-- Function to get user input safely
local function getNumber(prompt)
    print(prompt)
    local n = tonumber(read())
    while not n or n < 1 do
        print("Please enter a positive number.")
        n = tonumber(read())
    end
    return math.floor(n)
end

-- Prompt for dimensions and options
local length = getNumber("Enter length:")
local width = getNumber("Enter width:")
local height = getNumber("Enter height:")
print("Start at TOP or BOTTOM? (type 'top' or 'bottom')")
local startPos = read():lower()
while startPos ~= "top" and startPos ~= "bottom" do
    print("Please type 'top' or 'bottom'")
    startPos = read():lower()
end

-- Direction tracking (0=+X, 1=+Z, 2=-X, 3=-Z)
local dir = 0

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

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

local function face(targetDir)
    while dir ~= targetDir do
        turnRight()
    end
end

-- Movement functions with digging
local function tryDig() while turtle.detect() do turtle.dig(); sleep(0.2) end end
local function tryDigDown() while turtle.detectDown() do turtle.digDown(); sleep(0.2) end end
local function tryDigUp() while turtle.detectUp() do turtle.digUp(); sleep(0.2) end end

local function forward()
    tryDig()
    while not turtle.forward() do sleep(0.2) end
end

local function up()
    tryDigUp()
    while not turtle.up() do sleep(0.2) end
end

local function down()
    tryDigDown()
    while not turtle.down() do sleep(0.2) end
end

-- Fuel check
local estimatedFuel = length * width * height * 1.5 + (length + width + height) * 2
if turtle.getFuelLevel() < estimatedFuel then
    print("Warning: Low fuel! Required: "..estimatedFuel.." Current: "..turtle.getFuelLevel())
    print("Continue anyway? (y/n)")
    if read():lower() ~= "y" then return end
end

-- Dig one horizontal layer
local function digLayer()
    for w = 1, width do
        -- Dig the row
        for l = 1, length-1 do
            forward()
        end

        -- Turn and move to next row (except on last row)
        if w < width then
            if w % 2 == 1 then
                turnRight()
                forward()
                turnRight()
            else
                turnLeft()
                forward()
                turnLeft()
            end
        end
    end

    -- Return to starting position of layer
    if width % 2 == 0 then
        -- Even width means we ended facing opposite direction
        turnLeft()
        for w = 1, width-1 do forward() end
        turnLeft()
    else
        -- Odd width means we need to turn around
        turnLeft()
        turnLeft()
        for l = 1, length-1 do forward() end
        turnRight()
        turnRight()
    end
end

-- Move to starting position
if startPos == "top" then
    for h = 1, height-1 do
        down()
    end
end

-- Main digging loop
for h = 1, height do
    print("Digging layer "..h.." of "..height)
    digLayer()

    if h < height then
        if startPos == "bottom" then
            up()
        else
            down()
        end
    end
end

-- Return to starting height
if startPos == "bottom" then
    for h = 1, height-1 do down() end
else
    for h = 1, height-1 do up() end
end

print("Quarry complete!")