-- Program to control a farm made with the create mod

-- establish amounts of items to ensure
local LEVELS = {}
LEVELS["minecraft:oak_log"] = {4 * 64, "minecraft:oak_sapling"}

local STORAGE = ""
local HARVESTER = ""
local PLANTER = ""

local HARVESTER_RELAY = ""
local PLANTER_RELAY = ""

local SLEEP_TIME = 40
local SIGNAL_TIME = 2

-------------------------------- PROGRAM --------------------------------------

function pull_items (src, dest)
    local src = peripheral.wrap(src)
    if src.size() < 1 then return nil end
    for slot, _ in pairs(src.list()) do
        src.pushItems(dest, slot)
    end
end

-- need to return the sources for items that need farming
-- e.g. a sapling for wood
function check_levels (levels, src)
    local src = peripheral.wrap(src)
    local amounts = {}
    for _, item in pairs(src.list()) do
        if amounts[item.name] == nil then
            amounts[item.name] = item.count
        else
            amounts[item.name] = amounts[item.name] + item.count
        end
    end
    local needs_farming = {}
    for item, data in pairs(levels) do
        if amounts[item] ~= nil and amounts[item] < data[1] then
            table.insert(needs_farming, data[2])
        end
    end
    if needs_farming[1] == nil then
        return nil
    else
        return needs_farming
    end
end

function load_stack(item_name, src, dest)
    local src = peripheral.wrap(src)
    for slot, item in pairs(src.list()) do
        if item.name == item_name then
            return src.pushItems(dest, slot)
        end
    end
end

function send_machine (relay_and_side)
    local RELAY_COMMAND = "setOutput"
    local relay, side = relay_and_side:match"(.+):(.+)"
    peripheral.call(relay, RELAY_COMMAND, side, true)
    os.sleep(HARVESTER_SIGNAL_TIME)
    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
    local needs_farming = check_levels(LEVELS, STORAGE)
    if needs_farming ~= nil then
        for _, item in ipairs(needs_farming) do
            load_stack(item, STORAGE, PLANTER)
        end
        send_machine(PLANTER_RELAY)
        os.sleep(SLEEP_TIME)
    end
    send_machine(HARVESTER_RELAY)
    os.sleep(SLEEP_TIME)
    pull_items(HARVESTER, STORAGE)
end