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")
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
function torch ()
  local x, z = position.get.X(),
               position.get.Z() - 1
  -- rotation matrix whee
  local xr, zr = x * math.cos(a)
               - z * math.sin(a),
                 x * math.sin(a)
               + z * math.cos(a)

  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

--[[
local function digAround ()
  while t.detectUp()   or not t.up()      do t.digUp()   end
  while t.detect()                        do t.dig()     end
  while t.detectDown() or not t.down()    do t.digDown() end
  while t.detectDown() or not t.down()    do t.digDown() end
  while t.detect()     or not t.forward() do t.dig()     end
  while t.detect()     or not t.forward() do t.dig()     end
  while t.detectUp()   or not t.up()      do t.digUp()   end
  while t.detectUp()                      do t.digUp()   end
  while t.detect()                        do t.dig()     end
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

--]]