Wither Builder - OpenComputers

--Bootstrap
--[[
package.loaded.inventory = nil
package.loaded.nav = nil
package.loaded.status = nil
package.loaded.coord = nil

os.execute("pastebin get -f ntSeKmpP coord.lua")
os.execute("pastebin get -f vdUzxZT3 nav.lua")
os.execute("pastebin get -f 0W0MeXti inventory.lua")
os.execute("pastebin get -f 4ZnZ2iXE status.lua")

os.execute("pastebin get -f Xe3EHF5u wither.lua")

io.write("Done")
--]]

local inv = require("inventory")
local sides = require("sides")
local status = require("status")
local nav = require("nav")
local robot = require("robot")


local SAND = { name = "minecraft:soul_sand", id = 88 }
local SKULL = { name = "minecraft:skull", id = 397, damage = 1 }

local function abort(reason)
    io.write(reason.."\n")
    os.exit()
end

local function err(reason)
    io.write(reason.."\n")
    return false, reason
end

--Config
local distanceForward = 6
local timeBetweenSummons = 12 --seconds
local timeBetweenStockCheck = 1 --seconds


--State
local lastSummon = 0
local lastStock = 0

--Init
local chest = inv.getExternal(sides.bottom)
if chest == nil then abort("A chest below the robot is required to start") end
nav.setHome()
status.set("Initializing")


--Functions
function wait()
    local timeSinceLastSummon = os.time() - lastSummon
    local timeSinceLastStock = os.time() - lastStock

    if timeSinceLastStock > timeBetweenStockCheck and timeSinceLastSummon > timeBetweenSummons then return end
    os.sleep(timeBetweenStockCheck)
end

function stock()
    robot.select(1)
    lastStock = os.time()
    inv.stock(sides.bottom, SAND, 4)
    inv.stock(sides.bottom, SKULL, 3)

    if      inv.count(SAND) < 4     then status.set("Not enough Soul Sand")
    elseif  inv.count(SKULL) < 3    then status.set("Not enough Wither Skeleton Skulls")
    else    return true end

    return false
end

--Hack cuz angel upgrade is broken
function place()
    for i=1,distanceForward do
        nav.forward()
    end
    nav.down()

    inv.select(SAND)
    robot.placeDown()
    nav.up()

    robot.placeDown()
    nav.forward()
    robot.placeDown()

    inv.select(SKULL)
    robot.back()
    robot.place()
    robot.back()
    robot.place()

    inv.select(SAND)
    robot.placeDown()
    robot.back()

    inv.select(SKULL)
    robot.place()
    for i=1,distanceForward-2 do
        robot.back()
    end
    lastSummon = os.time()
end

repeat
    if stock() then
        status.set("Making withers")
        wait()
        place()
    else
        wait()
    end
until false