WatchSessionManager.swift

//
//  WatchSessionManager.swift
//

import WatchConnectivity

class WatchSessionManager: NSObject, WCSessionDelegate {

  static let sharedManager = WatchSessionManager()

  private let session: WCSession? = WCSession.isSupported() ? WCSession.defaultSession() : nil
  private var validSession: WCSession? {
    if let session = session where session.paired && session.watchAppInstalled {
      return session
    }
    return nil
  }

  var shelter: Shelter?

  func startSessionWithShelter(shelter: Shelter) {
    self.shelter = shelter
    session?.delegate = self
    session?.activateSession()

    if shelter.dogsLoaded == true {
      updateApplicationContext()
    }
  }
  
  func sessionWatchStateDidChange(session: WCSession) {
    if session.activationState == .Activated {
      updateApplicationContext()
    }
  }
  
  // Construct and send the updated application context to the watch.
  func updateApplicationContext() {
    let context = [String: AnyObject]()
    
    // Now, compute the values from your model object to send to the watch.

    do {
      try WatchSessionManager.sharedManager.updateApplicationContext(context)
    } catch {
      print("Error updating application context")
    }
  }

}

// MARK: Application Context
extension WatchSessionManager {

  // Sender
  func updateApplicationContext(applicationContext: [String : AnyObject]) throws {
    if let session = validSession {
      do {
        try session.updateApplicationContext(applicationContext)
      } catch let error {
        throw error
      }
    }
  }
  
}


// MARK: Interactive Messaging
extension WatchSessionManager {

  private var validReachableSession: WCSession? {
    if let session = validSession where session.reachable {
      return session
    }
    return nil
  }

  // Receiver
  func session(session: WCSession, didReceiveMessage message: [String : AnyObject],
               replyHandler: ([String : AnyObject]) -> Void) {
    if message[Key.Request.ApplicationContext] != nil {
        updateApplicationContext()
    }
  }

}