Alternative device connection

This commit is contained in:
Christoph Hagen 2023-06-29 10:13:37 +02:00
parent 7cd697fb01
commit 8b4c4800c9
6 changed files with 491 additions and 0 deletions

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import Foundation
enum BluetoothRequestType: UInt8 {
/**
* Request the number of bytes already recorded
*
* Request:
* - No additional bytes expected
*
* Response:
* - `BluetoothResponseType.success`
* - the number of recorded bytes as a `Uint16` (2 bytes)
* - the number of seconds until the next measurement as a `Uint16` (2 bytes)
* - the number of seconds between measurements as a `Uint16` (2 bytes)
* - the number of measurements as a `Uint16` (2 bytes)
* - the maximum number of bytes to request as a `Uint16` (2 bytes)
* - the number of seconds since power on as a `Uint32` (4 bytes)
*/
case getInfo = 0
/**
* Request recording data
*
* Request:
* - Bytes 1-2: Memory offset (`UInt16`)
* - Bytes 3-4: Number of bytes (`UInt16`)
*
* Response:
* - `BluetoothResponseType.success`, plus the requested bytes
* - `BluetoothResponseType.responseTooLarge` if too many bytes are requested
*/
case getRecordingData = 1
/**
* Request deletion of recordings
*
* Request:
* - Bytes 1-2: Number of bytes to clear (uint16_t)
*
* Response:
* - `BluetoothResponseType.success`
* - `BluetoothResponseType.invalidNumberOfBytesToDelete`, if the number of bytes does not match.
* This may happen when a new temperature recording is performed in between calls
*/
case clearRecordingBuffer = 2
}

