mine

local modem = peripheral.wrap("left")
local idealIron = 22
local idealDiamond = 12
local originX, originY, originZ = gps.locate()
local currentX, currentY, currentZ = gps.locate()
local counter = 0
if not currentX then
  log("Cannot determine my position! Exiting...")
  error()
end
if not originX then
  log("Cannot determine my origin! Exiting...")
  error()
end

function log(message)
  modem.transmit(99,1,message)
end

function move(direction)
  if direction == "fwd" then
    while not turtle.forward() do
      turtle.forward()
      log("Can't move forward")
    end
  elseif direction == "bwd" then
    while not turtle.backward() do
      turtle.back()
      log("Can't move backward")
    end
  elseif direction == "left" then
    turtle.turnLeft()
    while not turtle.forward() do
      turtle.forward()
      log("Can't move to the left")
    end
    turtle.turnRight()
  elseif direction == "right" then
    turtle.turnRight()
    while not turtle.forward() do
      turtle.forward()
      log("Can't move to the right")
    end
    turtle.turnLeft()
  else
    log("Invalid direction passed for move(Str)")
    error()
  end
  updatePos()
end

function updatePos()
  local newX, newY, newZ = gps.locate()
  if not newX then
    log("Cannot determine my current position! Exiting...")
    error()
  end
  currentX = newX
  currentY = newY
  currentZ = newZ
end

function dig(direction)
  local oX, oY, oZ = gps.locate()
  local distance = 0
  if not oX then
    log("Cannot determine position before digging")
    error()
  end
  if direction == "left" then
    turtle.turnLeft()
  elseif direction == "right" then
    turtle.turnRight()
  else
    log("Invalid direction for digging given!")
  end
  while distance < 32 do
    os.sleep(0.5)
    turtle.dig()
    turtle.digUp()
    turtle.forward()
    updatePos()
    local dX = currentX - oX
    local dY = currentY - oY
    local dZ = currentZ - oZ
    distance = math.sqrt(dX*dX+dY*dY+dZ*dZ)
  end
  turtle.turnLeft()
  turtle.turnLeft()
  log("Returning..")
  while distance > 0 do
    turtle.dig()
    turtle.digUp()
    turtle.forward()
    local dX = currentX - oX
    local dY = currentY - oY
    local dZ = currentZ - oZ
    updatePos()
    distance = math.sqrt(dX*dX+dY*dY+dZ*dZ)
  end
  if direction == "left" then
    turtle.turnLeft()
  elseif direction == "right" then
    turtle.turnRight()
  end
end

function store()
  local c
  for i=1,16 do
    turtle.select(i)
    c = c + turtle.getItemCount(i)
    turtle.drop(turtle.getItemCount(i))
  end
  log("Stored "..c.." items!")
end

while true do
  if(turtle.detect()) then
    turtle.dig()
    turtle.digUp()
  end
  move("fwd")
  if(turtle.detect()) then
    turtle.dig()
    turtle.digUp()
  end
  move("fwd")
  dig("left")
  dig("right")
  counter = counter + 2
  log("Completed tunnel #"..counter/2)
  if turtle.getItemCount(16)==64 then
    log("I think I'm full. Let'g go home")
    local pos = counter
    while counter>0 do
      move("bwd")
      counter = counter - 1
    end
    turtle.turnLeft()
    store()
    turtle.turnRight()
    while counter<pos do
      turtle.move("fwd")
      counter = counter +1
    end
  end
end