Fix/3711 refactor cached app config

src/xcode/ENA/ENA.xcodeproj/project.pbxproj

@@ -375,6 +375,7 @@
 		ABC6B7ED255AEF77000A1AC0 /* RiskProviderAndNewKeyPackagesTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABC6B7E8255AEF74000A1AC0 /* RiskProviderAndNewKeyPackagesTests.swift */; };
 		ABD2F634254C533200DC1958 /* KeyPackageDownload.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABD2F633254C533200DC1958 /* KeyPackageDownload.swift */; };
 		ABDA2792251CE308006BAE84 /* DMServerEnvironmentViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABDA2791251CE308006BAE84 /* DMServerEnvironmentViewController.swift */; };
+		ABFCE98A255C32EF0075FF13 /* AppConfigMetadata.swift in Sources */ = {isa = PBXBuildFile; fileRef = ABFCE989255C32EE0075FF13 /* AppConfigMetadata.swift */; };
 		B103193224E18A0A00DD02EF /* DMMenuItem.swift in Sources */ = {isa = PBXBuildFile; fileRef = B103193124E18A0A00DD02EF /* DMMenuItem.swift */; };
 		B10F9B8B249961BC00C418F4 /* DynamicTypeLabelTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = B10F9B89249961B500C418F4 /* DynamicTypeLabelTests.swift */; };
 		B10F9B8C249961CE00C418F4 /* UIFont+DynamicTypeTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = B163D11424993F64001A322C /* UIFont+DynamicTypeTests.swift */; };
@@ -979,6 +980,7 @@
 		ABC6B7E8255AEF74000A1AC0 /* RiskProviderAndNewKeyPackagesTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RiskProviderAndNewKeyPackagesTests.swift; sourceTree = "<group>"; };
 		ABD2F633254C533200DC1958 /* KeyPackageDownload.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = KeyPackageDownload.swift; sourceTree = "<group>"; };
 		ABDA2791251CE308006BAE84 /* DMServerEnvironmentViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DMServerEnvironmentViewController.swift; sourceTree = "<group>"; };
+		ABFCE989255C32EE0075FF13 /* AppConfigMetadata.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppConfigMetadata.swift; sourceTree = "<group>"; };
 		B102BDC22460410600CD55A2 /* README.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 		B103193124E18A0A00DD02EF /* DMMenuItem.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DMMenuItem.swift; sourceTree = "<group>"; };
 		B10F9B89249961B500C418F4 /* DynamicTypeLabelTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DynamicTypeLabelTests.swift; sourceTree = "<group>"; };
@@ -1448,6 +1450,7 @@
 				A16714BA248D18D20031B111 /* SummaryMetadata.swift */,
 				354E305824EFF26E00526C9F /* Country.swift */,
 				941ADDB12518C3FB00E421D9 /* ENSettingEuTracingViewModel.swift */,
+				ABFCE989255C32EE0075FF13 /* AppConfigMetadata.swift */,
 				94B255A52551B7C800649B4C /* WarnOthersReminder.swift */,
 				94427A4F25502B8900C36BE6 /* WarnOthersNotificationsTimeInterval.swift */,
 				948AFE662553DC5B0019579A /* WarnOthersRemindable.swift */,
@@ -3435,6 +3438,7 @@
 				A3816086250633D7002286E9 /* RequiresDismissConfirmation.swift in Sources */,
 				51D420B424583ABB00AD70CA /* AppStoryboard.swift in Sources */,
 				4026C2DC24852B7600926FB4 /* AppInformationViewController+LegalModel.swift in Sources */,
+				ABFCE98A255C32EF0075FF13 /* AppConfigMetadata.swift in Sources */,
 				01C6ABF42527273E0052814D /* String+Insertion.swift in Sources */,
 				EE278B30245F2C8A008B06F9 /* FriendsInviteController.swift in Sources */,
 				710ABB27247533FA00948792 /* DynamicTableViewController.swift in Sources */,

src/xcode/ENA/ENA/Source/Client/__tests__/Mocks/CachingHTTPClientMock.swift

@@ -27,6 +27,12 @@ final class CachingHTTPClientMock: CachingHTTPClient {
 		return config
 	}()
 
+	static let staticAppConfigMetadata: AppConfigMetadata = {
+		let bundle = Bundle(for: CachingHTTPClientMock.self)
+		let configMetadata = AppConfigMetadata(lastAppConfigETag: "\"SomeETag\"", lastAppConfigFetch: .distantPast, appConfig: CachingHTTPClientMock.staticAppConfig)
+		return configMetadata
+	}()
+
 	// MARK: AppConfigurationFetching
 
 	var onFetchAppConfiguration: ((String?, @escaping CachingHTTPClient.AppConfigResultHandler) -> Void)?

