Advanced mining turtle 1.1.?

term.clear()
term.setCursorPos(1,1)
sel = 0
if fs.exists("coords") == false then
    print("Hi, I am your mining robot!\n\nI will need to ask you a couple of questions before I start mining:\n\nWhat diameter would you like me to mine?\n")
     setSize =read()
    print("\nCool! Now insert the turtles current y coordinate\n")
    input = read()
    setDepth = input-4
    print("\nJust one more thing- put any blocks you don't want me to mine in slots 1-4 and press enter.. or just leave it empty to mine everything (I will be slower the more you put there)\n")
    temp=read()
    setJunkSlots = 0
    for i = 1,4 do
        if turtle.getItemCount(i) ~= 0 then
            setJunkSlots = setJunkSlots + 1
        end
    end
    print("\nOkay, I will start mining now :D")


    w = fs.open("coords","w")
    w.write(setSize.."\n"..setDepth.."\n1\n1\n1\n0\n"..setJunkSlots)
    w.close()
    w = fs.open("startup","w")
    w.write('shell.run("dig")')
    w.close()
    sleep(3)
    term.clear()
    term.setCursorPos(1,1)

end


h = fs.open("coords","r")
size = tonumber(h.readLine(1))
depth = tonumber(h.readLine(2))
x = tonumber(h.readLine(3))
y = tonumber(h.readLine(4))
z = tonumber(h.readLine(5))
facing = tonumber(h.readLine(6))
junkSlots = tonumber(h.readLine(7))
h.close()

--Gets the necessary variables from the file coords

function drop(fslot,lslot)
    for i=fslot,lslot do
        turtle.select(i)
        while turtle.drop() == false and turtle.getItemCount(i) ~= 0 do
            print("Can't drop items- full?")
            sleep(2)
        end
    end
end
function save()
        os.queueEvent("test")
        coroutine.yield()
        s = fs.open("coords","w")
        s.writeLine(size)
        s.writeLine(depth)
        s.writeLine(x)
        s.writeLine(y)
        s.writeLine(z)
        s.writeLine(facing)
        s.writeLine(junkSlots)
        s.close()
end
--save function, prints the turtles orientation and coords to a file
function rflforw()
    if turtle.forward() == true then
        if facing == 0  then
          x = x+1
          save()
        elseif facing == 1 then
          y= y-1
          save()
        elseif facing == 2  then
          x = x - 1
          save()
        elseif facing == 3 then
          y = y + 1
          save()
        else
            error("Invalid facing variable")
        end
    else
        print("Can't move forward, trying again...")
        while turtle.forward() == false do
            turtle.dig()
            sleep(0.3)
        end
        if facing == 0  then
          x = x+1
          save()
        elseif facing == 1 then
          y= y-1
          save()
        elseif facing == 2  then
          x = x - 1
          save()
        elseif facing == 3 then
          y = y + 1
          save()
        end
    end
end
--refuel-less forward function
function dig()
  turtle.dig()
end
function digdown()
   turtle.digDown()
end
function digup()
  turtle.digUp()
end
function refuel()
    local char = ""
    if turtle.getFuelLevel() < 300 then
        if turtle.getItemCount(16) == 0 then
            oldfacing = facing
            oldx = x
            oldy = y
            oldz = z
            while facing ~= 1 do
                left()
            end
            while y ~= 1 do
                rflforw()
            end
            while facing ~= 2 do
                left()
            end
            while x ~= 1 do
                rflforw()
            end
            while z ~= 1 do
                up()
            end
            drop(junkSlots + 1, 15)
            while facing ~= 1 do
                left()
            end
            turtle.select(16)
            turtle.drop()
            turtle.suck()
            while turtle.getItemCount(16) < 16 do
                print('Not enough fuel, Refill the chest and press enter')
                temp=read()
                turtle.drop()
                turtle.suck()
                turtle.refuel(1)
            end
            while facing ~= 0 do
                left()
            end
            while z ~= oldz do
                down()
            end
            while x ~= oldx do
                rflforw()
            end
            while facing ~= 3 do
                    left()
            end
            while y ~= oldy do
                    forw()
            end
            while facing ~= oldfacing do
                    left()
            end
            else
                while true do
                    turtle.select(16)
                    turtle.refuel(1)
                    turtle.select(1)
                    if turtle.getFuelLevel() > 300 then
                        break
                    elseif turtle.getItemCount(16) == 0 then
                        refuel()
                    end
                end
            end
    end
end
function forw()
    refuel()
    if turtle.forward() == true then
        if facing == 0  then
          x = x+1
          save()
        elseif facing == 1 then
          y= y-1
          save()
        elseif facing == 2  then
          x = x - 1
          save()
        elseif facing == 3 then
          y = y + 1
          save()
        else
            error("Invalid facing variable")
        end
    else
        print("Can't move forward, trying again...")
        while turtle.forward() == false do
            turtle.dig()
            sleep(0.3)
        end
        if facing == 0  then
          x = x+1
          save()
        elseif facing == 1 then
          y= y-1
          save()
        elseif facing == 2  then
          x = x - 1
          save()
        elseif facing == 3 then
          y = y + 1
          save()
        end
    end
end
function down()
        if turtle.down() == true then
                z = z + 1
        else
                print("Something is blocking my way down, trying again!")
                while turtle.down() == false do
                        sleep(0.3)
                        digdown()
                end
                z= z + 1
        end

