#!/usr/bin/env lua

local json = require "luci.jsonc"
local UCI = require "luci.model.uci"
local fs   = require "nixio.fs"
local sys  = require "luci.sys"

local methods = {
	get_status = {
		call = function()
			local uci = UCI.cursor()
			local lease_file = uci:get("upnpd", "config", "upnp_lease_file")

			local ipv4_hints = sys.net.ipv4_hints()
			local rule = { }

			local ipt = io.popen("iptables --line-numbers -t nat -xnvL MINIUPNPD 2>/dev/null")
			if ipt then
				local upnpf = lease_file and io.open(lease_file, "r")
				while true do
					local ln = ipt:read("*l")
					if not ln then
						break
					elseif ln:match("^%d+") then
						local num, proto, extport, intaddr, intport =
							ln:match("^(%d+).-([a-z]+).-dpt:(%d+) to:(%S-):(%d+)")
						local descr = ""

						if num and proto and extport and intaddr and intport then
							extport = tonumber(extport)
							intport = tonumber(intport)

							if upnpf then
								local uln = upnpf:read("*l")
								if uln then descr = uln:match(string.format("^%s:%d:%s:%d:%%d*:(.*)$", proto:upper(), extport, intaddr, intport)) end
								if not descr then descr = "" end
							end

							local host_hint, _, e

							for _,e in pairs(ipv4_hints) do
								if e[1] == intaddr then
									host_hint = e[2]
									break
								end
							end

							rule[#rule+1] = {
								num = num,
								proto   = proto:upper(),
								extport = extport,
								intaddr = intaddr,
								host_hint = host_hint,
								intport = intport,
								descr = descr
							}
						end
					end
				end

				if upnpf then upnpf:close() end
				ipt:close()
			end

			local nft = io.popen("nft --handle list chain inet fw4 upnp_prerouting")
			if nft then
				local num = 1
				local upnpf = lease_file and io.open(lease_file, "r")
				while true do
					local ln = nft:read("*l")
					if not ln then
						break
					elseif ln:match("iif ") then
						local proto, extport, intaddr, intport =
							ln:match('^\t\tiif ".-" @nh,72,8 (0x[0-9a-f]+) th dport ([0-9]+) dnat ip to ([0-9%.]+):([0-9]+)')
						local descr = ""

						if (proto == "0x6" or proto == "0x11") and extport and intaddr and intport then
							proto = (proto == "0x6") and "TCP" or "UDP"
							extport = tonumber(extport)
							intport = tonumber(intport)

							if upnpf then
								local uln = upnpf:read("*l")
								if uln then descr = uln:match(string.format("^%s:%d:%s:%d:%%d*:(.*)$", proto, extport, intaddr, intport)) end
								if not descr then descr = "" end
							end

							local host_hint, _, e

							for _,e in pairs(ipv4_hints) do
								if e[1] == intaddr then
									host_hint = e[2]
									break
								end
							end

							rule[#rule+1] = {
								num = tostring(num),
								proto   = proto,
								extport = extport,
								intaddr = intaddr,
								host_hint = host_hint,
								intport = intport,
								descr = descr
							}

							num = num + 1
						end
					end
				end

				if upnpf then upnpf:close() end
				nft:close()
			end

			return { rules = rule }
		end
	},
	delete_rule = {
		args = { token = "token" },
		call = function(args)
			local util = require "luci.util"
			local idx = args and tonumber(args.token)
			local res = {}

			if idx and idx > 0 then
				local uci = UCI.cursor()

				local lease_file = uci:get("upnpd", "config", "upnp_lease_file")
				if lease_file and fs.access(lease_file) then
					sys.call("sed -i -e '%dd' %s" %{ idx, util.shellquote(lease_file) })
					sys.call("/etc/init.d/miniupnpd restart")
				end

				uci.unload()

				return { result = "OK" }
			end

			return { result = "Bad request" }
		end
	}
}

local function parseInput()
	local parse = json.new()
	local done, err

	while true do
		local chunk = io.read(4096)
		if not chunk then
			break
		elseif not done and not err then
			done, err = parse:parse(chunk)
		end
	end

	if not done then
		print(json.stringify({ error = err or "Incomplete input" }))
		os.exit(1)
	end

	return parse:get()
end

local function validateArgs(func, uargs)
	local method = methods[func]
	if not method then
		print(json.stringify({ error = "Method not found" }))
		os.exit(1)
	end

	if type(uargs) ~= "table" then
		print(json.stringify({ error = "Invalid arguments" }))
		os.exit(1)
	end

	uargs.ubus_rpc_session = nil

	local k, v
	local margs = method.args or {}
	for k, v in pairs(uargs) do
		if margs[k] == nil or
		   (v ~= nil and type(v) ~= type(margs[k]))
		then
			print(json.stringify({ error = "Invalid arguments" }))
			os.exit(1)
		end
	end

	return method
end

if arg[1] == "list" then
	local _, method, rv = nil, nil, {}
	for _, method in pairs(methods) do rv[_] = method.args or {} end
	print((json.stringify(rv):gsub(":%[%]", ":{}")))
elseif arg[1] == "call" then
	local args = parseInput()
	local method = validateArgs(arg[2], args)
	local result, code = method.call(args)
	print((json.stringify(result):gsub("^%[%]$", "{}")))
	os.exit(code or 0)
end