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import Foundation
import CoreBluetooth
final class DeviceConnection: NSObject, CBCentralManagerDelegate, ObservableObject {
static let serviceUUID = CBUUID(string: "22071991-cccc-cccc-cccc-000000000001")
static let characteristicUUID = CBUUID(string: "22071991-cccc-cccc-cccc-000000000002")
private var manager: CBCentralManager! = nil
private(set) var lastRSSI: Int = 0 // TODO: Provide function to update
@Published
var state: DeviceState = .disconnected
var isConnected: Bool {
// Automatically updates with device state
if case .configured = state {
return true
}
return false
}
override init() {
super.init()
self.manager = CBCentralManager(delegate: self, queue: nil)
}
/**
Allow the client to scan for devices and connect to the first device found with the correct characteristic
*/
@discardableResult
func initiateDeviceConnection() -> Bool {
switch state {
case .bluetoothDisabled:
log.info("Can't connect, bluetooth disabled")
return false
case .disconnected:
break
default:
return true
}
guard !manager.isScanning else {
state = .scanning
return true
}
shouldConnectIfPossible = true
state = .scanning
manager.scanForPeripherals(withServices: [DeviceManager.serviceUUID])
return true
}
@discardableResult
func updateRSSIForConnectedDevice() -> Bool {
guard let device = state.device else {
return false
}
device.readRSSI()
return true
}
/**
Indicate that a connection should be attempted when found.
This does not necessarily indicate that the phone is scanning for devices.
*/
@Published
var shouldConnectIfPossible = true {
didSet {
guard oldValue != shouldConnectIfPossible else {
return
}
updateConnectionOnChange()
}
}
private func updateConnectionOnChange() {
if shouldConnectIfPossible {
ensureConnection()
} else {
disconnectIfNeeded()
}
}
private func ensureConnection() {
switch state {
case .disconnected:
initiateDeviceConnection()
default:
return
}
}
private func disconnectIfNeeded() {
switch state {
case .bluetoothDisabled, .disconnected:
return
default:
disconnect()
}
}
func disconnect() {
shouldConnectIfPossible = false
switch state {
case .bluetoothDisabled, .disconnected:
return
case .scanning:
manager.stopScan()
state = .disconnected
return
case .connecting(let device),
.discoveringCharacteristic(let device),
.discoveringServices(device: let device),
.configured(let device, _):
manager.cancelPeripheralConnection(device)
manager.stopScan()
state = .disconnected
return
}
}
private var requestContinuation: CheckedContinuation<Data?, Never>?
func getInfo() async -> DeviceInfo? {
await get(DeviceInfoRequest())
}
func getDeviceData(offset: Int, count: Int) async -> Data? {
await get(DeviceDataRequest(offset: offset, count: count))
}
func deleteDeviceData(byteCount: Int) async -> Bool {
await get(DeviceDataResetRequest(byteCount: byteCount)) != nil
}
private func get<Request>(_ request: Request) async -> Request.Response? where Request: DeviceRequest {
guard requestContinuation == nil else {
// Prevent parallel requests
return nil
}
guard case .configured(let device, let characteristic) = state else {
return nil
}
let requestData = Data([request.type.rawValue]) + request.payload
let responseData: Data? = await withCheckedContinuation { continuation in
requestContinuation = continuation
device.writeValue(requestData, for: characteristic, type: .withResponse)
device.readValue(for: characteristic)
DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(5)) { [weak self] in
guard let requestContinuation = self?.requestContinuation else { return }
log.info("Timed out for request \(request.type)")
requestContinuation.resume(returning: nil)
self?.requestContinuation = nil
}
}
guard let responseData else {
return nil
}
guard let responseCode = responseData.first else {
log.error("Request \(request.type) got response of zero bytes")
return nil
}
guard let responseType = BluetoothResponseType(rawValue: responseCode) else {
log.error("Request \(request.type) got unknown response code \(responseCode)")
return nil
}
switch responseType {
case .success, .responseTooLarge, .invalidNumberOfBytesToDelete:
break
case .invalidCommand:
log.error("Request \(request.type) failed: Invalid command")
return nil
case .unknownCommand:
log.error("Request \(request.type) failed: Unknown command")
return nil
case .responseInProgress:
log.info("Request \(request.type) failed: Device is busy")
return nil
}
return request.makeResponse(from: responseData.dropFirst(), responseType: responseType)
}
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
guard shouldConnectIfPossible else {
return
}
peripheral.delegate = self
manager.connect(peripheral)
manager.stopScan()
state = .connecting(device: peripheral)
}
func centralManagerDidUpdateState(_ central: CBCentralManager) {
switch central.state {
case .poweredOff:
state = .bluetoothDisabled
case .poweredOn:
state = .disconnected
initiateDeviceConnection()
case .unsupported:
state = .bluetoothDisabled
log.info("Bluetooth is not supported")
case .unknown:
state = .bluetoothDisabled
log.info("Bluetooth state is unknown")
case .resetting:
state = .bluetoothDisabled
log.info("Bluetooth is resetting")
case .unauthorized:
state = .bluetoothDisabled
log.info("Bluetooth is not authorized")
@unknown default:
state = .bluetoothDisabled
log.warning("Unknown state \(central.state)")
}
}
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
log.info("Connected to " + peripheral.name!)
peripheral.discoverServices([DeviceManager.serviceUUID])
state = .discoveringServices(device: peripheral)
}
func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?) {
log.info("Disconnected from " + peripheral.name!)
state = .disconnected
// Attempt to reconnect
if shouldConnectIfPossible {
initiateDeviceConnection()
}
}
func centralManager(_ central: CBCentralManager, didFailToConnect peripheral: CBPeripheral, error: Error?) {
log.warning("Failed to connect device '\(peripheral.name ?? "NO_NAME")'")
if let error = error {
log.warning(error.localizedDescription)
}
state = manager.isScanning ? .scanning : .disconnected
// Attempt to reconnect
if shouldConnectIfPossible {
initiateDeviceConnection()
}
}
}
extension DeviceConnection: CBPeripheralDelegate {
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
guard let services = peripheral.services, !services.isEmpty else {
log.error("No services found for device '\(peripheral.name ?? "NO_NAME")'")
manager.cancelPeripheralConnection(peripheral)
return
}
guard let service = services.first(where: { $0.uuid.uuidString == DeviceManager.serviceUUID.uuidString }) else {
log.error("Required service not found for '\(peripheral.name ?? "NO_NAME")': \(services.map { $0.uuid.uuidString})")
manager.cancelPeripheralConnection(peripheral)
return
}
peripheral.discoverCharacteristics([DeviceManager.characteristicUUID], for: service)
state = .discoveringCharacteristic(device: peripheral)
}
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
if let error = error {
log.error("Failed to discover characteristics: \(error)")
manager.cancelPeripheralConnection(peripheral)
return
}
guard let characteristics = service.characteristics, !characteristics.isEmpty else {
log.error("No characteristics found for device")
manager.cancelPeripheralConnection(peripheral)
return
}
for characteristic in characteristics {
guard characteristic.uuid == DeviceManager.characteristicUUID else {
log.warning("Unused characteristic \(characteristic.uuid.uuidString)")
continue
}
state = .configured(device: peripheral, characteristic: characteristic)
peripheral.setNotifyValue(true, for: characteristic)
}
}
func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
if let error = error {
log.error("Peripheral failed to write value for \(characteristic.uuid.uuidString): \(error)")
}
}
func peripheral(_ peripheral: CBPeripheral, didReadRSSI RSSI: NSNumber, error: Error?) {
if let error = error {
log.warning("Failed to get RSSI: \(error)")
return
}
lastRSSI = RSSI.intValue
log.info("RSSI: \(lastRSSI)")
}
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
if let error = error {
log.error("Failed to read value update: \(error)")
continueRequest(with: nil)
return
}
guard case .configured(device: _, characteristic: let storedCharacteristic) = state else {
log.warning("Received data while not properly configured")
continueRequest(with: nil)
return
}
guard characteristic.uuid == storedCharacteristic.uuid else {
log.warning("Read unknown characteristic \(characteristic.uuid.uuidString)")
continueRequest(with: nil)
return
}
guard let data = characteristic.value else {
log.warning("No data")
continueRequest(with: nil)
return
}
continueRequest(with: data)
}
private func continueRequest(with response: Data?) {
guard let requestContinuation else {
log.error("No continuation to handle request data (\(response?.count ?? 0) bytes)")
return
}
requestContinuation.resume(returning: response)
self.requestContinuation = nil
}
}

