mine.lua

local args = {...}

local blocks = args[1]

function checkForLava(direction)
    if direction == "up" then
        local success, data = turtle.inspectUp()
        if success then
            if data.name == "minecraft:lava" or data.name == "minecraft:flowing_lava" then
                turtle.place()
            end
        end
    elseif direction == "down" then
        local success, data = turtle.inspectUp()
        if success then
            if data.name == "minecraft:lava" or data.name == "minecraft:flowing_lava" then
                turtle.place()
            end
        end
    elseif direction == "front" then
        local success, data = turtle.inspect()
        if success then
            if data.name == "minecraft:lava" or data.name == "minecraft:flowing_lava" then
                turtle.place()
            end
        end
    end
end

function refuel()
    for i = 1, 16 do
        turtle.select(i)
        if turtle.getItemDetail() then
            local slot = turtle.getItemDetail()
            if slot.name == "minecraft:coal" then
                turtle.refuel()
                break
            end
        end
    end
end

function checkLeftRight()
    turtle.turnLeft()
    checkForLava("front")
    turtle.turnRight()
    turtle.turnRight()
    checkForLava("front")
    turtle.turnLeft()
end

for i = 1, blocks do
    refuel()
    if turtle.detect() then
        turtle.dig()
    end
    turtle.forward()
    if turtle.detectUp() then
        turtle.digUp()
    end
    if turtle.detectDown() then
        turtle.digDown()
    end
    checkLeftRight()
    turtle.down()
    checkLeftRight()
    checkForLava("down")
    turtle.up()
    turtle.up()
    checkLeftRight()
    turtle.down()
end