cactus

-- cactus
-- Harvests the top 2 blocks of cacti from the top
-- Turtle returns to its starting point when mission is completed or fuel runs low
-- Written by HarvDad, April 2014

args = {...}
nArgs = #args

print("cactus: Rev 1.2")

x = 0
y = 0
z = 0
face = 0
cactusSlot = 1
minimumFuel = 100
missionMessage = "Mission complete."
abort = false
local currentFuelLevel = turtle.getFuelLevel()

if nArgs == 0 or (nArgs == 1 and args[1]== "help") then
	print("length, width, and height")
    print("Usage: cactus <length> <width>")
	return
end

if nArgs ~= 2 then
  print("Usage: clear <length> <width>")
  return
end

length = tonumber(args[1])
if length == nil then
  print("\"", args[1], "\" is not a valid length")
  return
end
if length < 1 then
  print("length must be a positive number greater than zero")
end

width = tonumber(args[2])
if width == nil then
  print("\"", args[2], "\" is not a valid width")
  return
end
if width < 1 then
  print("width must be a positive number greater than zero")
end

targetArea = length * width
areaCovered = 1;

function chomp()
  turtle.select(cactusSlot)
  if turtle.compareDown() then
	turtle.digDown()
  end
  areaCovered = areaCovered+1
end

direction = "left"

local clock = os.clock
function sleep(n)  -- seconds
  local t0 = clock()
    while clock() - t0 <= n do end
end

function left()
 if face == 0 then face = 1 turtle.turnLeft() return end
 if face == 1 then face = 2 turtle.turnLeft() return end
 if face == 2 then face = 3 turtle.turnLeft() return end
 if face == 3 then face = 0 turtle.turnLeft() return end
 print("function left\(\): Bad face value: ", face)
end

function right()
 if face == 0 then face = 3 turtle.turnRight() return end
 if face == 1 then face = 0 turtle.turnRight() return end
 if face == 2 then face = 1 turtle.turnRight() return end
 if face == 3 then face = 2 turtle.turnRight() return end
 print("function right\(\): Bad face value: ", face)
end

function up()
	while turtle.detectUp() do	-- This loop added in case of falling sand or whatever
	  turtle.digUp()
	end
  turtle.up()
  y = y+1
end

function rise(nBlocks)
  local i
  for i=1,nBlocks do
    up()
  end
end

function down()
  if turtle.detectDown() then
    turtle.digDown()
  end
  turtle.down()
  y = y-1
end

function turn()
  if direction == "left" then
    left()
  else
    right()
  end
  chomp()
  forward()
  if direction == "left" then
	left()
  	direction = "right"
  else
	right()
    direction = "left"
  end
end

function forward()
	while turtle.detect() do	-- This loop added in case of falling sand or whatever
	  turtle.dig()
	end
	for i=1,10 do
		if turtle.forward() then
			break
		end
		turtle.attack()
		sleep(2)
	end
  	if face == 0 then z = z+1 return end
  	if face == 1 then x = x-1 return end
  	if face == 2 then z = z-1 return end
  	if face == 3 then x = x+1 return end
end

function setFace(f)
	if f == 0 then
	  if face == 0 then return end
	  if face == 1 then right() return end
	  if face == 2 then right() right() return end
	  if face == 3 then left() return end
	end

	if f == 1 then
	  if face == 0 then left() return end
	  if face == 1 then return end
	  if face == 2 then right() return end
	  if face == 3 then right() right() return end
	end

	if f == 2 then
	  if face == 0 then left() left() return end
	  if face == 1 then left() return end
	  if face == 2 then return end
	  if face == 3 then right() return end
	end

	if f == 3 then
	  if face == 0 then right() return end
	  if face == 1 then left() left() return end
	  if face == 2 then left() return end
	  if face == 3 then return end
	end
end

function home(targetY)
--  print("home:face ", face, ", x = ", x, ", z = ", z)
  if x < 0 then
	setFace(3)
	while x < 0 do
	  forward()
	end
  else
    if x > 0 then
  	  setFace(1)
	  while x > 0 do
	    forward()
	  end
    end
  end

  if z < 0 then
	setFace(0)
	while z < 0 do
	  forward()
	end
  else
    if z > 0 then
  	  setFace(2)
	  while z > 0 do
	    forward()
	  end
    end
  end
  setFace(0)

  if (targetY == 0) then
    while y < 0 do
	  up()
	end
  end
end

function harvest(nBlocks)
  local i
  for i=1,nBlocks do
  	chomp()
	checkFuel()
	if abort then
	  areaCovered = targetArea
	end

	if areaCovered < targetArea then
	  forward()
	end
  end
end


function checkFuel()
	if currentFuelLevel == "unlimited" then
		return true
	end

	if currentFuelLevel < minimumFuel then
	  if not turtle.refuel() then
		  areaCovered = targetArea
		  missionMessage = "Mission aborted due to low fuel."
		  abort = true
	    return false
	  end
	end
  return true
end

-- MAIN PROGRAM

turtle.select(1)

print("fuelLevel = ", currentFuelLevel)
print("length = ", length)
print("width = ", width)
up()
up()
up()

height = 2

for d=1,height do
  for w=1,width do
	harvest(length-1)
	if areaCovered < targetArea then
	  turn()
	end
	if abort then
	  home(0)
	end
  end
  home(99)
  if d < height then
    down()
	direction = "left"
	areaCovered = 1;
  end
end

print(missionMessage, " Current fuel level is ", turtle.getFuelLevel())
home(0)
down()
down()