add owner check - first user is owner and only owner can edit

init.lua

@@ -50,6 +50,16 @@ local function get_compass_meta_color(meta)
 end
 
 
+local function set_compass_meta_owner(meta, player_name)
+    meta:set_string("waypoint_compass:owner", player_name)
+end
+
+
+local function get_compass_meta_owner(meta)
+    return meta:get_string("waypoint_compass:owner")
+end
+
+
 -- local function set_compass_meta_pos(meta, pos)
 --     local pos_hash = minetest.hash_node_position(pos)
 --     meta:set_int("waypoint_compass:position", pos_hash)
@@ -188,6 +198,7 @@ local compass_dialog_context = {}
 
 local function show_basic_dialog(itemstack, player)
     local meta = itemstack:get_meta()
+    -- set focus to "close" button to preven accidental edting
     local formspec_head = "formspec_version[4]size[10,3]set_focus[close;]"
     local coords = coords_to_string(get_compass_meta_pos(meta))
     local field_coords = ("field[0.5,0.6;2.5,0.8;coords;Coords;%s]"):format(minetest.formspec_escape(coords))
@@ -208,6 +219,22 @@ end
 
 
 local function compass_use_callback(itemstack, user, pointed_thing)
+    if not (user and user:is_player()) then
+        return itemstack
+    end
+    local meta = itemstack:get_meta()
+    local owner = get_compass_meta_owner(meta)
+    print("owner", owner)
+    if owner == "" then
+        -- set first user as owner
+        print("set owner", user:get_player_name())
+        set_compass_meta_owner(meta, user:get_player_name())
+    elseif owner ~= user:get_player_name() then
+        -- already has owner
+        -- TODO show message "You are not the owner" (or maybe limit editing to color change?)
+        print("You are not the owner. Owner is " .. owner)
+        return itemstack
+    end
     if user:get_player_control()["sneak"] then
         if pointed_thing.type == "nothing" then
             if user and user:is_player() then
@@ -221,6 +248,7 @@ local function compass_use_callback(itemstack, user, pointed_thing)
             show_basic_dialog(itemstack, user)
         end
     end
+    return itemstack
 end
 
 
@@ -270,12 +298,10 @@ minetest.register_tool(
         wield_scale = {x = 0.5, y = 0.5, z = 0.5},
         range = 2.0, -- TODO what's the good range?
         on_place = function(itemstack, placer, pointed_thing)
-            compass_use_callback(itemstack, placer, pointed_thing)
-            return itemstack
+            return compass_use_callback(itemstack, placer, pointed_thing)
         end,
         on_secondary_use = function(itemstack, user, pointed_thing)
-            compass_use_callback(itemstack, user, pointed_thing)
-            return itemstack
+            return compass_use_callback(itemstack, user, pointed_thing)
         end,
 })