Update to subscription cookie (#1053)

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Please review the release process for BrowserServicesKit
[here](https://app.asana.com/0/1200194497630846/1200837094583426).

**Required**:

Task/Issue URL:
https://app.asana.com/0/1108686900785972/1208264562025859/f
iOS PR: duckduckgo/iOS#3512
macOS PR: duckduckgo/macos-browser#3489
What kind of version bump will this require?: Patch

**Description**:
Update to how the subscription cookie operates:
- constraint the cookie to `subscriptions.duckduckgo.com`
- on sign out do not fully remove the cookie - just clear the value
- gate the feature behind the
`setAccessTokenCookieForSubscriptionDomains` privacy config feature flag

**Steps to test this PR**:
See client PRs

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you expect the reviewer to test, then delete configurations you *know*
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**OS Testing**:

* [ ] iOS 14
* [ ] iOS 15
* [ ] iOS 16
* [ ] macOS 10.15
* [ ] macOS 11
* [ ] macOS 12

---
###### Internal references:
[Software Engineering
Expectations](https://app.asana.com/0/59792373528535/199064865822552)
[Technical Design
Template](https://app.asana.com/0/59792373528535/184709971311943)

Sources/BrowserServicesKit/PrivacyConfig/Features/PrivacyFeature.swift

@@ -152,6 +152,7 @@ public enum PrivacyProSubfeature: String, Equatable, PrivacySubfeature {
     case isLaunchedOverride
     case isLaunchedOverrideStripe
     case useUnifiedFeedback
+    case setAccessTokenCookieForSubscriptionDomains
 }
 
 public enum SslCertificatesSubfeature: String, PrivacySubfeature {

Sources/Subscription/SubscriptionCookie/SubscriptionCookieManager.swift

@@ -22,6 +22,9 @@ import os.log
 
 public protocol SubscriptionCookieManaging {
     init(subscriptionManager: SubscriptionManager, currentCookieStore: @MainActor @escaping () -> HTTPCookieStore?, eventMapping: EventMapping<SubscriptionCookieManagerEvent>)
+    func enableSettingSubscriptionCookie()
+    func disableSettingSubscriptionCookie() async
+
     func refreshSubscriptionCookie() async
     func resetLastRefreshDate()
 
@@ -30,7 +33,7 @@ public protocol SubscriptionCookieManaging {
 
 public final class SubscriptionCookieManager: SubscriptionCookieManaging {
 
-    public static let cookieDomain = ".duckduckgo.com"
+    public static let cookieDomain = "subscriptions.duckduckgo.com"
     public static let cookieName = "privacy_pro_access_token"
 
     private static let defaultRefreshTimeInterval: TimeInterval = .hours(4)
@@ -41,6 +44,7 @@ public final class SubscriptionCookieManager: SubscriptionCookieManaging {
 
     public private(set) var lastRefreshDate: Date?
     private let refreshTimeInterval: TimeInterval
+    private var isSettingSubscriptionCookieEnabled: Bool = false
 
     convenience nonisolated public required init(subscriptionManager: SubscriptionManager,
                                                  currentCookieStore: @MainActor @escaping () -> HTTPCookieStore?,
@@ -60,17 +64,28 @@ public final class SubscriptionCookieManager: SubscriptionCookieManaging {
         self.eventMapping = eventMapping
         self.refreshTimeInterval = refreshTimeInterval
 
-        registerForSubscriptionAccountManagerEvents()
-    }
-
-    private func registerForSubscriptionAccountManagerEvents() {
         NotificationCenter.default.addObserver(self, selector: #selector(handleAccountDidSignIn), name: .accountDidSignIn, object: nil)
         NotificationCenter.default.addObserver(self, selector: #selector(handleAccountDidSignOut), name: .accountDidSignOut, object: nil)
     }
 
+    public func enableSettingSubscriptionCookie() {
+        isSettingSubscriptionCookieEnabled = true
+    }
+
+    public func disableSettingSubscriptionCookie() async {
+        isSettingSubscriptionCookieEnabled = false
+        if let cookieStore = await currentCookieStore(),
+           let cookie = await cookieStore.fetchCurrentSubscriptionCookie() {
+            await cookieStore.deleteCookie(cookie)
+        }
+    }
+
     @objc private func handleAccountDidSignIn() {
         Task {
-            guard let cookieStore = await currentCookieStore() else { return }
+            guard isSettingSubscriptionCookieEnabled,
+                  let cookieStore = await currentCookieStore()
+            else { return }
+
             guard let accessToken = subscriptionManager.accountManager.accessToken else {
                 Logger.subscription.error("[SubscriptionCookieManager] Handle .accountDidSignIn - can't set the cookie, token is missing")
                 eventMapping.fire(.errorHandlingAccountDidSignInTokenIsMissing)
@@ -89,47 +104,47 @@ public final class SubscriptionCookieManager: SubscriptionCookieManaging {
 
