Add experimental push notification support

I added support for the experimental push notifications feature. There are many improvements to be made, so this feature is currently opt-in only. If the user does not opt-in, their device tokens will not be sent out and thus they will receive no push notifications.

We should perform more testing on real-life staging environments before fully releasing this feature.

Testing
-------

Testing was done gradually during development.

Device: iOS simulators
iOS: 17
Damus version: A few different but recent prototypes
Rough coverage:
1. Checked that no device tokens are sent out when setting is off
2. Checked that I can successfully receive device tokens when feature is ON and set to localhost.
3. Checked sending test push notifications of types "note" (kind: 1), reaction (kind: 7) and DMs (kind 4) works and shows a generic but reasonable push notification message
4. Checked that clicking on the notifications above take the user to the correct screen

Closes: https://github.com/damus-io/damus/issues/67
Changelog-Added: Add experimental push notification support
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
Signed-off-by: William Casarin <jb55@jb55.com>

damus/ContentView.swift

@@ -54,6 +54,7 @@ enum Sheets: Identifiable {
 
 struct ContentView: View {
     let keypair: Keypair
+    let appDelegate: AppDelegate?
     
     var pubkey: Pubkey {
         return keypair.pubkey
@@ -303,6 +304,7 @@ struct ContentView: View {
                 active_sheet = .onboardingSuggestions
                 hasSeenOnboardingSuggestions = true
             }
+            self.appDelegate?.settings = damus_state?.settings
         }
         .sheet(item: $active_sheet) { item in
             switch item {
@@ -694,7 +696,7 @@ struct ContentView: View {
 
 struct ContentView_Previews: PreviewProvider {
     static var previews: some View {
-        ContentView(keypair: Keypair(pubkey: test_pubkey, privkey: nil))
+        ContentView(keypair: Keypair(pubkey: test_pubkey, privkey: nil), appDelegate: nil)
     }
 }
 

damus/Models/UserSettingsStore.swift

@@ -191,6 +191,12 @@ class UserSettingsStore: ObservableObject {
     
     @Setting(key: "always_show_onboarding_suggestions", default_value: false)
     var always_show_onboarding_suggestions: Bool
+
+    @Setting(key: "enable_experimental_push_notifications", default_value: false)
+    var enable_experimental_push_notifications: Bool
+    
+    @Setting(key: "send_device_token_to_localhost", default_value: false)
+    var send_device_token_to_localhost: Bool
     
     @Setting(key: "emoji_reactions", default_value: default_emoji_reactions)
     var emoji_reactions: [String]

damus/Util/LocalNotification.swift

@@ -19,6 +19,9 @@ struct LossyLocalNotification {
     }
     
     static func from_user_info(user_info: [AnyHashable: Any]) -> LossyLocalNotification? {
+        if let encoded_nostr_event_push_data = user_info["nostr_event_info"] as? String {
+            return self.from(encoded_nostr_event_push_data: encoded_nostr_event_push_data)
+        }
         guard let id = user_info["id"] as? String,
               let target_id = MentionRef.from_bech32(str: id) else {
             return nil
@@ -28,6 +31,21 @@ struct LossyLocalNotification {
         
         return LossyLocalNotification(type: type, mention: target_id)
     }
+    
+    static func from(encoded_nostr_event_push_data: String) -> LossyLocalNotification? {
+        guard let json_data = encoded_nostr_event_push_data.data(using: .utf8),
+              let nostr_event_push_data = try? JSONDecoder().decode(NostrEventInfoFromPushNotification.self, from: json_data) else {
+            return nil
+        }
+        return self.from(nostr_event_push_data: nostr_event_push_data)
+    }
+    
+    static func from(nostr_event_push_data: NostrEventInfoFromPushNotification) -> LossyLocalNotification? {
+        guard let type = LocalNotificationType.from(nostr_kind: nostr_event_push_data.kind) else { return nil }
+        guard let note_id: NoteId = NoteId.init(hex: nostr_event_push_data.id) else { return nil }
+        let target: MentionRef = .note(note_id)
+        return LossyLocalNotification(type: type, mention: target)
+    }
 }
 
 struct LocalNotification {
@@ -48,4 +66,21 @@ enum LocalNotificationType: String {
     case repost
     case zap
     case profile_zap
+    
+    static func from(nostr_kind: NostrKind) -> Self? {
+        switch nostr_kind {
+            case .text:
+                return .mention
+            case .dm:
+                return .dm
+            case .like:
+                return .like
+            case .longform:
+                return .mention
+            case .zap:
+                return .zap
+            default:
+                return nil
+        }
+    }
 }

