local PROTOCOL = "resource-monitor"
local REFRESH_RATE = 5 -- seconds between every request

local function pprint(...)
	local pretty = require("cc.pretty")
	pretty.pretty_print(...)
end

local function isWirelessModem(peripheral_name)
	return peripheral.getType(peripheral_name) == "modem"
		 and peripheral.call(peripheral_name, "isWireless")
end

local function getWirelessModem()
	for _, name in ipairs(peripheral.getNames()) do
		if isWirelessModem(name) then
			return name
		end
	end
end

local function getItems(servers)
	local allItems = {}
	for _, id in ipairs(servers) do
		rednet.send(id, nil, PROTOCOL)
		local _, payload = rednet.receive(PROTOCOL)
		local items = textutils.unserialise(payload)
		for name, count in pairs(items) do
			allItems[name] = (allItems[name] or 0) + count
		end
	end

	local orderedItems = {}
	for name, count in pairs(allItems) do
		table.insert(orderedItems, { name = name, count = count })
	end
	table.sort(orderedItems, function(a, b) return a.count > b.count end)
	return orderedItems
end

local function getNumberLength(number)
	return math.floor(1+math.log10(number))
end

local function countColumnWidths(items)
	local multiplierWidth = 0
	local remainderWidth = 0

	for _, item in ipairs(items) do
		local multiplier = math.floor(item.count/64)
		if multiplier > 0 then
			multiplierWidth = math.max(multiplierWidth, getNumberLength(multiplier))
		end

		local remainder = item.count%64
		if remainder > 0 then
			remainderWidth = math.max(remainderWidth, getNumberLength(remainder))
		end
	end

	return multiplierWidth, remainderWidth
end

local function writeAlignedNumber(number, width)
	local x, y = term.getCursorPos()
	term.setCursorPos(x - math.floor(math.log10(number)+1) + width, y)
	term.write(number)
end

local function displayItems(items)
	local w, h = term.getSize()
	local multiplierColumnWidth, remainderColumnWidth = countColumnWidths(items)

	term.clear()
	term.setCursorPos(1, 1)
	print("==== Resource monitor ====")

	for i = 1, math.min(#items, h-1) do
		local item = items[i]
		term.setCursorPos(1, 1+i)
		term.write(item.name)
		term.write(" ")

		local multiplier = math.floor(item.count/64)
		local remainder = item.count%64

		local y = i+1
		if multiplier > 0 then
			local x = w-remainderColumnWidth-2
			if remainderColumnWidth > 0 then
				x = x - 1
			end
			term.setCursorPos(x, y)
			term.write("x64")

			term.setCursorPos(x-multiplierColumnWidth, y)
			writeAlignedNumber(multiplier, multiplierColumnWidth)
		end

		if remainder > 0 then
			term.setCursorPos(w-remainderColumnWidth+1, y)
			writeAlignedNumber(remainder, remainderColumnWidth)
		end

		if remainder > 0 and multiplier > 0 then
			term.setCursorPos(w-remainderColumnWidth, y)
			term.write("+")
		end
	end
end

local function main()
	local modem_name = getWirelessModem()
	if not modem_name then
		print("ERROR: please attach a wireless modem")
		return
	end
	rednet.open(modem_name)
	term.clear()
	term.setCursorPos(1, 1)
	print("Starting...")

	local servers = {rednet.lookup(PROTOCOL)}

	while true do
		local items = getItems(servers)
		displayItems(items)
		os.sleep(REFRESH_RATE)
	end

	rednet.close(modem_name)
end

main()