[ComputerCraft] CannonBuilder/Remover

--mc 1710, cc 173
local function body(place)
  function inverter()
    if place == true then
      turtle.place()
    elseif place == false then
      turtle.dig()
    end
  end

  function sleeve()
    turtle.turnRight()
    inverter()
    shell.run('go left 2')
    inverter()
    if place == true then
      turtle.placeDown()
    elseif place == false then
      turtle.digDown()
    end
    turtle.turnRight()
  end

  sleeve()
  turtle.back()
  sleeve()
  turtle.back()
  sleeve()
  shell.run('go left 2')
  inverter()
  turtle.up()
  turtle.back()
  turtle.up()
  for i = 1, 4 do
    turtle.turnRight()
    inverter()
  end
  shell.run('go left 2')
  turtle.down()
  turtle.forward()
  turtle.turnRight()
  inverter()
  shell.run('go left 2')
  inverter()
  turtle.turnRight()
end

local function finder(id, amount)
  for x = 1, 16 do
    if turtle.getItemCount(x) == 0 then
    else
      tItem = turtle.getItemDetail(x)
      if tItem.name == id and tItem.count >= amount then
        turtle.select(x)
        break
      end
    end
  end
end

local function buildCannon()
  finder('minecraft:obsidian', 16)
  body(true)
  finder('minecraft:stone_slab', 1)
  turtle.placeDown()
  shell.run('go back 2')
  finder('minecraft:water_bucket', 1)
  turtle.placeDown()
  turtle.forward()
end

local function removeCannon()
  turtle.back()
  finder('minecraft:bucket', 1)
  turtle.placeDown()
  shell.run('go forward 2')
  turtle.digDown()
  turtle.down()
  body(false)
  turtle.down()
end

local function shot()
  finder('minecraft:tnt', 3)
  turtle.place()
  turtle.placeDown()
  turtle.placeUp()

  rs.setOutput('top', true)
  rs.setOutput('bottom', true)
  sleep(0.4)
  rs.setOutput('top', false)
  rs.setOutput('bottom', false)
  sleep(0.1)
  rs.setOutput('front', true)
  sleep(0.1)
  rs.setOutput('front', false)

  turtle.back()
  sleep(5)
  turtle.forward()
end

function printUsage()
  print('Usage: cannon <build>')
  print('Usage: cannon <remove>')
  print('Usage: cannon <shot>')
  return
end

local tArgs = {...}
if tArgs[1] == 'build' then buildCannon()
elseif tArgs[1] == 'remove' then removeCannon()
elseif tArgs[1] == 'shot' then shot()
else printUsage()
end