SmartTurtle v0.6

term.clear()
term.setCursorPos(1,1)
print("SmartTurtle 0.5")
function goLeft()
  turtle.turnLeft()
  turtle.forward()
end
function goRight()
  turtle.turnRight()
  turtle.forward()
end
function detect()
  if not turtle.detect() then
    forward = false
  elseif turtle.detect() then
    forward = true
    turtle.turnRight()
    if turtle.detect() then
      right = true
    elseif not turtle.detect() then
      right = false
    end
    turtle.turnLeft()
    turtle.turnLeft()
    if turtle.detect() then
      left = true
    elseif not turtle.detect() then
      left = false
    end
    turtle.turnRight()
  end
  if left == true and right == true and forward == false then
    turtle.forward()
  end
  if left == false and right == true and forward == false then
    turtle.forward()
  end
  if left == false and right == false and forward == true then
    goRight()
    if turtle.detect() then
      canRight = false
    elseif not turtle.detect() then
      canRight = true
    end
    turtle.turnLeft()
    turtle.turnLeft()
    turtle.forward()
    turtle.forward()
    if turtle.detect() then
      canLeft = false
    elseif not turtle.detect() then
      canLeft = true
    end
    if canLeft == true and canRight == true then
      goRight()
    end
    if canLeft == true and canRight == false then
      goLeft()
    end
    if canLeft == false and canRight == true then
      goRight()
    end
  end
  if left == false and right == true and forward == true then
    goLeft()
  end
  if left == true and right == false and forward == true then
    goRight()
  end
  if left == true and right == true and forward == true then
    turtle.back()
  end
end
function refuel()
  turtle.select(16)
  turtle.refuel()
end
print("How long do you want the turtle to be free? 0 for unlimited")
term.write("Free: ")
local ans = read()
refuel()
if ans == '0' then
  while true do
    for i = 1,20 do
      detect()
    end
    refuel()
  end
else
  for i = 1,ans do
    detect()
    turtle.forward()
    refuel()
  end
end