added priorities

main.lua

@@ -1,71 +1,87 @@
+local function get_item_amount(station, item_id)
+	return 0
+end
 
+local function get_distance(stations, r_station_i, p_station_i)
+	return 0
+end
 
 local function send_train_between(stations, r_station_i, p_station_i)
 	stations[r_station_i].last_p_station_i = p_station_i
 	stations[p_station_i].last_r_station_i = r_station_i
 end
 
+--[[
+	station:
+		deliveries_total: int
+		train_limit: int
+		requester_limit: int
+		provider_limit: int
+		priority: int
+]]
 
-local function tick(stations)
-	--psuedocode
+local function tick(stations, all_items)
+	for _, item_id in pairs(all_items) do
+		local r_stations = {}
+		local p_stations = {}
 
-	local r_stations = {}
+		for station_i, station in pairs(stations) do
+			if station.deliveries_total < station.train_limit then
+				local item_amount = get_item_amount(station, item_id)
+				local delivery_amount = station.delivery_amount
 
-	for station_i, station in ipairs(stations) do
-		local r_item = station.item
-		if -r_item.amount >= station.requester_limit then
-			r_stations[#r_stations + 1] = station_i
-		end
-	end
-
-	local p_stations = {}
-
-	for station_i, station in ipairs(stations) do
-		local p_item = station.item
-		if p_item.amount >= station.provider_limit then
-			p_stations[#p_stations + 1] = station_i
-		end
-	end
-
-	--we do not dispatch more than one train per station per tick
-	if #r_stations > 0 and #p_stations > 0 then
-		if #r_stations <= #p_stations then
-			local last_p_station_i = stations[r_stations[1]].last_p_station_i
-			local i = 1
-			while true do
-				if i > #p_stations then
-					i = 1
-					break
-				elseif p_stations[i] > last_p_station_i then
-					break
-				else
-					i = i + 1
+				if -(item_amount + delivery_amount) >= station.requester_limit then
+					table.insert(r_stations, station_i)
+				elseif item_amount + delivery_amount >= station.provider_limit then
+					table.insert(p_stations, station_i)
 				end
 			end
-			for j = 1, #r_stations do
-				send_train_between(stations, r_stations[j], p_stations[i])
+		end
 
-				i = i%#p_stations + 1
-			end
-		else
-			local last_r_station_i = stations[p_stations[1]].last_r_station_i
-			local i = 1
-			while true do
-				if i > #r_stations then
-					i = 1
-					break
-				elseif r_stations[i] > last_r_station_i then
-					break
-				else
-					i = i + 1
+		--we do not dispatch more than one train per station per tick
+
+		if #r_stations > 0 and #p_stations > 0 then
+			if #r_stations <= #p_stations then
+				--backpressure, prioritize locality
+				for i, r_station_i in ipairs(r_stations) do
+					local best = 1
+					local best_dist = math.huge
+					local highest_prior = -math.huge
+					for j, p_station_i in ipairs(p_stations) do
+						local d = get_distance(stations, r_station_i, p_station_i)
+						local prior = stations[p_station_i].priority
+						if prior > highest_prior then
+							best = j
+							best_dist = d
+							highest_prior = prior
+						elseif prior == highest_prior and d < best_dist then
+							best = j
+							best_dist = d
+						end
+					end
+					send_train_between(stations, r_station_i, p_stations[best])
+					table.remove(p_stations, best)
+				end
+			else
+				--prioritize round robin
+				for j, p_station_i in ipairs(p_stations) do
+					local best = 1
+					local highest_prior = -math.huge
+					local last_r_station_i = stations[p_station_i].last_r_station_i
+					for i, r_station_i in ipairs(r_stations) do
+						local prior = stations[r_station_i].priority
+						if r_stations[i] > last_r_station_i then
+							prior = prior + .5
+						end
+						if prior > highest_prior then
+							best = i
+							highest_prior = prior
+						end
+					end
+					send_train_between(stations, r_stations[best], p_station_i)
+					table.remove(r_stations, best)
 				end
 			end
-			for j = 1, #p_stations do
-				send_train_between(stations, r_stations[i], p_stations[j])
-
-				i = i%#p_stations + 1
-			end
-
 		end
 	end
 end