RefuelBot

local function turnLeft(Times)
    Times = Times or 1
    for _ = 1, Times do
        turtle.turnLeft()
    end
end

local function turnRight(Times)
    Times = Times or 1
    for _ = 1, Times do
        turtle.turnRight()
    end
end

local function DigAndCollect(Side)
    Side = not Side and "f" or string.lower(Side)
    if Side == "f" then
        turtle.dig()
    elseif Side == "l" then
        turnLeft()
        turtle.dig()
    elseif Side == "r" then
        turnRight()
        turtle.dig()
        turnLeft()
    elseif Side == "b" then
        turnLeft(2)
        turtle.dig()
        turnLeft(2)
    elseif Side == "u" then
        turtle.digUp()
        turtle.suckUp()
        return;
    elseif Side == "d" then
        turtle.digDown()
        turtle.suckDown()
        return;
    end
    turtle.suck()
end

local Distance = 0;

while true do
    if Distance == 100 then
        DigAndCollect("l")
        turtle.forward()
        turnLeft()
    end

    turtle.suck()
    turtle.suckUp()
    if turtle.detectUp() then
        DigAndCollect("u")
    end
    if turtle.detect() then
        DigAndCollect("f")
    end
    turtle.forward()

    if not turtle.detectDown() then
        pcall(turtle.placeDown)
    end

    for i = 1, math.huge do
        local Success, Result = pcall(turtle.getItemDetail, i)
        if not Success then
            break;
        end

        if Result and Result.name ~= "minecraft:coal" then
            turtle.select(i)
            turtle.dropUp(64)
        elseif Result and Result.name == "minecraft:coal" then
            turtle.select(i)
            turtle.refuel()
        end
    end

    Distance = Distance + 1
    print("Block #" .. tostring(Distance))
end