feat: Manage Events - track app lifecycle events (#118)

* move all the logic inside confidence

* add evaluation extension in flag resolution

* cleanup

* have the evaluation in the confidence module for the flags

* update demo app to support only confidence

* fix some tests to move to confidence

* use int instead of int64 for 32bits system to work with default value for int, fix some more tests

* fixup! use int instead of int64 for 32bits system to work with default value for int, fix some more tests

* fixup! Merge branch 'main' into move-flag-evaluation-confidence

* fixup! fixup! Merge branch 'main' into move-flag-evaluation-confidence

* fixup! fixup! fixup! Merge branch 'main' into move-flag-evaluation-confidence

* add analytics for app and ui kit lifecycle, add the appear and disappear for demo app events

* fixup! add analytics for app and ui kit lifecycle, add the appear and disappear for demo app events

* handle app launch and app install and app updates

* add context producer and produce context for is_foreground and build and version

* fixup! merge main

* fixup! fixup! merge main

* refactor: Smaller refactor and fixes

* Remove some managed events

* wip: minor fixes and experiments

* introduce passthrough subject with buffer

* update the engine to remove the batches by default and add them if failed

* fixup! update the engine to remove the batches by default and add them if failed

* queue label prefix

* use semaphore to make upload serialz

* Remove dead code

* Make buffered passthrough serial

---------

Co-authored-by: Fabrizio Demaria <fabrizio.f.demaria@gmail.com>

ConfidenceDemoApp/ConfidenceDemoApp/ConfidenceDemoApp.swift

@@ -14,6 +14,8 @@ class Status: ObservableObject {
 
 @main
 struct ConfidenceDemoApp: App {
+    @StateObject private var lifecycleObserver = ConfidenceAppLifecycleProducer()
+
     var body: some Scene {
         WindowGroup {
             let secret = ProcessInfo.processInfo.environment["CLIENT_SECRET"] ?? ""
@@ -27,6 +29,7 @@ struct ConfidenceDemoApp: App {
             ContentView(confidence: confidence, status: status)
                 .task {
                     do {
+                        confidence.track(producer: lifecycleObserver)
                         try await self.setup(confidence: confidence)
                         status.state = .ready
                     } catch {

Sources/Confidence/BufferedPassthroughSubject.swift

@@ -0,0 +1,30 @@
+import Foundation
+import Combine
+
+class BufferedPassthrough<T> {
+    private let subject = PassthroughSubject<T, Never>()
+    private var buffer: [T] = []
+    private var isListening = false
+    private let queue = DispatchQueue(label: "com.confidence.passthrough_serial")
+
+    func send(_ value: T) {
+        queue.sync {
+            if isListening {
+                subject.send(value)
+            } else {
+                buffer.append(value)
+            }
+        }
+    }
+
+    func publisher() -> AnyPublisher<T, Never> {
+        return queue.sync {
+            isListening = true
+            let bufferedPublisher = buffer.publisher
+            buffer.removeAll()
+            return bufferedPublisher
+                .append(subject)
+                .eraseToAnyPublisher()
+        }
+    }
+}

Sources/Confidence/Confidence.swift

@@ -121,6 +121,30 @@ public class Confidence: ConfidenceEventSender {
         )
     }
 
+    public func track(producer: ConfidenceProducer) {
+        if let eventProducer = producer as? ConfidenceEventProducer {
+            eventProducer.produceEvents()
+                .sink { [weak self] event in
+                    guard let self = self else {
+                        return
+                    }
+                    self.track(eventName: event.name, message: event.message)
+                }
+                .store(in: &cancellables)
+        }
+
+        if let contextProducer = producer as? ConfidenceContextProducer {
+            contextProducer.produceContexts()
+                .sink { [weak self] context in
+                    guard let self = self else {
+                        return
+                    }
+                    self.putContext(context: context)
+                }
+                .store(in: &cancellables)
+        }
+    }
+
     private func withLock(callback: @escaping (Confidence) -> Void) {
         confidenceQueue.sync {  [weak self] in
             guard let self = self else {

