1 files changed, 83 insertions, 0 deletions
diff --git a/advtrains_interlocking/distant_signals.lua b/advtrains_interlocking/distant_signals.lua
new file mode 100644
index 0000000..0da1c10
--- /dev/null
+++ b/advtrains_interlocking/distant_signals.lua
@@ -0,0 +1,83 @@
+local interlocking = advtrains.interlocking
+local ildb = advtrains.interlocking.db
+
+local function update_distant(tcbs)
+	if not (tcbs and tcbs.signal) then return end
+	if not tcbs.aspect then tcbs.aspect = table.copy(interlocking.DANGER) end
+	local asp = tcbs.aspect
+	if tcbs.distant_of then
+		asp.dst = (ildb.get_tcbs(tcbs.distant_of[1]).aspect or interlocking.DANGER).main
+	end
+	interlocking.update_signal_aspect(tcbs)
+	if tcbs.distant then
+		local dst = tcbs.distant
+		for i = 1, #dst do
+			local s = ildb.get_tcbs(dst[i])
+			if not s.aspect then s.aspect = table.copy(interlocking.DANGER) end
+			s.aspect.dst = asp.main
+			interlocking.update_signal_aspect(s)
+		end
+	end
+end
+
+local function unassign_distant(dsts)
+	if not dsts then return end
+	local dof = dsts.distant_of
+	if not dof then return end
+	if dsts.signal and dsts.aspect then
+		dsts.aspect.dst = nil
+		interlocking.update_signal_aspect(dsts)
+	end
+	local sigd, idx = dof[1], dof[2]
+	local tcbs = ildb.get_tcbs(sigd)
+	local dst = tcbs.distant
+	dsts.distant_of = nil
+	if idx == #dst then
+		dst[#dst] = nil
+	else
+		local ent = dst[#dst]
+		dst[idx] = ent
+		dst[#dst] = nil
+		local repl = ildb.get_tcbs(ent)
+		repl.distant_of[2] = idx
+	end
+end
+
+local function assign_distant(sigd, dstd)
+	if not sigd then return end
+	if not dstd then return end
+	local tcbs = ildb.get_tcbs(sigd)
+	local dsts = ildb.get_tcbs(dstd)
+	unassign_distant(dsts)
+	if not (tcbs.signal and dsts.signal) then return end
+	local dst = tcbs.distant
+	if not dst then
+		dst = {}
+		tcbs.distant = dst
+	end
+	local newidx = #dst+1
+	dsts.distant_of = {sigd, newidx}
+	dst[newidx] = dstd
+	update_distant(dsts)
+end
+
+local function remove_distant(tcbs)
+	if not tcbs then return end
+	if tcbs.distant_of then
+		unassign_distant(tcbs)
+	end
+	if tcbs.distant then
+		local dst = tcbs.distant
+		for i = #dst, 1, -1 do
+			local s = ildb.get_tcbs(dst[i])
+			unassign_distant(s)
+		end
+	end
+end
+
+interlocking.distant = {
+	assign = assign_distant,
+	unassign = unassign_distant,
+	remove = remove_distant,
+	update = update_distant,
+}