Add reply counts

Changelog-Added: Reply counts

damus/Util/ReplyCounter.swift

@@ -0,0 +1,54 @@
+//
+//  ReplyCounter.swift
+//  damus
+//
+//  Created by William Casarin on 2023-04-04.
+//
+
+import Foundation
+
+class ReplyCounter {
+    private var replies: [String: Int]
+    private var counted: Set<String>
+    private var our_replies: [String: NostrEvent]
+    private let our_pubkey: String
+    
+    init(our_pubkey: String) {
+        self.our_pubkey = our_pubkey
+        replies = [:]
+        counted = Set()
+        our_replies = [:]
+    }
+    
+    func our_reply(_ evid: String) -> NostrEvent? {
+        return our_replies[evid]
+    }
+    
+    func get_replies(_ evid: String) -> Int {
+        return replies[evid] ?? 0
+    }
+    
+    func count_replies(_ event: NostrEvent) {
+        guard event.is_textlike else {
+            return
+        }
+        
+        if counted.contains(event.id) {
+            return
+        }
+        
+        counted.insert(event.id)
+        
+        for reply in event.direct_replies(nil) {
+            if event.pubkey == our_pubkey {
+                self.our_replies[reply.ref_id] = event
+            }
+            
+            if replies[reply.ref_id] != nil {
+                replies[reply.ref_id] = replies[reply.ref_id]! + 1
+            } else {
+                replies[reply.ref_id] = 1
+            }
+        }
+    }
+}