Sources/Confidence/ConfidenceAppLifecycleProducer.swift

@@ -0,0 +1,109 @@
+#if os(iOS) || os(tvOS) || os(visionOS) || targetEnvironment(macCatalyst)
+import Foundation
+import UIKit
+import Combine
+
+public class ConfidenceAppLifecycleProducer: ConfidenceEventProducer, ConfidenceContextProducer, ObservableObject {
+    public var currentProducedContext: CurrentValueSubject<ConfidenceStruct, Never> = CurrentValueSubject([:])
+    private var events: BufferedPassthrough<Event> = BufferedPassthrough()
+    private let queue = DispatchQueue(label: "com.confidence.lifecycle_producer")
+    private var appNotifications: [NSNotification.Name] = [
+        UIApplication.didEnterBackgroundNotification,
+        UIApplication.willEnterForegroundNotification,
+        UIApplication.didBecomeActiveNotification
+    ]
+
+    private static var versionNameKey = "CONFIDENCE_VERSION_NAME_KEY"
+    private static var buildNameKey = "CONFIDENCE_VERSIONN_KEY"
+    private let appLaunchedEventName = "app-launched"
+
+    public init() {
+        for notification in appNotifications {
+            NotificationCenter.default.addObserver(
+                self,
+                selector: #selector(notificationResponse),
+                name: notification,
+                object: nil
+            )
+        }
+
+        let currentVersion: String = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? ""
+        let currentBuild: String = Bundle.main.infoDictionary?["CFBundleVersion"] as? String ?? ""
+        let context: ConfidenceStruct = [
+            "version": .init(string: currentVersion),
+            "build": .init(string: currentBuild)
+        ]
+
+        self.currentProducedContext.send(context)
+    }
+
+    deinit {
+        NotificationCenter.default.removeObserver(self)
+    }
+
+    public func produceEvents() -> AnyPublisher<Event, Never> {
+        events.publisher()
+    }
+
+    public func produceContexts() -> AnyPublisher<ConfidenceStruct, Never> {
+        currentProducedContext
+            .filter { context in !context.isEmpty }
+            .eraseToAnyPublisher()
+    }
+
+    private func track(eventName: String) {
+        let previousBuild: String? = UserDefaults.standard.string(forKey: Self.buildNameKey)
+        let previousVersion: String? = UserDefaults.standard.string(forKey: Self.versionNameKey)
+
+        let currentVersion: String = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? ""
+        let currentBuild: String = Bundle.main.infoDictionary?["CFBundleVersion"] as? String ?? ""
+
+        let message: ConfidenceStruct = [
+            "version": .init(string: currentVersion),
+            "build": .init(string: currentBuild)
+        ]
+
+        if eventName == self.appLaunchedEventName {
+            if previousBuild == nil && previousVersion == nil {
+                events.send(Event(name: "app-installed", message: message))
+            } else if previousBuild != currentBuild || previousVersion != currentVersion {
+                events.send(Event(name: "app-updated", message: message))
+            }
+        }
+        events.send(Event(name: eventName, message: message))
+
+        UserDefaults.standard.setValue(currentVersion, forKey: Self.versionNameKey)
+        UserDefaults.standard.setValue(currentBuild, forKey: Self.buildNameKey)
+    }
+
+    private func updateContext(isForeground: Bool) {
+        withLock { [weak self] in
+            guard let self = self else {
+                return
+            }
+            var context = self.currentProducedContext.value
+            context.updateValue(.init(boolean: isForeground), forKey: "is_foreground")
+            self.currentProducedContext.send(context)
+        }
+    }
+
+    private func withLock(callback: @escaping () -> Void) {
+        queue.sync {
+            callback()
+        }
+    }
+
+    @objc func notificationResponse(notification: NSNotification) {
+        switch notification.name {
+        case UIApplication.didEnterBackgroundNotification:
+            updateContext(isForeground: false)
+        case UIApplication.willEnterForegroundNotification:
+            updateContext(isForeground: true)
+        case UIApplication.didBecomeActiveNotification:
+            track(eventName: appLaunchedEventName)
+        default:
+            break
+        }
+    }
+}
+#endif

Sources/Confidence/ConfidenceEventSender.swift

@@ -9,4 +9,8 @@ public protocol ConfidenceEventSender: Contextual {
     according to the configured flushing logic
     */
     func track(eventName: String, message: ConfidenceStruct)
+    /**
+    The ConfidenceProducer can be used to push context changes or event tracking
+    */
+    func track(producer: ConfidenceProducer)
 }

Sources/Confidence/ConfidenceProducer.swift

@@ -0,0 +1,32 @@
+import Foundation
+import Combine
+
+/**
+ConfidenceContextProducer or ConfidenceEventProducer
+*/
+public protocol ConfidenceProducer {
+}
+
+public struct Event {
+    let name: String
+    let message: ConfidenceStruct
+
+    public init(name: String, message: ConfidenceStruct = [:]) {
+        self.name = name
+        self.message = message
+    }
+}
+
+/**
+ConfidenceContextProducer implementer pushses context changes in a Publisher fashion
+*/
+public protocol ConfidenceContextProducer: ConfidenceProducer {
+    func produceContexts() -> AnyPublisher<ConfidenceStruct, Never>
+}
+
+/**
+ConfidenceContextProducer implementer emit events in a Publisher fashion
+*/
+public protocol ConfidenceEventProducer: ConfidenceProducer {
+    func produceEvents() -> AnyPublisher<Event, Never>
+}

