os.loadAPI("/apis/storage")
os.loadAPI("/apis/position")
os.loadAPI("/apis/sane")
os.loadAPI("/apis/digsafe")
local db = storage
sane.hook()
table.insert(digsafe.blacklist, "torch")
table.insert(digsafe.blacklist, "Thaumcraft")
table.insert(digsafe.blacklist, "ExtraBees")
digsafe.hook()

local t = turtle
local r = 62
local q = math.ceil(r / 2)

db.set("resume", "pitmine")

function border (x, z)
  return (3 == x or 3 == r - x) and (
    z < q + 7 and 3 == z % 7 or
    z > q and 3 == (r - z) % 7)
end

local d = math.sqrt(85)
local a = math.atan(1 / 13) + math.pi / 4
local s = math.sin(a)
local c = math.cos(a)
function torch ()
  local x, z = position.get.X(),
               position.get.Z() - 1
  -- rotation matrix whee
  local xr, zr = x * c - z * s,
                 x * s + z * c
  if (
    border(x, z) or border(z, x) or
    .5 > xr % d and .5 > zr % d
  ) then t.placeDown() end
end

function printcoords ()
  local p = position
  print(p.get.X(), "/", p.get.Y(), "/",
        p.get.Z(), "/", p.get.F())
end

function dig3_p2 (n)
  while t.digUp() do end
  while t.digDown() do end
  t.suckDown()
  t.suckUp()
  torch()
end

function dig3 (n)
  for i = n, 1, -1 do
    while
      t.detect() or
      not t.forward()
    do t.dig() end
    dig3_p2()
  end
end

local turn = db.get("turn") or false
function doTurn ()
  if turn then t.turnRight()
  else t.turnLeft() end
end

function levelDone ()
  local f = position.get.F()
  return ({ r, 0 })[
    0 == f % 3 and 1 or 2] == ({
    position.get.Z() - 1,
    position.get.X()
  })[f % 2 + 1]
end

function turnAround_p2 ()
  local x, z, f = position.get.X(),
                  position.get.Z() - 1,
                  position.get.F()
  if levelDone() then
    doTurn()
    local down = db.get("down") or 3
    for i = down, 1, -1 do
      db.set("down", i)
      t.down()
      if t.detectDown() then
        t.digDown()
      end
    end
    db.clear("down")
  else
    dig3(1)
  end
  doTurn()
  turn = not turn
  db.set("turn", turn)
  db.clear("turning")
end

function turnAround ()
  db.set("turning", true)
  doTurn()
  turnAround_p2()
end

-- resume turn if we were interrupted
if db.get("turning") then
  turnAround_p2()
end

dig3_p2() -- clean above and below
-- also triggers sane (inv/torches)
local x, z = position.get.X(),
             position.get.Z() - 1
dig3(({ -- to the end of this row
  r - z, x, z, r - x
})[position.get.F() + 1])

repeat
  turnAround()
  dig3(r)
until cows_come_home

--]]