devices-service.ts

import * as util from "util";
import * as helpers from "../../helpers";
import * as assert from "assert";
import * as constants from "../../constants";
import { exported } from "../../decorators";
import { settlePromises } from "../../helpers";
import { EventEmitter } from "events";
import { EOL } from "os";
import { CONNECTED_STATUS } from "../../constants";
import { isInteractive } from "../../helpers";
import { DebugCommandErrors } from "../../../constants";
import { performanceLog } from "../../decorators";

export class DevicesService extends EventEmitter implements Mobile.IDevicesService {
	private static DEVICE_LOOKING_INTERVAL = 200;
	private static EMULATOR_IMAGES_DETECTION_INTERVAL = 60 * 1000;
	private _devices: IDictionary<Mobile.IDevice> = {};
	private _availableEmulators: IDictionary<Mobile.IDeviceInfo> = {};
	private _platform: string;
	private _device: Mobile.IDevice;
	private _isInitialized = false;
	private _data: Mobile.IDevicesServicesInitializationOptions;
	private _otherDeviceDiscoveries: Mobile.IDeviceDiscovery[] = [];
	private _allDeviceDiscoveries: Mobile.IDeviceDiscovery[] = [];
	private deviceDetectionInterval: NodeJS.Timer;
	private emulatorDetectionInterval: NodeJS.Timer;

	constructor(private $logger: ILogger,
		private $errors: IErrors,
		private $iOSSimulatorDiscovery: Mobile.IiOSSimulatorDiscovery,
		private $iOSDeviceDiscovery: Mobile.IDeviceDiscovery,
		private $androidDeviceDiscovery: Mobile.IDeviceDiscovery,
		private $staticConfig: Config.IStaticConfig,
		private $messages: IMessages,
		private $mobileHelper: Mobile.IMobileHelper,
		private $deviceLogProvider: Mobile.IDeviceLogProvider,
		private $hostInfo: IHostInfo,
		private $injector: IInjector,
		private $options: IOptions,
		private $androidProcessService: Mobile.IAndroidProcessService,
		private $iOSEmulatorServices: Mobile.IiOSSimulatorService,
		private $androidEmulatorServices: Mobile.IEmulatorPlatformService,
		private $androidEmulatorDiscovery: Mobile.IDeviceDiscovery,
		private $emulatorHelper: Mobile.IEmulatorHelper,
		private $prompter: IPrompter) {
		super();
		this.attachToKnownDeviceDiscoveryEvents();
		this.attachToKnownEmulatorDiscoveryEvents();
		this._allDeviceDiscoveries = [this.$iOSDeviceDiscovery, this.$androidDeviceDiscovery, this.$iOSSimulatorDiscovery];
	}

	@performanceLog()
	public async pickSingleDevice(options: Mobile.IPickSingleDeviceOptions): Promise<Mobile.IDevice> {
		if (options.onlyDevices && options.onlyEmulators) {
			this.$errors.fail(DebugCommandErrors.UNABLE_TO_USE_FOR_DEVICE_AND_EMULATOR);
		}

		if (options.deviceId) {
			const device = await this.getDevice(options.deviceId);
			return device;
		}

		// Now let's take data for each device:
		const availableDevicesAndEmulators = this.getDeviceInstances()
			.filter(d => d.deviceInfo.status === CONNECTED_STATUS && (!this.platform || d.deviceInfo.platform.toLowerCase() === this.platform.toLowerCase()));

		const selectedDevices = availableDevicesAndEmulators.filter(d => options.onlyEmulators ? d.isEmulator : (options.onlyDevices ? !d.isEmulator : true));

		if (selectedDevices.length > 1) {
			if (isInteractive()) {
				const choices = selectedDevices.map(e => `${e.deviceInfo.identifier} - ${e.deviceInfo.displayName}`);

				const selectedDeviceString = await this.$prompter.promptForChoice("Select device for debugging", choices);

				const selectedDevice = _.find(selectedDevices, d => `${d.deviceInfo.identifier} - ${d.deviceInfo.displayName}` === selectedDeviceString);
				return selectedDevice;
			} else {
				const sortedInstances = _.sortBy(selectedDevices, e => e.deviceInfo.version);
				const emulators = sortedInstances.filter(e => e.isEmulator);
				const devices = sortedInstances.filter(d => !d.isEmulator);
				let selectedInstance: Mobile.IDevice;

				if (options.onlyEmulators || options.onlyDevices) {
					// When --emulator or --forDevice is passed, the instances are already filtered
					// So we are sure we have exactly the type we need and we can safely return the last one (highest OS version).
					selectedInstance = _.last(sortedInstances);
				} else {
					if (emulators.length) {
						selectedInstance = _.last(emulators);
					} else {
						selectedInstance = _.last(devices);
					}
				}

				this.$logger.warn(`Multiple devices/emulators found. Starting debugger on ${selectedInstance.deviceInfo.identifier}. ` +
					"If you want to debug on specific device/emulator, you can specify it with --device option.");

				return selectedInstance;
			}
		} else if (selectedDevices.length === 1) {
			return _.head(selectedDevices);
		}

		this.$errors.failWithoutHelp(DebugCommandErrors.NO_DEVICES_EMULATORS_FOUND_FOR_OPTIONS);
	}