Sources/Confidence/ConfidenceScreenTracker.swift

@@ -0,0 +1,102 @@
+#if os(iOS) || os(tvOS) || os(visionOS) || targetEnvironment(macCatalyst)
+import Foundation
+import UIKit
+import Combine
+
+public class ConfidenceScreenTracker: ConfidenceEventProducer {
+    private var events = BufferedPassthrough<Event>()
+    static let notificationName = Notification.Name(rawValue: "ConfidenceScreenTracker")
+    static let screenName = "screen_name"
+    static let messageKey = "message_json"
+    static let controllerKey = "controller"
+
+    public init() {
+        swizzle(
+            forClass: UIViewController.self,
+            original: #selector(UIViewController.viewDidAppear(_:)),
+            new: #selector(UIViewController.confidence__viewDidAppear)
+        )
+
+        swizzle(
+            forClass: UIViewController.self,
+            original: #selector(UIViewController.viewDidDisappear(_:)),
+            new: #selector(UIViewController.confidence__viewDidDisappear)
+        )
+
+        NotificationCenter.default.addObserver(
+            forName: Self.notificationName,
+            object: nil,
+            queue: OperationQueue.main) { [weak self] notification in
+                let name = notification.userInfo?[Self.screenName] as? String
+                let messageJson = (notification.userInfo?[Self.messageKey] as? String)?.data(using: .utf8)
+                var message: ConfidenceStruct = [:]
+                if let data = messageJson {
+                    let decoder = JSONDecoder()
+                    do {
+                        message = try decoder.decode(ConfidenceStruct.self, from: data)
+                    } catch {
+                    }
+                }
+
+                guard let self = self else {
+                    return
+                }
+                if let name = name {
+                    self.events.send(Event(name: name, message: message))
+                }
+        }
+    }
+
+    public func produceEvents() -> AnyPublisher<Event, Never> {
+        events.publisher()
+    }
+
+    private func swizzle(forClass: AnyClass, original: Selector, new: Selector) {
+        guard let originalMethod = class_getInstanceMethod(forClass, original) else { return }
+        guard let swizzledMethod = class_getInstanceMethod(forClass, new) else { return }
+        method_exchangeImplementations(originalMethod, swizzledMethod)
+    }
+}
+
+public protocol TrackableComponent {
+    func trackName() -> String
+}
+
+public protocol TrackableComponentWithMessage: TrackableComponent {
+    func trackMessage() -> ConfidenceStruct
+}
+
+extension UIViewController {
+    private func sendNotification(event: String) {
+        var className = String(describing: type(of: self))
+            .replacingOccurrences(of: "ViewController", with: "")
+        var message: [String: String] = [ConfidenceScreenTracker.screenName: className]
+
+        if let trackable = self as? TrackableComponent {
+            className = trackable.trackName()
+            if let trackableWithMessage = self as? TrackableComponentWithMessage {
+                let encoder = JSONEncoder()
+                do {
+                    let data = try encoder.encode(trackableWithMessage.trackMessage())
+                    let messageString = String(data: data, encoding: .utf8)
+                    if let json = messageString {
+                        message.updateValue(json, forKey: ConfidenceScreenTracker.messageKey)
+                    }
+                } catch {
+                }
+            }
+        }
+
+        NotificationCenter.default.post(
+            name: ConfidenceScreenTracker.notificationName,
+            object: self,
+            userInfo: message
+        )
+    }
+    @objc internal func confidence__viewDidAppear(animated: Bool) {
+    }
+
+    @objc internal func confidence__viewDidDisappear(animated: Bool) {
+    }
+}
+#endif

Sources/Confidence/EventSenderEngine.swift

@@ -22,6 +22,7 @@ final class EventSenderEngineImpl: EventSenderEngine {
     private let uploader: ConfidenceClient
     private let clientSecret: String
     private let payloadMerger: PayloadMerger = PayloadMergerImpl()
+    private let semaphore = DispatchSemaphore(value: 1)
 
     init(
         clientSecret: String,
@@ -52,10 +53,21 @@ final class EventSenderEngineImpl: EventSenderEngine {
         .store(in: &cancellables)
 
         uploadReqChannel.sink { [weak self] _ in
+            guard let self = self else { return }
+            await self.upload()
+        }
+        .store(in: &cancellables)
+    }
+
+    func upload() async {
+        await withSemaphore { [weak self] in
+            guard let self = self else { return }
             do {
-                guard let self = self else { return }
                 try self.storage.startNewBatch()
                 let ids = try storage.batchReadyIds()
+                if ids.isEmpty {
+                    return
+                }
                 for id in ids {
                     let events: [NetworkEvent] = try self.storage.eventsFrom(id: id)
                         .compactMap { event in
@@ -64,15 +76,26 @@ final class EventSenderEngineImpl: EventSenderEngine {
                                 payload: NetworkStruct(fields: TypeMapper.convert(structure: event.payload).fields),
                                 eventTime: Date.backport.toISOString(date: event.eventTime))
                         }
-                    let shouldCleanup = try await self.uploader.upload(events: events)
+                    var shouldCleanup = false
+                    if events.isEmpty {
+                        shouldCleanup = true
+                    } else {
+                        shouldCleanup = try await self.uploader.upload(events: events)
+                    }
+
                     if shouldCleanup {
                         try storage.remove(id: id)
                     }
                 }
             } catch {
             }
         }
-        .store(in: &cancellables)
+    }
+
+    func withSemaphore(callback: @escaping () async -> Void) async {
+        semaphore.wait()
+        await callback()
+        semaphore.signal()
     }
 
     func emit(eventName: String, message: ConfidenceStruct, context: ConfidenceStruct) {