Fuel Checker API

-- Fuel Check API --------------------------------------------------------------------------------------------------------------------
-- API to check a turtles fuel level and refuel itself
-- This API contains one function: refuel()
-- The refuel function takes has one parameter named fuelMargin.
-- The user can input a margin for fuel in units of moves. This margin is compared against the current fuel level of the turtle.
-- If the fuel margin (number of moves) is less than the fuel level of the turtle,
-- or no fuel margin is provided, the turtle will attempt to refuel itself
-- If the turtle finds combustable items in its inventory it will refuel with them, checking all inventory slots for combustable items.
-- After refueling, if the turtle's fuel level is still below the fuel margin (if provided), a message will be printed with fuel information

function refuel(fuelMargin)
    local isFueled = true
    if (fuelMargin and turtle.getFuelLevel() < fuelMargin or fuelMargin == nil) then
        isFueled = false
        for i = 1, 16 do
            turtle.select(i)
            local is_fuel = turtle.refuel(0)
            if is_fuel then
                turtle.refuel(64)
            end
        end
        local fuelLevel = turtle.getFuelLevel()
        if (fuelMargin and fuelLevel < fuelMargin ) then
            print("Fuel is still too low\nFuel Margin: " .. fuelMargin .. "\nFuel Level: " .. fuelLevel .. "\nFuel Needed: " .. fuelMargin-fuelLevel)
            return isFueled
        end
    end
end