Insert at on server side

internal/page/control.go

@@ -60,6 +60,14 @@ func (ctl *Control) ID() string {
 	return (*ctl)["i"].(string)
 }
 
+func (ctl *Control) At() int {
+	at, ok := (*ctl)["at"].(int)
+	if ok {
+		return at
+	}
+	return -1
+}
+
 // ParentID returns the ID of parent control.
 func (ctl *Control) ParentID() string {
 	return (*ctl)["p"].(string)
@@ -71,6 +79,11 @@ func (ctl *Control) AddChildID(childID string) {
 	(*ctl)["c"] = append(childIds, childID)
 }
 
+func (ctl *Control) InsertChildID(childID string, at int) {
+	childIds, _ := (*ctl)["c"].([]string)
+	(*ctl)["c"] = utils.InsertString(childIds, childID, at)
+}
+
 func (ctl *Control) RemoveChild(childID string) {
 	childIds, _ := (*ctl)["c"].([]string)
 	(*ctl)["c"] = utils.RemoveString(childIds, childID)

internal/page/session.go

@@ -168,6 +168,7 @@ func add(session *Session, cmd command.Command) (result string, err error) {
 
 		if parentAt != -1 {
 			batchItem.Control.SetAttr("at", parentAt)
+			topParentAt++
 		}
 
 		for k, v := range batchItem.Command.Attrs {
@@ -181,6 +182,8 @@ func add(session *Session, cmd command.Command) (result string, err error) {
 		payload.Controls = append(payload.Controls, batchItem.Control)
 	}
 
+	//log.Println("CONTROLS:", utils.ToJSON(session.Controls))
+
 	// broadcast new controls to all connected web clients
 	session.broadcastCommandToWebClients(NewMessage(AddPageControlsAction, payload))
 	return strings.Join(ids, " "), nil
@@ -352,7 +355,11 @@ func (session *Session) AddControl(ctrl *Control) error {
 		}
 
 		// update parent's childIds
-		parentctrl.AddChildID(ctrl.ID())
+		if at := ctrl.At(); at != -1 {
+			parentctrl.InsertChildID(ctrl.ID(), at)
+		} else {
+			parentctrl.AddChildID(ctrl.ID())
+		}
 	}
 
 	return nil

internal/utils/strings.go

@@ -33,6 +33,16 @@ func ContainsString(arr []string, str string) bool {
 	return false
 }
 
+// https://stackoverflow.com/questions/46128016/insert-a-value-in-a-slice-at-a-given-index
+func InsertString(arr []string, value string, index int) []string {
+	if index >= len(arr) { // nil or empty slice or after last element
+		return append(arr, value)
+	}
+	arr = append(arr[:index+1], arr[index:]...) // index < len(a)
+	arr[index] = value
+	return arr
+}
+
 func RemoveString(arr []string, str string) []string {
 	for i, v := range arr {
 		if v == str {