GiantTree

local x,y,z,fx,fz = 0,0,0,1,0
local map = {[0]={[0]={[0]=true}}}

local needReturn = false

local function lt()
  turtle.turnLeft()
  fx,fz = fz,-fx
end

local function rt()
  turtle.turnRight()
  fx,fz = -fz,fx
end

local function fd(n)
  for i=1,n do
    repeat
    until turtle.forward()
    x = x + fx
    z = z + fz
  end
end

local function tset(t,i1,i2,i3,v)
 if not t[i1] then
   t[i1] = {}
 end
 if not t[i1][i2] then
   t[i1][i2] = {}
 end
 t[i1][i2][i3] = v
end

local function tget(t,i1,i2,i3)
  if not t[i1] or not t[i1][i2] or t[i1][i2][i3] == nil then
    return nil
  end
  return t[i1][i2][i3]
end

--newSpot Helper function
local function c(toCheck,reached,j,nx,ny,nz)
  if tget(reached,j[1]+nx,j[2]+ny,j[3]+nz) == nil and
     tget(map,j[1]+nx,j[2]+ny,j[3]+nz) ~= false and
     (not needReturn or tget(map,j[1]+nx,j[2]+ny,j[3]+nz)) then
    table.insert(toCheck,{j[1]+nx,j[2]+ny,j[3]+nz})
    tset(reached,j[1]+nx,j[2]+ny,j[3]+nz,{unpack(j)})
  end
end

local function getPath(reached,j)
  local path = {{unpack(j)}}
  repeat
    table.insert(path,tget(reached,unpack(path[#path])))
  until path[#path] == true
  table.remove(path) --true
  table.remove(path) --current pos
  return path
end

local function newSpot()
  local toCheck = {{x,y,z}}
  local reached = {[x]={[y]={[z]=true}}}
  for i,j in ipairs(toCheck) do
    if tget(map,unpack(j)) == nil and not needReturn then
      return getPath(reached,j)
    end
    if needReturn and j[1] == 0 and
                      j[2] == 0 and
                      j[3] == 0 then
      return getPath(reached,j)
    end
    if i % 100 == 0 then
      sleep(0)
    end
    c(toCheck,reached,j,0,1,0)
    c(toCheck,reached,j,fx,0,fz)
    c(toCheck,reached,j,-fz,0,fx)
    c(toCheck,reached,j,-fx,0,-fz)
    c(toCheck,reached,j,fz,0,-fx)
    c(toCheck,reached,j,0,-1,0)
  end
  return getPath(reached,{0,0,0})
end

local function faceTo(tx,ty,tz)
  if math.abs(x - tx + z - tz) ~= 1 then
    return
  end
  if x + fz == tx and z - fx == tz then
    lt()
  end
  while x + fx ~= tx or z + fz ~= tz do
    rt()
  end
end

local function goTo(tx,ty,tz)
  if y < ty then
    repeat until turtle.up()
    y = y + 1
    return
  end
  if y > ty then
    repeat until turtle.down()
    y = y - 1
    return
  end
  faceTo(tx,ty,tz)
  if x + fx == tx and z + fz == tz then
    fd(1)
  end
end

local function checkLimit()
  for i=1,16 do
    if turtle.getItemCount(i) == 0 then
        return false
    end
  end
  return true
end

local function addToMap(isValid, nx, ny, nz)
  if isValid then
    needReturn = checkLimit()
  end
  tset(map,x + nx, y + ny, z + nz, isValid)
end
local goOn = true

while goOn do
  local path = newSpot()
  for i=#path,2,-1 do
    goTo(unpack(path[i]))
  end
  if #path > 0 and
     (path[1][1] ~= 0 or
     path[1][2] ~= 0 or
     path[1][3] ~= 0) then
    faceTo(unpack(path[1]))
    if turtle.getFuelLevel() < 1000 then
      turtle.refuel()
    end
    if path[1][2] > y then
      addToMap(turtle.digUp(),0,1,0)
    end
    if path[1][2] == y then
      addToMap(turtle.dig(),fx,0,fz)
    end
    if path[1][2] < y then
      addToMap(y > 0  and turtle.digDown(),0,-1,0)
    end
  else
    goTo(0,0,0)
    local a,b = turtle.inspectUp()
    if a and b.name == "minecraft:chest" and needReturn then
      for i=1,16 do
        if turtle.getItemCount(i) > 0 then
          turtle.select(i)
          turtle.dropUp()
        end
      end
      while checkLimit() do
        sleep(10)
      end
      needReturn = false
    else
      faceTo(1,0,0)
      print("Collected the whole Tree")
      goOn = false
    end
  end
end