-- CONFIG
local DISTANCE = 50

-- UTILITY
local function refuelIfNeeded()
  if turtle.getFuelLevel() == "unlimited" then return end
  if turtle.getFuelLevel() < 100 then
    for i = 1, 16 do
      turtle.select(i)
      if turtle.refuel(1) then break end
    end
  end
end

local function isOre(data)
  return data and data.name and string.find(data.name, "ore")
end

-- VEIN MINING
local function mineVein()
  for i = 1, 4 do
    local success, data = turtle.inspect()
    if success and isOre(data) then
      turtle.dig()
      turtle.forward()
      mineVein()
      turtle.back()
    end
    turtle.turnRight()
  end

  local successUp, dataUp = turtle.inspectUp()
  if successUp and isOre(dataUp) then
    turtle.digUp()
    turtle.up()
    mineVein()
    turtle.down()
  end

  local successDown, dataDown = turtle.inspectDown()
  if successDown and isOre(dataDown) then
    turtle.digDown()
    turtle.down()
    mineVein()
    turtle.up()
  end
end

-- MOVE FORWARD SAFELY
local function digForward()
  while turtle.detect() do
    turtle.dig()
    sleep(0.2)
  end
  turtle.forward()
end

-- MAIN MINING LOOP
for i = 1, DISTANCE do
  refuelIfNeeded()

  -- Bottom block
  digForward()
  mineVein()

  -- Top block (2-high tunnel)
  turtle.digUp()
  mineVein()
end

-- RETURN HOME
turtle.turnLeft()
turtle.turnLeft()

for i = 1, DISTANCE do
  turtle.forward()
end

turtle.turnLeft()
turtle.turnLeft()

print("Mining complete!")