fusion.lua

-- Imports
local component = require("component")
local sides = require("sides")
local gpu = component.gpu
local w, h = gpu.getResolution()

-- Vars
local card = component.proxy(component.list("redstone")())
local cardUUID = card.address
local outputSide = sides.east
local checkSide = sides.east

-- Helper functions

-- Makes screen green if true, red if false
function colorScreen(bool)
    gpu.fill(1, 1, w, h, " ") -- Clear screen
    if bool then
        gpu.setBackground(0x00FF00)
    else
        gpu.setBackground(0xFF0000)
    end
    gpu.fill(1, 1, w, h, " ") -- Clear screen
end

-- List of redstone interfaces excluding card
local rs = {}
for address, name in component.list("redstone", true) do
    if address ~= component.get(cardUUID) then
        table.insert( rs, component.proxy(address))
    end
end


-- Main loop
while true do
    local hasItems = 0
    for key,value in ipairs(rs) do
        hasItems = hasItems + value.getComparatorInput(checkSide)
    end
    if(hasItems > 0) then
        card.setOutput(sides.east, 255) -- 255 is max signal
        colorScreen(false)
    else
        card.setOutput(sides.east, 0)
        colorScreen(true)
    end
    os.sleep(1)
end