[Library] iTunes library (#5)

This PR contains the work done to implement the `iTunesService` service that fetches the reviews from the **Apple App Store**.

Reviewed-on: rock-n-code/app-reviews#5
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Libraries/iTunes/Kit/Endpoints/GetReviewsAPIEndpoint.swift

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+//
+//  GetReviewsAPIEndpoint.swift
+//  ReviewsiTunesKit
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+import ReviewsFoundationKit
+import ReviewsFeedKit
+
+struct GetReviewsAPIEndpoint: GetReviewsEndpoint {
+    
+    // MARK: Constants
+    let host: URL
+    let decoder: JSONDecoder
+    let session: URLSession
+
+    // MARK: Functions
+    @discardableResult func callAsFunction(
+        _ input: ReviewsFeedKit.GetReviewsInput
+    ) async throws -> ReviewsFeedKit.GetReviewsOutput {
+        let path = try makePath(with: input)
+        let url = {
+            if #available(iOS 16.0, *) {
+                host.appending(path: path)
+            } else {
+                host.appendingPathComponent(path)
+            }
+        }()
+        
+        let (data, response) = try await session.data(from: url)
+        
+        guard let urlResponse = response as? HTTPURLResponse else {
+            throw EndpointError.responseNotFound
+        }
+
+        guard urlResponse.statusCode == 200 else {
+            throw EndpointError.requestFailed(statusCode: urlResponse.statusCode)
+        }
+        
+        let feed = try decoder.decode(Feed.self, from: data)
+        
+        return .init(reviews: feed.entries)
+    }
+    
+    func makePath(with input: GetReviewsInput) throws -> String {
+        guard
+            !input.appID.isEmpty,
+            !input.countryCode.isEmpty
+        else{
+            throw EndpointError.inputParametersEmpty
+        }
+
+        return .init(
+            format: .Format.recentReviewsPath,
+            input.countryCode,
+            input.appID
+        )
+    }
+    
+}
+
+// MARK: - String+Formats
+private extension String {
+    enum Format {
+        static let recentReviewsPath = "/%@/rss/customerreviews/id=%@/sortby=mostrecent/json"
+    }
+}

Libraries/iTunes/Kit/Extensions/ServiceConfiguration+Inits.swift

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+//
+//  ServiceConfiguration+Inits.swift
+//  ReviewsiTunesKit
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+import ReviewsFoundationKit
+import ReviewsFeedKit
+
+extension ServiceConfiguration {
+    
+    // MARK: Initialisers
+    init(session: URLSessionConfiguration = .ephemeral) {
+        self.init(
+            host: .iTunes,
+            session: session,
+            decoder: .default
+        )
+    }
+    
+}

Libraries/iTunes/Kit/Extensions/URL+Constants.swift

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+//
+//  URL+Constants.swift
+//  ReviewsiTunesKit
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+import ReviewsFoundationKit
+
+extension URL {
+    
+    // MARK: Constants
+    static let iTunes: URL = .init(string: "https://itunes.apple.com") ?? .bitBucket
+    
+}

Libraries/iTunes/Kit/Models/Feed.swift

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+//
+//  Feed.swift
+//  ReviewsiTunesKit
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import ReviewsFeedKit
+
+struct Feed {
+    
+    // MARK: Constants
+    let entries: [Review]
+    
+}
+
+// MARK: - Decodable
+extension Feed: Decodable {
+    
+    // MARK: Enumerations
+    enum FeedKeys: String, CodingKey {
+        case feed
+    }
+    
+    enum EntryKeys: String, CodingKey {
+        case entry
+    }
+    
+    // MARK: Initialisers
+    init(from decoder: any Decoder) throws {
+        let feed = try decoder.container(keyedBy: FeedKeys.self)
+        let feedEntry = try feed.nestedContainer(keyedBy: EntryKeys.self, forKey: .feed)
+        
+        self.entries = try feedEntry.decode([Review].self, forKey: .entry)
+    }
+    
+}
+
+// MARK: - Encodable
+extension Feed: Encodable {
+    
+    // MARK: Functions
+    func encode(to encoder: any Encoder) throws {
+        var feed = encoder.container(keyedBy: FeedKeys.self)
+        var feedEntry = feed.nestedContainer(keyedBy: EntryKeys.self, forKey: .feed)
+        
+        try feedEntry.encode(entries, forKey: .entry)
+    }
+    
+}

