Deprecate old 4590 crossings

This is done with a task that runs once when the nodedb is loaded. A new
field of advtrains_ndb will keep a version integer to indicate migration
versions. This introduces verson 1, no version being equivalent to 0.
An LBM is also registered to replace the tracks in the world.

advtrains/nodedb.lua

@@ -30,6 +30,7 @@ local ndb={}
 --local variables for performance
 local ndb_nodeids={}
 local ndb_nodes={}
+local ndb_ver
 
 local function ndbget(x,y,z)
 	local ny=ndb_nodes[y]
@@ -57,6 +58,16 @@ local path=minetest.get_worldpath()..DIR_DELIM.."advtrains_ndb2"
 --nodeids get loaded by advtrains init.lua and passed here
 function ndb.load_data(data)
 	ndb_nodeids = data and data.nodeids or {}
+	ndb_ver = data and data.ver or 0
+	if ndb_ver < 1 then
+		for k,v in pairs(ndb_nodeids) do
+			if v == "advtrains:dtrack_xing4590_st" then
+				cidDepr = k
+			elseif v == "advtrains:dtrack_xing90plusx_45l" then
+				cidNew = k
+			end
+		end
+	end
 	local file, err = io.open(path, "rb")
 	if not file then
 		atwarn("Couldn't load the node database: ", err or "Unknown Error")
@@ -67,6 +78,9 @@ function ndb.load_data(data)
 		local hst_x=file:read(2)
 		local cid=file:read(2)
 		while hst_z and hst_y and hst_x and cid and #hst_z==2 and #hst_y==2 and #hst_x==2 and #cid==2 do
+			if (ndb_ver < 1 and cid == cidDepr) then
+				cid = cidNew
+			end
 			ndbset(bytes_to_int(hst_x), bytes_to_int(hst_y), bytes_to_int(hst_z), bytes_to_int(cid))
 			cnt=cnt+1
 			hst_z=file:read(2)
@@ -77,6 +91,7 @@ function ndb.load_data(data)
 		atlog("nodedb: read", cnt, "nodes.")
 		file:close()
 	end
+	ndb_ver = 1
 end
 
 --save
@@ -99,7 +114,7 @@ function ndb.save_data()
 		file:close()
 	end
 	os.rename(tmppath, path)
-	return {nodeids = ndb_nodeids}
+	return {nodeids = ndb_nodeids, ver = ndb_ver}
 end
 
 --function to get node. track database is not helpful here.

advtrains_train_track/init.lua

@@ -62,6 +62,25 @@ minetest.register_craft({
 		{'', '', 'advtrains:dtrack_placer'}
 	}
 })
+-- Deprecate any rails using the old name scheme
+minetest.register_lbm({
+	label = "Upgrade legacy 4590 rails",
+	name = "advtrains_train_track:replace_legacy_4590",
+	nodenames = {"advtrains:dtrack_xing4590_st"},
+	run_at_every_load = true,
+	action = function(pos, node)
+		minetest.log("actionPos!: " .. pos.x .. "," .. pos.y .. "," .. pos.z)
+		minetest.log("node!: " .. node.name .. "," .. node.param1 .. "," .. node.param2)
+		advtrains.ndb.swap_node(pos,
+		{
+			name="advtrains:dtrack_xing90plusx_45l",
+			param1=node.param1,
+			param2=node.param2,
+		})
+	end
+})
+-- This will replace any items left in the inventory
+minetest.register_alias("advtrains:dtrack_xing4590_placer", "advtrains:dtrack_xing90plusx_placer")
 
 -- Diagonal
 -- This set of rail crossings is named based on the angle of each intersecting