Variations: Ask for user confirmation before creating variations

WooCommerce/Classes/ViewRelated/Products/Variations/ProductVariationsViewController.swift

@@ -626,6 +626,21 @@ private extension ProductVariationsViewController {
         let notice = Notice(title: error.errorTitle, message: error.errorDescription)
         noticePresenter.enqueue(notice: notice)
     }
+
+    /// Asks the merchant for confirmation before generating all variations.
+    ///
+    private func presentGenerationConfirmation(numberOfVariations: Int, onCompletion: @escaping (_ confirmed: Bool) -> Void) {
+        let controller = UIAlertController(title: Localization.confirmationTitle,
+                                           message: Localization.confirmationDescription(variationCount: numberOfVariations),
+                                           preferredStyle: .alert)
+        controller.addDefaultActionWithTitle(Localization.ok) { _ in
+            onCompletion(true)
+        }
+        controller.addCancelActionWithTitle(Localization.cancel) { _ in
+            onCompletion(false)
+        }
+        present(controller, animated: true)
+    }
 }
 
 // MARK: - Placeholders
@@ -702,18 +717,25 @@ extension ProductVariationsViewController: SyncingCoordinatorDelegate {
     /// Generates all possible variations for the product attributes.
     ///
     private func generateAllVariations() {
-        viewModel.generateAllVariations(for: product) { [weak self] result in
-            guard let self else { return }
-            switch result {
-            case .success:
+        viewModel.generateAllVariations(for: product) { [weak self] currentState in
+            switch currentState {
+            case .fetching:
+                break // TODO: Show fetching loading Indicator
+            case .confirmation(let variationCount, let onCompletion):
+                self?.presentGenerationConfirmation(numberOfVariations: variationCount, onCompletion: onCompletion)
+            case .creating:
+                break // TODO: Show creating loading Indicator
+            case .canceled:
+                break // TODO: Remove loading indicator
+            case .finished(let variationsCreated):
+                // TODO: Remove loading indicator
+                // TODO: Inform about created variations
                 break
-            case .failure(let error):
-                self.presentGenerationError(error)
+            case .error(let error):
+                // TODO: Remove loading indicator
+                self?.presentGenerationError(error)
             }
         }
-        // TODO:
-        // - Show Loading Indicator
-        // - Hide Loading Indicator
     }
 }
 
@@ -820,6 +842,17 @@ private extension ProductVariationsViewController {
         static let generateVariationError = NSLocalizedString("The variation couldn't be generated.",
                                                               comment: "Error title when failing to generate a variation.")
         static let variationCreated = NSLocalizedString("Variation created", comment: "Text for the notice after creating the first variation.")
+
+        static let confirmationTitle = NSLocalizedString("Generate all variations?",
+                                                         comment: "Alert title to allow the user confirm if they want to generate all variations")
+        static func confirmationDescription(variationCount: Int) -> String {
+            let format = NSLocalizedString("This will create a variation for each and every possible combination of variation attributes (%d variations).",
+                                           comment: "Alert description to allow the user confirm if they want to generate all variations")
+            return String.localizedStringWithFormat(format, variationCount)
+        }
+        static let ok = NSLocalizedString("OK", comment: "Button text to confirm that we want to generate all variations")
+        static let cancel = NSLocalizedString("Cancel", comment: "Button text to confirm that we don't want to generate all variations")
+
     }
 
     /// Localizated strings for the  action sheet options

WooCommerce/Classes/ViewRelated/Products/Variations/ProductVariationsViewModel.swift

@@ -26,27 +26,49 @@ final class ProductVariationsViewModel {
     }
 
     /// Generates all missing variations for a product. Up to 100 variations.
+    /// Parameters:
+    /// - `Product`: Product on which we will be creating the variations
+    /// - `onStateChanged`: Closure invoked every time there is a significant state change in the generation process.
     ///
-    func generateAllVariations(for product: Product, onCompletion: @escaping (Result<Void, GenerationError>) -> Void) {
+    func generateAllVariations(for product: Product, onStateChanged: @escaping (GenerationState) -> Void) {
 
+        // Fetch Previous variations
+        onStateChanged(.fetching)
         fetchAllVariations(of: product) { [weak self] result in
-            guard let self else { return }
             switch result {
             case .success(let existingVariations):
 
+                // Generate variations locally
                 let variationsToGenerate = ProductVariationGenerator.generateVariations(for: product, excluding: existingVariations)
 
                 // Guard for 100 variation limit
                 guard variationsToGenerate.count <= 100 else {
-                    return onCompletion(.failure(.tooManyVariations(variationCount: variationsToGenerate.count)))
+                    return onStateChanged(.error(.tooManyVariations(variationCount: variationsToGenerate.count)))
                 }
 
+                // Guard for no variations to generate
                 guard variationsToGenerate.count > 0 else {
-                    // TODO: Inform user that no variation will be created
-                    return onCompletion(.success(()))
+                    return onStateChanged(.finished(false))
                 }
 
