damus

NotificationsManager.swift (8967B)

---

 //
 //  NotificationsManager.swift
 //  damus
 //
 //  Handles several aspects of notification logic (Both local and push notifications)
 //
 //  Created by Daniel D’Aquino on 2023-11-24.
 //
 
 import Foundation
 import UIKit
 
 let EVENT_MAX_AGE_FOR_NOTIFICATION: TimeInterval = 12 * 60 * 60
 
 func process_local_notification(state: HeadlessDamusState, event ev: NostrEvent) {
     guard should_display_notification(state: state, event: ev) else {
         // We should not display notification. Exit.
         return
     }
 
     guard let local_notification = generate_local_notification_object(from: ev, state: state) else {
         return
     }
 
     create_local_notification(profiles: state.profiles, notify: local_notification)
 }
 
 func should_display_notification(state: HeadlessDamusState, event ev: NostrEvent) -> Bool {
     if ev.known_kind == nil {
         return false
     }
 
     if state.settings.notification_only_from_following,
        state.contacts.follow_state(ev.pubkey) != .follows
         {
         return false
     }
 
     // Don't show notifications that match mute list.
     if state.mutelist_manager.is_event_muted(ev) {
         return false
     }
 
     // Don't show notifications for old events
     guard ev.age < EVENT_MAX_AGE_FOR_NOTIFICATION else {
         return false
     }
     
     return true
 }
 
 func generate_local_notification_object(from ev: NostrEvent, state: HeadlessDamusState) -> LocalNotification? {
     guard let type = ev.known_kind else {
         return nil
     }
     
     if type == .text, state.settings.mention_notification {
         let blocks = ev.blocks(state.keypair).blocks
         for case .mention(let mention) in blocks {
             guard case .pubkey(let pk) = mention.ref, pk == state.keypair.pubkey else {
                 continue
             }
             let content_preview = render_notification_content_preview(ev: ev, profiles: state.profiles, keypair: state.keypair)
             return LocalNotification(type: .mention, event: ev, target: ev, content: content_preview)
         }
     } else if type == .boost,
               state.settings.repost_notification,
               let inner_ev = ev.get_inner_event()
     {
         let content_preview = render_notification_content_preview(ev: inner_ev, profiles: state.profiles, keypair: state.keypair)
         return LocalNotification(type: .repost, event: ev, target: inner_ev, content: content_preview)
     } else if type == .like,
               state.settings.like_notification,
               let evid = ev.referenced_ids.last,
               let txn = state.ndb.lookup_note(evid, txn_name: "local_notification_like"),
               let liked_event = txn.unsafeUnownedValue?.to_owned()
     {
         let content_preview = render_notification_content_preview(ev: liked_event, profiles: state.profiles, keypair: state.keypair)
         return LocalNotification(type: .like, event: ev, target: liked_event, content: content_preview)
     }
     else if type == .dm,
             state.settings.dm_notification {
         let convo = ev.decrypted(keypair: state.keypair) ?? NSLocalizedString("New encrypted direct message", comment: "Notification that the user has received a new direct message")
         return LocalNotification(type: .dm, event: ev, target: ev, content: convo)
     }
     else if type == .zap,
             state.settings.zap_notification {
         return LocalNotification(type: .zap, event: ev, target: ev, content: ev.content)
     }
     
     return nil
 }
 
 func create_local_notification(profiles: Profiles, notify: LocalNotification) {
     let displayName = event_author_name(profiles: profiles, pubkey: notify.event.pubkey)
     
     guard let (content, identifier) = NotificationFormatter.shared.format_message(displayName: displayName, notify: notify) else { return }
 
     let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 1, repeats: false)
 
     let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)
 
     UNUserNotificationCenter.current().add(request) { error in
         if let error = error {
             print("Error: \(error)")
         } else {
             print("Local notification scheduled")
         }
     }
 }
 
 func render_notification_content_preview(ev: NostrEvent, profiles: Profiles, keypair: Keypair) -> String {
 
     let prefix_len = 300
     let artifacts = render_note_content(ev: ev, profiles: profiles, keypair: keypair)
 