	@exported("devicesService")
	public async getEmulatorImages(options?: Mobile.IListEmulatorsOptions): Promise<Mobile.IListEmulatorsOutput> {
		const result = Object.create(null);

		if (this.$hostInfo.isDarwin && (!options || !options.platform || this.$mobileHelper.isiOSPlatform(options.platform))) {
			result.ios = await this.$iOSEmulatorServices.getEmulatorImages();
		}

		if (!options || !options.platform || this.$mobileHelper.isAndroidPlatform(options.platform)) {
			result.android = await this.$androidEmulatorServices.getEmulatorImages();
		}

		return result;
	}

	@exported("devicesService")
	public async startEmulator(options: Mobile.IStartEmulatorOptions): Promise<string[]> {
		if (!options || (!options.imageIdentifier && !options.emulatorIdOrName)) {
			return ["Missing mandatory image identifier or name option."];
		}

		const availableEmulatorsOutput = await this.getEmulatorImages({ platform: options.platform });
		const emulators = this.$emulatorHelper.getEmulatorsFromAvailableEmulatorsOutput(availableEmulatorsOutput);
		const errors = this.$emulatorHelper.getErrorsFromAvailableEmulatorsOutput(availableEmulatorsOutput);

		let emulator = null;
		if (options.imageIdentifier) {
			emulator = this.$emulatorHelper.getEmulatorByImageIdentifier(options.imageIdentifier, emulators);
		} else if (options.emulatorIdOrName) {
			emulator = this.$emulatorHelper.getEmulatorByIdOrName(options.emulatorIdOrName, emulators);
		}

		if (!emulator) {
			const additionalErrors = errors && errors.length ? errors : [];
			return [`Unable to find emulator with provided options: ${options}`, ...additionalErrors];
		}

		// emulator is already running
		if (emulator.status === constants.RUNNING_EMULATOR_STATUS) {
			return null;
		}

		options.emulator = emulator;
		const emulatorService = this.resolveEmulatorServices(emulator.platform);
		const result = await emulatorService.startEmulator(options);
		return result.errors && result.errors.length ? result.errors : null;
	}

	public get platform(): string {
		return this._platform;
	}

	public get deviceCount(): number {
		return this._device ? 1 : this.getDeviceInstances().length;
	}

	@exported("devicesService")
	public getDevices(): Mobile.IDeviceInfo[] {
		return this.getDeviceInstances().map(deviceInstance => deviceInstance.deviceInfo);
	}

	public getDevicesForPlatform(platform: string): Mobile.IDevice[] {
		return _.filter(this.getDeviceInstances(), d => d.deviceInfo.platform.toLowerCase() === platform.toLowerCase());
	}

	public isAndroidDevice(device: Mobile.IDevice): boolean {
		return this.$mobileHelper.isAndroidPlatform(device.deviceInfo.platform);
	}

	public isiOSDevice(device: Mobile.IDevice): boolean {
		return this.$mobileHelper.isiOSPlatform(device.deviceInfo.platform) && !device.isEmulator;
	}

	public isiOSSimulator(device: Mobile.IDevice): boolean {
		return !!(this.$mobileHelper.isiOSPlatform(device.deviceInfo.platform) && device.isEmulator);
	}

	/* tslint:disable:no-unused-variable */
	@exported("devicesService")
	public setLogLevel(logLevel: string, deviceIdentifier?: string): void {
		this.$deviceLogProvider.setLogLevel(logLevel, deviceIdentifier);
	}
	/* tslint:enable:no-unused-variable */

	@exported("devicesService")
	public isAppInstalledOnDevices(deviceIdentifiers: string[], appId: string, projectName: string, projectDir: string): Promise<IAppInstalledInfo>[] {
		this.$logger.trace(`Called isInstalledOnDevices for identifiers ${deviceIdentifiers}. AppIdentifier is ${appId}.`);
		return _.map(deviceIdentifiers, deviceIdentifier => this.isApplicationInstalledOnDevice(deviceIdentifier, { appId, projectName, projectDir }));
	}

	public getDeviceInstances(): Mobile.IDevice[] {
		return _.values(this._devices);
	}

	@exported("devicesService")
	public async getInstalledApplications(deviceIdentifier: string): Promise<string[]> {
		const device = await this.getDevice(deviceIdentifier);
		return device.applicationManager.getInstalledApplications();
	}

	@exported("devicesService")
	public addDeviceDiscovery(deviceDiscovery: Mobile.IDeviceDiscovery): void {
		this._otherDeviceDiscoveries.push(deviceDiscovery);
		this._allDeviceDiscoveries.push(deviceDiscovery);
		this.attachToDeviceDiscoveryEvents(deviceDiscovery);
	}

	private attachToKnownDeviceDiscoveryEvents(): void {
		[this.$iOSSimulatorDiscovery, this.$iOSDeviceDiscovery, this.$androidDeviceDiscovery].forEach(this.attachToDeviceDiscoveryEvents.bind(this));
	}

	private attachToKnownEmulatorDiscoveryEvents(): void {
		this.$androidEmulatorDiscovery.on(constants.EmulatorDiscoveryNames.EMULATOR_IMAGE_FOUND, (emulator: Mobile.IDeviceInfo) => this.onEmulatorImageFound(emulator));
		this.$androidEmulatorDiscovery.on(constants.EmulatorDiscoveryNames.EMULATOR_IMAGE_LOST, (emulator: Mobile.IDeviceInfo) => this.onEmulatorImageLost(emulator));
		this.$iOSSimulatorDiscovery.on(constants.EmulatorDiscoveryNames.EMULATOR_IMAGE_FOUND, (emulator: Mobile.IDeviceInfo) => this.onEmulatorImageFound(emulator));
		this.$iOSSimulatorDiscovery.on(constants.EmulatorDiscoveryNames.EMULATOR_IMAGE_LOST, (emulator: Mobile.IDeviceInfo) => this.onEmulatorImageLost(emulator));
	}

	private attachToDeviceDiscoveryEvents(deviceDiscovery: Mobile.IDeviceDiscovery): void {
		deviceDiscovery.on(constants.DeviceDiscoveryEventNames.DEVICE_FOUND, (device: Mobile.IDevice) => this.onDeviceFound(device));
		deviceDiscovery.on(constants.DeviceDiscoveryEventNames.DEVICE_LOST, (device: Mobile.IDevice) => this.onDeviceLost(device));
	}

	private onDeviceFound(device: Mobile.IDevice): void {
		this.$logger.trace(`Found device with identifier '${device.deviceInfo.identifier}'`);
		this._devices[device.deviceInfo.identifier] = device;
		this.emit(constants.DeviceDiscoveryEventNames.DEVICE_FOUND, device);
	}

	private onDeviceLost(device: Mobile.IDevice): void {
		this.$logger.trace(`Lost device with identifier '${device.deviceInfo.identifier}'`);

		if (device.detach) {
			device.detach();
		}

		delete this._devices[device.deviceInfo.identifier];
		this.emit(constants.DeviceDiscoveryEventNames.DEVICE_LOST, device);
	}

	private onEmulatorImageFound(emulator: Mobile.IDeviceInfo): void {
		this.$logger.trace(`Found emulator with image identifier: ${emulator.imageIdentifier}`);
		this._availableEmulators[emulator.imageIdentifier] = emulator;
		this.emit(constants.EmulatorDiscoveryNames.EMULATOR_IMAGE_FOUND, emulator);
	}

	private onEmulatorImageLost(emulator: Mobile.IDeviceInfo): void {
		this.$logger.trace(`Lost emulator with image identifier ${emulator.imageIdentifier}`);
		delete this._availableEmulators[emulator.imageIdentifier];
		this.emit(constants.EmulatorDiscoveryNames.EMULATOR_IMAGE_LOST, emulator);
	}

	/**
	 * Starts looking for devices. Any found devices are pushed to "_devices" variable.
	 */
	protected async detectCurrentlyAttachedDevices(deviceInitOpts?: Mobile.IDeviceLookingOptions): Promise<void> {
		const options = this.getDeviceLookingOptions(deviceInitOpts);

		for (const deviceDiscovery of this._allDeviceDiscoveries) {
			try {
				await deviceDiscovery.startLookingForDevices(options);
			} catch (err) {
				this.$logger.trace("Error while checking for devices.", err);
			}
		}
	}

	protected async detectCurrentlyAvailableEmulators() {
		try {
			await this.$androidEmulatorDiscovery.startLookingForDevices();
		} catch (err) {
			this.$logger.trace(`Error while checking for Android emulators. ${err}`);
		}

		try {
			await this.$iOSSimulatorDiscovery.checkForAvailableSimulators();
		} catch (err) {
			this.$logger.trace(`Error while checking for iOS simulators. ${err}`);
		}
	}