-                self.createVariationsRemotely(for: product, variations: variationsToGenerate, onCompletion: onCompletion)
+                // Confirm generation with merchant
+                onStateChanged(.confirmation(variationsToGenerate.count, { confirmed in
+
+                    guard confirmed else {
+                        return onStateChanged(.canceled)
+                    }
+
+                    // Create variations remotely
+                    onStateChanged(.creating)
+                    self?.createVariationsRemotely(for: product, variations: variationsToGenerate) { result in
+                        switch result {
+                        case .success:
+                            onStateChanged(.finished(true))
+                        case .failure(let error):
+                            onStateChanged(.error(error))
+                        }
+                    }
+                }))
 
             case .failure:
                 // TODO: Log and inform error
@@ -106,7 +128,36 @@ extension ProductVariationsViewModel {
     }
 }
 
+// MARK: Definitions for Generate All Variations
 extension ProductVariationsViewModel {
+    /// Type that represents the possible states while all variations are being created.
+    ///
+    enum GenerationState {
+        /// State while previous variations are being fetched
+        ///
+        case fetching
+
+        /// State to allow merchant to confirm the variation generation
+        ///
+        case confirmation(_ numberOfVariations: Int, _ onCompletion: (_ confirmed: Bool) -> Void)
+
+        /// State while the variations are being created remotely
+        ///
+        case creating
+
+        ///State when the merchant decides to not continue with the generation process.
+        ///
+        case canceled
+
+        /// State when the the process is finished. `variationsCreated` indicates if  variations were created or not.
+        ///
+        case finished(_ variationsCreated: Bool)
+
+        /// Error state in any part of the process.
+        ///
+        case error(GenerationError)
+    }
+
     /// Type to represent known generation errors
     ///
     enum GenerationError: LocalizedError, Equatable {

WooCommerce/WooCommerceTests/ViewRelated/Products/Variations/ProductVariationsViewModelTests.swift

@@ -137,8 +137,8 @@ final class ProductVariationsViewModelTests: XCTestCase {
 
         // When
         let error = waitFor { promise in
-            viewModel.generateAllVariations(for: product) { result in
-                if case let .failure(error) = result {
+            viewModel.generateAllVariations(for: product) { state in
+                if case let .error(error) = state {
                     promise(error)
                 }
             }
@@ -148,7 +148,7 @@ final class ProductVariationsViewModelTests: XCTestCase {
         XCTAssertEqual(error, .tooManyVariations(variationCount: 125))
     }
 
-    func test_generating_less_than_100_variations_invokes_create_action() {
+    func test_generating_less_than_100_variations_ask_for_confirmation_and_creates_variations() {
         // Given
         let product = Product.fake().copy(attributes: [
             ProductAttribute.fake().copy(attributeID: 1, name: "Size", options: ["XS", "S", "M", "L", "XL"]),
@@ -171,8 +171,11 @@ final class ProductVariationsViewModelTests: XCTestCase {
 
         // When
         let succeeded = waitFor { promise in
-            viewModel.generateAllVariations(for: product) { result in
-                if case .success = result {
+            viewModel.generateAllVariations(for: product) { state in
+                if case let .confirmation(_, onCompletion) = state {
+                    onCompletion(true)
+                }
+                if case .finished = state {
                     promise(true)
                 }
             }
@@ -181,4 +184,41 @@ final class ProductVariationsViewModelTests: XCTestCase {
         // Then
         XCTAssertTrue(succeeded)
     }
+
+    func test_generating_less_than_100_variations_ask_for_confirmation_and_sends_cancel_state() {
+        // Given
+        let product = Product.fake().copy(attributes: [
+            ProductAttribute.fake().copy(attributeID: 1, name: "Size", options: ["XS", "S", "M", "L", "XL"]),
+            ProductAttribute.fake().copy(attributeID: 2, name: "Color", options: ["Red", "Green", "Blue", "White", "Black"]),
+        ])
+
+        let stores = MockStoresManager(sessionManager: SessionManager.makeForTesting())
+        stores.whenReceivingAction(ofType: ProductVariationAction.self) { action in
+            switch action {
+            case .synchronizeAllProductVariations(_, _, let onCompletion):
+                onCompletion(.success([]))
+            case .createProductVariations(_, _, _, let onCompletion):
+                onCompletion(.success([]))
+            default:
+                break
+            }
+        }
+
+        let viewModel = ProductVariationsViewModel(stores: stores, formType: .edit)
+
+        // When
+        let canceled = waitFor { promise in
+            viewModel.generateAllVariations(for: product) { state in
+                if case let .confirmation(_, onCompletion) = state {
+                    onCompletion(false)
+                }
+                if case .canceled = state {
+                    promise(true)
+                }
+            }
+        }
+
+        // Then
+        XCTAssertTrue(canceled)
+    }
 }