Update to farm_control for non-replanting support

farm_control.lua

@@ -39,7 +39,11 @@ function check_levels (levels, src)
     local needs_farming = {}
     for item, data in pairs(levels) do
         if amounts[item] ~= nil and amounts[item] < data[1] then
+            if data[2] ~= nil then
                 table.insert(needs_farming, data[2])
+            else
+                table.insert(needs_farming, true)
+            end
         end
     end
     if needs_farming[1] == nil then
@@ -66,10 +70,10 @@ function send_machine (relay_and_side)
     peripheral.call(relay, RELAY_COMMAND, side, false)
 end
 
--- TODO make a different loop for crops controlled by a CLI arg
--- the other loop doesn't need to load the harvester, but also doesn't need
--- to send the harvester unless stock drops below a level
-while true do
+-- if the first argument to this program is "replant", a separate machine will
+-- be sent out to replant crops between harvests
+if arg[1] == "replant" then
+    while true do
         local needs_farming = check_levels(LEVELS, STORAGE)
         if needs_farming ~= nil then
             for _, item in ipairs(needs_farming) do
@@ -81,4 +85,16 @@ while true do
         send_machine(HARVESTER_RELAY)
         os.sleep(SLEEP_TIME)
         pull_items(HARVESTER, STORAGE)
+    end
+-- otherwise, the harvester will just be sent out when a crop's levels drop too
+-- low
+else
+    while true do
+        local needs_farming = check_levels(LEVELS, STORAGE)
+        if needs_farming ~= nil then
+            send_machine(HARVESTER_RELAY)
+        end
+        os.sleep(SLEEP_TIME)
+        pull_items(HARVESTER, STORAGE)
+    end
 end