	@exported("devicesService")
	public startDeviceDetectionInterval(deviceInitOpts: Mobile.IDeviceLookingOptions = <any>{}): void {
		if (!this.deviceDetectionInterval) {
			let isDeviceDetectionIntervalInProgress = false;

			this.deviceDetectionInterval = setInterval(async () => {
				if (isDeviceDetectionIntervalInProgress) {
					return;
				}

				isDeviceDetectionIntervalInProgress = true;

				await this.detectCurrentlyAttachedDevices(deviceInitOpts);

				try {
					const trustedDevices = _.filter(this._devices, device => device.deviceInfo.status === constants.CONNECTED_STATUS);
					await settlePromises(_.map(trustedDevices, device => device.applicationManager.checkForApplicationUpdates()));
				} catch (err) {
					this.$logger.trace("Error checking for application updates on devices.", err);
				}

				isDeviceDetectionIntervalInProgress = false;

			}, deviceInitOpts.detectionInterval || DevicesService.DEVICE_LOOKING_INTERVAL);

			this.deviceDetectionInterval.unref();
		}
	}

	@exported("devicesService")
	public startEmulatorDetectionInterval(opts: Mobile.IHasDetectionInterval = {}): void {
		let isEmulatorDetectionIntervalRunning = false;
		this.emulatorDetectionInterval = setInterval(async () => {
			if (isEmulatorDetectionIntervalRunning) {
				return;
			}

			isEmulatorDetectionIntervalRunning = true;
			await this.detectCurrentlyAvailableEmulators();
			isEmulatorDetectionIntervalRunning = false;
		}, opts.detectionInterval || DevicesService.EMULATOR_IMAGES_DETECTION_INTERVAL);

		this.emulatorDetectionInterval.unref();
	}

	@exported("devicesService")
	public stopDeviceDetectionInterval(): void {
		if (this.deviceDetectionInterval) {
			clearInterval(this.deviceDetectionInterval);
		}
	}

	@exported("devicesService")
	public stopEmulatorDetectionInterval(): void {
		if (this.emulatorDetectionInterval) {
			clearInterval(this.emulatorDetectionInterval);
		}
	}

	/**
	 * Returns device that matches an identifier.
	 * The identifier is expected to be the same as the running device declares it (emulator-5554 for android or GUID for ios).
	 * @param identifier running emulator or device identifier
	 */
	public getDeviceByIdentifier(identifier: string): Mobile.IDevice {
		const searchedDevice = _.find(this.getDeviceInstances(), (device: Mobile.IDevice) => {
			if (this.$mobileHelper.isiOSPlatform(device.deviceInfo.platform) && device.isEmulator) {
				return device.deviceInfo.identifier === identifier || device.deviceInfo.displayName === identifier;
			}
			return device.deviceInfo.identifier === identifier;
		});
		if (!searchedDevice) {
			this.$errors.fail(this.$messages.Devices.NotFoundDeviceByIdentifierErrorMessageWithIdentifier, identifier, this.$staticConfig.CLIENT_NAME.toLowerCase());
		}

		return searchedDevice;
	}

	/**
	 * Starts looking for running devices. All found devices are pushed to _devices variable.
	 */
	private async startLookingForDevices(deviceInitOpts?: Mobile.IDeviceLookingOptions): Promise<void> {
		this.$logger.trace("startLookingForDevices; platform is %s", this._platform);

		if (this._platform) {
			return this.detectCurrentlyAttachedDevices(deviceInitOpts);
		}

		await this.detectCurrentlyAttachedDevices(deviceInitOpts);
		await this.detectCurrentlyAvailableEmulators();

		await this.startDeviceDetectionInterval(deviceInitOpts);
	}

	/**
	 * Returns device depending on the passed index.
	 * The index refers to assigned number to listed devices by tns device command.
	 * @param index assigned device number
	 */
	private getDeviceByIndex(index: number): Mobile.IDevice {
		this.validateIndex(index - 1);
		return this.getDeviceInstances()[index - 1];
	}

	/**
	 * Returns running device for specified --device <DeviceId>.
	 * Method expects running devices.
	 * @param deviceOption parameter passed by the user to --device flag. Can be name, identifier or imageIdentifier.
	 */
	public async getDevice(deviceOption: string): Promise<Mobile.IDevice> {
		let device: Mobile.IDevice = null;

		if (!device) {
			device = _.find(this.getDeviceInstances(), d =>
				(d.deviceInfo.identifier && d.deviceInfo.identifier === deviceOption) ||
				(d.deviceInfo.displayName && d.deviceInfo.displayName === deviceOption) ||
				(d.deviceInfo.imageIdentifier && d.deviceInfo.imageIdentifier === deviceOption));
		}

		if (!device && helpers.isNumberWithoutExponent(deviceOption)) {
			device = this.getDeviceByIndex(parseInt(deviceOption, 10));
		}

