[Framework] Show top words for filtered items in the Feed List (#12)

This PR contains the work done to show the top 3 words belonging to the filtered reviews  in the `FeedListViewController` view controller.

Reviewed-on: rock-n-code/app-reviews#12
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Frameworks/Feed/Bundle/Sources/Logic/Extensions/TopWord+DTOs.swift

@@ -0,0 +1,23 @@
+//
+//  TopWord+DTOs.swift
+//  ReviewsFeed
+//
+//  Created by Javier Cicchelli on 21/03/2024.
+//  Copyright © 2024 Röck+Cöde. All rights reserved.
+//
+
+import Foundation
+import ReviewsFilterKit
+
+extension TopWord {
+    
+    // MARK: Initialisers
+    init(_ dto: WordCount) {
+        self = .init(
+            id: UUID().uuidString,
+            term: dto.word.term,
+            count: dto.count
+        )
+    }
+    
+}

Frameworks/Feed/Bundle/Sources/Logic/Models/TopWord.swift

@@ -0,0 +1,16 @@
+//
+//  TopWord.swift
+//  ReviewsFeed
+//
+//  Created by Javier Cicchelli on 21/03/2024.
+//  Copyright © 2024 Röck+Cöde. All rights reserved.
+//
+
+struct TopWord: Identifiable {
+    
+    // MARK: Constants
+    let id: String
+    let term: String
+    let count: Int
+    
+}

Frameworks/Feed/Bundle/Sources/Logic/View Models/FeedListViewModel.swift

@@ -18,6 +18,9 @@ extension FeedListViewController {
         
         // MARK: Constants
         private let configuration: Configuration
+        
+        private let filterWords: FilterWordsUseCase = .init()
+        private let topWords: TopWordsUseCase = .init()
 
         // MARK: Properties
         @Published var filter: FilterOption = .all
@@ -26,9 +29,11 @@ extension FeedListViewController {
         @Published var isLoading: Bool = false
 
         var items: [Review] = []
+        var words: [TopWord] = []
         
         private var reviewsAll: [Review] = []
         private var reviewsFiltered: FilteredReviews = [:]
+        private var reviewsTopWords: TopWordsReviews = [:]
         
         lazy private var iTunesService: iTunesService = {
             .init(configuration: .init(session: configuration.session))
@@ -38,6 +43,18 @@ extension FeedListViewController {
         init(configuration: Configuration = .init()) {
             self.configuration = configuration
         }
+        
+        // MARK: Computed
+        var itemsCount: Int {
+            isWordsShowing
+                ? items.count
+                : items.count + 1
+        }
+        
+        var isWordsShowing: Bool {
+            filter != .all
+            && !words.isEmpty
+        }
 
         // MARK: Functions
         func fetch() {
@@ -56,6 +73,14 @@ extension FeedListViewController {
                         .reduce(into: FilteredReviews()) { partialResult, option in
                             partialResult[option] = reviewsAll.filter { $0.rating.stars == option.rawValue }
                         }
+                    reviewsTopWords = reviewsFiltered
+                        .mapValues { reviews in
+                            reviews.map(\.comment)
+                                .compactMap { try? filterWords($0) }
+                        }
+                        .mapValues {
+                            topWords($0).map(TopWord.init)
+                        }
 
                     items = reviewsAll
                     isFilterEnabled = !items.isEmpty
@@ -74,9 +99,18 @@ extension FeedListViewController {
             items = option == .all
                 ? reviewsAll
                 : reviewsFiltered[option] ?? []
-            
+            words = reviewsTopWords[option] ?? []
+
             filter = option
         }
+        
+        func item(for index: Int) -> Review? {
+            guard index < items.count else { return nil }
+            
+            return isWordsShowing
+                ? items[index - 1]
+                : items[index]
+        }
 
     }
 }
@@ -86,5 +120,6 @@ private extension FeedListViewController.ViewModel {
     
     // MARK: Type aliases
     typealias FilteredReviews = [FilterOption: [Review]]
+    typealias TopWordsReviews = [FilterOption: [TopWord]]
 
 }