     @objc private func handleAccountDidSignOut() {
         Task {
-            guard let cookieStore = await currentCookieStore() else { return }
-            guard let subscriptionCookie = await cookieStore.fetchCurrentSubscriptionCookie() else {
-                Logger.subscription.error("[SubscriptionCookieManager] Handle .accountDidSignOut - can't delete the cookie, cookie is missing")
-                eventMapping.fire(.errorHandlingAccountDidSignOutCookieIsMissing)
-                return
-            }
+            guard isSettingSubscriptionCookieEnabled,
+                  let cookieStore = await currentCookieStore()
+            else { return }
             Logger.subscription.info("[SubscriptionCookieManager] Handle .accountDidSignOut - deleting cookie")
-            await cookieStore.deleteCookie(subscriptionCookie)
-            updateLastRefreshDateToNow()
+
+            do {
+                try await cookieStore.setEmptySubscriptionCookie()
+                updateLastRefreshDateToNow()
+            } catch {
+                eventMapping.fire(.failedToSetSubscriptionCookie)
+            }
         }
     }
 
     public func refreshSubscriptionCookie() async {
-        guard shouldRefreshSubscriptionCookie() else { return }
-        guard let cookieStore = await currentCookieStore() else { return }
+        guard isSettingSubscriptionCookieEnabled,
+              shouldRefreshSubscriptionCookie(),
+              let cookieStore = await currentCookieStore() else { return }
 
         Logger.subscription.info("[SubscriptionCookieManager] Refresh subscription cookie")
         updateLastRefreshDateToNow()
 
         let accessToken: String? = subscriptionManager.accountManager.accessToken
         let subscriptionCookie = await cookieStore.fetchCurrentSubscriptionCookie()
 
-        if let accessToken {
-            if subscriptionCookie == nil || subscriptionCookie?.value != accessToken {
-                Logger.subscription.info("[SubscriptionCookieManager] Refresh: No cookie or one with different value")
-                do {
+        let noCookieOrWithUnexpectedValue = (accessToken ?? "") != subscriptionCookie?.value
+
+        do {
+            if noCookieOrWithUnexpectedValue {
+                Logger.subscription.info("[SubscriptionCookieManager] Refresh: No cookie or one with unexpected value")
+
+                if let accessToken {
                     try await cookieStore.setSubscriptionCookie(for: accessToken)
-                    eventMapping.fire(.subscriptionCookieRefreshedWithUpdate)
-                } catch {
-                    eventMapping.fire(.failedToSetSubscriptionCookie)
+                    eventMapping.fire(.subscriptionCookieRefreshedWithAccessToken)
+                } else {
+                    try await cookieStore.setEmptySubscriptionCookie()
+                    eventMapping.fire(.subscriptionCookieRefreshedWithEmptyValue)
                 }
-            } else {
-                Logger.subscription.info("[SubscriptionCookieManager] Refresh: Cookie exists and is up to date")
-                return
-            }
-        } else {
-            if let subscriptionCookie {
-                Logger.subscription.info("[SubscriptionCookieManager] Refresh: No access token but old cookie exists, deleting it")
-                await cookieStore.deleteCookie(subscriptionCookie)
-                eventMapping.fire(.subscriptionCookieRefreshedWithDelete)
             }
+        } catch {
+            eventMapping.fire(.failedToSetSubscriptionCookie)
         }
     }
 
@@ -161,6 +176,10 @@ private extension HTTPCookieStore {
         await allCookies().first { $0.domain == SubscriptionCookieManager.cookieDomain && $0.name == SubscriptionCookieManager.cookieName }
     }
 
+    func setEmptySubscriptionCookie() async throws {
+        try await setSubscriptionCookie(for: "")
+    }
+
     func setSubscriptionCookie(for token: String) async throws {
         guard let cookie = HTTPCookie(properties: [
             .domain: SubscriptionCookieManager.cookieDomain,

Sources/Subscription/SubscriptionCookie/SubscriptionCookieManagerEvent.swift

@@ -20,10 +20,9 @@ import Foundation
 
 public enum SubscriptionCookieManagerEvent {
     case errorHandlingAccountDidSignInTokenIsMissing
-    case errorHandlingAccountDidSignOutCookieIsMissing
 
