/**
 * Connects to the wifi access point at specified [ssid] with specified [networkId]
 * And returns the [WifiInfo] of the network that has been connected to
 */
private fun connect(context: Context,
                    wifiManager: WifiManager,
                    ssid: String,
                    networkId: Int) = Single.create<WifiInfo> { emitter ->

    val wifiConnectionReceiver = object : BroadcastReceiver() {
        var oldSupplicantState: SupplicantState? = null

        override fun onReceive(context: Context, intent: Intent) {
            if (intent.action == WifiManager.NETWORK_STATE_CHANGED_ACTION) {
                val networkInfo = intent.getParcelableExtra<NetworkInfo>(WifiManager.EXTRA_NETWORK_INFO) ?: return

                if (networkInfo.detailedState == NetworkInfo.DetailedState.DISCONNECTED) {
                    context.applicationContext.unregisterReceiver(this)
                    emitter.onError(WiFiException("Failed to connect to wifi network"))
                }
                else if (networkInfo.detailedState == NetworkInfo.DetailedState.CONNECTED) {
                    val wifiInfo = intent.getParcelableExtra<WifiInfo>(WifiManager.EXTRA_WIFI_INFO) ?: return
                    if (ssid == wifiInfo.ssid.unescape()) {
                        context.applicationContext.unregisterReceiver(this)
                        emitter.onSuccess(wifiInfo)
                    }
                }
            } else if (intent.action == WifiManager.SUPPLICANT_STATE_CHANGED_ACTION) {
                val supplicantState = intent.getParcelableExtra<SupplicantState>(WifiManager.EXTRA_NEW_STATE)
                val oldSupplicantState = this.oldSupplicantState
                this.oldSupplicantState = supplicantState

                if (supplicantState == SupplicantState.DISCONNECTED) {
                    if (oldSupplicantState == null || oldSupplicantState == SupplicantState.COMPLETED) {
                        return
                    }
                    val possibleError = intent.getIntExtra(WifiManager.EXTRA_SUPPLICANT_ERROR, -1)
                    if (possibleError == WifiManager.ERROR_AUTHENTICATING) {
                        context.applicationContext.unregisterReceiver(this)
                        emitter.onError(WiFiException("Wifi authentication failed"))
                    }
                } else if (supplicantState == SupplicantState.SCANNING && oldSupplicantState == SupplicantState.DISCONNECTED) {
                    context.applicationContext.unregisterReceiver(this)
                    emitter.onError(WiFiException("Failed to connect to wifi network"))
                }
            }
        }
    }

    val networkStateChangedFilter = IntentFilter(WifiManager.NETWORK_STATE_CHANGED_ACTION)
    networkStateChangedFilter.addAction(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION)

    context.applicationContext.registerReceiver(wifiConnectionReceiver, networkStateChangedFilter)

    emitter.setCancellable {
        if (!emitter.isDisposed)
            context.applicationContext.unregisterReceiver(wifiConnectionReceiver)
    }

    wifiManager.enableNetwork(networkId, true)
}