end
function up()
        if turtle.up() == true then
                z = z - 1
        else
                print("Something is blocking my way up, trying again!")
                while turtle.up() == false do
                        sleep(0.3)
                        digup()
                end
                z= z - 1
        end

end
function left()
        turtle.turnLeft()
        facing = facing - 1
        facing = facing % 4
        save()
end
function right()
        turtle.turnRight()
        facing = facing + 1
        facing = facing % 4
        save()
end
function comine()
    local isJunkd = false
    local isJunku = false
    sel = sel + 1
    sel = sel % junkSlots
    if sel == 0 then
        for i = 1 , junkSlots do
            turtle.select(i)
            if turtle.compareUp()== true then
                isJunku = true
            end
            if turtle.compareDown()== true then
                isJunkd = true
            end
        end
    else
        for i = junkSlots , 1, -1 do
            turtle.select(i)
            if turtle.compareUp()== true then
                isJunku = true
            end
            if turtle.compareDown()== true then
                isJunkd = true
            end
        end
    end
    if isJunku == false then
        digup()
    end
    if isJunkd == false then
        digdown()
    end

end
function diglayer()
        for j = 1,size - 1 do
                        comine()
                        dig()
                        forw()
                        if turtle.getItemCount(15) > 0 then
                                oldfacing = facing
                                oldx = x
                                oldy = y
                                oldz = z
                                while facing ~= 1 do
                                        left()
                                end
                                while y ~= 1 do
                                        forw()
                                end
                                while facing ~= 2 do
                                        left()
                                end
                                while x ~= 1 do
                                        forw()
                                end
                                while z ~= 1 do
                                        up()
                                end
                                drop(junkSlots + 1, 15)
                                turtle.select(sel + 1)
                                while facing ~= 0 do
                                        left()
                                end
                                while z ~= oldz do
                                        down()
                                end
                                while x ~= oldx do
                                        forw()
                                end
                                while facing ~= 3 do
                                        left()
                                end
                                while y ~= oldy do
                                        forw()
                                end
                                while facing ~= oldfacing do
                                        left()
                                end
                        end
                end
        end
function program()
    if size % 2 == 0 then
        for i = 1 , size / 2 - 1 do
            diglayer()
            comine()
            left()
            dig()
            forw()
            left()
            diglayer()
            comine()
            right()
            dig()
            forw()
            right()
        end
        diglayer()
        comine()
        left()
        dig()
        forw()
        left()
        diglayer()
        comine()
        left()
        for i = 1, size-1 do
            forw()
        end
        left()
    else
        for i = 1, (size - 1)/2 do
            diglayer()
            comine()
            left()
            dig()
            forw()
            left()
            diglayer()
            comine()
            right()
            dig()
            forw()
            right()
        end
        diglayer()
        comine()
        right()
        while y ~= 1 do
            forw()
        end
        right()
        while x ~= 1 do
            forw()
        end
        left()
        left()
    end
end
refuel()
refuel()
if x ~= 1 or y ~= 1 or facing ~= 0 then
        while facing ~= 1 do
            left()
        end
        while y ~= 1 do
            forw()
        end
        while facing ~= 2 do
            right()
        end
        while x ~= 1 do
            forw()
        end
        while facing ~= 0 do
            left()
        end
end
while z ~= depth do
        program()
        for i = 1, 3 do
            if z == depth then
                break
            end
            digdown()
            down()
        end
end
program()
while facing ~=2 do
        left()
end
while z ~= 1 do
        up()
end
drop(1,16)
fs.delete("startup")
fs.delete("coords")
print("I am done now :D")