-    case subscriptionCookieRefreshedWithUpdate
-    case subscriptionCookieRefreshedWithDelete
+    case subscriptionCookieRefreshedWithAccessToken
+    case subscriptionCookieRefreshedWithEmptyValue
 
     case failedToSetSubscriptionCookie
 }

Sources/SubscriptionTestingUtilities/SubscriptionCookie/SubscriptionCookieManagerMock.swift

@@ -48,6 +48,8 @@ public final class SubscriptionCookieManagerMock: SubscriptionCookieManaging {
 
     }
 
+    public func enableSettingSubscriptionCookie() { }
+    public func disableSettingSubscriptionCookie() async { }
     public func refreshSubscriptionCookie() async { }
     public func resetLastRefreshDate() { }
 }

Tests/SubscriptionTests/SubscriptionCookie/SubscriptionCookieManagerTests.swift

@@ -76,6 +76,7 @@ final class SubscriptionCookieManagerTests: XCTestCase {
         accountManager.accessToken = Constants.accessToken
 
         // When
+        subscriptionCookieManager.enableSettingSubscriptionCookie()
         NotificationCenter.default.post(name: .accountDidSignIn, object: self, userInfo: nil)
         try await Task.sleep(seconds: 0.1)
 
@@ -88,11 +89,12 @@ final class SubscriptionCookieManagerTests: XCTestCase {
         await ensureSubscriptionCookieIsInTheCookieStore()
 
         // When
+        subscriptionCookieManager.enableSettingSubscriptionCookie()
         NotificationCenter.default.post(name: .accountDidSignOut, object: self, userInfo: nil)
         try await Task.sleep(seconds: 0.1)
 
         // Then
-        await checkSubscriptionCookieIsNotPresent()
+        await checkSubscriptionCookieIsHasEmptyValue()
     }
 
     func testRefreshWhenSignedInButCookieIsMissing() async throws {
@@ -101,6 +103,7 @@ final class SubscriptionCookieManagerTests: XCTestCase {
         await ensureNoSubscriptionCookieInTheCookieStore()
 
         // When
+        subscriptionCookieManager.enableSettingSubscriptionCookie()
         await subscriptionCookieManager.refreshSubscriptionCookie()
         try await Task.sleep(seconds: 0.1)
 
@@ -114,11 +117,12 @@ final class SubscriptionCookieManagerTests: XCTestCase {
         await ensureSubscriptionCookieIsInTheCookieStore()
 
         // When
+        subscriptionCookieManager.enableSettingSubscriptionCookie()
         await subscriptionCookieManager.refreshSubscriptionCookie()
         try await Task.sleep(seconds: 0.1)
 
         // Then
-        await checkSubscriptionCookieIsNotPresent()
+        await checkSubscriptionCookieIsHasEmptyValue()
     }
 
     func testRefreshNotTriggeredTwiceWithinSetRefreshInterval() async throws {
@@ -127,6 +131,7 @@ final class SubscriptionCookieManagerTests: XCTestCase {
         let secondRefreshDate: Date?
 
         // When
+        subscriptionCookieManager.enableSettingSubscriptionCookie()
         await subscriptionCookieManager.refreshSubscriptionCookie()
         firstRefreshDate = subscriptionCookieManager.lastRefreshDate
 
@@ -145,6 +150,7 @@ final class SubscriptionCookieManagerTests: XCTestCase {
         let secondRefreshDate: Date?
 
         // When
+        subscriptionCookieManager.enableSettingSubscriptionCookie()
         await subscriptionCookieManager.refreshSubscriptionCookie()
         firstRefreshDate = subscriptionCookieManager.lastRefreshDate
 
@@ -186,9 +192,12 @@ final class SubscriptionCookieManagerTests: XCTestCase {
         XCTAssertEqual(subscriptionCookie.value, Constants.accessToken)
     }
 
-    private func checkSubscriptionCookieIsNotPresent() async {
-        let cookie = await cookieStore.fetchSubscriptionCookie()
-        XCTAssertNil(cookie)
+    private func checkSubscriptionCookieIsHasEmptyValue() async {
+        guard let subscriptionCookie = await cookieStore.fetchSubscriptionCookie() else {
+            XCTFail("No subscription cookie in the store")
+            return
+        }
+        XCTAssertEqual(subscriptionCookie.value, "")
     }
 
 }
@@ -213,6 +222,7 @@ class MockHTTPCookieStore: HTTPCookieStore {
     }
 
     func setCookie(_ cookie: HTTPCookie) async {
+        cookies.removeAll { $0.domain == cookie.domain }
         cookies.append(cookie)
     }