src/xcode/ENA/ENA/Source/Developer Menu/Features/DMStoreViewController.swift

@@ -42,13 +42,13 @@ final class DMStoreViewController: UITableViewController {
 				store.previousRiskLevel?.description ?? ""
 			},
 			DMStoreItem(attribute: "lastAppConfigETag") { store in
-				store.lastAppConfigETag?.description ?? "<nil>"
+				store.appConfigMetadata?.lastAppConfigETag.description ?? "<nil>"
 			},
 			DMStoreItem(attribute: "lastAppConfigFetch") { store in
-				store.lastAppConfigFetch?.description ?? "<nil>"
+				store.appConfigMetadata?.lastAppConfigFetch.description ?? "<nil>"
 			},
 			DMStoreItem(attribute: "appConfig") { store in
-				store.appConfig?.debugDescription ?? "<nil>"
+				store.appConfigMetadata?.appConfig.debugDescription ?? "<nil>"
 			}
 		]
 	}()

src/xcode/ENA/ENA/Source/Models/Exposure/AppConfigMetadata.swift

@@ -0,0 +1,73 @@
+//
+// Corona-Warn-App
+//
+// SAP SE and all other contributors
+// copyright owners license this file to you under the Apache
+// License, Version 2.0 (the "License"); you may not use this
+// file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+//
+
+import Foundation
+
+struct AppConfigMetadata: Codable, Equatable {
+
+	// MARK: - Init
+
+	init(
+		lastAppConfigETag: String,
+		lastAppConfigFetch: Date,
+		appConfig: SAP_Internal_ApplicationConfiguration
+	) {
+		self.lastAppConfigETag = lastAppConfigETag
+		self.lastAppConfigFetch = lastAppConfigFetch
+		self.appConfig = appConfig
+	}
+
+	// MARK: - Protocol Codable
+
+	enum CodingKeys: String, CodingKey {
+		case lastAppConfigETag
+		case lastAppConfigFetch
+		case appConfig
+	}
+
+	init(from decoder: Decoder) throws {
+		let container = try decoder.container(keyedBy: CodingKeys.self)
+
+		lastAppConfigETag = try container.decode(String.self, forKey: .lastAppConfigETag)
+		lastAppConfigFetch = try container.decode(Date.self, forKey: .lastAppConfigFetch)
+
+		let appConfigData = try container.decode(Data.self, forKey: .appConfig)
+		appConfig = try SAP_Internal_ApplicationConfiguration(serializedData: appConfigData)
+	}
+
+	func encode(to encoder: Encoder) throws {
+		var container = encoder.container(keyedBy: CodingKeys.self)
+
+		try container.encode(lastAppConfigETag, forKey: .lastAppConfigETag)
+		try container.encode(lastAppConfigFetch, forKey: .lastAppConfigFetch)
+
+		let appConfigData = try appConfig.serializedData()
+		try container.encode(appConfigData, forKey: .appConfig)
+	}
+
+	// MARK: - Internal
+
+	var lastAppConfigETag: String
+	var lastAppConfigFetch: Date
+	var appConfig: SAP_Internal_ApplicationConfiguration
+
+	mutating func refeshLastAppConfigFetchDate() {
+		lastAppConfigFetch = Date()
+	}
+}

src/xcode/ENA/ENA/Source/Services/Exposure Transaction/ExposureDetectionExecutor.swift

@@ -76,9 +76,7 @@ final class ExposureDetectionExecutor: ExposureDetectionDelegate {
 				downloadedPackagesStore.open()
 
 				// Clear the app config
-				store.appConfig = nil
-				store.lastAppConfigETag = nil
-				store.lastAppConfigFetch = nil
+				store.appConfigMetadata = nil
 			}
 		}
 

src/xcode/ENA/ENA/Source/Services/Exposure Transaction/__tests__/ExposureDetectionExecutorTests.swift

