-- Quarry program with stairs, custom dimensions, and inventory management
-- User input for quarry dimensions
local length, width
local currentX, currentY, currentZ = 0, 0, 0  -- Position of the turtle relative to the starting point
local dir = 0 -- Direction: 0 = forward, 1 = right, 2 = backward, 3 = left

-- Input the dimensions
print("Enter quarry length:")
length = tonumber(read())
print("Enter quarry width:")
width = tonumber(read())

-- Fuel Management
local function refuelIfNeeded()
    if turtle.getFuelLevel() < (length * width * 2) then  -- Arbitrary number; adjust as needed for distance
        turtle.select(16)
        turtle.suckUp()
        turtle.refuel()
    end
end

-- Inventory Management: Return to the start, unload, refuel, then return to digging
local function returnToStartAndUnload()
    -- Return to starting position
    while dir ~= 2 do  -- Ensure turtle faces "backward" (towards starting point)
        turtle.turnRight()
        dir = (dir + 1) % 4
    end
    for i = 1, currentX do
        turtle.forward()
    end
    for i = 1, currentZ do
        turtle.up()
    end

    -- Unload items in chest above
    for i = 1, 15 do  -- Leave slot 16 for fuel
        turtle.select(i)
        turtle.dropUp()
    end

    -- Refuel if needed
    refuelIfNeeded()

    -- Return to digging position
    for i = 1, currentZ do
        turtle.down()
    end
    for i = 1, currentX do
        turtle.back()
    end
    turtle.turnLeft() -- Return to facing forward
    dir = 0
end

-- Check if the inventory is full
local function isInventoryFull()
    for i = 1, 15 do
        if turtle.getItemCount(i) == 0 then
            return false
        end
    end
    return true
end

-- Move forward safely (handle block detection)
local function safeForward()
    while not turtle.forward() do
        turtle.dig()
    end
    currentX = currentX + 1
end

-- Turn right and update direction
local function turnRight()
    turtle.turnRight()
    dir = (dir + 1) % 4
end

-- Turn left and update direction
local function turnLeft()
    turtle.turnLeft()
    dir = (dir + 3) % 4
end

-- Move down and dig stairs
local function digDown()
    turtle.digDown()
    turtle.down()
    currentZ = currentZ + 1
    if currentX % 2 == 0 then  -- Every second block, dig a stair block
        turtle.dig()
        safeForward()
    end
end

-- Main quarry function
local function quarry()
    for z = 1, math.huge do  -- Keep going until bedrock
        for w = 1, width do
            for l = 1, length - 1 do
                if isInventoryFull() then
                    returnToStartAndUnload()
                end
                turtle.digDown()  -- Quarry digs down each block it moves over
                safeForward()
            end
            -- Check if the turtle needs to move to the next row
            if w < width then
                if w % 2 == 1 then
                    turnRight()
                    if isInventoryFull() then
                        returnToStartAndUnload()
                    end
                    turtle.digDown()
                    safeForward()
                    turnRight()
                else
                    turnLeft()
                    if isInventoryFull() then
                        returnToStartAndUnload()
                    end
                    turtle.digDown()
                    safeForward()
                    turnLeft()
                end
            end
        end
        -- When a full layer is done, dig down to the next layer
        if turtle.detectDown() then  -- If bedrock or no block below
            print("Reached bedrock or obstruction")
            break
        else
            digDown()
            if z % 2 == 0 then
                turtle.dig()  -- Digging stair every second layer
                safeForward()
            end
        end
    end
    -- Return to starting position when done
    returnToStartAndUnload()
end

-- Run the quarry function
quarry()