[Library] Top words filtering in Filter library (#8)

This PR contains the work done to implement the `TopWordsUseCase` use case  in the `Filter` library, to obtain the top words out of a given groups of word counts.

Reviewed-on: #8
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Libraries/Filter/Kit/Sources/Models/Word.swift

@@ -0,0 +1,24 @@
+//
+//  Word.swift
+//  ReviewsFilterKit
+//
+//  Created by Javier Cicchelli on 18/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+public struct Word: Equatable {
+    
+    // MARK: Constants
+    public let term: String
+    public let token: String
+    
+    // MARK: Initialisers
+    public init(
+        term: String,
+        token: String
+    ) {
+        self.term = term
+        self.token = token
+    }
+    
+}

Libraries/Filter/Kit/Sources/Models/WordCount.swift

@@ -0,0 +1,24 @@
+//
+//  WordCount.swift
+//  ReviewsFilterKit
+//
+//  Created by Javier Cicchelli on 18/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+public struct WordCount: Equatable {
+    
+    // MARK: Constants
+    public let count: Int
+    public let word: Word
+    
+    // MARK: Initialisers
+    public init(
+        word: Word,
+        count: Int
+    ) {
+        self.count = count
+        self.word = word
+    }
+    
+}

Libraries/Filter/Kit/Sources/Use Cases/FilterWordsUseCase.swift

@@ -1,18 +1,19 @@
 //
 //  FilterWordsUseCase.swift
-//  ReviewsParserKit
+//  ReviewsFilterKit
 //
 //  Created by Javier Cicchelli on 17/03/2024.
 //  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
 //
 
 import Foundation
+import ReviewsFoundationKit
 
 public struct FilterWordsUseCase {
     
     // MARK: Type aliases
     public typealias Input = String
-    public typealias Output = [Tuple]
+    public typealias Output = [WordCount]
     
     // MARK: Initialisers
     public init() {}
@@ -32,42 +33,45 @@ public struct FilterWordsUseCase {
         
         guard !matches.isEmpty else { return [] }
         
-        let wordsAll = matches.compactMap {
+        let terms = matches.compactMap {
             Range($0.range, in: input).map { String(input[$0]) }
         }
+
+        let wordsAll = terms
+                .map { ($0, $0.folding(options: .caseInsensitive, locale: nil)) }
+                .map(Word.init)
+
+        let wordsCount = wordsAll.map { word -> WordCount in
+            .init(
+                word: word,
+                count: terms.filter { $0 == word.term }.count
+            )
+        }.reduce(into: [WordCount]()) { partialResult, wordCount in
+            guard partialResult.filter({ $0 == wordCount }).isEmpty else { return }
+
+            partialResult.append(wordCount)
+        }
         
-        let wordsUnique = wordsAll
+        let wordsUnique = Dictionary(grouping: wordsCount) { wordCount -> String in
-            .reduce(into: [String]()) { partialResult, word in
-                guard partialResult
-                    .filter({ compareWords(word, $0) })
-                    .isEmpty
-                else { return }
-                
-                partialResult.append(
-                    word.folding(
-                        options: [
-                            .caseInsensitive,
-                            .diacriticInsensitive
-                        ],
-                        locale: .current
-                    )
-                    .capitalized
-                )
-            }
-        
-        return Dictionary(grouping: wordsUnique) { word in
             wordsAll
-                .filter { compareWords(word, $0) }
+                .filter { $0.token == wordCount.word.token }
-                .count
+                .map(\.token)
+                .first ?? .empty
+        }.map { (key, values) -> WordCount in
+            .init(
+                word: .init(
+                    term: key.capitalized,
+                    token: key
+                ),
+                count: values
+                    .map(\.count)
+                    .reduce(0, +)
+            )
         }
-        .flatMap { (key, values) -> Output in
+
-            values.map {
+        return wordsUnique.sorted {
-                .init(word: $0, count: key)
-            }
-        }
-        .sorted {
             guard $0.count != $1.count else {
-                return $0.word < $1.word
+                return $0.word.token < $1.word.token
             }
             
             return $0.count > $1.count
@@ -92,26 +96,6 @@ private extension FilterWordsUseCase {
     
 }
 
-// MARK: - Structs
-extension FilterWordsUseCase {
-    public struct Tuple: Equatable {
-        
-        // MARK: Constants
-        let word: String
-        let count: Int
-        
-        // MARK: Initialisers
-        public init(
-            word: String,
-            count: Int
-        ) {
-            self.word = word
-            self.count = count
-        }
-
-    }
-}
-
 // MARK: - String+Constants
 private extension String {
     enum Pattern {

