node == rhs.node &&
+            lhs.node.children.count == rhs.node.children.count &&
             lhs.section == rhs.section &&
             lhs.isSelected == rhs.isSelected &&
             lhs.indentationLevel == rhs.indentationLevel

ios/MullvadVPN/View controllers/SelectLocation/LocationDataSource.swift

@@ -185,7 +185,7 @@ final class LocationDataSource:
 
         let rootNode = selectedItem.node.root
 
-        // Exit early if no changes to the node tree are necessary.
+        // Exit early if no changes to the node tree should be made.
         guard selectedItem.node != rootNode else {
             completion?()
             return