Show Add Favorite placeholder as last favorite item on New Tab Page (#…

…3375)

Task/Issue URL:
https://app.asana.com/0/72649045549333/1208244619690578/f
Tech Design URL:
CC:

**Description**:

Adds a possibility to show an Add button in favorites collection,
allowing to create a favorite right from New Tab Page.
([Figma](https://www.figma.com/design/N2GbF5HEvopp5iwmAlMwyD/New-Tab-Page-Customization?node-id=611-147700&m=dev)).
Add button is currently navigating to an empty view, which is expected.
The view will be implemented in additional PR.

In order to reduce the amount of duplicated code and separate additional
display elements from pure Favorites data, DataSource for Favorites was
defined which is used in common ViewModel logic for Favorites, hence the
rename of `NewTabPageModel` -> `NewTabPageViewModel`.

There was also a need to keep some of the items immovable, which
required a change in `ReorderableForEach`.

**Steps to test this PR**:

1. Open NTP without Favorites, + button should be visible as a first
element.
2. Add a couple of Favorites, + button should be visible as last item.
3. Try reordering Favorites, + button should be kept stationary and it
shouldn't be posible to drop favorite after it.

**Definition of Done (Internal Only)**:

* [ ] Does this PR satisfy our [Definition of
Done](https://app.asana.com/0/1202500774821704/1207634633537039/f)?

---
###### Internal references:
[Software Engineering
Expectations](https://app.asana.com/0/59792373528535/199064865822552)
[Technical Design
Template](https://app.asana.com/0/59792373528535/184709971311943)

DuckDuckGo.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -50,8 +50,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/duckduckgo/DesignResourcesKit",
       "state" : {
-        "revision" : "fe3c383b5e21e0a419e0f979f7f2cd4e67385b15",
-        "version" : "3.2.0"
+        "revision" : "ad133f76501edcb2bfa841e33aebc0da5f92bb5c",
+        "version" : "3.3.0"
       }
     },
     {

DuckDuckGo/AddFavoritePlaceholderItemView.swift

@@ -0,0 +1,38 @@
+//
+//  AddFavoritePlaceholderItemView.swift
+//  DuckDuckGo
+//
+//  Copyright © 2024 DuckDuckGo. All rights reserved.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+import SwiftUI
+import DesignResourcesKit
+
+struct AddFavoritePlaceholderItemView: View {
+    var body: some View {
+        RoundedRectangle(cornerRadius: 8, style: .continuous)
+            .fill(.clear)
+            .overlay {
+                Image(.add24)
+                    .tintIfAvailable(Color(designSystemColor: .icons))
+            }
+            .aspectRatio(1.0, contentMode: .fit)
+    }
+}
+
+#Preview {
+    AddFavoritePlaceholderItemView()
+        .frame(width: 100)
+}

DuckDuckGo/EditableShortcutsView.swift

@@ -61,12 +61,12 @@ private extension View {
 
 extension NewTabPageSettingsModel.NTPSetting<NewTabPageShortcut>: Reorderable, Hashable, Equatable {
 
-    var dropItemProvider: NSItemProvider {
-        NSItemProvider(object: item.id as NSString)
+    var trait: ReorderableTrait {
+        let itemProvider = NSItemProvider(object: item.id as NSString)
+        let metadata = MoveMetadata(itemProvider: itemProvider, type: .text)
+        return .movable(metadata)
     }
 
-    var dropType: UTType { .text }
-
     static func == (lhs: Self, rhs: Self) -> Bool {
         lhs.item == rhs.item
     }

DuckDuckGo/FavoriteDataSource.swift

@@ -0,0 +1,95 @@
+//
+//  FavoriteDataSource.swift
+//  DuckDuckGo
+//
+//  Copyright © 2024 DuckDuckGo. All rights reserved.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+import Foundation
+import Combine
+import Bookmarks
+
+final class FavoritesListInteractingAdapter: NewTabPageFavoriteDataSource {
+
+    let favoritesListInteracting: FavoritesListInteracting
+
+    init(favoritesListInteracting: FavoritesListInteracting) {
+        self.favoritesListInteracting = favoritesListInteracting
+    }
+
+    var externalUpdates: AnyPublisher<Void, Never> { favoritesListInteracting.externalUpdates }
+
+    var favorites: [Favorite] {
+        (try? favoritesListInteracting.favorites.map(Favorite.init)) ?? []
+    }
+
+    func moveFavorite(_ favorite: Favorite, fromIndex: Int, toIndex: Int) {
+        guard let entity = bookmarkEntity(for: favorite) else { return }
+
+        // adjust for different target index handling
+        let toIndex = toIndex > fromIndex ? toIndex - 1 : toIndex
+        favoritesListInteracting.moveFavorite(entity, fromIndex: fromIndex, toIndex: toIndex)
+    }
+
+    func bookmarkEntity(for favorite: Favorite) -> BookmarkEntity? {
+        favoritesListInteracting.favorites.first {
+            $0.uuid == favorite.id
+        }
+    }
+
+    func favorite(at index: Int) throws -> Favorite? {
+        try favoritesListInteracting.favorite(at: index).map(Favorite.init)
+    }
+
+    func removeFavorite(_ favorite: Favorite) {
+        guard let entity = bookmarkEntity(for: favorite) else { return }
+
+        favoritesListInteracting.removeFavorite(entity)
+    }
+}
+
+private extension Favorite {
+    init(_ bookmark: BookmarkEntity) throws {
+        guard let uuid = bookmark.uuid else {
+            throw FavoriteMappingError.missingUUID
+        }
+
+        self.id = uuid
+        self.title = bookmark.displayTitle
+        self.domain = bookmark.host
+        self.urlObject = bookmark.urlObject
+    }
+}
+
+private extension BookmarkEntity {
+
+    var displayTitle: String {
+        if let title = title?.trimmingWhitespace(), !title.isEmpty {
+            return title
+        }
+
+        if let host = urlObject?.host?.droppingWwwPrefix() {
+            return host
+        }
+
+        assertionFailure("Unable to create display title")
+        return ""
+    }
+
+    var host: String {
+        return urlObject?.host ?? ""
+    }
+
+}

DuckDuckGo/FavoriteItem.swift

@@ -0,0 +1,50 @@
+//
+//  FavoriteItem.swift
+//  DuckDuckGo
+//
+//  Copyright © 2024 DuckDuckGo. All rights reserved.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+import Foundation
+import UniformTypeIdentifiers
+
+enum FavoriteItem {
+    case favorite(Favorite)
+    case addFavorite
+}
+
+extension FavoriteItem: Identifiable {
+    var id: String {
+        switch self {
+        case .favorite(let favorite):
+            return favorite.id
+        case .addFavorite:
+            return "addFavorite"
+        }
+    }
+}
+
+extension FavoriteItem: Reorderable {
+    var trait: ReorderableTrait {
+        switch self {
+        case .favorite(let favorite):
+            let itemProvider = NSItemProvider(object: (favorite.urlObject?.absoluteString ?? "") as NSString)
+            let metadata = MoveMetadata(itemProvider: itemProvider, type: .plainText)
+            return .movable(metadata)
+        case .addFavorite:
+            return .stationary
+        }
+    }
+}