Forbid track modification when train, IP or TCB is on it, better handle removing of TCBs (H#149)

advtrains/locale/advtrains.de.tr

@@ -64,3 +64,8 @@ Passenger Wagon=Passagierwaggon
 Box wagon=Güterwaggon
 Subway Passenger Wagon=U-Bahn-Waggon
 The wagon's inventory is not empty!=Das Inventar dieses Waggons ist nicht leer!
+This track can not be changed!=Diese Schiene kann nicht geändert werden!
+This track can not be rotated!=Diese Schiene kann nicht gedreht werden!
+Position is occupied by a train.=Ein Zug steht an dieser Position.
+There's a Track Circuit Break here.=Hier ist eine Gleisabschnittsgrenze (TCB).
+There's a Signal Influence Point here.=Hier ist ein Signal-Beeinflussungspunkt.

advtrains/trackplacer.lua

@@ -120,6 +120,11 @@ function tp.rail_and_can_be_bent(originpos, conn)
 			return advtrains.conn_matches_to(conn, cconns)
 		end
 	end
+	-- If the rail is not allowed to be modified, also only use if already in desired direction
+	if not advtrains.can_dig_or_modify_track(pos) then
+		local cconns=advtrains.get_track_connections(node.name, node.param2)
+		return advtrains.conn_matches_to(conn, cconns)
+	end
 	--rail at other end?
 	local adj1, adj2=tp.find_already_connected(pos)
 	if adj1 and adj2 then
@@ -326,14 +331,6 @@ minetest.register_craftitem("advtrains:trackworker",{
 				local node=minetest.get_node(pos)
 
 				--if not advtrains.is_track_and_drives_on(minetest.get_node(pos).name, advtrains.all_tracktypes) then return end
-				if advtrains.get_train_at_pos(pos) then return end
-				
-				if has_aux1_down then
-					--feature: flip the node by 180°
-					--i've always wanted this!
-					advtrains.ndb.swap_node(pos, {name=node.name, param2=(node.param2+2)%4})
-					return
-				end
 				
 				local nnprefix, suffix, rotation=string.match(node.name, "^(.+)_([^_]+)(_[^_]+)$")
 				--atdebug(node.name.."\npattern recognizes:"..nnprefix.." / "..suffix.." / "..rotation)
@@ -346,6 +343,28 @@ minetest.register_craftitem("advtrains:trackworker",{
 						return
 					end
 				end
+				
+				-- check if the node is modify-protected
+				if advtrains.is_track_and_drives_on(minetest.get_node(pos).name, advtrains.all_tracktypes) then
+					-- is a track, we can query
+					local can_modify, reason = advtrains.can_dig_or_modify_track(pos)
+					if not can_modify then
+						local str = attrans("This track can not be rotated!")
+						if reason then
+							str = str .. " " .. reason
+						end
+						minetest.chat_send_player(placer:get_player_name(), str)
+						return
+					end
+				end
+				
+				if has_aux1_down then
+					--feature: flip the node by 180°
+					--i've always wanted this!
+					advtrains.ndb.swap_node(pos, {name=node.name, param2=(node.param2+2)%4})
+					return
+				end
+				
 				local modext=tp.tracks[nnprefix].twrotate[suffix]
 
 				if rotation==modext[#modext] then --increase param2
@@ -390,6 +409,21 @@ minetest.register_craftitem("advtrains:trackworker",{
 					return
 				  end
 				end
+				
+				-- check if the node is modify-protected
+				if advtrains.is_track_and_drives_on(minetest.get_node(pos).name, advtrains.all_tracktypes) then
+					-- is a track, we can query
+					local can_modify, reason = advtrains.can_dig_or_modify_track(pos)
+					if not can_modify then
+						local str = attrans("This track can not be changed!")
+						if reason then
+							str = str .. " " .. reason
+						end
+						minetest.chat_send_player(user:get_player_name(), str)
+						return
+					end
+				end
+				
 				local nextsuffix=tp.tracks[nnprefix].twcycle[suffix]
 				advtrains.ndb.swap_node(pos, {name=nnprefix.."_"..nextsuffix..rotation, param2=node.param2})
 				

advtrains/tracks.lua

@@ -478,9 +478,7 @@ function advtrains.register_tracks(tracktype, def, preset)
 						not_blocking_trains=1,
 					},
 						
