Plot Border

if not turtle then
    return
end

local fd = turtle.forward
local bk = turtle.back
local up = turtle.up
local dn = turtle.down
local lt = turtle.turnLeft
local rt = turtle.turnRight
local dg = turtle.dig
local pl = turtle.place
local rf,el,er = turtle.refuel,turtle.equipLeft,turtle.equipRight
local gfl = turtle.getFuelLevel

local cy = coroutine.yield
local pc = pcall
local smt = setmetatable
local oc = os.clock
local ost = os.startTimer

local lfl
local ok,x,y,z= pcall(gps.locate)

if not y then--modem not found bug
    for i=1,16 do
        if turtle.getItemCount(i) == 0 then
            turtle.select(i)
            break
        end
    end
    if turtle.getItemCount() == 0 then
        turtle.equipLeft()
        turtle.equipLeft()
        turtle.equipRight()
        turtle.equipRight()
        ok,x,y,z= pcall(gps.locate)
    end
end

if not ok then
    x = nil
end

turtle.native = nil
local function checkGps(ignore)
    if not x or ignore then
        _G.turtle = smt({refuel=rf,equipLeft=el,equipRight=er},{__index=function() return function() error("The turtle functions are blocked",2) end end})
        if not x then print ("Gps Locating failed") end
        error("Turtle functions blocked.",0)
    end
end
checkGps()

local isAdmin = false

if x%39<4 or x%39>35 or z%39<4 or z%39>35 then
    isAdmin = true
end

if fs.exists("rom/adminturtles/"..os.getComputerID()) then
    isAdmin = true
end

if isAdmin then
print("This is an admin turtle now")
return
end

local fx,fz =1,0

local function isInBounds(fm,ym)
    return (x+fx*fm)%39>=4 and (x+fx*fm)%39<=35 and (z+fz*fm)%39>=4 and (z+fz*fm)%39<=35
end

for i=1,4 do
    if not isInBounds(1,0) then
        printError("Turtle can't start on the border of a plot")
        checkGps(true)
    end
    fx,fz=fz,-fx
end
fx,fz = nil,nil

local testOK = pcall(function()
while not fx do
if turtle.forward() then
local nx,ny,nz = gps.locate()
fx,fz = nx-x,nz-z
repeat until turtle.back()
elseif turtle.back() then
local nx,ny,nz = gps.locate()
fx,fz = x-nx,z-nz
repeat until turtle.forward()
end
end
end)
if not testOK then
checkGps(true) --block it
end

lfl = gfl()


local function checkIfMoved(move,fm,ym)
    if isInBounds(fm,ym) then
        local stime = oc()
        local o,r,r2=pc(move)
        if not o then
            print("reached")
            ost(2)
            repeat
                cy("timer")
            until oc()-stime >= 2
        end
        local o2,fl = pc(gfl)
        if not o2 then
            checkGps(true)
        end
        if fl < lfl then
            x=x+fx*fm
            y=y+ym
            z=z+fz*fm
            lfl = fl
        end
        if o then
            return r,r2
        else
            error(r,0)
        end
    end
    sleep(0.2)
    return false,"Can not move out of the plot"
end

function turtle.back()
    return checkIfMoved(bk,-1,0)
end

function turtle.forward()
    return checkIfMoved(fd,1,0)
end

function turtle.up()
    return checkIfMoved(up,0,1)
end

function turtle.down()
    return checkIfMoved(dn,0,-1)
end

function turtle.turnLeft()
fx,fz=fz,-fx
return lt()
end
function turtle.turnRight()
fx,fz=-fz,fx
return rt()
end

function turtle.dig()
if isInBounds(1,0) then
return dg()
end
return false,"Can not dig outside of the plot"
end

function turtle.place()
if isInBounds(1,0) then
return pl()
end
return false,"Can not place blocks outside of the plot"
end

--Just because it is easier
gps.locate = function() return x,y,z end