CC_Lava Tank Filler

local args = {...}
if args[1] then
    local mdist = args[1]
end

local dist = 0

while true do
    if (dist == mdist) then
        break
    end
    if not turtle.forward() then -- Hit a wall, return to start
        break
    end
    dist = dist + 1
    turtle.select(1)
    while not turtle.placeUp() do -- Placing tank
        turtle.digUp()
        turtle.attackUp()
    end
    turtle.select(2)
    if not turtle.placeDown() then -- No lava below, return to start
        turtle.select(1)
        turtle.digUp()
        break
    end
    if not turtle.placeUp() then -- Tank full, return to start
        turtle.select(1)
        turtle.digUp()
        break
    end
    turtle.select(1)
    turtle.digUp()
end

for i=1,dist do
    turtle.back()
end