Prohibit removing/changing of TCBs and sections while routes or signals are set

4 files changed, 101 insertions, 40 deletions

diff --git a/advtrains_interlocking/database.lua b/advtrains_interlocking/database.lua
index 12853c0..af20bea 100644
--- a/advtrains_interlocking/database.lua
+++ b/advtrains_interlocking/database.lua
@@ -304,6 +304,9 @@ local function merge_ts(root_id, merge_id)
 	if not mts then return end -- This may be the case when sync_tcb_neighbors
 	-- inserts the same id twice. do nothing.
 	
+	if not ildb.may_modify_ts(rts) then return false end
+	if not ildb.may_modify_ts(mts) then return false end
+	
 	-- cobble together the list of TCBs
 	for _, msigd in ipairs(mts.tc_breaks) do
 		local tcbs = ildb.get_tcbs(msigd)
@@ -384,12 +387,14 @@ end
 
 function ildb.remove_from_interlocking(sigd)
 	local tcbs = ildb.get_tcbs(sigd)
+	if not ildb.may_modify_tcbs(tcbs) then return false end
+	
 	if tcbs.ts_id then
 		local tsid = tcbs.ts_id
 		local ts = ildb.get_ts(tsid)
 		if not ts then
 			tcbs.ts_id = nil
-			return
+			return true
 		end
 		
 		-- remove entry from the list
@@ -411,24 +416,54 @@ function ildb.remove_from_interlocking(sigd)
 		end
 	end
 	advtrains.interlocking.show_tcb_marker(sigd.p)
+	return true
 end
 
 function ildb.remove_tcb(pos)
 	local pts = advtrains.roundfloorpts(pos)
 	if not track_circuit_breaks[pts] then return end
 	for connid=1,2 do
-		ildb.remove_from_interlocking({p=pos, s=connid})
+		if not ildb.remove_from_interlocking({p=pos, s=connid}) then
+			return false
+		end
 	end
 	track_circuit_breaks[pts] = nil
+	return true
 end
 
 function ildb.dissolve_ts(ts_id)
 	local ts = ildb.get_ts(ts_id)
+	if not ildb.may_modify_ts(ts) then return false end
 	local tcbr = advtrains.merge_tables(ts.tc_breaks)
 	for _,sigd in ipairs(tcbr) do
 		ildb.remove_from_interlocking(sigd)
 	end
 	-- Note: ts gets removed in the moment of the removal of the last TCB.
+	return true
+end
+
+-- Returns true if it is allowed to modify any property of a track section, such as
+-- - removing TCBs
+-- - merging and dissolving sections
+-- As of now the action will be denied if a route is set or if a train is in the section.
+function ildb.may_modify_ts(ts)
+	if ts.route or ts.route_post or #ts.trains>0 then
+		return false
+	end
+	return true
+end
+
+
+function ildb.may_modify_tcbs(tcbs)
+	if tcbs.signal then
+		return false
+	elseif tcbs.ts_id then
+		local ts = ildb.get_ts(tcbs.ts_id)
+		if ts and not ildb.may_modify_ts(ts) then
+			return false
+		end
+	end
+	return true
 end
 
 -- Utilize the traverser to find the track section at the specified position
diff --git a/advtrains_interlocking/route_ui.lua b/advtrains_interlocking/route_ui.lua
index 9c1f794..d615841 100644
--- a/advtrains_interlocking/route_ui.lua
+++ b/advtrains_interlocking/route_ui.lua
@@ -130,7 +130,7 @@ function atil.show_route_edit_form(pname, sigd, routeid)
 	form = form.."button[3.5,6;2,1;aspect;Signal Aspect]"
 	form = form.."button[5.5,6;2,1;delete;Delete Route]"
 	
-	atdebug(route.ars)
+	--atdebug(route.ars)
 	form = form.."textarea[1,7.3;5.2,3;ars;ARS Rule List;"..ars_to_text(route.ars).."]"
 	form = form.."button[6,7.7;1,1;savears;Save]"
 	
diff --git a/advtrains_interlocking/routesetting.lua b/advtrains_interlocking/routesetting.lua
index 7b08c4e..44f4592 100644
--- a/advtrains_interlocking/routesetting.lua
+++ b/advtrains_interlocking/routesetting.lua
@@ -226,14 +226,22 @@ function ilrs.cancel_route_from(sigd)
 	while c_sigd do
 		--atdebug("cancel_route_from: at sigd",c_sigd)
 		c_tcbs = ildb.get_tcbs(c_sigd)
+		if not c_tcbs then
+			atwarn("Failed to cancel route, no TCBS at",c_sigd)
+			return false
+		end
 		c_ts_id = c_tcbs.ts_id
+		if not c_tcbs then
+			atwarn("Failed to cancel route, end of interlocking at",c_sigd)
+			return false
+		end
 		c_ts = ildb.get_ts(c_ts_id)
 		
 		if not c_ts
 			or not c_ts.route
 			or not sigd_equal(c_ts.route.entry, c_sigd) then
 			--atdebug("cancel_route_from: abort (eoi/no route):")
-			return
+			return false
 		end
 		
 		--atdebug("cancelling",c_ts.route.rsn)
@@ -258,6 +266,7 @@ function ilrs.cancel_route_from(sigd)
 		minetest.after(0, advtrains.interlocking.route.update_waiting, "ts", c_ts_id)
 	end
 	--atdebug("cancel_route_from: done (no final sigd)")
+	return true
 end
 
