Bonjour.swift

import Foundation

public protocol BonjourObserver: AnyObject {
    func bonjour(_ bonjour: Bonjour, didAdd instance: DiscoveredHomeAssistant)
    func bonjour(_ bonjour: Bonjour, didRemoveInstanceWithName name: String)
}

public protocol BonjourProtocol {
    var observer: BonjourObserver? { get set }
    func start()
    func stop()
}

public class Bonjour: NSObject, NetServiceBrowserDelegate, NetServiceDelegate, BonjourProtocol {
    public weak var observer: BonjourObserver?

    private var browser: NetServiceBrowser
    private var resolving = [NetService]()
    private var resolvingDict = [String: NetService]()
    private var browserIsRunning: Bool = false

    override public init() {
        self.browser = NetServiceBrowser()
        super.init()
    }

    public func start() {
        precondition(Thread.isMainThread)
        guard !browserIsRunning else { return }
        Current.Log.info()
        browserIsRunning = true
        browser.delegate = self
        browser.searchForServices(ofType: "_home-assistant._tcp.", inDomain: "")
    }

    public func stop() {
        precondition(Thread.isMainThread)
        guard browserIsRunning else { return }
        Current.Log.info()
        browserIsRunning = false
        browser.stop()
        browser.delegate = nil
    }

    // Browser methods

    public func netServiceBrowser(
        _ netServiceBrowser: NetServiceBrowser,
        didFind netService: NetService,
        moreComing moreServicesComing: Bool
    ) {
        Current.Log.verbose()
        netService.delegate = self
        resolvingDict[netService.name] = netService
        netService.resolve(withTimeout: 0.0)
    }

    public func netServiceDidResolveAddress(_ sender: NetService) {
        Current.Log.verbose()

        guard let txtRecord = sender.txtRecordData() else { return }

        let potentialServiceDict = NetService.dictionary(fromTXTRecord: txtRecord) as NSDictionary

        // This fixes a crash in 0.110, the root cause is the dictionary returned
        // above contains NSNull instead of NSData, which Swift will crash trying
        // to cast to the Swift dictionary. So we do it the hard way.
        let serviceDict = (potentialServiceDict as? [String: Any])?
            .compactMapValues { $0 as? Data } ?? [:]

        do {
            let discovered = try discoveredHomeAssistant(
                bonjourName: sender.name,
                netServiceDictionary: serviceDict
            )
            observer?.bonjour(self, didAdd: discovered)
        } catch {
            Current.Log.error(error)
        }
    }

    public func netServiceBrowser(
        _ netServiceBrowser: NetServiceBrowser,
        didRemove netService: NetService,
        moreComing moreServicesComing: Bool
    ) {
        Current.Log.verbose(netService.name)

        observer?.bonjour(self, didRemoveInstanceWithName: netService.name)
        resolvingDict.removeValue(forKey: netService.name)
    }

    private func discoveredHomeAssistant(
        bonjourName: String,
        netServiceDictionary: [String: Data]
    ) throws -> DiscoveredHomeAssistant {
        var outputDict: [String: Any] = [:]
        for (key, value) in netServiceDictionary {
            outputDict[key] = String(data: value, encoding: .utf8)
        }
        if outputDict["location_name"] == nil {
            outputDict["location_name"] = bonjourName
        }
        var instance = try DiscoveredHomeAssistant(JSON: outputDict, context: nil)
        instance.bonjourName = bonjourName
        return instance
    }
}