     // special case for longform events
     if ev.known_kind == .longform {
         let longform = LongformEvent(event: ev)
         return longform.title ?? longform.summary ?? "Longform Event"
     }
     
     switch artifacts {
     case .longform:
         // we should never hit this until we have more note types built out of parts
         // since we handle this case above in known_kind == .longform
         return String(ev.content.prefix(prefix_len))
         
     case .separated(let artifacts):
         return String(NSAttributedString(artifacts.content.attributed).string.prefix(prefix_len))
     }
 }
 
 func event_author_name(profiles: Profiles, pubkey: Pubkey) -> String {
     let profile_txn = profiles.lookup(id: pubkey)
     let profile = profile_txn?.unsafeUnownedValue
     return Profile.displayName(profile: profile, pubkey: pubkey).username.truncate(maxLength: 50)
 }
 
 @MainActor
 func get_zap(from ev: NostrEvent, state: HeadlessDamusState) async -> Zap? {
     return await withCheckedContinuation { continuation in
         process_zap_event(state: state, ev: ev) { zapres in
             continuation.resume(returning: zapres.get_zap())
         }
     }
 }
 
 @MainActor
 func process_zap_event(state: HeadlessDamusState, ev: NostrEvent, completion: @escaping (ProcessZapResult) -> Void) {
     // These are zap notifications
     guard let ptag = get_zap_target_pubkey(ev: ev, ndb: state.ndb) else {
         completion(.failed)
         return
     }
 
     // just return the zap if we already have it
     if let zap = state.zaps.zaps[ev.id], case .zap(let z) = zap {
         completion(.already_processed(z))
         return
     }
     
     if let local_zapper = state.profiles.lookup_zapper(pubkey: ptag) {
         guard let zap = process_zap_event_with_zapper(state: state, ev: ev, zapper: local_zapper) else {
             completion(.failed)
             return
         }
         state.add_zap(zap: .zap(zap))
         completion(.done(zap))
         return
     }
     
     guard let txn = state.profiles.lookup_with_timestamp(ptag),
           let lnurl = txn.map({ pr in pr?.lnurl }).value else {
         completion(.failed)
         return
     }
 
     Task { [lnurl] in
         guard let zapper = await fetch_zapper_from_lnurl(lnurls: state.lnurls, pubkey: ptag, lnurl: lnurl) else {
             completion(.failed)
             return
         }
         
         DispatchQueue.main.async {
             state.profiles.profile_data(ptag).zapper = zapper
             guard let zap = process_zap_event_with_zapper(state: state, ev: ev, zapper: zapper) else {
                 completion(.failed)
                 return
             }
             state.add_zap(zap: .zap(zap))
             completion(.done(zap))
         }
     }
 }
 
 // securely get the zap target's pubkey. this can be faked so we need to be
 // careful
 func get_zap_target_pubkey(ev: NostrEvent, ndb: Ndb) -> Pubkey? {
     let etags = Array(ev.referenced_ids)
 
     guard let etag = etags.first else {
         // no etags, ptag-only case
 
         guard let a = ev.referenced_pubkeys.just_one() else {
             return nil
         }
 
         // TODO: just return data here
         return a
     }
 
     // we have an e-tag
 
     // ensure that there is only 1 etag to stop fake note zap attacks
     guard etags.count == 1 else {
         return nil
     }
 
     // we can't trust the p tag on note zaps because they can be faked
     guard let txn = ndb.lookup_note(etag),
           let pk = txn.unsafeUnownedValue?.pubkey else {
         // We don't have the event in cache so we can't check the pubkey.
 
         // We could return this as an invalid zap but that wouldn't be correct
         // all of the time, and may reject valid zaps. What we need is a new
         // unvalidated zap state, but for now we simply leak a bit of correctness...
 
         return ev.referenced_pubkeys.just_one()
     }
 
     return pk
 }
 
 fileprivate func process_zap_event_with_zapper(state: HeadlessDamusState, ev: NostrEvent, zapper: Pubkey) -> Zap? {
     let our_keypair = state.keypair
     
     guard let zap = Zap.from_zap_event(zap_ev: ev, zapper: zapper, our_privkey: our_keypair.privkey) else {
         return nil
     }
     
     state.add_zap(zap: .zap(zap))
     
     return zap
 }
 
 enum ProcessZapResult {
     case already_processed(Zap)
     case done(Zap)
     case failed
     
     func get_zap() -> Zap? {
         switch self {
             case .already_processed(let zap):
                 return zap
             case .done(let zap):
                 return zap
             default:
                 return nil
         }
     }
 }