		if (!device) {
			this.$errors.fail(this.$messages.Devices.NotFoundDeviceByIdentifierErrorMessageWithIdentifier, deviceOption, this.$staticConfig.CLIENT_NAME.toLowerCase());
		}

		return device;
	}

	/**
	 * Method runs action for a --device (value), specified by the user.
	 * @param action action to be executed if canExecute returns true
	 * @param canExecute predicate to decide whether the command can be ran
	 */
	private async executeOnDevice<T>(action: (dev: Mobile.IDevice) => Promise<T>, canExecute?: (_dev: Mobile.IDevice) => boolean): Promise<Mobile.IDeviceActionResult<T>> {
		if (!canExecute || canExecute(this._device)) {
			return { deviceIdentifier: this._device.deviceInfo.identifier, result: await action(this._device) };
		}
	}

	/**
	 * Executes passed action for each found device.
	 * @param action action to be executed if canExecute returns true
	 * @param canExecute predicate to decide whether the command can be ran
	 */
	private async executeOnAllConnectedDevices<T>(action: (dev: Mobile.IDevice) => Promise<T>, canExecute?: (_dev: Mobile.IDevice) => boolean): Promise<Mobile.IDeviceActionResult<T>[]> {
		const devices = this.filterDevicesByPlatform();
		const sortedDevices = _.sortBy(devices, device => device.deviceInfo.platform);
		const result: Mobile.IDeviceActionResult<T>[] = [];

		const errors: Mobile.IDeviceError[] = [];
		for (const device of sortedDevices) {
			try {
				if (!canExecute || canExecute(device)) {
					result.push({ deviceIdentifier: device.deviceInfo.identifier, result: await action(device) });
				}
			} catch (err) {
				err.deviceIdentifier = device.deviceInfo.identifier;
				this.$logger.trace(`Error while executing action on device ${device.deviceInfo.identifier}. The error is`, err);
				errors.push(err);
			}
		}

		if (errors.length) {
			let preErrorMsg = "";
			if (errors.length > 1) {
				preErrorMsg = "Multiple errors were thrown:" + EOL;
			}

			const errorMessage = `${preErrorMsg}${errors.map(e => e.message || e).join(EOL)}`;
			const suppressCommandHelp = _.some(errors, (e: any) => e.suppressCommandHelp);
			this.$errors.fail({ formatStr: errorMessage, suppressCommandHelp });
		}

		return result;
	}

	@exported("devicesService")
	public deployOnDevices(deviceIdentifiers: string[], packagePath: string, appId: string | Mobile.IProjectIdentifier, projectName: string, projectDir: string): Promise<void>[] {
		this.$logger.trace(`Called deployOnDevices for identifiers ${deviceIdentifiers} for packageFile: ${packagePath}. Application identifier is ${appId}. Project Name is: ${projectName}`);
		return _.map(deviceIdentifiers, async deviceIdentifier => {
			const device = this.getDeviceByIdentifier(deviceIdentifier);

			let identifier: string;
			if (typeof appId === "string") {
				identifier = appId;
			} else {
				identifier = appId[device.deviceInfo.platform.toLowerCase()];
			}

			return this.deployOnDevice(device, { packagePath, appId: identifier, projectName, projectDir});
		});
	}

	/**
	 * Runs the passed action if the predicate "canExecute" returns true
	 * @param action action to be executed if canExecute returns true.
	 * @param canExecute predicate to decide whether the command can be ran
	 * @param options all possible options that can be passed to the command.
	 */
	public async execute<T>(action: (device: Mobile.IDevice) => Promise<T>, canExecute?: (dev: Mobile.IDevice) => boolean, options?: { allowNoDevices?: boolean }): Promise<Mobile.IDeviceActionResult<T>[]> {
		assert.ok(this._isInitialized, "Devices services not initialized!");

		if (this.hasDevices) {
			if (this.$hostInfo.isDarwin && this._platform
				&& this.$mobileHelper.isiOSPlatform(this._platform)
				&& this.$options.emulator && !this.isOnlyiOSSimultorRunning()) {
				// Executes the command only on iOS simulator
				const originalCanExecute = canExecute;
				canExecute = (dev: Mobile.IDevice): boolean => this.isiOSSimulator(dev) && (!originalCanExecute || !!(originalCanExecute(dev)));
			}

			return this.executeCore(action, canExecute);
		} else {
			const message = constants.ERROR_NO_DEVICES;
			if (options && options.allowNoDevices) {
				this.$logger.info(message);
			} else {
				if (!this.$hostInfo.isDarwin && this._platform && this.$mobileHelper.isiOSPlatform(this._platform)) {
					this.$errors.failWithoutHelp(message);
				} else {
					return this.executeCore(action, canExecute);
				}
			}
		}
	}