Libraries/Filter/Kit/Sources/Use Cases/TopWordsUseCase.swift

@@ -0,0 +1,58 @@
+//
+//  TopWordsUseCase.swift
+//  ReviewsParserKit
+//
+//  Created by Javier Cicchelli on 18/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+
+public struct TopWordsUseCase {
+    
+    // MARK: Type aliases
+    public typealias Input = [[WordCount]]
+    public typealias Output = [WordCount]
+    
+    // MARK: Initialisers
+    public init() {}
+    
+    // MARK: Functions
+    public func callAsFunction(_ input: Input) -> Output {
+        let wordCounts = input
+            .reduce([WordCount](), +)
+            .reduce(into: [WordCount]()) { partialResult, wordCount in
+                guard
+                    let wordCountFound = partialResult.first(where: { $0.word == wordCount.word })
+                else {
+                    partialResult.append(wordCount)
+                    return
+                }
+                
+                partialResult.removeAll { $0 == wordCountFound }
+                partialResult.append(.init(
+                    word: wordCount.word,
+                    count: wordCount.count + wordCountFound.count
+                ))
+            }
+            .sorted {
+                guard $0.count != $1.count else {
+                    return $0.word.token < $1.word.token
+                }
+                
+                return $0.count > $1.count
+            }
+
+        return wordCounts.count >= .Max.words
+            ? Array(wordCounts[0...2])
+            : wordCounts
+    }
+    
+}
+
+// MARK: - Int+Constants
+private extension Int {
+    enum Max {
+        static let words: Int = 3
+    }
+}

Libraries/Filter/Test/Tests/Use Cases/FilterWordsUseCaseTests.swift

@@ -33,12 +33,12 @@ final class FilterWordsUseCaseTests: XCTestCase {
         // THEN
         XCTAssertFalse(output.isEmpty)
         XCTAssertEqual(output, [
-            .init(word: "Eight", count: 1),
+            .init(word: .init(term: "Eight", token: "eight"), count: 1),
-            .init(word: "Five", count: 1),
+            .init(word: .init(term: "Five", token: "five"), count: 1),
-            .init(word: "Four", count: 1),
+            .init(word: .init(term: "Four", token: "four"), count: 1),
-            .init(word: "Nine", count: 1),
+            .init(word: .init(term: "Nine", token: "nine"), count: 1),
-            .init(word: "Seven", count: 1),
+            .init(word: .init(term: "Seven", token: "seven"), count: 1),
-            .init(word: "Three", count: 1),
+            .init(word: .init(term: "Three", token: "three"), count: 1),
         ])
     }
     
@@ -52,18 +52,18 @@ final class FilterWordsUseCaseTests: XCTestCase {
         // THEN
         XCTAssertFalse(output.isEmpty)
         XCTAssertEqual(output, [
-            .init(word: "Five", count: 2),
+            .init(word: .init(term: "Five", token: "five"), count: 2),
-            .init(word: "Nine", count: 2),
+            .init(word: .init(term: "Nine", token: "nine"), count: 2),
-            .init(word: "Three", count: 2),
+            .init(word: .init(term: "Three", token: "three"), count: 2),
-            .init(word: "Eight", count: 1),
+            .init(word: .init(term: "Eight", token: "eight"), count: 1),
-            .init(word: "Four", count: 1),
+            .init(word: .init(term: "Four", token: "four"), count: 1),
-            .init(word: "Seven", count: 1),
+            .init(word: .init(term: "Seven", token: "seven"), count: 1),
         ])
     }
     
     func testCallAsFunction_withInput_hasSomeRepeatedCaseSensitiveLongWords() throws {
         // GIVEN
-        input = "one two three Three four Five five six seven eight nine nine ten"
+        input = "one two three ThReE four FIVE five six seven eight NiNe nInE ten"
         
         // WHEN
         output = try sut(input)
@@ -71,18 +71,18 @@ final class FilterWordsUseCaseTests: XCTestCase {
         // THEN
         XCTAssertFalse(output.isEmpty)
         XCTAssertEqual(output, [
-            .init(word: "Five", count: 2),
+            .init(word: .init(term: "Five", token: "five"), count: 2),
-            .init(word: "Nine", count: 2),
+            .init(word: .init(term: "Nine", token: "nine"), count: 2),
-            .init(word: "Three", count: 2),
+            .init(word: .init(term: "Three", token: "three"), count: 2),
-            .init(word: "Eight", count: 1),
+            .init(word: .init(term: "Eight", token: "eight"), count: 1),
-            .init(word: "Four", count: 1),
+            .init(word: .init(term: "Four", token: "four"), count: 1),
-            .init(word: "Seven", count: 1),
+            .init(word: .init(term: "Seven", token: "seven"), count: 1),
         ])
     }
     
-    func testCallAsFunction_withInput_hasSomeRepeatedDiacriticSensitiveLongWords() throws {
+    func testCallAsFunction_withInput_hasSomeDiacriticSensitiveLongWords() throws {
         // GIVEN
-        input = "one two thrèé Three four Fíve fïve six Šëvêń seven eight niñe nine ten"
+        input = "one two three Thrèé four FiVe FIVE six Šëvêń seven eight niñe nine ten"
         
