BUILD_HOUSE.lua

-- === UTILITY FUNCTIONS ===

function selectNextSlot()
    for i = 1, 16 do
        local slot = (turtle.getSelectedSlot() % 16) + 1
        turtle.select(slot)
        if turtle.getItemCount() > 0 then return true end
    end
    return false
end

function placeDown()
    while not turtle.placeDown() do
        if turtle.getItemCount() == 0 and not selectNextSlot() then
            error("Out of blocks!")
        end
        sleep(0.1)
    end
end

function placeForward()
    while not turtle.place() do
        if turtle.getItemCount() == 0 and not selectNextSlot() then
            error("Out of blocks!")
        end
        sleep(0.1)
    end
end

function forwardSafe()
    while not turtle.forward() do
        turtle.dig()
        sleep(0.1)
    end
end

function upSafe()
    while not turtle.up() do
        turtle.digUp()
        sleep(0.1)
    end
end

function downSafe()
    while not turtle.down() do
        turtle.digDown()
        sleep(0.1)
    end
end

-- === BUILD FUNCTIONS ===

function buildFloor(length, width)
    for z = 1, width do
        for x = 1, length do
            placeDown()
            if x < length then forwardSafe() end
        end
        if z < width then
            if z % 2 == 1 then
                turtle.turnRight()
                forwardSafe()
                turtle.turnRight()
            else
                turtle.turnLeft()
                forwardSafe()
                turtle.turnLeft()
            end
        end
    end
    -- Return to origin
    if width % 2 == 1 then
        turtle.turnRight()
        for i = 1, length - 1 do turtle.back() end
        turtle.turnRight()
    else
        turtle.turnLeft()
        for i = 1, length - 1 do turtle.back() end
        turtle.turnLeft()
    end
    for i = 1, width - 1 do turtle.back() end
end

function buildWalls(length, width, height)
    local wallHeight = height - 2
    if wallHeight < 1 then return end

    -- Move up to wall base level (Y=2)
    upSafe()

    -- Build wall perimeter
    for h = 1, wallHeight do
        for side = 1, 4 do
            local distance = (side % 2 == 1) and length or width
            for i = 1, distance do
                if i == 1 or i == distance then
                    placeForward()
                elseif side == 1 or side == 3 then
                    if h == 1 then placeForward() end
                end
                if i < distance then forwardSafe() end
            end
            turtle.turnRight()
        end
        -- Go up for next wall layer
        if h < wallHeight then upSafe() end
    end

    -- Return down to floor
    for i = 1, wallHeight do downSafe() end
end

function buildCeiling(length, width, height)
    for i = 1, height - 1 do upSafe() end

    for z = 1, width do
        for x = 1, length do
            placeDown()
            if x < length then forwardSafe() end
        end
        if z < width then
            if z % 2 == 1 then
                turtle.turnRight()
                forwardSafe()
                turtle.turnRight()
            else
                turtle.turnLeft()
                forwardSafe()
                turtle.turnLeft()
            end
        end
    end

    -- Return to floor level and origin
    if width % 2 == 1 then
        turtle.turnRight()
        for i = 1, length - 1 do turtle.back() end
        turtle.turnRight()
    else
        turtle.turnLeft()
        for i = 1, length - 1 do turtle.back() end
        turtle.turnLeft()
    end
    for i = 1, width - 1 do turtle.back() end

    for i = 1, height - 1 do downSafe() end
end

-- === MAIN BUILD FUNCTION ===

function buildHollowBox(length, width, height)
    if length < 2 or width < 2 or height < 3 then
        error("❌ Dimensions must be at least 2x2x3")
    end

    if turtle.getFuelLevel() == 0 then
        error("❌ Turtle needs fuel! Use turtle.refuel()")
    end

    if turtle.getItemCount() == 0 and not selectNextSlot() then
        error("❌ No blocks available")
    end

    print("▶ Building floor...")
    buildFloor(length, width)

    print("▶ Building walls...")
    buildWalls(length, width, height)

    print("▶ Building ceiling...")
    buildCeiling(length, width, height)

    print("✅ Done.")
end

-- === MENU ===

function promptNumber(prompt)
    while true do
        io.write(prompt)
        local input = read()
        local number = tonumber(input)
        if number and number >= 2 then
            return math.floor(number)
        else
            print("Please enter a number ≥ 2.")
        end
    end
end

-- === START ===

print("=== Build Hollow Structure ===")
local len = promptNumber("Enter length (≥2): ")
local wid = promptNumber("Enter width (≥2): ")
local hei = promptNumber("Enter height (≥3): ")

print("▶ Starting build: " .. len .. " x " .. wid .. " x " .. hei)
buildHollowBox(len, wid, hei)