Observe Characteristic changes and HAP getValues

Sources/HAP/Base/Accessory.swift

@@ -27,6 +27,8 @@ struct AIDGenerator: Sequence, IteratorProtocol, Codable {
 
 open class Accessory: JSONSerializable {
     public weak var device: Device?
+    public weak var delegate: AccessoryDelegate?
+
     internal var aid: InstanceID = 0
     public let type: AccessoryType
     public let info: Service.Info
@@ -103,11 +105,12 @@ open class Accessory: JSONSerializable {
 
     /// Characteristic's value was changed by controller. Used for bubbling up
     /// to the device, which will notify the delegate.
-    open func characteristic<T>(_ characteristic: GenericCharacteristic<T>,
+    internal func characteristic<T>(_ characteristic: GenericCharacteristic<T>,
                                 ofService service: Service,
                                 didChangeValue newValue: T?) {
         device?.characteristic(characteristic, ofService: service, ofAccessory: self, didChangeValue: newValue)
-    }
+        delegate?.characteristic(characteristic, ofService: service, didChangeValue: newValue)
+   }
 
     public func serialized() -> [String: JSONValueType] {
         [
@@ -116,3 +119,39 @@ open class Accessory: JSONSerializable {
         ]
     }
 }
+
+/// A HAP `Characteristic` calls the methods of this delegate to report
+/// set/gets from a HAP controller.
+///
+/// Implement this protocol in an accessory-specific object (such as a subclass
+/// of a given accessory) in order to make the accessory react accordingly.
+/// For example, you might want to update the value of certain characteristics
+/// if the HAP controller is showing interest or makes a change.
+///
+public protocol AccessoryDelegate: AnyObject {
+    /// Characteristic's value was changed by controller. Used for notifying
+    func characteristic<T>(
+        _ characteristic: GenericCharacteristic<T>,
+        ofService: Service,
+        didChangeValue: T?)
+    /// Characteristic's value was observed by controller. Used for lazy updating
+    func characteristic<T>(
+        _ characteristic: GenericCharacteristic<T>,
+        ofService: Service,
+        didGetValue: T?)
+
+    /// Tells the delegate that identification of the device was requested.
+    ///
+    /// When the user configures a device, there might be multiple similar
+    /// devices. In order to identify the individual device, HAP
+    /// accommodates for an identification event. When possible, you should
+    /// make the physical device emit sound and/or light for the user to be
+    /// able to identify the device.
+    func didRequestIdentification()
+
+}
+
+public extension AccessoryDelegate {
+    // Default implementation ignores the request
+    func didRequestIdentification() { }
+}

Sources/HAP/Base/Characteristic.swift

@@ -18,7 +18,8 @@ protocol Characteristic: class, JSONSerializable {
     var iid: InstanceID { get set }
     var type: CharacteristicType { get }
     var permissions: [CharacteristicPermission] { get }
-    func getValue() -> JSONValueType?
+    func jsonValue() -> JSONValueType?
+    func getValue(fromChannel: Channel?) -> JSONValueType?
     func setValue(_: Any?, fromChannel: Channel?) throws
     var description: String? { get }
     var format: CharacteristicFormat? { get }
@@ -41,7 +42,7 @@ extension Characteristic {
 
         if permissions.contains(.read) {
             // TODO: fixit
-            serialized["value"] = getValue() ?? 0 //NSNull()
+            serialized["value"] = jsonValue() ?? 0 //NSNull()
         }
 
         if let description = description { serialized["description"] = description }
@@ -89,13 +90,33 @@ public class GenericCharacteristic<T: CharacteristicValueType>: Characteristic,
             if let device = service?.accessory?.device {
                 device.fireCharacteristicChangeEvent(self)
             }
+            if let service = self.service,
+               let accessory = service.accessory,
+               let device = accessory.device {
+                device.characteristic(self,
+                                      ofService: service,
+                                      ofAccessory: accessory,
+                                      didChangeValue: _value)
+            }
         }
     }
 
-    func getValue() -> JSONValueType? {
+    func jsonValue() -> JSONValueType? {
         value?.jsonValueType
     }
 
+    // Get Value for HAP controller
+    func getValue(fromChannel channel: Channel?) -> JSONValueType? {
+        let currentValue = _value
+        DispatchQueue.main.async { [weak self] in
+            if let self = self, let service = self.service {
+                service.accessory?.delegate?.characteristic(self, ofService: service, didGetValue: currentValue)
+            }
+        }
+        return jsonValue()
+    }
+
+    // Set Value by HAP controller
     func setValue(_ newValue: Any?, fromChannel channel: Channel?) throws {
         switch newValue {
         case let some?:

Sources/HAP/Base/Info.swift

@@ -22,6 +22,7 @@ extension Service {
             if characteristic === identify {
                 if let accessory = accessory {
                     accessory.device?.delegate?.didRequestIdentificationOf(accessory)
+                    accessory.delegate?.didRequestIdentification()
                 }
             }
             super.characteristic(characteristic, didChangeValue: newValue)

Sources/HAP/Endpoints/characteristics().swift

@@ -56,7 +56,7 @@ func characteristics(device: Device, channel: Channel, request: HTTPRequest) ->
                 }
 
                 var value: Protocol.Value?
-                switch characteristic.getValue() {
+                switch characteristic.getValue(fromChannel: channel) {
                 case let _value as Double: value = .double(_value)
                 case let _value as Float: value = .double(Double(_value))
                 case let _value as UInt8: value = .int(Int(_value))

Sources/HAP/Utils/Event.swift

@@ -62,7 +62,7 @@ struct Event {
             guard let aid = char.service?.accessory?.aid else {
                 throw Error.characteristicWithoutAccessory
             }
-            payload.append(["aid": aid, "iid": char.iid, "value": char.getValue() ?? NSNull()])
+            payload.append(["aid": aid, "iid": char.iid, "value": char.jsonValue() ?? NSNull()])
         }
         let serialized = ["characteristics": payload]
         guard let body = try? JSONSerialization.data(withJSONObject: serialized, options: []) else {

Tests/HAPTests/CharacteristicTests.swift

@@ -13,7 +13,7 @@ class CharacteristicTests: XCTestCase {
 
     func testReadOptionalValueType() {
         let characteristic = GenericCharacteristic<Bool?>(type: .identify, value: false)
-        guard let value = characteristic.getValue() as? Bool? else {
+        guard let value = characteristic.getValue(fromChannel: nil) as? Bool? else {
             XCTFail("Could not get value")
             return
         }
@@ -36,7 +36,7 @@ class CharacteristicTests: XCTestCase {
         } catch {
             XCTFail("Could not set value: \(error)")
         }
-        guard let value = characteristic.getValue() as? Bool? else {
+        guard let value = characteristic.getValue(fromChannel: nil) as? Bool? else {
             XCTFail("Could not get value")
             return
         }