os.loadAPI("apis/storage")
local db = storage
local t = turtle

blacklist = {}

local function blacklisted (what)
  for _, b in ipairs(blacklist) do
    if string.match(what, b) then
      return true
    end
  end
  return false
end

-- FIXME leaves block below obstruction
local dugUp = db.get("dugup") or 0
local function digAround ()
  dugUp = dugUp + 1
  t.up()
  db.set("dugup", dugUp)
  return t.dig()
end

function hook ()
  if t.digsafe then return false end

  t.digsafe = {
    ["digUp"] = t.digUp,
    ["dig"] = t.dig,
    ["digDown"] = t.digDown
  }

  t.digUp = function ()
    local x, y = t.inspectUp()
    if not x then return false end
    if blacklisted(y["name"]) then
      return false
    end
    return t.digsafe.digUp()
  end

  t.digDown = function ()
    local x, y = t.inspectDown()
    if not x then return false end
    if blacklisted(y["name"]) then
      return false
    end
    if 0 ~= dugUp and t.digsafe.digDown() then
      print("previously dug up " .. dugUp .. " times, digging back down.")
      t.down()
      dugUp = dugUp - 1
      db.set("dugup", dugUp)
      return t.digDown()
    end
    return t.digsafe.digDown()
  end

  t.dig = function ()
    local x, y = t.inspect()
    if not x then return false end
    if blacklisted(y["name"]) then
      print("digging around blacklisted block " .. y["name"])
      return digAround()
    end
    return t.digsafe.dig()
  end

  return true
end