Ios log 4 (#569)

iOS logging refactoring

client/platforms/ios/Log.swift

@@ -0,0 +1,82 @@
+import Foundation
+import os.log
+
+struct Log {
+  private static let IsLoggingEnabledKey = "IsLoggingEnabled"
+  static var isLoggingEnabled: Bool {
+    get {
+      sharedUserDefaults.bool(forKey: IsLoggingEnabledKey)
+    }
+    set {
+      sharedUserDefaults.setValue(newValue, forKey: IsLoggingEnabledKey)
+    }
+  }
+
+  private static let appGroupID = "group.org.amnezia.AmneziaVPN"
+  
+  static let neLogURL = {
+    let sharedContainerURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: appGroupID)!
+    return sharedContainerURL.appendingPathComponent("ne.log", isDirectory: false)
+  }()
+  
+  private static var sharedUserDefaults = {
+    UserDefaults(suiteName: appGroupID)!
+  }()
+  
+  static let dateFormatter: DateFormatter = {
+      let dateFormatter = DateFormatter()
+      dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
+      return dateFormatter
+  }()
+
+  var records: [Record]
+  
+  init() {
+    self.records = []
+  }
+  
+  init(_ str: String) {
+    self.records = str.split(whereSeparator: \.isNewline)
+      .compactMap {
+        Record(String($0))!
+      }
+  }
+  
+  init?(at url: URL) {
+    if !FileManager.default.fileExists(atPath: url.path) {
+      guard let _ = try? "".data(using: .utf8)?.write(to: url) else { return nil }
+    }
+    
+    guard let fileHandle = try? FileHandle(forUpdating: url) else { return nil }
+    
+    defer { fileHandle.closeFile() }
+    
+    guard
+      let data = try? fileHandle.readToEnd(),
+      let str = String(data: data, encoding: .utf8) else {
+      return nil
+    }
+    
+    self.init(str)
+  }
+  
+  static func clear(at url: URL) {
+    if FileManager.default.fileExists(atPath: url.path) {
+      guard let fileHandle = try? FileHandle(forUpdating: url) else { return }
+      
+      defer { fileHandle.closeFile() }
+      
+      try? fileHandle.truncate(atOffset: 0)
+    }
+  }
+}
+
+extension Log: CustomStringConvertible {
+  var description: String {
+    records
+      .map {
+        $0.description
+      }
+      .joined(separator: "\n")
+  }
+}