local PROTOCOL = "wireless-todo"
local TODOS_FILE = "todos.data.lua"

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 readTodos(filename)
	if fs.exists(filename) then
		return loadfile(filename)()
	else
		return {}
	end
end

local function writeTodos(filename, todos)
	local f = fs.open(filename, "w")
	f.write("return ")
	f.write(textutils.serialise(todos))
	f.close()
end

local function includeValue(set, value)
	for _, v in ipairs(set) do
		if v == value then
			return
		end
	end

	table.insert(set, value)
end

local function decodeMessage(message)
	local parts = {}
	for part in message:gmatch("([^\n]+)") do
		table.insert(parts, part)
	end
	return parts
end

local function sendToMultiple(recipients, payload, protocol, except_recepient)
	for _, recipient in ipairs(recipients) do
		if recipient ~= except_recepient then
			rednet.send(recipient, payload, protocol)
		end
	end
end

local function main(hostname)
	if not hostname then
		print("ERROR: please provide a hostname")
		return
	end

	local modem_name = getWirelessModem()
	if not modem_name then
		print("ERROR: please attach a wireless modem")
		return
	end

	rednet.open(modem_name)
	rednet.host(PROTOCOL, hostname)

	local seen_users = {}
	local todos = readTodos(TODOS_FILE)

	local function updateUsersTodos(except_user)
		writeTodos(TODOS_FILE, todos)
		local payload = textutils.serialise(todos, { compact = true })
		sendToMultiple(seen_users, payload, PROTOCOL, except_user)
	end

	while true do
		local sender, message = rednet.receive(PROTOCOL)
		print(sender, message)
		local parts = decodeMessage(message)
		pprint(parts)
		if parts[1] == "get" then
			includeValue(seen_users, sender)
			local payload = textutils.serialise(todos, { compact = true })
			rednet.send(sender, payload, PROTOCOL)
		elseif parts[1] == "edit" then
			local index = tonumber(parts[2])
			todos[index].text = parts[3]

			updateUsersTodos(sender)
		elseif parts[1] == "mark" then
			local index = tonumber(parts[2])
			todos[index].marked = true

			updateUsersTodos(sender)
		elseif parts[1] == "unmark" then
			local index = tonumber(parts[2])
			todos[index].marked = false

			updateUsersTodos(sender)
		elseif parts[1] == "add" then
			table.insert(todos, {
				text = parts[2] or "",
				marked = false
			})

			updateUsersTodos(sender)
		elseif parts[1] == "remove" then
			local index = tonumber(parts[2])
			table.remove(todos, index)

			updateUsersTodos(sender)
		elseif parts[1] == "move-up" then
			local index = tonumber(parts[2])
			-- TOOD: finish this

			updateUsersTodos(sender)
		elseif parts[1] == "move-down" then
			local index = tonumber(parts[2])
			-- TOOD: finish this

			updateUsersTodos(sender)
		end
	end
end

main(...)