args = {...}

-- Init variables
local size = args[1] or 5

local maxSteps = size * size
local step = 1
local dir = true -- True for away, false for towards starting position

local pos = {
    x = 1,
    y = 1,
    z = 0,
    f = 0
}

--  States:
--      Mining
--      PutToChest
local state = "Mining"

--Functions
local function tryToRefuel( fuelNeeded )
    for i = 1, 16 do
        turtle.select(i)
        while turtle.refuel(0) and turtle.getFuelLevel() < fuelNeeded * 1.5 do
            turtle.refuel(1)
        end
    end
    turtle.select(1)

    if turtle.getFuelLevel() < fuelNeeded * 1.5 then
        return false
    else
        return true
    end
end

local function checkFuel()
    local fuelNeeded = math.abs(pos.z) + size * 2
    if turtle.getFuelLevel() < fuelNeeded then
        tryToRefuel(fuelNeeded) -- If false return to chest
    end
end

local function moveForward()
    checkFuel()

    while turtle.detect() do turtle.dig() end
    turtle.forward()

    if pos.f == 0 then pos.x = pos.x + 1 end
    if pos.f == 2 then pos.x = pos.x - 1 end
    if pos.f == 1 then pos.y = pos.y + 1 end
    if pos.f == 3 then pos.y = pos.y - 1 end

    step = step + 1
end

local function moveUp()
    while turtle.detectUp() do turtle.digUp() end
    turtle.up()
    pos.z = pos.z + 1
end

local function moveDown()
    while turtle.detectDown() do turtle.digDown() end
    turtle.down()
    pos.z = pos.z - 1
end

local function turnLeft()
    turtle.turnLeft()
    pos.f = (pos.f - 1) % 4
end

local function turnRight()
    turtle.turnRight()
    pos.f = (pos.f + 1) % 4
end

local function mine()
    if step == maxSteps then
        turnRight()
        turnRight()
        moveDown()
        step = 1
        dir = not dir
    end

    if dir then
        if pos.x == size then
            turnRight()
            moveForward()
            turnRight()
        elseif pos.x == 1 then
            turnLeft()
            moveForward()
            turnLeft()
        else
            moveForward()
        end
    else
        if pos.x == size then
            turnLeft()
            moveForward()
            turnLeft()
        elseif pos.x == 1 then
            turnRight()
            moveForward()
            turnRight()
        else
            moveForward()
        end
    end
end
-- Main Code

moveDown()
tryToRefuel(10)
moveForward()

print("Quarry size: "..size)

-- Main Loop
while true do
    if state == "Mining" then
        mine()
        print(dir)
    end
end