ldd-CC/disknet.lua

local disknet = {}

local tArg = {...}

disknet.mainPath = tArg[1] or "disk/DISKNET"
local limitChannelsToModem = false
local maximumBufferSize = 32

local openChannels = {}
local yourID = os.getComputerID()
local uniqueID = math.random(1, 2^31 - 1) -- prevents receiving your own messages
local msgCheckList = {} -- makes sure duplicate messages aren't received

-- do not think for one second that os.epoch("utc") would be a proper substitute
local getTime = function()
	return os.time() + (-1 + os.day()) * 24
end

local readFile = function(path)
	local file = fs.open(path, "r")
	local contents = file.readAll()
	file.close()
	return contents
end

local writeFile = function(path, contents)
	local file = fs.open(path, "w")
	file.write(contents)
	file.close()
end

-- if 'limitChannelsToModem', then will make sure that channel is a number between 0 and 65535
local checkValidChannel = function(channel)
	if limitChannelsToModem then
		if type(channel) == "number" then
			if channel < 0 or channel > 65535 then
				return false, "channel must be between 0 and 65535"
			else
				return true
			end
		else
			return false, "channel must be number"
		end
	else
		if type(channel) == "string" or type(channel) == "number" then
			return true
		else
			return false, "channel must be castable to string"
		end
	end
end

disknet.isOpen = function(channel)
	local valid, grr = checkValidChannel(channel)
	if valid then
		for i = 1, #openChannels do
			if openChannels[i] == channel then
				return true
			end
		end
		return false
	else
		error(grr)
	end
end

disknet.open = function(channel)
	local valid, grr = checkValidChannel(channel)
	if valid then
		openChannels[#openChannels + 1] = channel
		return true
	else
		error(grr)
	end
end

disknet.close = function(channel)
	local valid, grr = checkValidChannel(channel)
	if valid then
		for i = 1, #openChannels do
			if openChannels[i] == channel then
				table.remove(openChannels, i)
				return true
			end
		end
		return false
	else
		error(grr)
	end
end

disknet.closeAll = function()
	openChannels = {}
end

disknet.send = function(channel, message)
	local valid, grr = checkValidChannel(channel)
	if valid then
		if not fs.exists(fs.combine(disknet.mainPath, tostring(channel))) then
			fs.open(fs.combine(disknet.mainPath, tostring(channel)), "w").close()
		end
		local contents = textutils.unserialize(readFile(fs.combine(disknet.mainPath, tostring(channel))))
		if disknet.isOpen(channel) then
			local file = fs.open(fs.combine(disknet.mainPath, tostring(channel)), "w")
			if contents then
				contents[#contents + 1] = {
					time = getTime(),
					id = yourID,
					uniqueID = uniqueID,
					messageID = math.random(1, 2^31 - 1),
					channel = channel,
					message = message,
				}
				if #contents > maximumBufferSize then
					table.remove(contents, 1)
				end
				file.write(textutils.serialize(contents))
			else
				file.write(textutils.serialize({{
					time = getTime(),
					id = yourID,
					uniqueID = uniqueID,
					messageID = math.random(1, 2^31 - 1),
					channel = channel,
					message = message,
				}}))
			end
			file.close()
			return true
		else
			return false
		end
	else
		error(grr)
	end
end

local fList, pList = {}, {}

local loadFList = function()
	fList, pList = {}, {}
	if channel then
		fList = {fs.open(fs.combine(disknet.mainPath, tostring(channel)), "r")}
		pList = {fs.combine(disknet.mainPath, tostring(channel))}
	else
		for i = 1, #openChannels do
			fList[i] = fs.open(fs.combine(disknet.mainPath, tostring(openChannels[i])), "r")
			pList[i] = fs.combine(disknet.mainPath, tostring(openChannels[i]))
		end
	end
end

disknet.receive = function(channel)
	local valid, grr = checkValidChannel(channel)
	if valid or not channel then

		local output, contents
		local doRewrite = false

		loadFList()

		while true do
			for i = 1, #fList do
				contents = fList[i].readAll()
				if contents ~= "" then
					fList[i].close()
					fList[i] = fs.open(pList[i], "r")
					contents = textutils.unserialize(fList[i].readAll())
					if type(contents) == "table" then
						if contents[1] then
							if not output then
								for look = 1, #contents do
									if (contents[look].uniqueID ~= uniqueID) and (not msgCheckList[contents[look].messageID]) then
										if getTime() - (contents[look].time or 0) <= 0.001 then
											msgCheckList[contents[look].messageID] = true
											output = {}
											for k,v in pairs(contents[look]) do
												output[k] = v
											end
											break
										end
									end
								end
							end

							-- delete old msesages
							doRewrite = false
							for t = #contents, 1, -1 do
								if getTime() - (contents[t].time or 0) > 0.001 then
									msgCheckList[contents[t].messageID] = nil
									table.remove(contents, t)
									doRewrite = true
								end
							end
							if doRewrite then
								writeFile(pList[i], textutils.serialize(contents))
							end
							if output then
								for i = 1, #fList do
									fList[i].close()
								end
								break
							end
						end
					end
				end
			end
			if output then
				break
			else
				os.queueEvent("")
				os.pullEvent("")
			end
		end

		if contents then
			return output.message, output.channel, output.id, output.time
		else
			return nil
		end
	else
		error(grr)
	end
end

return disknet