Turtle API for digging programs v1.0

--by morganamilo

local x = 0 -- increases as turtle goes forward relative to direction it faced when first placed
local y = 0 -- increases as turtle goes left relative to direction it faced when first placed, decreases when turtle goes right
local z = 0 -- increases as turtle goes up, decreases as turtle does down

local xDiff = {1, 0, -1, 0} -- what to add to 'x' depending on the orientation
local yDiff = {0, 1, 0, -1}

local orient = 1

function get(var) -- returns respective varible
  if     var == 'x' then return x
  elseif var == 'y' then return y
  elseif var == 'z' then return z
  elseif var == 'orient' then return orient end
end

function refuelIfEmpty() -- refuels if fuel level is 0
  if turtle.getFuelLevel() == 0 then
    print('Out of fuel\nWaiting for fuel in slot ' .. turtle.getSelectedSlot() .. '...')
    while not turtle.refuel do os.pullEvent('turtle_inventory') end
    print('Fuel level is: ' .. turtle.getFuelLevel())
  end
end

function refuelAtIfNeeded(fuelX, fuelY, fuelZ) -- refuels using chest at specified location
  local currentX, currentY, currentZ, currentO = x, y, z, orient

  if turtle.getFuelLevel() == getDistanceFrom(fuelX, fuelY, fuelZ) then
    print('looking for fuel in current slot...')
    if turtle.refuel() then
      print('fuel found, continuing')
    else
      print('heading back to refuel...')
      turtle.drop()

      if     x < fuelX then goTo(fuelX + 1, fuelY, fuelZ, 'z' 'y') end
      elseif x > fuelX then goTo(fuelX - 1, fuelY, fuelZ, 'z' 'y') end

      turtle.suck()
      if not turtle.refuel() then
        print('fuel not found, waiting for fuel in current slot...')
        while not turtle.refuel() do os.pullEvent('turtle_inventory') end
      end

      print('fuel found, continuing')
    end
    goTo(currentX, currentY, currentZ, 'z' 'y')
    faceDir(currentO)
  end
end

function forward(limit) -- moves forward, digs up/down if respective blocks need to be dug
  x = x + xDiff[orient]
  y = y + yDiff[orient]

  while not turtle.forward() do
    refuelIfEmpty()
    if turtle.detect() then turtle.dig() end
  end

  if z > -limit + 1 and turtle.detectDown() then turtle.digDown() end
  if turtle.detectUp() and z < limit -1  then turtle.digUp() end
end

function left() -- turns left, takes 1 from orient
  orient = (orient + 2) % 4 + 1
  turtle.turnLeft()
end

function right() -- turns right, adds 1 to orient
  orient = orient % 4 + 1
  turtle.turnRight()
end

function faceDir(direction) -- turns to face specified direction, using any number other than '1, 2, 3, 4' will cause a u-turn
  if direction ~= orient then
    if     direction == (orient + 2) % 4 + 1 then left()
    elseif direction == orient % 4 + 1 then right()
    else left() left() end
  end
end

function up(limit) -- moves up, adds 1 to z
  repeat
    if turtle.detectUp() then turtle.digUp() end
  until turtle.up()

  z = z + 1
  if turtle.detectUp() and z < limit - 1 then turtle.digUp() end
end

function down(limit) -- moves down, takes 1 from z
  repeat
    if turtle.detectDown() then turtle.digDown() end
  until turtle.down()

  z = z - 1
  if turtle.detectDown() and z > -limit + 1 then turtle.digDown() end
end

function goTo(newX, newY, newZ, prior1, prior2) -- goes to given coordinate
  local functs = {x = {goToX, newX}, y = {goToY, newY}, z = {goToZ, newZ}}
  local prior3

  for k, v in pairs({'x', 'y', 'z'}) do
    if not (prior1 == v or prior2 == v) then prior3 = v end
  end

  for k, v in pairs({prior1, prior2, prior3}) do
    functs[v][1](functs[v][2])
  end
end

function goToX(newX)
  if newX > x then faceDir(1) end
  if newX < x then faceDir(3) end
  while newX ~= x do forward(1) end
end

function goToY(newY)
  if newY > y then faceDir(2) end
  if newY < y then faceDir(4) end
  while newY ~= y do forward(1) end
end

function goToZ(newZ)
  while newZ > z do up(1) end
  while newZ < z do down(1) end
end

function round(n) -- rounds numbers
  return math.floor(n + 0.5)
end

function inRad(x, y, rad) -- checks if given x and y are in radius
  return round(math.sqrt(x*x+y*y)) < rad
end

function nextInRad(rad)
  nextX = x + xDiff[orient]
  nextY = y + yDiff[orient]
  return inRad(nextX, nextY, rad)
end

function isEven(n) -- true if n is even
  if n % 2 == 0 then return true
  else return false end
end

function turn(n) -- turns left if n is even otherwise right, used for alternating turning in for loops
  if isEven(n) then left()
  else right() end
end