local tArgs = {...}
if #tArgs < 2 or tonumber(tArgs[1]) == nil or tonumber(tArgs[2] == nil) then
  print('Usage: wartfarmer <forward> <right>')
  print('  The size of the field is relative')
  print('  to the turtle\'s start point. Turtle')
  print('  should be *above* the netherwart.')
  return
end

local FORWARD_LEN = tonumber(tArgs[1])
local RIGHT_LEN = tonumber(tArgs[2])
local i


local function plantWart()
  for i=1,16 do
    itemData = turtle.getItemDetail(i)
    if itemData ~= nil and itemData['name'] == 'minecraft:nether_wart' then
      turtle.placeDown() -- plant netherwart
      break
    end
  end
end

-- note that "forward" and "right" are relative to the turtle's start
local forwardPos = 1
local rightPos = 1
local movingForward = true
local outOfFuel = false
local wartCount = 0

-- quick fuel check
if turtle.getFuelLevel() == 0 then
  print('Out of fuel!')
end

print('Hold Ctrl-T to stop farmer.')
--main program
while true do
  -- check if below is a chest
  local exists, block = turtle.inspectDown()

  if exists and (string.find(block['name'], 'chest') or string.find(block['name'], 'barrel')) then
    -- drop off inventory into chest
    print('Dropping off inventory into chest...')
    for i=1,16 do
      turtle.select(i)
      itemData = turtle.getItemDetail()
      if itemData ~= nil and itemData['name'] == 'minecraft:nether_wart' then
        wartCount = wartCount + turtle.getItemCount()
      end
      turtle.dropDown(64) -- deposit everything into chest, warts and whatever
    end
    print('  ', wartCount, ' warts deposited.')
    wartCount = 0
  elseif not exists then
    -- nothing is under the turtle, so try to plant netherwart
    plantWart()
  elseif block['name'] == 'minecraft:nether_wart' and block['metadata'] == 3 then
    -- netherart (and fully mature) is below, so harvest it
    turtle.digDown()
    turtle.suckDown() -- pick up any netherwart
    plantWart()
  end

  -- move the turtle along 1 block
  if movingForward and forwardPos < FORWARD_LEN then
    -- moving forward down the row
    moved = turtle.forward()
    if not moved then outOfFuel = true end
    forwardPos = forwardPos + 1 -- keep track of where we are
  elseif movingForward and forwardPos == FORWARD_LEN then
    -- at the end of the row
    if rightPos < RIGHT_LEN then
      -- go to next row
      turtle.turnRight()
      moved = turtle.forward()
      if not moved then outOfFuel = true end
      rightPos = rightPos + 1 -- keep track of where we are
      turtle.turnRight()
      movingForward = false
    elseif rightPos == RIGHT_LEN then
      -- end of the last row, go back home
      turtle.turnRight()
      turtle.turnRight()
      for i=1,(FORWARD_LEN-1) do
        moved = turtle.forward()
        if not moved then outOfFuel = true end
      end
      turtle.turnRight()
      for i=1,(RIGHT_LEN-1) do
        moved = turtle.forward()
        if not moved then outOfFuel = true end
      end
      turtle.turnRight()
      -- should be back at start now in correct orientation
      forwardPos = 1
      rightPos = 1
      movingForward = true
      sleep(210) -- wait 3:30 for regrow
    end
  elseif not movingForward and forwardPos > 1 then
    -- moving back down the row
    moved = turtle.forward()
    if not moved then outOfFuel = true end
    forwardPos = forwardPos - 1 -- keep track of where we are
  elseif not movingForward and forwardPos == 1 then
    -- back at start of row, turn to next row
    if rightPos < RIGHT_LEN then
      -- go to next row
      turtle.turnLeft()
      moved = turtle.forward()
      if not moved then outOfFuel = true end
      rightPos = rightPos + 1 -- keep track of where we are
      turtle.turnLeft()
      movingForward = true
    elseif rightPos == RIGHT_LEN then
      -- end of the last row, go back home
      turtle.turnRight()
      for i=1,(RIGHT_LEN-1) do
        moved = turtle.forward()
        if not moved then outOfFuel = true end
      end
      turtle.turnRight()
      -- should be back at start now in correct orientation
      forwardPos = 1
      rightPos = 1
      movingForward = true
      sleep(210) -- wait 3:30 for regrow
    end
  end

  --print('Pos: ', forwardPos, ', ', rightPos)

  if outOfFuel then
    print('Out of fuel (or blocked)! Refuel and')
    print('move turtle back to start point.')
    return
  end
end