mine

os.loadAPI("robot")

function init()
    term.write('Neue Position? [j/n]')
    i = read()
    if i == 'j' then
        robot.initGPS()
    elseif i == 'n' then
        robot.load()
    else
        term.clear()
        term.setCursorPos(0, 0)
        init()
    end
end
init()

IGNORE_COUNT = 4

CHUNKS = 1
MIN_HEIGHT = 8
MAX_HEIGHT = 38
Y_STEPS = 3
LAYERS = math.floor((MAX_HEIGHT - MIN_HEIGHT) / Y_STEPS)

STEPS_PER_CHUNK = 16

LENGTH = CHUNKS * STEPS_PER_CHUNK
STEPS = LENGTH - 1

X_START = robot.getX()
Y_START = robot.getY()
Z_START = robot.getZ()
DIR_START = robot.getDirection()

current_layer = 0

moves_per_layer = LENGTH * LENGTH + LENGTH - 2
moves_y = (Y_START - (MAX_HEIGHT - MIN_HEIGHT)) * LAYERS * 2
moves = moves_per_layer * LAYERS + moves_y
fuel_level_start = turtle.getFuelLevel()

function checkDown()
    for i = 1, IGNORE_COUNT do
        if robot.compareDownTo(i) then
            return false
        end
    end
    return true
end

function checkUp()
    for i = 1, IGNORE_COUNT do
        if robot.compareUpTo(i) then
            return false
        end
    end
    return true
end

function compare()
    if checkUp() then turtle.digUp() end
    if checkDown() then turtle.digDown() end
end

function mine()
    for current_layer = 0, LAYERS - 1 do

        robot.moveToY(MIN_HEIGHT + current_layer * Y_STEPS)

        for i = 1, LENGTH / 2 do
            robot.moveZ(STEPS, compare)
            robot.moveX(1, compare)
            robot.moveZ(-STEPS, compare)

            if i < LENGTH / 2 then
                robot.moveX(1, compare)
            end
            for j = 1, IGNORE_COUNT do
                robot.drop(j, -1)
                for k = IGNORE_COUNT  + 1, 16 do
                    if robot.compareItems(j, k) then
                        robot.drop(k)
                    end
                end
            end
        end

        robot.moveToX(X_START)
        robot.moveToZ(Z_START)

        robot.turnTo(DIR_START)

        robot.moveToY(Y_START)

        term.clear()
        term.setCursorPos(1, 1)
        cur_layer = current_layer + 1
        moves_done = fuel_level_start - turtle.getFuelLevel()
        print("layer "..cur_layer.."/"..LAYERS)
        print(moves_done.."/"..moves.." moves")

        for j = IGNORE_COUNT+1, 16 do
            robot.drop(j)
        end
    end
end

term.clear()
term.setCursorPos(1, 1)
print("Total moves: " .. moves)
print("Fuel: " .. fuel_level_start)
fuel = fuel_level_start - moves

if fuel < 0 then
    fuel = math.abs(fuel)
    coal_needed = math.ceil(fuel/80)
    print("Not enough fuel - "..fuel.." fuel needed. ("..coal_needed.." coal)")
else
    os.sleep(3)
    mine()
end