 -- TCBS Routesetting helper: generic update function for
diff --git a/advtrains_interlocking/tcb_ts_ui.lua b/advtrains_interlocking/tcb_ts_ui.lua
index 91c2697..a81b12a 100644
--- a/advtrains_interlocking/tcb_ts_ui.lua
+++ b/advtrains_interlocking/tcb_ts_ui.lua
@@ -182,8 +182,11 @@ local function mktcbformspec(tcbs, btnpref, offset, pname)
 	if ts then
 		form = form.."label[0.5,"..offset..";Side "..btnpref..": "..ts.name.."]"
 		form = form.."button[0.5,"..(offset+0.5)..";5,1;"..btnpref.."_gotots;Show track section]"
-		form = form.."button[0.5,"..(offset+1.5)..";2.5,1;"..btnpref.."_update;Update near TCBs]"
-		form = form.."button[3  ,"..(offset+1.5)..";2.5,1;"..btnpref.."_remove;Remove from section]"
+		if ildb.may_modify_tcbs(tcbs) then
+			-- Note: the security check to prohibit those actions is located in database.lua in the corresponding functions.
+			form = form.."button[0.5,"..(offset+1.5)..";2.5,1;"..btnpref.."_update;Update near TCBs]"
+			form = form.."button[3  ,"..(offset+1.5)..";2.5,1;"..btnpref.."_remove;Remove from section]"
+		end
 	else
 		tcbs.ts_id = nil
 		form = form.."label[0.5,"..offset..";Side "..btnpref..": ".."End of interlocking]"
@@ -323,22 +326,30 @@ function advtrains.interlocking.show_ts_form(ts_id, pname, sel_tcb)
 	end
 	
 	form = form.."textlist[0.5,3;5,3;tcblist;"..table.concat(strtab, ",").."]"
-	if players_link_ts[pname] then
-		local other_id = players_link_ts[pname]
-		local other_ts = ildb.get_ts(other_id)
-		if other_ts then
-			form = form.."button[5.5,3;3.5,1;mklink;Join with "..other_ts.name.."]"
-			form = form.."button[9  ,3;0.5,1;cancellink;X]"
+	
+	if ildb.may_modify_ts(ts) then
+		
+		if players_link_ts[pname] then
+			local other_id = players_link_ts[pname]
+			local other_ts = ildb.get_ts(other_id)
+			if other_ts then
+				if ildb.may_modify_ts(other_ts) then
+					form = form.."button[5.5,3;3.5,1;mklink;Join with "..other_ts.name.."]"
+					form = form.."button[9  ,3;0.5,1;cancellink;X]"
+				end
+			end
+		else
+			form = form.."button[5.5,3;4,1;link;Join into other section]"
+			hint = 1
+		end
+		form = form.."button[5.5,4;4,1;dissolve;Dissolve Section]"
+		form = form.."tooltip[dissolve;This will remove the track section and set all its end points to End Of Interlocking]"
+		if sel_tcb then
+			form = form.."button[5.5,5;4,1;del_tcb;Unlink selected TCB]"
+			hint = 2
 		end
 	else
-		form = form.."button[5.5,3;4,1;link;Join into other section]"
-		hint = 1
-	end
-	form = form.."button[5.5,4;4,1;dissolve;Dissolve Section]"
-	form = form.."tooltip[dissolve;This will remove the track section and set all its end points to End Of Interlocking]"
-	if sel_tcb then
-		form = form.."button[5.5,5;4,1;del_tcb;Unlink selected TCB]"
-		hint = 2
+		hint=3
 	end
 	
 	if ts.route then
@@ -360,6 +371,8 @@ function advtrains.interlocking.show_ts_form(ts_id, pname, sel_tcb)
 		form = form.."label[0.5,0.75;Use the 'Join' button to designate rail crosses and link not listed far-away TCBs]"
 	elseif hint == 2 then
 		form = form.."label[0.5,0.75;Unlinking a TCB will set it to non-interlocked mode.]"
+	elseif hint == 3 then
+		form = form.."label[0.5,0.75;You cannot modify track sections when a route is set or a train is on the section.]"
 		--form = form.."label[0.5,1;Trying to unlink a TCB directly connected to this track will not work.]"
 	end
 	
@@ -392,27 +405,31 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 			sel_tcb = tpsi
 		end
 		
-		if players_link_ts[pname] then
-			if fields.cancellink then
-				players_link_ts[pname] = nil
-			elseif fields.mklink then
-				ildb.link_track_sections(players_link_ts[pname], ts_id)
-				players_link_ts[pname] = nil
+		if ildb.may_modify_ts(ts) then
+			if players_link_ts[pname] then
+				if fields.cancellink then
+					players_link_ts[pname] = nil
+				elseif fields.mklink then
+					ildb.link_track_sections(players_link_ts[pname], ts_id)
+					players_link_ts[pname] = nil
+				end
+			end
+			
+			if fields.del_tcb and sel_tcb and sel_tcb > 0 and sel_tcb <= #ts.tc_breaks then
+				if not ildb.remove_from_interlocking(ts.tc_breaks[sel_tcb]) then
+					minetest.chat_send_player(pname, "Please unassign signal first!")
+				end
+				sel_tcb = nil
+			end
+			
+			if fields.link then
+				players_link_ts[pname] = ts_id
+			end
+			if fields.dissolve then
+				ildb.dissolve_ts(ts_id)
+				minetest.close_formspec(pname, formname)
+				return
 			end
-		end
-		
-		if fields.del_tcb and sel_tcb and sel_tcb > 0 and sel_tcb <= #ts.tc_breaks then
-			ildb.remove_from_interlocking(ts.tc_breaks[sel_tcb])
-			sel_tcb = nil
-		end
-		
-		if fields.link then
-			players_link_ts[pname] = ts_id
-		end
-		if fields.dissolve then
-			ildb.dissolve_ts(ts_id)
-			minetest.close_formspec(pname, formname)
-			return
 		end
 		
 		if fields.setname then