         // WHEN
         output = try sut(input)
@@ -90,12 +90,15 @@ final class FilterWordsUseCaseTests: XCTestCase {
         // THEN
         XCTAssertFalse(output.isEmpty)
         XCTAssertEqual(output, [
-            .init(word: "Five", count: 2),
+            .init(word: .init(term: "Five", token: "five"), count: 2),
-            .init(word: "Nine", count: 2),
+            .init(word: .init(term: "Eight", token: "eight"), count: 1),
-            .init(word: "Seven", count: 2),
+            .init(word: .init(term: "Four", token: "four"), count: 1),
-            .init(word: "Three", count: 2),
+            .init(word: .init(term: "Nine", token: "nine"), count: 1),
-            .init(word: "Eight", count: 1),
+            .init(word: .init(term: "Niñe", token: "niñe"), count: 1),
-            .init(word: "Four", count: 1),
+            .init(word: .init(term: "Seven", token: "seven"), count: 1),
+            .init(word: .init(term: "Three", token: "three"), count: 1),
+            .init(word: .init(term: "Thrèé", token: "thrèé"), count: 1),
+            .init(word: .init(term: "Šëvêń", token: "šëvêń"), count: 1),
         ])
     }
     

Libraries/Filter/Test/Tests/Use Cases/TopWordsUseCaseTests.swift

@@ -0,0 +1,110 @@
+//
+//  TopWordsUseCaseTests.swift
+//  ReviewsFilterTest
+//
+//  Created by Javier Cicchelli on 18/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import ReviewsFilterKit
+import XCTest
+
+final class TopWordsUseCaseTests: XCTestCase {
+    
+    // MARK: Properties
+    private var input: TopWordsUseCase.Input!
+    private var output: TopWordsUseCase.Output!
+    private var sut: TopWordsUseCase!
+    
+    // MARK: Setup
+    override func setUp() async throws {
+        sut = .init()
+    }
+    
+    // MARK: Functions
+    func testCallAsFunction_withInput_hasDifferentWords() {
+        // GIVEN
+        input = [[
+            .init(word: .init(term: "One", token: "one"), count: 3)
+        ], [
+            .init(word: .init(term: "Two", token: "two"), count: 1)
+        ], [
+            .init(word: .init(term: "Three", token: "three"), count: 5),
+            .init(word: .init(term: "Four", token: "four"), count: 2),
+        ]]
+        
+        // WHEN
+        output = sut(input)
+        
+        // THEN
+        XCTAssertFalse(output.isEmpty)
+        XCTAssertEqual(output.count, 3)
+        XCTAssertEqual(output, [
+            .init(word: .init(term: "Three", token: "three"), count: 5),
+            .init(word: .init(term: "One", token: "one"), count: 3),
+            .init(word: .init(term: "Four", token: "four"), count: 2)
+        ])
+    }
+    
+    func testCallAsFunction_withInput_hasSomeCommonWords() {
+        // GIVEN
+        input = [[
+            .init(word: .init(term: "One", token: "one"), count: 3),
+            .init(word: .init(term: "Two", token: "two"), count: 7),
+            .init(word: .init(term: "Three", token: "three"), count: 1),
+        ], [
+            .init(word: .init(term: "Four", token: "four"), count: 5),
+            .init(word: .init(term: "Two", token: "two"), count: 2),
+            .init(word: .init(term: "Five", token: "five"), count: 6),
+        ], [
+            .init(word: .init(term: "Six", token: "six"), count: 9),
+            .init(word: .init(term: "Four", token: "four"), count: 4),
+            .init(word: .init(term: "Two", token: "two"), count: 1),
+        ]]
+        
+        // WHEN
+        output = sut(input)
+        
+        // THEN
+        XCTAssertFalse(output.isEmpty)
+        XCTAssertEqual(output.count, 3)
+        XCTAssertEqual(output, [
+            .init(word: .init(term: "Two", token: "two"), count: 10),
+            .init(word: .init(term: "Four", token: "four"), count: 9),
+            .init(word: .init(term: "Six", token: "six"), count: 9)
+        ])
+    }
+    
+    func testCallAsFunction_withInput_hasFewWords() {
+        // GIVEN
+        input = [[
+            .init(word: .init(term: "One", token: "one"), count: 3),
+        ], [
+            .init(word: .init(term: "Four", token: "four"), count: 5),
+        ]]
+        
+        // WHEN
+        output = sut(input)
+        
+        // THEN
+        XCTAssertFalse(output.isEmpty)
+        XCTAssertEqual(output.count, 2)
+        XCTAssertEqual(output, [
+            .init(word: .init(term: "Four", token: "four"), count: 5),
+            .init(word: .init(term: "One", token: "one"), count: 3)
+        ])
+    }
+    
+    func testCallAsFunction_withEmptyInput() {
+        // GIVEN
+        input = []
+        
+        // WHEN
+        output = sut(input)
+        
+        // THEN
+        XCTAssertTrue(output.isEmpty)
+        XCTAssertEqual(output, [])
+    }
+    
+}