-					can_dig=function(pos)
-						return not advtrains.get_train_at_pos(pos)
-					end,
+					can_dig = advtrains.can_dig_or_modify_track,
 					after_dig_node=function(pos)
 						advtrains.ndb.update(pos)
 					end,
@@ -602,6 +600,26 @@ function advtrains.get_track_connections(name, param2)
 	return advtrains.rotate_conn_by(nodedef.at_conns, noderot*AT_CMAX/4), (nodedef.at_rail_y or 0), tracktype
 end
 
+-- Function called when a track is about to be dug or modified by the trackworker
+-- Returns either true (ok) or false,"translated string describing reason why it isn't allowed"
+function advtrains.can_dig_or_modify_track(pos)
+	if advtrains.get_train_at_pos(pos) then
+		return false, attrans("Position is occupied by a train.")
+	end
+	-- interlocking: tcb, signal IP a.s.o.
+	if advtrains.interlocking then
+		-- TCB?
+		if advtrains.interlocking.db.get_tcb(pos) then
+			return false, attrans("There's a Track Circuit Break here.")
+		end
+		-- signal ip?
+		if advtrains.interlocking.db.is_ip_at(pos) then
+			return false, attrans("There's a Signal Influence Point here.")
+		end
+	end
+	return true
+end
+
 -- slope placer. Defined in register_tracks.
 --crafted with rail and gravel
 local sl={}

advtrains_interlocking/database.lua

@@ -526,6 +526,14 @@ function ildb.set_sigd_for_signal(pos, sigd)
 	signal_assignments[pts] = sigd
 end
 
+-- checks if there's any influence point set to this position
+function ildb.is_ip_at(pos)
+	local pts = advtrains.roundfloorpts(pos)
+	if influence_points[pts] then
+		return true
+	end
+	return false
+end
 
 -- checks if a signal is influencing here
 function ildb.get_ip_signal(pts, connid)

advtrains_interlocking/tcb_ts_ui.lua

@@ -49,12 +49,13 @@ minetest.register_node("advtrains_interlocking:tcb_node", {
 		local tcbpts = meta:get_string("tcb_pos")
 		if tcbpts ~= "" then
 			local tcbpos = minetest.string_to_pos(tcbpts)
+			local tcb = ildb.get_tcb(tcbpos)
+			if tcb then
 				advtrains.interlocking.show_tcb_form(tcbpos, pname)
 			else
-			if not minetest.check_player_privs(pname, "interlocking") then
-				minetest.chat_send_player(pname, "Insufficient privileges to use this!")
-				return
+				minetest.chat_send_player(pname, "This TCB has been removed. Please dig marker.")
 			end
+		else
 			--unconfigured
 			minetest.chat_send_player(pname, "Configuring TCB: Please punch the rail you want to assign this TCB to.")
 			
@@ -88,6 +89,11 @@ minetest.register_node("advtrains_interlocking:tcb_node", {
 			if not tcb then return true end
 			for connid=1,2 do
 				if tcb[connid].ts_id or tcb[connid].signal then
+					minetest.chat_send_player(pname, "Can't remove TCB: Both sides must have no track section and no signal assigned!")
+					return false
+				end
+				if not ildb.may_modify_tcbs(tcb[connid]) then
+					minetest.chat_send_player(pname, "Can't remove TCB: Side "..connid.." forbids modification (shouldn't happen).")
 					return false
 				end
 			end
@@ -99,7 +105,15 @@ minetest.register_node("advtrains_interlocking:tcb_node", {
 		local tcbpts = oldmetadata.fields.tcb_pos
 		if tcbpts and tcbpts ~= "" then
 			local tcbpos = minetest.string_to_pos(tcbpts)
-			ildb.remove_tcb(tcbpos)
+			local success = ildb.remove_tcb(tcbpos)
+			if success and player then
+				minetest.chat_send_player(player:get_player_name(), "TCB has been removed.")
+			else
+				minetest.chat_send_player(player:get_player_name(), "Failed to remove TCB!")
+				minetest.set_node(pos, oldnode)
+				local meta = minetest.get_meta(pos)
+				meta:set_string("tcb_pos", minetest.pos_to_string(tcbpos))
+			end
 		end
 	end,
 })
@@ -118,7 +132,7 @@ minetest.register_on_punchnode(function(pos, node, player, pointed_thing)
 				local ok = ildb.create_tcb(pos)
 				
 				if not ok then
-					minetest.chat_send_player(pname, "Configuring TCB: TCB already exists at this position. Aborted.")
+					minetest.chat_send_player(pname, "Configuring TCB: TCB already exists at this position! It has now been re-assigned.")
 				end
 				
 				ildb.sync_tcb_neighbors(pos, 1)