	/**
	 * Starts emulator or simulator if necessary depending on --device or --emulator flags.
	 * If no options are passed runs default emulator/simulator if no devices are connected.
	 * @param deviceInitOpts mainly contains information about --emulator and --deviceId flags.
	 */
	protected async startEmulatorIfNecessary(deviceInitOpts?: Mobile.IDevicesServicesInitializationOptions): Promise<void> {
		if (deviceInitOpts && deviceInitOpts.deviceId && deviceInitOpts.emulator) {
			this.$errors.failWithoutHelp(`--device and --emulator are incompatible options.
			If you are trying to run on specific emulator, use "${this.$staticConfig.CLIENT_NAME} run --device <DeviceID>`);
		}

		if (deviceInitOpts && deviceInitOpts.platform && !deviceInitOpts.skipEmulatorStart) {
			// are there any running devices
			this._platform = deviceInitOpts.platform;
			try {
				await this.startLookingForDevices(<Mobile.IDeviceLookingOptions>deviceInitOpts);
			} catch (err) {
				this.$logger.trace("Error while checking for devices.", err);
			}
			const deviceInstances = this.getDeviceInstances();

			if (!deviceInitOpts.deviceId && _.isEmpty(deviceInstances)) {
				if (!this.$hostInfo.isDarwin && this.$mobileHelper.isiOSPlatform(deviceInitOpts.platform)) {
					this.$errors.failWithoutHelp(constants.ERROR_NO_DEVICES_CANT_USE_IOS_SIMULATOR);
				}
			}

			try {
				await this._startEmulatorIfNecessary(deviceInitOpts);
			} catch (err) {
				const errorMessage = this.getEmulatorError(err, deviceInitOpts.platform);

				this.$errors.failWithoutHelp(errorMessage);
			}
		}
	}

	private async _startEmulatorIfNecessary(data?: Mobile.IDevicesServicesInitializationOptions): Promise<void> {
		const deviceInstances = this.getDeviceInstances();

		//if no --device is passed and no devices are found, the default emulator is started
		if (!data.deviceId && _.isEmpty(deviceInstances)) {
			return this.startEmulatorCore(data);
		}

		//check if --device(value) is running, if it's not or it's not the same as is specified, start with name from --device(value)
		if (data.deviceId) {
			if (!helpers.isNumberWithoutExponent(data.deviceId)) {
				const activeDeviceInstance = _.find(deviceInstances, (device: Mobile.IDevice) => device.deviceInfo.identifier === data.deviceId);
				if (!activeDeviceInstance) {
					return this.startEmulatorCore(data);
				}
			}
		}

		// if only emulator flag is passed and no other emulators are running, start default emulator
		if (data.emulator && deviceInstances.length) {
			const runningDeviceInstance = _.some(deviceInstances, (value) => value.isEmulator);
			if (!runningDeviceInstance) {
				return this.startEmulatorCore(data);
			}
		}
	}

	private _deviceInitializePromise: Promise<void>;
	/**
	 * Takes care of gathering information about all running devices.
	 * Sets "_isInitialized" to true after infomation is present.
	 * Method expects running devices.
	 * @param data mainly contains information about --emulator and --deviceId flags.
	 */
	@exported("devicesService")
	public async initialize(data?: Mobile.IDevicesServicesInitializationOptions): Promise<void> {
		if (!this._deviceInitializePromise) {
			this._deviceInitializePromise = this.initializeCore(data);
		}

		try {
			await this._deviceInitializePromise;
		} catch (err) {
			// In case the initalization fails, we want to allow calling `initlialize` again with other arguments for example, so remove the cached promise value.
			this.$logger.trace(`Error while initializing devicesService: ${err}`);
			this._deviceInitializePromise = null;
			throw err;
		}
	}

	public getPlatformsFromDeviceDescriptors(deviceDescriptors: ILiveSyncDeviceDescriptor[]): string[] {
		const platforms = _(deviceDescriptors)
			.map(device => this.getDeviceByIdentifier(device.identifier))
			.map(device => device.deviceInfo.platform.toLowerCase())
			.uniq()
			.value();

		return platforms;
	}

	private async initializeCore(deviceInitOpts?: Mobile.IDevicesServicesInitializationOptions): Promise<void> {
		if (this._isInitialized) {
			return;
		}

		this.$logger.info("Searching for devices...");

		deviceInitOpts = deviceInitOpts || {};
		this._data = deviceInitOpts;

		if (!deviceInitOpts.skipEmulatorStart) {
			// TODO: Remove from here as it calls startLookingForDevices, so we double the calls to specific device detection services
			await this.startEmulatorIfNecessary(deviceInitOpts);
		}

		const platform = deviceInitOpts.platform;
		const deviceOption = deviceInitOpts.deviceId;
		const deviceLookingOptions: Mobile.IDeviceLookingOptions = {
			emulator: deviceInitOpts.emulator,
			platform: deviceInitOpts.platform,
			shouldReturnImmediateResult: deviceInitOpts.shouldReturnImmediateResult,
			detectionInterval: deviceInitOpts.detectionInterval
		};

