Turtle Farming

local clr, cp = term.clear, term.setCursorPos

local function ensure(func, ...) -- Thanks Fatboychummy
  local args = table.pack(...)
  while not func() do
    for i = 1, args.n do
      args[i]()
    end
  end
end

local function find(item)
    local slot = 1
    while slot ~= 17 do
        local data = turtle.getItemDetail(slot)
        if data then
            if data.name == item then return slot end
        end
        slot = slot + 1
    end
    return false
end

local function refuel()
    if turtle.getFuelLevel() == 0 then
        print("Refueling...")
        turtle.select(find("minecraft:coal_block") or find("minecraft:coal") or 1)
        turtle.refuel(1)
        if turtle.getFuelLevel() == 0 then
            print("Refuel Needed.")
            while turtle.getFuelLevel() == 0 do
                sleep(.5) turtle.select(find("minecraft:coal") or 1) turtle.refuel(1)
            end
        end
    end
end

local function forward() refuel() write("0") ensure(turtle.forward) end
local function reverse() refuel() write("1") ensure(turtle.back) end
local function turn(d) write("2") if d == 1 then ensure(turtle.turnRight) else ensure(turtle.turnLeft) end end

--[[

Only when idle: <<= create the config only when it is time to move
    - config file does not exist
Only while moving forward: <<= only edit config when starting to turn
    - config file exists with:
        - turned = false
Only while turning: <<== edit on every stage of turn
    - config file exists with:
        - turned = true
        - stage = x

--]]

local wait = 1800
local tbl = {}
local function reset()
    local d = tbl.data or {farmed = 0}
    tbl = {waittimes = {wait, 0}, running = false, staging = false, stage = 0, ended = 0, data=d}
end reset()

local function save()
    write("*")
    local f = fs.open("/ft_config.lua", "w") f.write(textutils.serialize(tbl)) f.close()
end

if fs.exists("/ft_config.lua") then
    local f = fs.open("/ft_config.lua", "r")
    if not f then return printError("Failed to open ft_config.lua") end
    tbl = textutils.unserialize(f.readAll()) f.close()
    if type(tbl) ~= "table" then return printError("Failed to read ft_config.lua") end
end

clr()
print("Rebooted:")
print(textutils.serialize(tbl)) sleep(3) clr()


local stages = {
    turtle.turnRight,
    forward,
    turtle.turnRight,
    turtle.turnLeft,
    forward,
    turtle.turnLeft,
}

--[[
tbl.stage = tbl.stage + 1 save()
    if tbl.stage > #stages then
        tbl.stage = 0
    elseif tbl.stage == 2 or tbl.stage == 5 then
        if turtle.detect() then
            print("Journey ended.")
            tbl.staging = false
            tbl.ended = 1 -- has started it's 1st phase of returning
        end
    end
--]]


local function doStage()
    tbl.stage = tbl.stage + 1
    if turtle.detect() then
        if tbl.stage == 2 or tbl.stage == 5 then tbl.staging, tbl.ended = false, 1 return end
    end
    if tbl.stage == 6 then tbl.staging = false end
    if tbl.stage > 6 then tbl.stage = 1 end
    local tmp = tbl.stage
    if tbl.stage == 3 then tbl.staging = false end save()
    if tbl.ended ~= 1 then write("4["..tbl.stage.."]") stages[tmp]() end
end


while true do
    if tbl.running then
        while tbl.staging do
            doStage() if tbl.ended == 1 then turn(1) end
        end
        while not tbl.staging do
            if not turtle.detect() then
                local a,data = turtle.inspectDown()
                if a then
                    if data.metadata == 7 then
                        turtle.digDown() tbl.data.farmed = tbl.data.farmed + 1 save()
                        local a = find("minecraft:carrot")
                        if a ~= false then
                            turtle.select(a)
                            turtle.placeDown()
                        end
                    end
                else
                    local a = find("minecraft:carrot")
                    if a ~= false then turtle.select(a) turtle.placeDown() end
                end
                forward()
            else
                write("5")
                if tbl.ended == 1 then
                    tbl.ended = 2 -- has started it's last phase of returning
                    turn(1)
                elseif tbl.ended == 2 then
                    turn() -- ENDED
                    for i=1, 16 do
                        local a = turtle.getItemDetail(i)
                        if a then if a.name ~= "minecraft:coal_block" and a.name ~= "minecraft:coal" then turtle.select(i) turtle.drop(64) end end
                    end turn() turn()
                    reset() save() clr() break
                else
                    tbl.staging = true
                end
            end
        end
    else
        cp(1,1) print("Time left: "..tbl.waittimes[1]-tbl.waittimes[2].."  ")
        print("Starts in "..math.ceil((tbl.waittimes[1]-tbl.waittimes[2])/60).." minutes  ") print("Farmed: "..tbl.data.farmed)
        sleep(1) tbl.waittimes[2] = tbl.waittimes[2] + 1 if tbl.waittimes[2] >= tbl.waittimes[1] then tbl.waittimes[2] = 0 tbl.running = true end save()
    end
end