Refactor direct messages model

We can track the pubkey in the DirectMessageModel instead of having a
janky tuple.

damus/Models/DirectMessagesModel.swift

@@ -8,20 +8,43 @@
 import Foundation
 
 class DirectMessagesModel: ObservableObject {
-    @Published var dms: [(String, DirectMessageModel)] = []
+    @Published var dms: [DirectMessageModel] = []
     @Published var loading: Bool = false
+    @Published var open_dm: Bool = false
+    @Published private(set) var active_model: DirectMessageModel = DirectMessageModel(our_pubkey: "", pubkey: "")
     let our_pubkey: String
     
     init(our_pubkey: String) {
         self.our_pubkey = our_pubkey
     }
     
-    var message_requests: [(String, DirectMessageModel)] {
-        return dms.filter { dm in dm.1.is_request }
+    var message_requests: [DirectMessageModel] {
+        return dms.filter { dm in dm.is_request }
     }
     
-    var friend_dms: [(String, DirectMessageModel)] {
-        return dms.filter { dm in !dm.1.is_request }
+    var friend_dms: [DirectMessageModel] {
+        return dms.filter { dm in !dm.is_request }
+    }
+
+    func set_active_dm_model(_ model: DirectMessageModel) {
+        self.active_model = model
+    }
+    
+    func open_dm_by_pk(_ pubkey: String) {
+        self.set_active_dm(pubkey)
+        self.open_dm = true
+    }
+    
+    func open_dm_by_model(_ model: DirectMessageModel) {
+        self.set_active_dm_model(model)
+        self.open_dm = true
+    }
+    
+    func set_active_dm(_ pubkey: String) {
+        for model in self.dms where model.pubkey == pubkey {
+            self.set_active_dm_model(model)
+            break
+        }
     }
     
     func lookup_or_create(_ pubkey: String) -> DirectMessageModel {
@@ -29,15 +52,15 @@ class DirectMessagesModel: ObservableObject {
             return dm
         }
         
-        let new = DirectMessageModel(our_pubkey: our_pubkey)
-        dms.append((pubkey, new))
+        let new = DirectMessageModel(our_pubkey: our_pubkey, pubkey: pubkey)
+        dms.append(new)
         return new
     }
     
     func lookup(_ pubkey: String) -> DirectMessageModel? {
         for dm in dms {
-            if pubkey == dm.0 {
-                return dm.1
+            if pubkey == dm.pubkey {
+                return dm
             }
         }