Libraries/iTunes/Kit/Models/Review+Codable.swift

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+//
+//  Review+Codable.swift
+//  ReviewsiTunesKit
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+import ReviewsFeedKit
+
+// MARK: - Decodable
+extension Review: Decodable {
+    
+    // MARK: Enumerations
+    enum ReviewKeys: String, CodingKey {
+        case author
+        case content
+        case id
+        case rating = "im:rating"
+        case title
+        case updated
+        case version = "im:version"
+    }
+    
+    enum NameKeys: String, CodingKey {
+        case name
+    }
+    
+    enum LabelKeys: String, CodingKey {
+        case label
+    }
+    
+    // MARK: Initialisers
+    public init(from decoder: any Decoder) throws {
+        let review = try decoder.container(keyedBy: ReviewKeys.self)
+        let authorName = try review.nestedContainer(keyedBy: NameKeys.self, forKey: .author)
+        let authorLabel = try authorName.nestedContainer(keyedBy: LabelKeys.self, forKey: .name)
+        let contentLabel = try review.nestedContainer(keyedBy: LabelKeys.self, forKey: .content)
+        let idLabel = try review.nestedContainer(keyedBy: LabelKeys.self, forKey: .id)
+        let ratingLabel = try review.nestedContainer(keyedBy: LabelKeys.self, forKey: .rating)
+        let titleLabel = try review.nestedContainer(keyedBy: LabelKeys.self, forKey: .title)
+        let versionLabel = try review.nestedContainer(keyedBy: LabelKeys.self, forKey: .version)
+        let updatedLabel = try review.nestedContainer(keyedBy: LabelKeys.self, forKey: .updated)
+
+        self.init(
+            id: Int(try idLabel.decode(String.self, forKey: .label)) ?? 0,
+            author: try authorLabel.decode(String.self, forKey: .label),
+            title: try titleLabel.decode(String.self, forKey: .label),
+            content: try contentLabel.decode(String.self, forKey: .label),
+            rating: Int(try ratingLabel.decode(String.self, forKey: .label)) ?? 0,
+            version: try versionLabel.decode(String.self, forKey: .label),
+            updated: try updatedLabel.decode(Date.self, forKey: .label)
+        )
+    }
+    
+}
+
+// MARK: - Encodable
+extension Review: Encodable {
+    
+    // MARK: Functions
+    
+    public func encode(to encoder: any Encoder) throws {
+        var review = encoder.container(keyedBy: ReviewKeys.self)
+        var authorName = review.nestedContainer(keyedBy: NameKeys.self, forKey: .author)
+        var authorLabel = authorName.nestedContainer(keyedBy: LabelKeys.self, forKey: .name)
+        var contentLabel = review.nestedContainer(keyedBy: LabelKeys.self, forKey: .content)
+        var idLabel = review.nestedContainer(keyedBy: LabelKeys.self, forKey: .id)
+        var ratingLabel = review.nestedContainer(keyedBy: LabelKeys.self, forKey: .rating)
+        var titleLabel = review.nestedContainer(keyedBy: LabelKeys.self, forKey: .title)
+        var versionLabel = review.nestedContainer(keyedBy: LabelKeys.self, forKey: .version)
+        var updatedLabel = review.nestedContainer(keyedBy: LabelKeys.self, forKey: .updated)
+
+        try authorLabel.encode(author, forKey: .label)
+        try contentLabel.encode(content, forKey: .label)
+        try idLabel.encode(String(id), forKey: .label)
+        try ratingLabel.encode(String(rating), forKey: .label)
+        try titleLabel.encode(title, forKey: .label)
+        try versionLabel.encode(version, forKey: .label)
+        try updatedLabel.encode(updated, forKey: .label)
+    }
+    
+}

Libraries/iTunes/Kit/Services/iTunesService.swift

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+//
+//  iTunesService.swift
+//  ReviewsiTunes
+//
+//  Created by Javier Cicchelli on 17/03/2024.
+//  Copyright © 2024 Röck+Cöde VoF. All rights reserved.
+//
+
+import Foundation
+import ReviewsFeedKit
+
+public actor iTunesService: Service {
+    
+    // MARK: Constants
+    public let configuration: ServiceConfiguration
+    public let decoder: JSONDecoder
+    public let session: URLSession
+    
+    // MARK: Properties
+    private lazy var getReviewsEndpoint: GetReviewsAPIEndpoint = {
+        .init(
+            host: configuration.host,
+            decoder: decoder,
+            session: session
+        )
+    }()
+    
+    // MARK: Initialisers
+    public init(configuration: ServiceConfiguration) {
+        self.configuration = configuration
+        self.decoder = configuration.decoder
+        self.session = .init(configuration: configuration.session)
+    }
+    
+    // MARK: Functions
+    @discardableResult public func getReviews(
+        _ input: GetReviewsInput
+    ) async throws -> GetReviewsOutput {
+        try await getReviewsEndpoint(input)
+    }
+    
+}
+