CountdownerServiceManager.swift

// Copyright 2016-2017, Ralf Ebert
// License   https://opensource.org/licenses/MIT
// Source    https://www.ralfebert.de/tutorials/ios-swift-multipeer-connectivity/

import Foundation
import MultipeerConnectivity

enum Action: String {
    case start
    case pause
    case reset
}

protocol CountdownerServiceManagerDelegate {

    func connectedDevicesChanged(manager: CountdownerServiceManager, connectedDevices: [String])
    func actionReceived(manager: CountdownerServiceManager, action: Action)

}

#if os(iOS) || os(watchOS) || os(tvOS)
    let displayName = UIDevice.current.name
#elseif os(OSX)
    let displayName = Host.current().name!
#endif

class CountdownerServiceManager: NSObject {

    // Service type must be a unique string, at most 15 characters long
    // and can contain only ASCII lowercase letters, numbers and hyphens.
    private let CountdownerServiceType = "countdowner"

    private let myPeerId = MCPeerID(displayName: displayName)

    private let serviceAdvertiser : MCNearbyServiceAdvertiser
    private let serviceBrowser : MCNearbyServiceBrowser

    var delegate : CountdownerServiceManagerDelegate?

    lazy var session : MCSession = {
        let session = MCSession(peer: self.myPeerId, securityIdentity: nil, encryptionPreference: .required)
        session.delegate = self
        return session
    }()

    override init() {
        self.serviceAdvertiser = MCNearbyServiceAdvertiser(peer: myPeerId, discoveryInfo: nil, serviceType: CountdownerServiceType)
        self.serviceBrowser = MCNearbyServiceBrowser(peer: myPeerId, serviceType: CountdownerServiceType)

        super.init()

        self.serviceAdvertiser.delegate = self
        self.serviceAdvertiser.startAdvertisingPeer()

        self.serviceBrowser.delegate = self
        self.serviceBrowser.startBrowsingForPeers()
    }

    func send(action: Action) {
        // NSLog("%@", "action: \(action) to \(session.connectedPeers.count) peers")

        if session.connectedPeers.count > 0 {
            do {
                try self.session.send(action.rawValue.data(using: .utf8)!, toPeers: session.connectedPeers, with: .reliable)
            }
            catch {
                NSLog("%@", "Error for sending: \(error)")
            }
        }

    }

    deinit {
        self.serviceAdvertiser.stopAdvertisingPeer()
        self.serviceBrowser.stopBrowsingForPeers()
    }

}

extension CountdownerServiceManager : MCNearbyServiceAdvertiserDelegate {

    func advertiser(_ advertiser: MCNearbyServiceAdvertiser, didNotStartAdvertisingPeer error: Error) {
        // NSLog("%@", "didNotStartAdvertisingPeer: \(error)")
    }

    func advertiser(_ advertiser: MCNearbyServiceAdvertiser, didReceiveInvitationFromPeer peerID: MCPeerID, withContext context: Data?, invitationHandler: @escaping (Bool, MCSession?) -> Void) {
        // NSLog("%@", "didReceiveInvitationFromPeer \(peerID)")
        invitationHandler(true, self.session)
    }

}

extension CountdownerServiceManager : MCNearbyServiceBrowserDelegate {

    func browser(_ browser: MCNearbyServiceBrowser, didNotStartBrowsingForPeers error: Error) {
        // NSLog("%@", "didNotStartBrowsingForPeers: \(error)")
    }

    func browser(_ browser: MCNearbyServiceBrowser, foundPeer peerID: MCPeerID, withDiscoveryInfo info: [String : String]?) {
        // NSLog("%@", "foundPeer: \(peerID)")
        // NSLog("%@", "invitePeer: \(peerID)")
        browser.invitePeer(peerID, to: self.session, withContext: nil, timeout: 10)
    }

    func browser(_ browser: MCNearbyServiceBrowser, lostPeer peerID: MCPeerID) {
        // NSLog("%@", "lostPeer: \(peerID)")
    }

}

extension CountdownerServiceManager : MCSessionDelegate {

    func session(_ session: MCSession, peer peerID: MCPeerID, didChange state: MCSessionState) {
        // NSLog("%@", "peer \(peerID) didChangeState: \(state)")
        self.delegate?.connectedDevicesChanged(manager: self, connectedDevices:
            session.connectedPeers.map {$0.displayName} )
    }

    func session(_ session: MCSession, didReceive data: Data, fromPeer peerID: MCPeerID) {
        // NSLog("%@", "didReceiveData: \(data)")
        if let action = Action(rawValue: String(data: data, encoding: .utf8)!) {
            // self.delegate?.actionReceived(manager: self, action: action, counter: <#Int#>)
            self.delegate?.actionReceived(manager: self, action: action)
        }
    }

    func session(_ session: MCSession, didReceive stream: InputStream, withName streamName: String, fromPeer peerID: MCPeerID) {
        // NSLog("%@", "didReceiveStream")
    }

    func session(_ session: MCSession, didStartReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, with progress: Progress) {
        // NSLog("%@", "didStartReceivingResourceWithName")
    }

    func session(_ session: MCSession, didFinishReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, at localURL: URL?, withError error: Error?) {
        // NSLog("%@", "didFinishReceivingResourceWithName")
    }

}