BUILD_HOUSE.lua

-- Helper: Select next non-empty slot
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

-- Helper: Try placing a block in a direction, handling slot changes
function placeBlockDown()
    while not turtle.placeDown() do
        if turtle.getItemCount() == 0 then
            if not selectNextSlot() then error("Out of blocks!") end
        else
            sleep(0.2)
        end
    end
end

function placeBlockUp()
    while not turtle.placeUp() do
        if turtle.getItemCount() == 0 then
            if not selectNextSlot() then error("Out of blocks!") end
        else
            sleep(0.2)
        end
    end
end

function placeBlockForward()
    while not turtle.place() do
        if turtle.getItemCount() == 0 then
            if not selectNextSlot() then error("Out of blocks!") end
        else
            sleep(0.2)
        end
    end
end

-- Helpers: Movement (with digging if needed)
function forwardSafe()
    while not turtle.forward() do
        turtle.dig()
        sleep(0.2)
    end
end

function upSafe()
    while not turtle.up() do
        turtle.digUp()
        sleep(0.2)
    end
end

function downSafe()
    while not turtle.down() do
        turtle.digDown()
        sleep(0.2)
    end
end

-- Build the floor at the current level
function buildFloor(length, width)
    for w = 1, width do
        for l = 1, length do
            placeBlockDown()
            if l < length then forwardSafe() end
        end
        if w < width then
            if w % 2 == 1 then
                turtle.turnRight()
                forwardSafe()
                turtle.turnRight()
            else
                turtle.turnLeft()
                forwardSafe()
                turtle.turnLeft()
            end
        end
    end

    -- Return to bottom-left corner facing original direction
    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

-- Build walls around the structure
function buildWalls(length, width, height)
    local function buildWallSegment()
        for h = 1, height - 2 do
            upSafe()
            placeBlockForward()
        end
        for i = 1, height - 2 do downSafe() end
    end

    local function moveAndWall(dist)
        for i = 1, dist - 1 do
            forwardSafe()
            buildWallSegment()
        end
    end

    buildWallSegment()
    moveAndWall(length)
    turtle.turnRight()
    buildWallSegment()
    moveAndWall(width)
    turtle.turnRight()
    buildWallSegment()
    moveAndWall(length)
    turtle.turnRight()
    buildWallSegment()
    moveAndWall(width)
    turtle.turnRight()
end

-- Build ceiling (go to height, then build floor again at top)
function buildCeiling(length, width, height)
    for i = 1, height - 1 do upSafe() end
    buildFloor(length, width)
    for i = 1, height - 1 do downSafe() end
end

-- Main function
function buildHollowBox(length, width, height)
    if length < 2 or width < 2 or height < 2 then
        error("Dimensions must be at least 2x2x2.")
    end

    -- Ensure a valid slot is selected
    if turtle.getItemCount() == 0 then
        if not selectNextSlot() then
            error("No blocks in inventory!")
        end
    end

    buildFloor(length, width)
    buildWalls(length, width, height)
    buildCeiling(length, width, height)

    print("✅ Hollow structure complete.")
end

-- Example call:
-- Uncomment and customize the below line to run directly:
-- buildHollowBox(5, 4, 3)