Keep a {id: item} cache for ModelStore models

Accelerates the ModelStore ListView find() function,
which now just has to get an object key instead of looping through the
whole model.

src/gui/ModelStore.qml

@@ -13,6 +13,7 @@ QtObject {
         readonly property Component model: Component {
             ListModel {
                 property var modelId
+                property var idToItems: ({})
 
                 // Used by HFilterModel
                 signal fieldsChanged(int index, var changes)
@@ -25,10 +26,7 @@ QtObject {
                 }
 
                 function find(id, default_=null) {
-                    for (let i = 0; i < count; i++)
-                        if (get(i).id === id) return get(i)
-
-                    return default_
+                    return idToItems[id] || default_
                 }
             }
         }

src/gui/Pages/Chat/Chat.qml

@@ -12,8 +12,8 @@ Item {
     property string userId
     property string roomId
 
-    property QtObject userInfo: null
-    property QtObject roomInfo: null
+    property QtObject userInfo: ModelStore.get("accounts").find(userId)
+    property QtObject roomInfo: ModelStore.get(userId, "rooms").find(roomId)
 
     property bool ready: Boolean(userInfo && roomInfo)
     property bool longLoading: false
@@ -58,22 +58,6 @@ Item {
         )
     }
 
-    Timer {
-        interval: 100
-        running: ! userInfo
-        repeat: true
-        triggeredOnStart: true
-        onTriggered: userInfo = ModelStore.get("accounts").find(userId)
-    }
-
-    Timer {
-        interval: 100
-        running: ! roomInfo
-        repeat: true
-        triggeredOnStart: true
-        onTriggered: roomInfo = ModelStore.get(userId, "rooms").find(roomId)
-    }
-
     Timer {
         interval: 300
         running: ! ready

src/gui/PythonBridge/EventHandlers.qml

@@ -51,16 +51,19 @@ QtObject {
         py.showError(type, traceback, message)
     }
 
-    function onModelItemSet(syncId, indexThen, indexNow, changedFields){
+    function onModelItemSet(syncId, indexThen, indexNow, changedFields) {
+        const model = ModelStore.get(syncId)
+
         if (indexThen === undefined) {
             // print("insert", syncId, indexThen, indexNow,
                   // JSON.stringify(changedFields))
-            ModelStore.get(syncId).insert(indexNow, changedFields)
+            model.insert(indexNow, changedFields)
+            model.idToItems[changedFields.id] = model.get(indexNow)
+            model.idToItemsChanged()
 
         } else {
             // print("set", syncId, indexThen, indexNow,
                   // JSON.stringify(changedFields))
-            const model = ModelStore.get(syncId)
             model.set(indexThen, changedFields)
 
             if (indexThen !== indexNow) model.move(indexThen, indexNow, 1)
@@ -69,14 +72,22 @@ QtObject {
         }
     }
 
-    function onModelItemDeleted(syncId, index, count=1) {
-        // print("delete", syncId, index, count)
-        ModelStore.get(syncId).remove(index, count)
+    function onModelItemDeleted(syncId, index, count=1, ids=[]) {
+        // print("delete", syncId, index, count, ids)
+        const model = ModelStore.get(syncId)
+        model.remove(index, count)
+
+        for (let i = 0; i < ids.length; i++) {
+            delete model.idToItems[ids[i]]
+        }
+
+        if (ids.length) model.idToItemsChanged()
     }
 
     function onModelCleared(syncId) {
         // print("clear", syncId)
         ModelStore.get(syncId).clear()
+        model.idToItems = {}
     }
 
     function onDevicesUpdated(forAccount) {