add ability to check the freshness of a PersistedProfile

damus/Nostr/ProfileDatabase.swift

@@ -66,7 +66,7 @@ final class ProfileDatabase {
         background_context?.mergePolicy = NSMergePolicy(merge: .mergeByPropertyObjectTrumpMergePolicyType)
     }
     
-    private func get_persisted(id: String) -> PersistedProfile? {
+    func get_persisted(id: String) -> PersistedProfile? {
         let request = NSFetchRequest<PersistedProfile>(entityName: entity_name)
         request.predicate = NSPredicate(format: "id == %@", id)
         request.fetchLimit = 1

damus/Nostr/Profiles.swift

@@ -9,6 +9,8 @@ import Foundation
 
 class Profiles {
     
+    static let db_freshness_threshold: TimeInterval = 24 * 60 * 60
+    
     /// This queue is used to synchronize access to the profiles dictionary, which
     /// prevents data races from crashing the app.
     private var queue = DispatchQueue(label: "io.damus.profiles",
@@ -55,4 +57,22 @@ class Profiles {
             return profiles[id]
         }
     }
+    
+    func has_fresh_profile(id: String) -> Bool {
+        // check memory first
+        var profile: Profile?
+        queue.sync {
+            profile = profiles[id]?.profile
+        }
+        if profile != nil {
+            return true
+        }
+        
+        // then disk
+        guard let persisted_profile = database.get_persisted(id: id),
+              let pull_date = persisted_profile.network_pull_date else {
+            return false
+        }
+        return Date.now.timeIntervalSince(pull_date) < Profiles.db_freshness_threshold
+    }
 }