local function new_config(name)
	local path = "/etc/" .. name

	local function read_key_in_line(line, key)
		local prefix = key .. ":"
		local prefix_len = string.len(prefix)
		local actual = string.sub(line, 0, prefix_len)
		if not (prefix == actual) then return nil end
		local value = string.sub(line, prefix_len + 1)
		return value
	end

	local function get(key, default)
		local file = fs.open(path, "r")
		if file == nil then return default end
		while true do
			local line = file.readLine()
			if line == nil then return default end
			local value = read_key_in_line(line, key)
			if not (value == nil) then return value end
		end
	end

	local function get_num(key, default)
		local str = get(key, nil)
		if str == nil then return default end
		local result = tonumber(str)
		if result == nil then
			error("Tried to parse conf '" .. path .. "'\nkey \"" .. key .. "\": \"" .. str .. "\"  as number.")
		end
		return result
	end

	return { get = get, get_num = get_num }
end

local function item_list_to_map(item_list)
	local result_ = {}
	for _, item in pairs(item_list) do
		local name = item.name
		result_[name] = item.amount
	end
	return result_
end

local function diff_items(prev_item_map, item_map)
	local diff = {}
	for name, amount in pairs(item_map) do
		local prev_amount = prev_item_map[name]
		if prev_amount == nil then
			diff[#diff + 1] = { name = name, amount = amount }
		else
			local item_diff = amount - prev_amount
			if not (item_diff == 0) then
				diff[#diff + 1] = { name = name, amount = item_diff }
			end
		end
	end
	return diff
end

local function add_frame_item_pos(frame, max)
	for _, item in pairs(frame) do
		item.pos = math.random(max)
	end
end

local function display_name(complete)
	local index = string.find(complete, ":")
	local name = string.sub(complete, index + 1)
	local initials = string.sub(name, 1, 2)
	local last_found = 1
	while true do
		local index_ = string.find(name, "_", last_found)
		if index_ == nil then break end
		last_found = index_ + 1
		initials = initials .. "_" .. string.sub(name, last_found, last_found + 1)
	end
	return initials
end

local function main()
	local ae = peripheral.find("meBridge")
	if ae == nil then
		print("ME bridge not found")
		return
	end

	local monitor = peripheral.find("monitor")
	if monitor == nil then
		print("Monitor not found")
		return
	end
	monitor.setTextScale(0.5)
	local width, height = monitor.getSize()
	local delay = new_config("me-matrix").get_num("delay", 0.1)
	print("Running with: res (", width, ",", height, "), delay ", delay, "s")

	local prev_item_map = item_list_to_map(ae.listItems())
	local frames = {}
	local iteration = 0
	while true
	do
		local item_map = item_list_to_map(ae.listItems())
		local frame = diff_items(prev_item_map, item_map)
		prev_item_map = item_map

		add_frame_item_pos(frame, width)
		table.insert(frames, 1, frame)
		table.remove(frames, height + 1)

		monitor.clear()
		for frame_index, frame_ in ipairs(frames) do
			for _, item in ipairs(frame_) do
				monitor.setCursorPos(item.pos, frame_index)
				if item.amount > 0 then
					monitor.setTextColour(colors.lightBlue)
				else
					monitor.setTextColour(colors.purple)
				end
				monitor.write(display_name(item.name))
			end
		end

		iteration = iteration + 1
		if iteration % 10 == 0 then print("Iteration", iteration) end
		os.sleep(delay)
	end
end

main()