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, recipient)
	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,
					recipient = recipient,
					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()

		local good, goddamnit = pcall(function()
			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 (not conetnts[look].recipient) or contents[look].recipient == yourID 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
								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
									fList, pList = {}, {}
									break
								end
							end
						end
					end
				end
				if output then
					break
				else
					os.queueEvent("")
					os.pullEvent("")
				end
			end
		end)

		if good then
			if contents then
				return output.message, output.channel, output.id, output.time
			else
				return nil
			end
		else
			for i = 1, #fList do
				fList[i].close()
			end
			error(goddamnit, 0)
		end
	else
		error(grr)
	end
end

return disknet