Disknet (computercraft)

local disknet = {}

local tArg = {...}

disknet.mainPath = "disk/DISKNET"   -- path of shared file
local limitChannelsToModem = false  -- if true, can only use number channels from 1 to 65535
local checkDelay = 0.05             -- amount of time (seconds) between checking the file -- if 0, checks super fast so don't do that
local maximumBufferSize = 64        -- largest amount of messages per channel buffered

local isUsingTweaked = false
if _HOST then
    if _HOST:find("CCEmuX") or _HOST:find("CC:Tweaked") then
        isUsingTweaked = true
    end
end

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
local ageToToss = 0.005 -- amount of time before a message is removed

--  used for synching times between different emulators
disknet._timeMod = 0

-- 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) + disknet._timeMod
end

local function serialize(tbl)
    local output = "{"
    local noKlist = {}
    local cc = table.concat
    for i = 1, #tbl do
        if type(tbl[i]) == "table" then
            output = output .. serialize(tbl[i])
        elseif type(tbl[i]) == "string" then
            output = cc({output, "\"", tbl[i], "\""})
        else
            output = output .. tbl[i]
        end
        noKlist[i] = true
        output = output .. ","
    end
    for k,v in pairs(tbl) do
        if not noKlist[k] then
            if type(k) == "number" or type(k) == "table" then
                output = cc({output, "[", k, "]="})
            else
                output = cc({output, k, "="})
            end
            if type(v) == "table" then
                output = output .. serialize(v)
            elseif type(v) == "string" then
                output = cc({output, "\"", v, "\""})
            else
                output = output .. v
            end
            output = output .. ","
        end
    end
    return output:sub(1, -2):gsub("\n", "\\n") .. "}"
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))))
        local cTime = getTime()
        if disknet.isOpen(channel) then
            local file = fs.open(fs.combine(disknet.mainPath, tostring(channel)), "w")
            if contents then
                contents[#contents + 1] = {
                    time = cTime,
                    id = yourID,
                    uniqueID = uniqueID,
                    messageID = math.random(1, 2^31 - 1),
                    channel = channel,
                    recipient = recipient,
                    message = message,
                }
                for i = #contents, 1, -1 do
                    if cTime - (contents[i].time or 0) > ageToToss then
                        table.remove(contents, i)
                    end
                end
                if #contents > maximumBufferSize then
                    table.remove(contents, 1)
                end
                file.write(serialize(contents))
            else
                file.write(serialize({{
                    time = cTime,
                    id = yourID,
                    uniqueID = uniqueID,
                    messageID = math.random(1, 2^31 - 1),
                    channel = channel,
                    message = message,
                }}):gsub("\n[ ]*", ""))
            end
            file.close()
            return true
        else
            return false
        end
    else
        error(grr)
    end
end

local fList, pList, sList = {}, {}, {}

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, senderFilter)
    local valid, grr = checkValidChannel(channel)
    if valid or not channel then

        local output, contents
        local doRewrite = false

        local good, goddamnit = pcall(function()
            local cTime = getTime()
            local goWithIt = false
            while true do
                loadFList()
                for i = 1, #fList do
                    contents = fList[i].readAll()
                    if contents ~= "" then
                        contents = textutils.unserialize(contents)
                        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  -- make sure you're not receiving messages that you sent
                                            if (not contents[look].recipient) or contents[look].recipient == yourID then                -- make sure that messages intended for others aren't picked up
                                                if (not channel) or channel == contents[look].channel then                              -- make sure that messages are the same channel as the filter, if any
                                                    if (not senderFilter) or senderFilter == contents[look].id then                     -- make sure that the sender is the same as the id filter, if any
                                                        if (not isUsingTweaked) and math.abs(contents[look].time - getTime()) >= ageToToss then     -- if using something besides CC:Tweaked/CCEmuX, adjust your time.
                                                            disknet._timeMod = contents[look].time - getTime()
                                                            cTime = getTime()
                                                            goWithIt = true
                                                        end
                                                        if cTime - (contents[look].time or 0) <= ageToToss or goWithIt then                     -- make sure the message isn't too old
                                                            msgCheckList[contents[look].messageID] = true
                                                            output = {}
                                                            for k,v in pairs(contents[look]) do
                                                                output[k] = v
                                                            end
                                                            break
                                                        end
                                                    end
                                                end
                                            end
                                        end
                                    end
                                end

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

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

-- not really needed if going between CCEmuX and another emulator, but may be needed between two separate CCEmuX daemons
disknet.receive_TS = function(...)
    local message, channel, id, time = disknet.receive(...)
    if time then
        disknet._timeMod = time - getTime()
    end
    return message, channel, id, time
end

return disknet