damus/Views/Settings/DeveloperSettingsView.swift

@@ -17,7 +17,12 @@ struct DeveloperSettingsView: View {
                 Toggle(NSLocalizedString("Developer Mode", comment: "Setting to enable developer mode"), isOn: $settings.developer_mode)
                     .toggleStyle(.switch)
                 if settings.developer_mode {
-                    Toggle(NSLocalizedString("Always show onboarding", comment: "Setting to always show onboarding suggestions, for developers who need to test onboarding"), isOn: $settings.always_show_onboarding_suggestions)
+                    Toggle("Always show onboarding", isOn: $settings.always_show_onboarding_suggestions)
+
+                    Toggle("Enable experimental push notifications", isOn: $settings.enable_experimental_push_notifications)
+                        .toggleStyle(.switch)
+
+                    Toggle("Send device token to localhost", isOn: $settings.send_device_token_to_localhost)
                         .toggleStyle(.switch)
                 }
             }

damus/damus.entitlements

@@ -13,6 +13,10 @@
 	<true/>
 	<key>com.apple.security.app-sandbox</key>
 	<true/>
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>group.com.damus</string>
+	</array>
 	<key>com.apple.security.device.audio-input</key>
 	<true/>
 	<key>com.apple.security.device.camera</key>

damus/damusApp.swift

@@ -12,7 +12,7 @@ struct damusApp: App {
     @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
     var body: some Scene {
         WindowGroup {
-            MainView()
+            MainView(appDelegate: appDelegate)
         }
     }
 }
@@ -21,11 +21,12 @@ struct MainView: View {
     @State var needs_setup = false;
     @State var keypair: Keypair? = nil;
     @StateObject private var orientationTracker = OrientationTracker()
+    var appDelegate: AppDelegate
     
     var body: some View {
         Group {
             if let kp = keypair, !needs_setup {
-                ContentView(keypair: kp)
+                ContentView(keypair: kp, appDelegate: appDelegate)
                     .environmentObject(orientationTracker)
             } else {
                 SetupView()
@@ -49,15 +50,67 @@ struct MainView: View {
         .onAppear {
             orientationTracker.setDeviceMajorAxis()
             keypair = get_saved_keypair()
+            appDelegate.keypair = keypair
         }
     }
 }
 
 class AppDelegate: NSObject, UIApplicationDelegate, UNUserNotificationCenterDelegate {
+    var keypair: Keypair? = nil
+    var settings: UserSettingsStore? = nil
+    
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
         UNUserNotificationCenter.current().delegate = self
         return true
     }
+    
+    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
+        // Return if this feature is disabled
+        guard let settings = self.settings else { return }
+        if !settings.enable_experimental_push_notifications {
+            return
+        }
+        
+        // Send the device token and pubkey to the server
+        let token = deviceToken.map { String(format: "%02.2hhx", $0) }.joined()
+        
+        print("Received device token: \(token)")
+
+        guard let pubkey = keypair?.pubkey else {
+            return
+        }
+
+        // Send those as JSON to the server
+        let json: [String: Any] = ["deviceToken": token, "pubkey": pubkey.hex()]
+
+        // create post request
+        let url = URL(string: settings.send_device_token_to_localhost ? "http://localhost:8000/user-info" : "https://notify.damus.io:8000/user-info")!
+        var request = URLRequest(url: url)
+        request.httpMethod = "POST"
+
+        // insert json data to the request
+        request.httpBody = try? JSONSerialization.data(withJSONObject: json, options: [])
+        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+
+        let task = URLSession.shared.dataTask(with: request) { data, response, error in
+            guard let data = data, error == nil else {
+                print(error?.localizedDescription ?? "No data")
+                return
+            }
+
+            if let response = response as? HTTPURLResponse, !(200...299).contains(response.statusCode) {
+                print("Unexpected status code: \(response.statusCode)")
+                return
+            }
+
+            let responseJSON = try? JSONSerialization.jsonObject(with: data, options: [])
+            if let responseJSON = responseJSON as? [String: Any] {
+                print(responseJSON)
+            }
+        }
+
+        task.resume()
+    }
 
     // Handle the notification in the foreground state
     func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {