DigAlpha

-- Stores the turtle's position relative to the starting point
local x, y, z = 0, 0, 0
local facing = 0  -- 0 = forward, 1 = right, 2 = backward, 3 = left

function refuel()
    if turtle.getFuelLevel() < 50 then
        turtle.refuel()
    end
end

function digMove()
    refuel()
    turtle.digUp()
    turtle.dig()
    turtle.digDown()
    turtle.forward()
    updatePosition(1)

    if inventoryFull() then
        returnToStart()
        dropOffItems()
        returnToLastPosition()
    end
end

function updatePosition(moveForward)
    if moveForward then
        if facing == 0 then x = x + 1
        elseif facing == 1 then z = z + 1
        elseif facing == 2 then x = x - 1
        elseif facing == 3 then z = z - 1
        end
    end
end

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

function turnLeft()
    turtle.turnLeft()
    facing = (facing - 1) % 4
    if facing < 0 then facing = 3 end
end

function inventoryFull()
    return turtle.getItemCount(16) > 0  -- Checks if last slot is filled
end

function safeMoveBack()
    while not turtle.back() do
        turtle.dig()
    end
end

function safeMoveUp()
    while not turtle.up() do
        turtle.digUp()
    end
end

function safeMoveDown()
    while not turtle.down() do
        turtle.digDown()
    end
end

function returnToStart()
    print("Returning to start...")

    -- Move back to (0,0,0), clearing obstacles
    while x > 0 do safeMoveBack(); x = x - 1 end
    while z > 0 do turnLeft(); safeMoveBack(); z = z - 1; turnRight() end
    while y < 0 do safeMoveUp(); y = y + 1 end
end

function dropOffItems()
    print("Dropping off items...")
    for i = 2, 16 do  -- Keep only slot 1 (fuel)
        turtle.select(i)
        turtle.drop()
    end
    turtle.select(1)  -- Re-select fuel slot
end

function returnToLastPosition()
    print("Returning to last dig position...")

    -- Move back down
    while y > 0 do safeMoveDown(); y = y - 1 end
    -- Move back on z-axis
    while z < 0 do turnRight(); safeMoveBack(); z = z + 1; turnLeft() end
    -- Move forward to x position
    while x < 0 do turtle.forward(); x = x + 1 end

    print("Resuming excavation.")
end

function digLayer(width, length)
    for row = 1, length do
        for col = 1, width - 1 do
            digMove()
        end

        if row < length then
            if row % 2 == 1 then
                turnRight()
                digMove()
                turnRight()
            else
                turnLeft()
                digMove()
                turnLeft()
            end
        end
    end

    if length % 2 == 0 then
        turnRight()
        for i = 1, width - 1 do
            digMove()
        end
        turnRight()
    else
        turnLeft()
        turnLeft()
    end
end

function digArea(width, length, depth)
    for level = 1, depth do
        digLayer(width, length)

        if level < depth then
            for _ = 1, 3 do  -- Move down 3 blocks per layer
                turtle.digDown()
                turtle.down()
                y = y - 1
            end
        end
    end
end

function start()
    print("Enter width, length, and depth:")
    local width = tonumber(io.read())
    local length = tonumber(io.read())
    local depth = tonumber(io.read())

    if width < 1 or length < 1 or depth < 1 then
        print("Dimensions must be positive numbers.")
        return
    end

    digArea(width, length, depth)
    print("Excavation complete!")
end

start()