Merge pull request #5828 from woocommerce/issue/5767-load-next-page

Coupons: Add loading next page functionality to coupon list

Author: itsmeichigo

Networking/Networking/Mapper/CouponListMapper.swift

@@ -12,7 +12,9 @@ struct CouponListMapper: Mapper {
     ///
     func map(response: Data) throws -> [Coupon] {
         let coupons = try Coupon.decoder.decode(CouponListEnvelope.self, from: response).coupons
-        return coupons.map { $0.copy(siteID: siteID) }
+        return coupons
+            .map { $0.copy(siteID: siteID) }
+            .filter { $0.mappedDiscountType != nil }
     }
 }
 

Networking/Networking/Model/Coupon.swift

@@ -26,7 +26,22 @@ public struct Coupon {
     public let dateModified: Date
 
     /// Determines the type of discount that will be applied. Options: `.percent` `.fixedCart` and `.fixedProduct`
-    public let discountType: DiscountType
+    public var discountType: DiscountType {
+        if let type = mappedDiscountType {
+            return type
+        } else {
+            // Returns default value for fallback case to avoid working with optionals.
+            // Since `CouponListMapper` filters out nil `mappedDiscountType`,
+            // this case is unlikely to happen.
+            return .fixedCart
+        }
+    }
+
+    /// Discount type if matched with any of the ones supported by Core.
+    /// Returns nil if other types are found.
+    /// Used to filter only coupons with default types, so internal to this module only.
+    ///
+    internal let mappedDiscountType: DiscountType?
 
     public let description: String
 
@@ -78,6 +93,9 @@ public struct Coupon {
     /// Email addresses of customers who have used this coupon
     public let usedBy: [String]
 
+    /// Discount types supported by Core.
+    /// There are other types supported by other plugins, but those are not supported for now.
+    ///
     public enum DiscountType: String {
         case percent = "percent"
         case fixedCart = "fixed_cart"
@@ -114,7 +132,7 @@ public struct Coupon {
         self.amount = amount
         self.dateCreated = dateCreated
         self.dateModified = dateModified
-        self.discountType = discountType
+        self.mappedDiscountType = discountType
         self.description = description
         self.dateExpires = dateExpires
         self.usageCount = usageCount
@@ -148,7 +166,7 @@ extension Coupon: Codable {
         case amount
         case dateCreated = "dateCreatedGmt"
         case dateModified = "dateModifiedGmt"
-        case discountType
+        case mappedDiscountType
         case description
         case dateExpires = "dateExpiresGmt"
         case usageCount

WooCommerce/Classes/ViewRelated/Coupons/CouponListViewController.swift

@@ -18,6 +18,14 @@ final class CouponListViewController: UIViewController {
         return refreshControl
     }()
 
+    /// Footer "Loading More" Spinner.
+    ///
+    private lazy var footerSpinnerView = FooterSpinnerView()
+
+    /// Empty Footer Placeholder. Replaces spinner view and allows footer to collapse and be completely hidden.
+    ///
+    private lazy var footerEmptyView = UIView(frame: .zero)
+
     private var subscriptions: Set<AnyCancellable> = []
 
     init(siteID: Int64) {
@@ -51,6 +59,8 @@ final class CouponListViewController: UIViewController {
                     self.tableView.reloadData()
                 case .refreshing:
                     self.refreshControl.beginRefreshing()
+                case .loadingNextPage:
+                    self.startFooterLoadingIndicator()
                 case .initialized:
                     break
                 }
@@ -75,10 +85,33 @@ private extension CouponListViewController {
     func resetViews() {
         removeNoResultsOverlay()
         removePlaceholderCoupons()
+        stopFooterLoadingIndicator()
         if refreshControl.isRefreshing {
             refreshControl.endRefreshing()
         }
     }
+
+    /// Starts the loading indicator in the footer, to show that another page is being fetched
+    ///
+    func startFooterLoadingIndicator() {
+        tableView?.tableFooterView = footerSpinnerView
+        footerSpinnerView.startAnimating()
+    }
+
+    /// Stops the loading indicator in the footer
+    ///
+    func stopFooterLoadingIndicator() {
+        footerSpinnerView.stopAnimating()
+        tableView?.tableFooterView = footerEmptyView
+    }
+}
+
+// MARK: - TableView Delegate
+//
+extension CouponListViewController: UITableViewDelegate {
+    func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
+        viewModel.tableWillDisplayCell(at: indexPath)
+    }
 }
 
 
@@ -95,6 +128,7 @@ private extension CouponListViewController {
         tableView.estimatedRowHeight = Constants.estimatedRowHeight
         tableView.rowHeight = UITableView.automaticDimension
         tableView.addSubview(refreshControl)
+        tableView.delegate = self
     }
 
     func registerTableViewCells() {

WooCommerce/Classes/ViewRelated/Coupons/CouponManagementListViewModel.swift

@@ -16,6 +16,7 @@ enum CouponListState {
     case empty // View should display the empty state
     case coupons // View should display the contents of `couponViewModels`
     case refreshing // View should display the refresh control
+    case loadingNextPage // View should display a bottom loading indicator and contents of `couponViewModels`
 }
 
 final class CouponListViewModel {
@@ -69,7 +70,7 @@ final class CouponListViewModel {
                                                 storageManager: StorageManagerType) -> ResultsController<StorageCoupon> {
         let predicate = NSPredicate(format: "siteID == %lld", siteID)
         let descriptor = NSSortDescriptor(keyPath: \StorageCoupon.dateCreated,
-                                          ascending: true)
+                                          ascending: false)
 
         return ResultsController<StorageCoupon>(storageManager: storageManager,
                                                 matching: predicate,
@@ -123,6 +124,12 @@ final class CouponListViewModel {
     func refreshCoupons() {
         syncingCoordinator.resynchronize(reason: nil, onCompletion: nil)
     }
+
+    /// The ViewController can trigger loading of the next page when the user scrolls to the bottom
+    ///
+    func tableWillDisplayCell(at indexPath: IndexPath) {
+        syncingCoordinator.ensureNextPageIsSynchronized(lastVisibleIndex: indexPath.row)
+    }
 }
 
 
@@ -172,6 +179,8 @@ private extension CouponListViewModel {
     func transitionToSyncingState(pageNumber: Int, hasData: Bool) {
         if pageNumber == 1 {
             state = hasData ? .refreshing : .loading
+        } else {
+            state = .loadingNextPage
         }
     }
 

WooCommerce/WooCommerceTests/ViewRelated/Coupons/CouponListViewModelTests.swift

@@ -145,4 +145,24 @@ final class CouponListViewModelTests: XCTestCase {
         // Then
         XCTAssertEqual(sut.state, .coupons)
     }
+
+    func test_tableWillDisplayCellAtIndexPath_calls_ensureNextPageIsSynchronized_on_syncCoordinator() {
+        // Given
+        sut = CouponListViewModel(siteID: 123, syncingCoordinator: mockSyncingCoordinator)
+
+        // When
+        sut.tableWillDisplayCell(at: IndexPath(row: 3, section: 0))
+
+        // Then
+        XCTAssertTrue(mockSyncingCoordinator.spyDidCallEnsureNextPageIsSynchronized)
+        XCTAssertEqual(mockSyncingCoordinator.spyEnsureNextPageIsSynchronizedLastVisibleIndex, 3)
+    }
+
+    func test_sync_updates_state_correctly_when_syncing_next_page() {
+        // When
+        sut.sync(pageNumber: 2, pageSize: 10, reason: nil, onCompletion: nil)
+
+        // Then
+        XCTAssertEqual(sut.state, .loadingNextPage)
+    }
 }