excav

local location = {0,0,0}
local origin = {0,0,0}
local dir=1
local modX= {0,1,0,-1}
local modZ = {1,0,-1,0}
local max = {5,2,5}
turtle.select(1)

function turnLeft()
  turtle.turnLeft()
  dir = dir - 1
  if dir < 1 then dir = 4 end
end

function turnAround()
  turnLeft()
  turnLeft()
end

function turnRight()
  turtle.turnRight()
  dir = dir + 1
  if dir > 4 then dir = 1 end
end

function addLocStep()
  location[1] = location[1] + modX[dir]
  location[3] = location[3] + modZ[dir]
end

function subLocStep()
  location[1] = location[1] - modX[dir]
  location[3] = location[3] - modZ[dir]
end

function forward()
  local b = turtle.forward()
  if b then
    addLocStep()
    return true
  else
    return false
  end
end

function back()
  local b = turtle.back()
  if b then
    subLocStep()
    return true
  else
    return false
  end
end

function dig()
  while turtle.detect() do
    turtle.dig()
    sleep(0)
  end
end

function digUp()
  while turtle.detectUp() do
    turtle.digUp()
    sleep(0.5)
  end
end

function digForward()
  while forward() == false do
    dig()
    sleep(0)
  end
end

function digBack()
  while back() == false do
    turnAround()
    dig()
    turnAround()
    sleep(0)
  end
end

function turnOriginLeft()
  while dir ~= 4 do
    turnLeft()
  end
end

function turnOriginRight()
  while dir ~= 2 do
    turnLeft()
  end
end

function turnOriginDown()
  while dir ~= 3 do
    turnLeft()
  end
end

function turnOriginUp()
  while dir ~= 1 do
    turnLeft()
  end
end


local input = ""
while input ~= "start" do
  input = read()
  sleep(0)
end

function checkInventory()
  if turtle.getItemCount(9) > 0 then
    return true
  else
    return false
  end
end

function getLocCopy()
  local copy = {}
  for i,n in ipairs(location) do
    copy[i] = n
  end
  return copy
end

function doDropOff(goBack)
  local orgDir = dir
  local orgPos = getLocCopy()
  moveToOrigin()
  turnOriginDown()
  forward()
  forward()
  dropAll()
  moveToOrigin()
  if goBack then
    moveTo(orgPos[1],origin[3])
    moveTo(orgPos[1],orgPos[3])
    while orgDir ~= dir do
        turnLeft()
        sleep(0)
    end
  end
end

function dropAll()
  for i=1,9,1 do
    turtle.select(i)
    if turtle.getItemCount(i) > 0 then
      turtle.drop()
    end
  end
  turtle.select(1)
end

function moveToOrigin()
  moveTo(origin[1],location[3])
  moveTo(origin[1],origin[3])
end

function turnToX(x)
  if location[1] < x then
    turnOriginRight()
  elseif location[1] > x then
    turnOriginLeft()
  end
end

function turnToZ(z)
  if location[3] < z then
    turnOriginUp()
  elseif location[3] > z then
    turnOriginDown()
  end
end

function moveTo(x,z)
  turnToX(x)
  while location[1] ~= x do
    forward()
    sleep(0)
  end
  turnToZ(z)
  while location[3]~=z do
    forward()
    sleep(0)
  end
end

for x=1,max[1],1 do
  for z=1,max[3],1 do
    if x ~= 1 and z == 1 then
    else
    print(tostring(x).."/"..tostring(z).."  /// " .. tostring(location[1]) .. "/"..tostring(location[2]).."/"..tostring(location[3]))

    digForward()
    digUp()
    if checkInventory() then
      doDropOff(true)
    end
    end
  end
  turnOriginLeft()
  digForward()
  digUp()
  if x % 2 == 1 then
    turnOriginDown()
  else
    turnOriginUp()
  end
  --turnOriginDown()
  --digBack()
end

doDropOff(false)