OSX Launcher: general cleanup, responsibility delegation, and fixes

launchers/macosx/I2PLauncher/Utils/FolderContentMonitor.swift

@@ -0,0 +1,111 @@
+//
+//  FolderContentMonitor.swift
+//  I2PLauncher
+//
+//  Created by Mikal Villa on 28/09/2018.
+//  Copyright © 2018 The I2P Project. All rights reserved.
+//
+
+import Foundation
+
+/*
+ infix operator ~>
+ 
+ private let queue = DispatchQueue(label: "background")
+ 
+ func ~> <R> (
+ backgroundClosure:   @escaping () -> R,
+ mainClosure:         @escaping (_ result: R) -> ())
+ {
+ queue.async {
+ let result = backgroundClosure()
+ DispatchQueue.main.async(execute: {
+ mainClosure(result)
+ })
+ }
+ }
+ */
+
+public struct Event: CustomStringConvertible {
+  
+  public let eventId: FSEventStreamEventId
+  public let eventPath: String
+  public let eventFlags: FSEventStreamEventFlags
+  
+  public var description: String {
+    return "\(eventId) - \(eventFlags) - \(eventPath)"
+  }
+}
+
+public class FolderContentMonitor {
+  
+  let callback: (Event) -> Void
+  
+  public init(pathsToWatch: [String], sinceWhen: FSEventStreamEventId = FSEventStreamEventId(kFSEventStreamEventIdSinceNow), callback: @escaping (Event) -> Void) {
+    
+    self.lastEventId = sinceWhen
+    self.pathsToWatch = pathsToWatch
+    self.callback = callback
+  }
+  
+  deinit {
+    stop()
+  }
+  
+  // MARK: - Private Properties
+  private let eventCallback: FSEventStreamCallback = {
+    (stream: ConstFSEventStreamRef,
+    contextInfo: UnsafeMutableRawPointer?,
+    numEvents: Int,
+    eventPaths: UnsafeMutableRawPointer,
+    eventFlags: UnsafePointer<FSEventStreamEventFlags>,
+    eventIds: UnsafePointer<FSEventStreamEventId>) in
+    
+    let fileSystemWatcher: FolderContentMonitor = unsafeBitCast(contextInfo, to: FolderContentMonitor.self)
+    
+    guard let paths = unsafeBitCast(eventPaths, to: NSArray.self) as? [String] else { return }
+    
+    for index in 0..<numEvents {
+      fileSystemWatcher.processEvent(eventId: eventIds[index], eventPath: paths[index], eventFlags: eventFlags[index])
+    }
+    
+    fileSystemWatcher.lastEventId = eventIds[numEvents - 1]
+  }
+  
+  private let pathsToWatch: [String]
+  private var started = false
+  private var streamRef: FSEventStreamRef!
+  
+  private func processEvent(eventId: FSEventStreamEventId, eventPath: String, eventFlags: FSEventStreamEventFlags) {
+    
+    let event = Event(eventId: eventId, eventPath: eventPath, eventFlags: eventFlags)
+    callback(event)
+  }
+  
+  public private(set) var lastEventId: FSEventStreamEventId
+  
+  public func start() {
+    guard started == false else { return }
+    
+    var context = FSEventStreamContext(version: 0, info: nil, retain: nil, release: nil, copyDescription: nil)
+    context.info = Unmanaged.passUnretained(self).toOpaque()
+    let flags = UInt32(kFSEventStreamCreateFlagUseCFTypes | kFSEventStreamCreateFlagFileEvents)
+    streamRef = FSEventStreamCreate(kCFAllocatorDefault, eventCallback, &context, pathsToWatch as CFArray, lastEventId, 0, flags)
+    
+    FSEventStreamScheduleWithRunLoop(streamRef, CFRunLoopGetMain(), CFRunLoopMode.defaultMode.rawValue)
+    FSEventStreamStart(streamRef)
+    
+    started = true
+  }
+  
+  public func stop() {
+    guard started == true else { return }
+    
+    FSEventStreamStop(streamRef)
+    FSEventStreamInvalidate(streamRef)
+    FSEventStreamRelease(streamRef)
+    streamRef = nil
+    
+    started = false
+  }
+}