customTunnel

args = {...}
totalPath = 0

-- put excluded block in 15 and 16 slots
-- turtle will return after fill 14 slots

-- exclude block in last slot(16)
function excludeItemForward()
    turtle.select(16)

    return turtle.compare()
end

-- exclude block in last slot(16)
function excludeItemTop()
    turtle.select(16)

    return turtle.compareUp()
end

function dropExcludeItem()
    turtle.select(15)

    turtle.drop(1)
end

function overflowForward()
    for i=1,14 do
        turtle.select(i)

        if turtle.getItemSpace(i) ~= 0 then
            if turtle.compare() or turtle.getItemCount(i) == 0 then
                return false
            end
        end
    end

    return true
end

function overflowTop()
    for i=1,14 do
        turtle.select(i)

        if turtle.getItemSpace(i) ~= 0 then
            if turtle.compareUp() or turtle.getItemCount(i) == 0 then
                return false
            end
        end
    end

    return true
end

function digForward()
    local isDropItem = excludeItemForward()

    if overflowForward() then
        return false
    end

    turtle.select(1)

    if turtle.detect() then
        if isDropItem then
            turtle.select(15)
        end
        turtle.dig()
    end

    if isDropItem then
        dropExcludeItem()
    end

    while turtle.forward() == false do
        if turtle.detect() then
            turtle.dig()
        end
    end

    return true
end

function digTop()
    local isDropItem = excludeItemTop()

    if overflowTop() then
        return false
    end

    turtle.select(1)

    if turtle.detectUp() then
        if isDropItem then
            turtle.select(15)
        end
        turtle.digUp()
    end

    if isDropItem then
        dropExcludeItem()
    end

    while turtle.up() == false do
        if turtle.detectUp() then
            turtle.digUp()
        end
    end

    return true
end

function turnAround()
    turtle.turnRight()
    turtle.turnRight()
end

function returnBackStart()
    turnAround()

    for i=1,totalPath do
        while turtle.forward() == false do

        end
    end

    for i=1,14 do
        turtle.select(i)

        turtle.drop()
    end

    turnAround()
end

function returnBackTop(currentHeight)
    for i=1,currentHeight - 1 do
        turtle.down()
    end

    returnBackStart()
end

function returnBack(widthFromCenter, currentHeight, side)
    turnAround()

    for i=1,widthFromCenter do
        while turtle.forward() == false do

        end
    end

    if side == "left" then
        turtle.turnRight()
    elseif side == "right" then
        turtle.turnLeft()
    end

    for i=1,currentHeight - 1 do
        while turtle.down() == false do

        end
    end

    for i=1,totalPath do
        while turtle.forward() == false do

        end
    end

    for i=1,14 do
        turtle.select(i)

        turtle.drop()
    end

    turnAround()

end

if #args ~= 2 then
    print("Must be 2 arguments")
    return
end

local width = tonumber(args[1])
local height = tonumber(args[2])
local isEnd = false

width = math.floor(width / 2)

while not isEnd do
    if digForward() then
        totalPath = totalPath + 1
    else
        returnBackStart()

        isEnd = true

        break

        -- return back
    end

    if isEnd then
        break
    end

    for i=1,height do
        turtle.turnRight()

        for j=1,width do
            if not digForward() then
                returnBack(j - 1, i, "right")

                isEnd = true

                break

                -- return back
            end
        end

        if isEnd then
            break
        end

        turnAround()

        for j=1,width do
            while turtle.forward() == false do
                digForward()

                turtle.attack()

                break
            end
        end

        for j=1,width do
            if not digForward() then
                returnBack(j - 1, i, "left")

                isEnd = true

                break

                -- return back
            end

        end

        if isEnd then
            break
        end

        turnAround()

        for j=1,width do
            while turtle.forward() == false do
                digForward()

                turtle.attack()

                break
            end
        end

        turtle.turnLeft()

        if i ~= height then
            if not digTop() then
                returnBackTop(i)

                isEnd = true

                break

                -- return back
            end

        else
            for j=1,height - 1 do
                while turtle.down() == false do

                end
            end
        end

    end

end