@@ -9,6 +9,14 @@ import XCTest
 
 final class ExposureDetectionExecutorTests: XCTestCase {
 
+	private var dummyAppConfigMetadata: AppConfigMetadata {
+		AppConfigMetadata(
+			lastAppConfigETag: "ETag",
+			lastAppConfigFetch: Date(),
+			appConfig: SAP_Internal_ApplicationConfiguration()
+		)
+	}
+
 	// MARK: - Write Downloaded Package Tests
 
 	func testWriteDownloadedPackage() throws {
@@ -139,7 +147,7 @@ final class ExposureDetectionExecutorTests: XCTestCase {
 		try packageStore.set(country: "DE", day: "SomeDay", etag: nil, package: package)
 
 		let store = MockTestStore()
-		store.appConfig = SAP_Internal_ApplicationConfiguration()
+		store.appConfigMetadata = dummyAppConfigMetadata
 
 		let sut = ExposureDetectionExecutor.makeWith(
 			packageStore: packageStore,
@@ -153,7 +161,7 @@ final class ExposureDetectionExecutorTests: XCTestCase {
 		)
 
 		XCTAssertNotEqual(packageStore.allDays(country: "DE").count, 0)
-		XCTAssertNotNil(store.appConfig)
+		XCTAssertNotNil(store.appConfigMetadata)
 
 		_ = sut.exposureDetection(
 			exposureDetection,
@@ -162,9 +170,7 @@ final class ExposureDetectionExecutorTests: XCTestCase {
 			completion: { _ in
 
 				XCTAssertEqual(packageStore.allDays(country: "DE").count, 0)
-				XCTAssertNil(store.appConfig)
-				XCTAssertNil(store.lastAppConfigETag)
-				XCTAssertNil(store.lastAppConfigFetch)
+				XCTAssertNil(store.appConfigMetadata)
 
 				completionExpectation.fulfill()
 			}

src/xcode/ENA/ENA/Source/Services/Risk/Provider/Helper/CachedAppConfiguration.swift

@@ -32,63 +32,75 @@ final class CachedAppConfiguration {
 		deviceTimeCheck: DeviceTimeCheckProtocol? = nil,
 		configurationDidChange: (() -> Void)? = nil
 	) {
+		Log.debug("CachedAppConfiguration init called", log: .appConfig)
+
 		self.client = client
 		self.store = store
 		self.configurationDidChange = configurationDidChange
 
 		self.deviceTimeCheck = deviceTimeCheck ?? DeviceTimeCheck(store: store)
 
-		guard shouldFetch() else { return }
 
-		// edge case: if no app config is cached, omit a potentially existing ETag to force fetch a new configuration
-		let etag = store.appConfig == nil ? nil : store.lastAppConfigETag
+		guard shouldFetch() else { return }
 
 		// check for updated or fetch initial app configuration
-		fetchConfig(with: etag)
+		fetchConfig(with: store.appConfigMetadata?.lastAppConfigETag)
 	}
 
 	private func fetchConfig(with etag: String?, completion: Completion? = nil) {
+		Log.debug("fetchConfig called with etag:\(etag ?? "nil")", log: .appConfig)
+
 		client.fetchAppConfiguration(etag: etag) { [weak self] result in
 			guard let self = self else { return }
 
 			switch result.0 /* fyi, `result.1` would be the server time */{
 			case .success(let response):
-				self.store.lastAppConfigETag = response.eTag
-				self.store.appConfig = response.config
-				self.completeOnMain(completion: completion, result: .success(response.config))
+				let configMetadata = AppConfigMetadata(
+					lastAppConfigETag: response.eTag ?? "\"ReloadMe\"",
+					lastAppConfigFetch: Date(),
+					appConfig: response.config
+				)
+
+				// Skip processing of config if it didn't change.
+				guard self.store.appConfigMetadata?.lastAppConfigETag != configMetadata.lastAppConfigETag else {
+					Log.debug("Skip processing app config, because it didn't change", log: .appConfig)
+					self.completeOnMain(completion: completion, result: .success(response.config))
+					return
+				}
 
-				// keep track of last successful fetch
-				self.store.lastAppConfigFetch = Date()
+				Log.debug("Persist new app configuration", log: .appConfig)
+				self.store.appConfigMetadata = configMetadata
 
 				// update revokation list
-				let revokationList = self.store.appConfig?.revokationEtags ?? []
+				let revokationList = self.store.appConfigMetadata?.appConfig.revokationEtags ?? []
 				self.packageStore?.revokationList = revokationList // for future package-operations
 				// validate currently stored key packages
 				do {
 					try self.packageStore?.validateCachedKeyPackages(revokationList: revokationList)
 				} catch {
-					Log.error("Error while removing invalidated key packages.", log: .localData, error: error)
+					Log.error("Error while removing invalidated key packages.", log: .appConfig, error: error)
 					// no further action - yet
 				}
 