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import Foundation
struct DeviceDataRequest: DeviceRequest {
typealias Response = Data
static let type: BluetoothRequestType = .getRecordingData
let offset: Int
let count: Int
var payload: Data {
count.twoByteData + offset.twoByteData
}
init(offset: Int, count: Int) {
self.offset = offset
self.count = count
}
func makeResponse(from responseData: Data, responseType: BluetoothResponseType) -> Data? {
switch responseType {
case .success:
break
case .responseTooLarge:
log.warning("Exceeded payload size for device data request (offset: \(offset), count: \(count))")
break
default:
log.warning("Invalid response \(responseType) to device data request")
return nil
}
guard responseData.count == count else {
log.warning("Got \(responseData.count) for device data request (offset: \(offset), count: \(count))")
return nil
}
return responseData
}
}

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import Foundation
struct DeviceDataResetRequest: DeviceRequest {
typealias Response = Void
static var type: BluetoothRequestType { .clearRecordingBuffer }
var payload: Data {
byteCount.twoByteData
}
let byteCount: Int
init(byteCount: Int) {
self.byteCount = byteCount
}
func makeResponse(from responseData: Data, responseType: BluetoothResponseType) -> Void? {
switch responseType {
case .success:
return ()
case .invalidNumberOfBytesToDelete:
log.error("Device data reset failed: Invalid number of bytes")
return nil
default:
log.warning("Invalid response \(responseType) to device data reset request")
return nil
}
}
}

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import Foundation
struct DeviceInfoRequest: DeviceRequest {
typealias Response = DeviceInfo
static let type: BluetoothRequestType = .getInfo
let payload = Data()
func makeResponse(from responseData: Data, responseType: BluetoothResponseType) -> DeviceInfo? {
guard responseType == .success else {
log.warning("Invalid response \(responseType) to device info request")
return nil
}
do {
return try .init(info: responseData)
} catch {
log.error("Failed to decode device info: \(error)")
return nil
}
}
}

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import Foundation
protocol DeviceRequest {
associatedtype Response
static var type: BluetoothRequestType { get }
var payload: Data { get }
func makeResponse(from responseData: Data, responseType: BluetoothResponseType) -> Response?
}
extension DeviceRequest {
var type: BluetoothRequestType { Self.type }
}