		if (platform && deviceOption) {
			this._platform = this.$mobileHelper.validatePlatformName(deviceInitOpts.platform);
			await this.startLookingForDevices(deviceLookingOptions);
			this._device = await this.getDevice(deviceOption);
			if (this._device.deviceInfo.platform !== this._platform) {
				this.$errors.fail(constants.ERROR_CANNOT_RESOLVE_DEVICE);
			}
			this.$logger.warn("Your application will be deployed only on the device specified by the provided index or identifier.");
		} else if (!platform && deviceOption) {
			await this.startLookingForDevices(deviceLookingOptions);
			this._device = await this.getDevice(deviceOption);
			this._platform = this._device.deviceInfo.platform;
		} else if (platform && !deviceOption) {
			this._platform = this.$mobileHelper.validatePlatformName(platform);
			await this.startLookingForDevices(deviceLookingOptions);
		} else {
			// platform and deviceId are not specified
			if (deviceInitOpts.skipInferPlatform) {
				if (deviceInitOpts.skipDeviceDetectionInterval) {
					await this.detectCurrentlyAttachedDevices(deviceLookingOptions);
				} else {
					deviceInitOpts.shouldReturnImmediateResult = true;
					await this.startLookingForDevices(deviceLookingOptions);
				}
			} else {
				await this.startLookingForDevices(deviceLookingOptions);

				const devices = this.getDeviceInstances();
				const platforms = _(devices)
					.map(device => device.deviceInfo.platform)
					.filter(pl => {
						try {
							return !!this.$mobileHelper.validatePlatformName(pl);
						} catch (err) {
							this.$logger.warn(err.message);
							return null;
						}
					})
					.uniq()
					.value();

				if (platforms.length === 1) {
					this._platform = platforms[0];
				} else if (platforms.length === 0) {
					this.$errors.fail({ formatStr: constants.ERROR_NO_DEVICES, suppressCommandHelp: true });
				} else {
					this.$errors.fail("Multiple device platforms detected (%s). Specify platform or device on command line.",
						helpers.formatListOfNames(platforms, "and"));
				}
			}
		}

		if (!this.$hostInfo.isDarwin && this._platform && this.$mobileHelper.isiOSPlatform(this._platform) && this.$options.emulator) {
			this.$errors.failWithoutHelp(constants.ERROR_CANT_USE_SIMULATOR);
		}
		this._isInitialized = true;
	}

	public get hasDevices(): boolean {
		if (!this._platform) {
			return this.getDeviceInstances().length !== 0;
		} else {
			return this.filterDevicesByPlatform().length !== 0;
		}
	}

	public isOnlyiOSSimultorRunning(): boolean {
		const devices = this.getDeviceInstances();
		return this._platform && this.$mobileHelper.isiOSPlatform(this._platform) && _.find(devices, d => d.isEmulator) && !_.find(devices, d => !d.isEmulator);
	}

	public getDeviceByDeviceOption(): Mobile.IDevice {
		return this._device;
	}

	@exported("devicesService")
	public async mapAbstractToTcpPort(deviceIdentifier: string, appIdentifier: string, framework: string): Promise<string> {
		return this.$androidProcessService.mapAbstractToTcpPort(deviceIdentifier, appIdentifier, framework);
	}

	@exported("devicesService")
	public getDebuggableApps(deviceIdentifiers: string[]): Promise<Mobile.IDeviceApplicationInformation[]>[] {
		return _.map(deviceIdentifiers, (deviceIdentifier: string) => this.getDebuggableAppsCore(deviceIdentifier));
	}

	@exported("devicesService")
	public async getDebuggableViews(deviceIdentifier: string, appIdentifier: string): Promise<Mobile.IDebugWebViewInfo[]> {
		const device = this.getDeviceByIdentifier(deviceIdentifier),
			debuggableViewsPerApp = await device.applicationManager.getDebuggableAppViews([appIdentifier]);

		return debuggableViewsPerApp && debuggableViewsPerApp[appIdentifier];
	}

	private getDebuggableAppsCore(deviceIdentifier: string): Promise<Mobile.IDeviceApplicationInformation[]> {
		const device = this.getDeviceByIdentifier(deviceIdentifier);
		return device.applicationManager.getDebuggableApps();
	}

	private async deployOnDevice(device: Mobile.IDevice, appData: Mobile.IInstallAppData): Promise<void> {
		await device.applicationManager.reinstallApplication(appData.appId, appData.packagePath);
		this.$logger.info(`Successfully deployed on device with identifier '${device.deviceInfo.identifier}'.`);
		await device.applicationManager.tryStartApplication(appData);
	}

