String trimming in a centralized manner (#1079)

* String trimming in a centralized manner

* Fix empty-nickname case

bitchat/ViewModels/Extensions/ChatViewModel+Nostr.swift

@@ -77,7 +77,7 @@ extension ChatViewModel {
         }
         
         if let nickTag = event.tags.first(where: { $0.first == "n" }), nickTag.count >= 2 {
-            let nick = nickTag[1].trimmingCharacters(in: .whitespacesAndNewlines)
+            let nick = nickTag[1].trimmed
             geoNicknames[event.pubkey.lowercased()] = nick
         }
         
@@ -115,8 +115,8 @@ extension ChatViewModel {
         }
         
         let senderName = displayNameForNostrPubkey(event.pubkey)
-        let content = event.content.trimmingCharacters(in: .whitespacesAndNewlines)
-        
+        let content = event.content.trimmed
+
         // Clamp future timestamps to now to avoid future-dated messages skewing order
         let rawTs = Date(timeIntervalSince1970: TimeInterval(event.created_at))
         let timestamp = min(rawTs, Date())
@@ -192,7 +192,7 @@ extension ChatViewModel {
         case .mesh:
             refreshVisibleMessages(from: .mesh)
             // Debug: log if any empty messages are present
-            let emptyMesh = messages.filter { $0.content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty }.count
+            let emptyMesh = messages.filter { $0.content.trimmed.isEmpty }.count
             if emptyMesh > 0 {
                 SecureLogger.debug("RenderGuard: mesh timeline contains \(emptyMesh) empty messages", category: .session)
             }
@@ -308,8 +308,7 @@ extension ChatViewModel {
         
         // Cache nickname from tag if present
         if let nickTag = event.tags.first(where: { $0.first == "n" }), nickTag.count >= 2 {
-            let nick = nickTag[1].trimmingCharacters(in: .whitespacesAndNewlines)
-            geoNicknames[event.pubkey.lowercased()] = nick
+            geoNicknames[event.pubkey.lowercased()] = nickTag[1].trimmed
         }
         
         // Store mapping for geohash DM initiation
@@ -325,8 +324,10 @@ extension ChatViewModel {
         let content = event.content
         
         // If this is a teleport presence event (no content), don't add to timeline
-        if let teleTag = event.tags.first(where: { $0.first == "t" }), teleTag.count >= 2, (teleTag[1] == "teleport"),
-           content.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
+        if let teleTag = event.tags.first(where: { $0.first == "t" }),
+           teleTag.count >= 2,
+           teleTag[1] == "teleport",
+           content.trimmed.isEmpty {
             return
         }
         
@@ -496,9 +497,8 @@ extension ChatViewModel {
         participantTracker.recordParticipant(pubkeyHex: event.pubkey, geohash: gh)
         
         // Notify only on rising-edge: previously zero people, now someone sends a chat
-        let content = event.content.trimmingCharacters(in: .whitespacesAndNewlines)
-        guard !content.isEmpty else { return }
-        
+        guard let content = event.content.trimmedOrNilIfEmpty else { return }
+
         // Respect geohash blocks
         if identityManager.isNostrBlocked(pubkeyHexLowercased: event.pubkey.lowercased()) { return }
         

bitchat/ViewModels/Extensions/ChatViewModel+PrivateChat.swift

@@ -548,13 +548,15 @@ extension ChatViewModel {
     func cleanupLocalFile(forMessage message: BitchatMessage) {
         // Check both outgoing and incoming directories for thorough cleanup
         let categories: [MimeType.Category] = [.audio, .image, .file]
-        guard let category = categories.first(where: { message.content.hasPrefix($0.messagePrefix) }) else { return }
-        let rawFilename = String(message.content.dropFirst(category.messagePrefix.count)).trimmingCharacters(in: .whitespacesAndNewlines)
-        guard !rawFilename.isEmpty, let base = try? applicationFilesDirectory() else { return }
-
-        // Security: Extract only the last path component to prevent directory traversal
-        let safeFilename = (rawFilename as NSString).lastPathComponent
-        guard !safeFilename.isEmpty && safeFilename != "." && safeFilename != ".." else { return }
+        guard let category = categories.first(where: { message.content.hasPrefix($0.messagePrefix) }),
+              let rawFilename = String(message.content.dropFirst(category.messagePrefix.count)).trimmedOrNilIfEmpty,
+              let base = try? applicationFilesDirectory(),
+              // Security: Extract only the last path component to prevent directory traversal
+              let safeFilename = (rawFilename as NSString).lastPathComponent.nilIfEmpty,
+              safeFilename != "." && safeFilename != ".."
+        else {
+            return
+        }
 
         // Try all possible locations (outgoing and incoming)
         let subdirs = categories.flatMap { ["\($0.mediaDir)/outgoing", "\($0.mediaDir)/incoming"] }