killer

-- note, when first placing the turtle, make sure he's facing south

local loc = {}
loc = {

  x = 0,
  y = 0,
  z = 0,
  facing = 0,


  facingToAxis = {
    [0] = { axis = 'z', unit = 1 },
    [1] = { axis = 'x', unit = -1 },
    [2] = { axis = 'z', unit = -1 },
    [3] = { axis = 'x', unit = 1 }
  },

  getAxisForFacing = function()
    return loc.facingToAxis[loc.facing]['axis'], loc.facingToAxis[loc.facing]['unit']
  end,

  turnleft = function()
    loc.facing = (loc.facing - 1) % 4
    turtle.turnLeft()
  end,

  turnright = function()
    loc.facing = (loc.facing + 1) % 4
    turtle.turnRight()
  end,

  turnaround = function()
    loc.turnright()
    loc.turnright()
  end,

  moveforward = function()
    if turtle.forward() then
      local axis, unit = loc.getAxisForFacing()
      loc[axis] = loc[axis] + unit
      return true
     else
      return false
     end
  end,

  face = function(faceto)
    local dirdif = (faceto - loc.facing) % 4
    if dirdif == 1 then
      loc.turnright()
    elseif dirdif == 2 then
      loc.turnaround()
    elseif dirdif == 3 then
      loc.turnleft()
    end
  end,

  movez = function(d)
    if d < 0 then loc.face(2) elseif d > 0 then loc.face(0) end
    return loc.moveforward()
  end,

  movex = function(d)
    if d < 0 then loc.face(1) elseif d > 0 then loc.face(3) end
    return loc.moveforward()
  end,

  movey = function(d)
    if d < 0 then
      return loc.movedown()
    else
      return loc.moveup()
    end
  end,

  moveup = function()
    if turtle.up() then
      loc.y = loc.y + 1
    end
    return false
  end,

  movedown = function()
    if turtle.down() then
      loc.y = loc.y - 1
    end
    return false
  end,

  distanceto = function(x, y, z)
    return math.abs(x) + math.abs(y) + math.abs(z)
  end,

  distancetopos = function(pos)
    return loc.distanceto(pos.X, pos.Y, pos.Z)
  end,

  sortpos = function(a, b)
      return math.abs(a.pos) > math.abs(b.pos)
  end,

  headtowards = function (x, y, z)
    local d = {
      { axis = 'x', pos = x },
      { axis = 'y', pos = y },
      { axis = 'z', pos = z }
    }

    table.sort(d, loc.sortpos)

    for k, v in ipairs(d) do
      print('move'..v.axis)
      if loc['move'..v.axis](v.pos) then
        break
      end
    end

  end
}

os.loadAPI("ocs/apis/sensor")
local sensor = sensor.wrap("right")
while true do
  local targets = sensor.getTargets()
  local closest
  local closestDistance = 10000000
  for k, btarget in pairs(targets) do
    local dist = loc.distancetopos(btarget.Position)
    if dist < closestDistance and btarget.type == "Player" then
      closestDistance = dist
      closest = btarget
    end
  end
  if closest ~= nil then
    loc.headtowards(closest.Position.X, closest.Position.Y, closest.Position.Z)
  else
    sleep(0.1)
  end
  print(closestDistance)
  if closestDistance < 4 then
   turtle.attack()
  end
end