	private filterDevicesByPlatform(): Mobile.IDevice[] {
		return _.filter(this.getDeviceInstances(), (device: Mobile.IDevice) => {
			if (this.$options.emulator && !device.isEmulator) {
				return false;
			}
			if (this._platform) {
				return device.deviceInfo.platform === this._platform;
			}
			return true;
		});
	}

	private validateIndex(index: number): void {
		if (index < 0 || index > this.getDeviceInstances().length) {
			throw new Error(util.format(this.$messages.Devices.NotFoundDeviceByIndexErrorMessage, index, this.$staticConfig.CLIENT_NAME.toLowerCase()));
		}
	}

	private resolveEmulatorServices(platform?: string): Mobile.IEmulatorPlatformService {
		platform = platform || this._platform;
		if (this.$mobileHelper.isiOSPlatform(platform)) {
			return this.$injector.resolve("iOSEmulatorServices");
		} else if (this.$mobileHelper.isAndroidPlatform(platform)) {
			return this.$injector.resolve("androidEmulatorServices");
		}

		return null;
	}

	/**
	 * Starts emulator for platform and makes sure started devices/emulators/simulators are in _devices array before finishing.
	 * @param platform (optional) platform to start emulator/simulator for
	 * @param emulatorIdOrName (optional) emulator/simulator image identifier or name
	 */
	protected async startEmulatorCore(deviceInitOpts: Mobile.IDevicesServicesInitializationOptions = {}): Promise<void> {
		const { deviceId } = deviceInitOpts;
		const platform = deviceInitOpts.platform || this._platform;
		const emulatorServices = this.resolveEmulatorServices(platform);
		if (!emulatorServices) {
			this.$errors.failWithoutHelp("Unable to detect platform for which to start emulator.");
		}

		const result = await emulatorServices.startEmulator({ emulatorIdOrName: deviceId, imageIdentifier: deviceId, platform: platform, sdk: this._data && this._data.sdk });
		if (result && result.errors && result.errors.length) {
			this.$errors.failWithoutHelp(result.errors.join("\n"));
		}

		const deviceLookingOptions = this.getDeviceLookingOptions(deviceInitOpts);
		if (this.$mobileHelper.isAndroidPlatform(platform)) {
			await this.$androidDeviceDiscovery.startLookingForDevices(deviceLookingOptions);
		} else if (this.$mobileHelper.isiOSPlatform(platform) && this.$hostInfo.isDarwin) {
			await this.$iOSSimulatorDiscovery.startLookingForDevices(deviceLookingOptions);
		}
	}

	private async executeCore<T>(action: (device: Mobile.IDevice) => Promise<T>, canExecute?: (dev: Mobile.IDevice) => boolean): Promise<Mobile.IDeviceActionResult<T>[]> {
		if (this._device) {
			return [await this.executeOnDevice(action, canExecute)];
		}

		return this.executeOnAllConnectedDevices(action, canExecute);
	}

	private async isApplicationInstalledOnDevice(deviceIdentifier: string, appData: Mobile.IApplicationData): Promise<IAppInstalledInfo> {
		let isInstalled = false;
		const device = this.getDeviceByIdentifier(deviceIdentifier);

		try {
			isInstalled = await device.applicationManager.isApplicationInstalled(appData.appId);
			await device.applicationManager.tryStartApplication(appData);
		} catch (err) {
			this.$logger.trace("Error while checking is application installed. Error is: ", err);
		}

		return {
			appIdentifier: appData.appId,
			deviceIdentifier,
			isInstalled
		};
	}

	private getDeviceLookingOptions(deviceInitOpts: Mobile.IDevicesServicesInitializationOptions = {}): Mobile.IDeviceLookingOptions {
		const { shouldReturnImmediateResult, emulator } = deviceInitOpts;
		const platform = deviceInitOpts.platform || this._platform;

		return { platform, shouldReturnImmediateResult: !!shouldReturnImmediateResult, emulator: !!emulator };
	}

	private getEmulatorError(error: Error, platform: string): string {
		let emulatorName = constants.DeviceTypes.Emulator;

		if (this.$mobileHelper.isiOSPlatform(platform)) {
			emulatorName = constants.DeviceTypes.Simulator;
		}

		return `Cannot find connected devices.${EOL}` +
			`${emulatorName} start failed with: ${error.message}${EOL}` +
			`To list currently connected devices and verify that the specified identifier exists, run '${this.$staticConfig.CLIENT_NAME.toLowerCase()} device'.${EOL}` +
			`To list available ${emulatorName.toLowerCase()} images, run '${this.$staticConfig.CLIENT_NAME.toLowerCase()} device <Platform> --available-devices'.`;
	}
}

$injector.register("devicesService", DevicesService);