+				self.completeOnMain(completion: completion, result: .success(response.config))
+
 				self.configurationDidChange?()
 			case .failure(let error):
 				switch error {
-				case CachedAppConfiguration.CacheError.notModified where self.store.appConfig != nil:
-					Log.error("config not modified", log: .api)
+				case CachedAppConfiguration.CacheError.notModified where self.store.appConfigMetadata != nil:
+					Log.error("Config not modified", log: .appConfig)
 					// server is not modified and we have a cached config
-					guard let config = self.store.appConfig else {
+					guard var appConfigMetadata = self.store.appConfigMetadata else {
 						fatalError("App configuration cache broken!") // in `where` we trust
 					}
-					self.completeOnMain(completion: completion, result: .success(config))
 
 					// server response HTTP 304 is considered a 'successful fetch'
-					self.store.lastAppConfigFetch = Date()
-				default:
-					// ensure reset
-					self.store.lastAppConfigETag = nil
-					self.store.lastAppConfigFetch = nil
+					Log.debug("Update lastAppConfigFetchDate of persisted app configuration", log: .appConfig)
+					appConfigMetadata.refeshLastAppConfigFetchDate()
+					self.store.appConfigMetadata = appConfigMetadata
 
+					self.completeOnMain(completion: completion, result: .success(appConfigMetadata.appConfig))
+				default:
 					self.completeOnMain(completion: completion, result: .failure(error))
 				}
 			}
@@ -117,16 +129,18 @@ extension CachedAppConfiguration: AppConfigurationProviding {
 	fileprivate static let timestampKey = "LastAppConfigFetch"
 
 	func appConfiguration(forceFetch: Bool = false, completion: @escaping Completion) {
+		Log.debug("Request app configuration forceFetch: \(forceFetch)", log: .appConfig)
+
 		let force = shouldFetch() || forceFetch
 
-		if let cachedVersion = store.appConfig, !force {
-			Log.debug("[App Config] fetching cached app configuration", log: .localData)
+		if let cachedVersion = store.appConfigMetadata, !force {
+			Log.debug("fetching cached app configuration", log: .appConfig)
 			// use the cached version
-			completeOnMain(completion: completion, result: .success(cachedVersion))
+			completeOnMain(completion: completion, result: .success(cachedVersion.appConfig))
 		} else {
-			Log.debug("[App Config] fetching fresh app configuration", log: .localData)
+			Log.debug("fetching fresh app configuration. forceFetch: \(forceFetch), force: \(force)", log: .appConfig)
 			// fetch a new one
-			fetchConfig(with: store.lastAppConfigETag, completion: completion)
+			fetchConfig(with: store.appConfigMetadata?.lastAppConfigETag, completion: completion)
 		}
 	}
 
@@ -139,14 +153,19 @@ extension CachedAppConfiguration: AppConfigurationProviding {
 	///   which does not easily return response headers. This requires further refactoring of `URLSession+Convenience.swift`.
 	/// - Returns: `true` is a network call should be done; `false` if cache should be used
 	private func shouldFetch() -> Bool {
-		if store.appConfig == nil { return true }
+		Log.debug("shouldFetch called", log: .appConfig)
+
+		if store.appConfigMetadata == nil {
+			Log.debug("store.appConfigMetadata is nil", log: .appConfig)
+			return true
+		}
 
 		// naïve cache control
-		guard let lastFetch = store.lastAppConfigFetch else {
-			Log.debug("[Cache-Control] no last config fetch timestamp stored", log: .localData)
+		guard let lastFetch = store.appConfigMetadata?.lastAppConfigFetch else {
+			Log.debug("no last config fetch timestamp stored", log: .appConfig)
 			return true
 		}
-        Log.debug("[Cache-Control] timestamp >= 300s? \(abs(lastFetch.distance(to: Date())) >= 300)", log: .localData)
+        Log.debug("timestamp >= 300s? \(abs(lastFetch.distance(to: Date())) >= 300)", log: .appConfig)
         return abs(lastFetch.distance(to: Date())) >= 300
 	}
 }

src/xcode/ENA/ENA/Source/Services/Risk/Provider/Helper/DeviceTimeCheck.swift

@@ -39,7 +39,7 @@ final class DeviceTimeCheck: DeviceTimeCheckProtocol {
 				deviceTime: deviceTime
 			),
 			isDeviceTimeCheckKillSwitchActive: self.isDeviceTimeCheckKillSwitchActive(
-				config: self.store.appConfig
+				config: self.store.appConfigMetadata?.appConfig
 			)
 		)
 	}