ep 16

0016-dependency-injection/Environment.playground/Contents.swift

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+import UIKit
+import SafariServices
+
+enum Result<Value, Error> {
+  case success(Value)
+  case failure(Error)
+}
+//
+//protocol GitHubProtocol {
+//  func fetchRepos(onComplete completionHandler: (@escaping (Result<[GitHub.Repo], Error>) -> Void))
+//}
+
+struct GitHub { //: GitHubProtocol {
+  struct Repo: Decodable {
+    var archived: Bool
+    var description: String?
+    var htmlUrl: URL
+    var name: String
+    var pushedAt: Date?
+  }
+
+  var fetchRepos = fetchRepos(onComplete:)
+}
+
+private func fetchRepos(onComplete completionHandler: (@escaping (Result<[GitHub.Repo], Error>) -> Void)) {
+  dataTask("orgs/pointfreeco/repos", completionHandler: completionHandler)
+}
+
+private func dataTask<T: Decodable>(_ path: String, completionHandler: (@escaping (Result<T, Error>) -> Void)) {
+  let request = URLRequest(url: URL(string: "https://api.github.com/" + path)!)
+  URLSession.shared.dataTask(with: request) { data, urlResponse, error in
+    do {
+      if let error = error {
+        throw error
+      } else if let data = data {
+        let formatter = DateFormatter()
+        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
+        formatter.locale = Locale(identifier: "en_US_POSIX")
+        formatter.timeZone = TimeZone(secondsFromGMT: 0)
+
+        let decoder = JSONDecoder()
+        decoder.dateDecodingStrategy = .formatted(formatter)
+        decoder.keyDecodingStrategy = .convertFromSnakeCase
+        completionHandler(.success(try decoder.decode(T.self, from: data)))
+      } else {
+        fatalError()
+      }
+    } catch let finalError {
+      completionHandler(.failure(finalError))
+    }
+    }.resume()
+}
+
+struct Analytics {
+  struct Event {
+    var name: String
+    var properties: [String: String]
+
+    static func tappedRepo(_ repo: GitHub.Repo) -> Event {
+      return Event(
+        name: "tapped_repo",
+        properties: [
+          "repo_name": repo.name,
+          "build": Bundle.main.object(forInfoDictionaryKey: "CFBundleVersion") as? String ?? "Unknown",
+          "release": Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as? String ?? "Unknown",
+          "screen_height": String(describing: UIScreen.main.bounds.height),
+          "screen_width": String(describing: UIScreen.main.bounds.width),
+          "system_name": UIDevice.current.systemName,
+          "system_version": UIDevice.current.systemVersion,
+          ]
+      )
+    }
+  }
+
+  var track = track(_:)
+}
+
+private func track(_ event: Analytics.Event) {
+  print("Tracked", event)
+}
+
+struct Environment {
+  var analytics = Analytics()
+  var date: () -> Date = Date.init
+  var gitHub = GitHub()
+}
+
+var Current = Environment()
+
+class ReposViewController: UITableViewController {
+  var repos: [GitHub.Repo] = [] {
+    didSet {
+      self.tableView.reloadData()
+    }
+  }
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+
+    self.title = "Point-Free Repos"
+    self.view.backgroundColor = .white
+
+    Current.gitHub.fetchRepos { [weak self] result in
+      DispatchQueue.main.async {
+        switch result {
+        case let .success(repos):
+          self?.repos = repos
+            .filter { !$0.archived }
+            .sorted(by: {
+              guard let lhs = $0.pushedAt, let rhs = $1.pushedAt else { return false }
+              return lhs > rhs
+            })
+        case let .failure(error):
+          let alert = UIAlertController(
+            title: "Something went wrong",
+            message: error.localizedDescription,
+            preferredStyle: .alert
+          )
+          self?.present(alert, animated: true, completion: nil)
+        }
+      }
+    }
+  }
+
+  override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
+    return self.repos.count
+  }
+
+  override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
+    let repo = self.repos[indexPath.row]
+
+    let cell = UITableViewCell(style: .subtitle, reuseIdentifier: nil)
+    cell.textLabel?.text = repo.name
+    cell.detailTextLabel?.text = repo.description
+
+    let dateComponentsFormatter = DateComponentsFormatter()
+    dateComponentsFormatter.allowedUnits = [.day, .hour, .minute, .second]
+    dateComponentsFormatter.maximumUnitCount = 1
+    dateComponentsFormatter.unitsStyle = .abbreviated
+
+    let label = UILabel()
+    if let pushedAt = repo.pushedAt {
+      label.text = dateComponentsFormatter.string(from: pushedAt, to: Current.date())
+    }
+    label.sizeToFit()
+
+    cell.accessoryView = label
+
+    return cell
+  }
+
+  override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
+    let repo = self.repos[indexPath.row]
+    Current.analytics.track(.tappedRepo(repo))
+    let vc = SFSafariViewController(url: repo.htmlUrl)
+    self.present(vc, animated: true, completion: nil)
+  }
+}
+
+extension GitHub {
+  static let mock = GitHub(fetchRepos: { callback in
+    callback(
+      .success(
+        [
+          GitHub.Repo(archived: false, description: "Blob's blog", htmlUrl: URL(string: "https://www.pointfree.co")!, name: "Bloblog", pushedAt: Date(timeIntervalSinceReferenceDate: 547152021))
+        ]
+      )
+    )
+  })
+}
+
+extension Analytics {
+  static let mock = Analytics(track: { event in
+    print("Mock track", event)
+  })
+}
+
+extension Environment {
+  static let mock = Environment(
+    analytics: .mock,
+    date: { Date(timeIntervalSinceReferenceDate: 557152051) },
+    gitHub: .mock
+  )
+}
+
+//Current = .mock
+
+//Current.gitHub.fetchRepos = { callback in
+//  callback(.failure(NSError.init(domain: "co.pointfree", code: 1, userInfo: [NSLocalizedDescriptionKey: "Ooops!"])))
+//}
+
+let reposViewController = ReposViewController()
+//let reposViewController = ReposViewController.init(
+//  date: { Date(timeIntervalSinceReferenceDate: 557152051) },
+//  gitHub: GitHubMock.init(result: .failure(NSError.init(domain: "co.pointfree", code: 1, userInfo: [NSLocalizedDescriptionKey: "Ooops!"])))
+//)
+
+
+import PlaygroundSupport
+let vc = UINavigationController(rootViewController: reposViewController)
+PlaygroundPage.current.liveView = vc

0016-dependency-injection/Environment.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

0016-dependency-injection/README.md

@@ -0,0 +1,8 @@
+### [Point-Free](https://www.pointfree.co) Episode #16
+
+### Dependency Injection Made Easy
+
+> Today we’re going to control the world! Well, dependencies to the outside world, at least. We’ll define the “dependency injection” problem and show a lightweight solution that can be implemented in your code base with little work and no third party library.
+
+This directory contains code from Point-Free Episode #16:
+[Dependency Injection Made Easy](https://www.pointfree.co/episodes/ep16-dependency-injection-made-easy)