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
}
local lastData = {
    x = 0,
    y = 0,
    z = 0,
    f = 0,
    step = 0,
    dir = false
}

--  States:
--      0 - Mining
--      1 - PutToChest
local state = 0

--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)
end

local function checkFuel()
    local fuelNeeded = math.abs(pos.z) * 2 + size * 4
    if turtle.getFuelLevel() < fuelNeeded then
        tryToRefuel(fuelNeeded)
    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 checkInventory()
    local a = 0
    for i = 1, 16 do
        turtle.select(i)
        if turtle.getItemCount() > 0 then a = a + 1 end
    end
    if a == 16 then
        state = 1
        lastData.x = pos.x
        lastData.y = pos.y
        lastData.z = pos.z
        lastData.f = pos.f
        lastData.step = step
        lastData.dir = dir
    end
end

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

    if dir then
        if pos.x == size and pos.f == 0 then
            turnRight()
            moveForward()
            turnRight()
        elseif pos.x == 1 and pos.f == 2 then
            turnLeft()
            moveForward()
            turnLeft()
        else
            moveForward()
        end
    else
        if pos.x == size and pos.f == 0 then
            turnLeft()
            moveForward()
            turnLeft()
        elseif pos.x == 1 and pos.f == 2 then
            turnRight()
            moveForward()
            turnRight()
        else
            moveForward()
        end
    end
end

local function goTo(x, y, z, f)
    if pos.z < z then
        while pos.z ~= z do moveUp() end
    elseif pos.z > z then
        while pos.z ~= z do moveDown() end
    end

    if pos.y < y then
        while pos.f ~= 1 do turnRight() end
    elseif pos.y > y then
        while pos.f ~= 3 do turnRight() end
    end
    while pos.y ~= y do moveForward() end

    if pos.x < x then
        while pos.f ~= 0 do turnRight() end
    elseif pos.x > x then
        while pos.f ~= 2 do turnRight() end
    end
    while pos.x ~= x do moveForward() end

    while pos.f ~= f do turnRight() end
end

local function dropAll()
    for i = 1, 16 do
        turtle.select(i)
        turtle.drop()
    end
    turtle.select(1)
end

-- Main Code
tryToRefuel(10)

print("Quarry size: "..size)

-- Main Loop
while true do
    if state == 0 then
        mine()
    elseif state == 1 then
        goTo(1, 1, 0, 2)
        tryToRefuel(math.abs(lastData.z) * 2 + size * 4)
        dropAll()
        goTo(lastData.x, lastData.y, lastData.z, lastData.f)
        step = lastData.step
        dir = lastData.dir
        state = 0
    end
end