mSend String Metatable File Transfer

--This program uses the String Metatable hack for transfering files without modems.
--[[
THIS PROGRAM HAS BEEN PATCHED AS OF CC 1.7. Sorry.
You will only be able to use this program on servers that have enabled it manually...but good luck on that!
--]]

local tArg = {...}
function showControls()
    print("*msend send [filename] <target id>")
    print("*msend receive <filter id>")
    print("*msend about")
    print("*msend update")
    print("[neccessary] <optional>")
end

function showAbout()
    print("    mSend was programmed by LDDestroier.")
    print("    mSend is a utility to send and receive individual files from machine to machine across infinite distance and across different multiplayer worlds. It does this by setting a string metatable to the contents of a file, along with some metadata to make sure that the intended recipiant gets the file, then converts it back to a file.")
    os.pullEvent("key")
    print("    mSend can send files to anyone listening and send files to individual computer IDs. mSend can also receive files from anyone, or only receive files from a certain ID.")
    print("    Beware, that not inputting an ID argument will allow anyone to send you a file, or anyone to take your file. For private functions, it is reccommended that you input ID arguments.")
    print("    If there is an update, it is reccommended that you update. LDDestroier put a lot of hard work so that you could easily update it using a simple argument. New updates bring new features, usually.")
    print("    mSend may not work in ComputerCraft 1.7 and later. Sorry.")
end

local function makeFile(getFile, name)
    local file = fs.open(name, "w")
    file.write( fileContents )
    file.close()
end

local function updateProgram(directory)
    local updateFile = http.get("http://pastebin.com/raw.php?i=ZaenH6wc")
    if fs.exists("/msendupdate") then
        fs.delete("/msendupdate")
    end
    local file = fs.open("/msendupdate", "w")
    local update = updateFile:readAll()
    file.write(update)
    file.close()
    shell.run("msendupdate " .. directory)
    print("done.")
    fs.delete("/msendupdate")
    return true
end

local function receive(id, timeout)
    if id == -1 then
        print("Receiving file...ID is " .. os.getComputerID())
    else
        print("Receiving file from " .. id .. "...ID is " .. os.getComputerID())
    end
    while true do
        if id == -1 then
            if getmetatable("").targetFileID == -1 or getmetatable("").targetFileID == os.getComputerID() then
                receiveFile()
                return true
            end
        else
            if getmetatable("").senderFileID == tonumber(id) then
                if getmetatable("").targetFileID == -1 or getmetatable("").targetFileID == os.getComputerID() then
                    receiveFile()
                    return true
                end
            end
        end
        sleep(0.04)
    end
end

function local receiveFile()
    localID = getmetatable("").targetFileID
    fileName = getmetatable("").fileName
    fileContents = getmetatable("").fileContents
    senderFileID = getmetatable("").senderFileID
    if fs.exists(shell.dir() .. fileName) then
        if fileName == "msend" then
            print("'" .. fileName .. "' would overwrite msend! Canceled.")
            return false
        else
            print("'" .. fileName .. "' already exists. Overwrite? (y/n)")
            while true do
                local event, key = os.pullEvent("char")
                if key == "n" then
                    print("Cancelled.")
                    return false
                end
                if key == "y" then
                    fs.delete(fs.combine(shell.dir(), fileName))
                    makeFile(fileContents, fileName)
                    print(fileName .. " overwritten from " .. senderFileID .. ".")
                    return true
                end
            end
        end
    else
        makeFile(fileContents, fileName)
        print(fileName .. " received from " .. senderFileID .. ".")
    end
end

local function send(name, id)
    if fs.exists(name) == true then
        local file = fs.open(name, "r")
        getmetatable("").targetFileID = tonumber(id)
        getmetatable("").senderFileID = os.getComputerID()
        getmetatable("").fileContents = file.readAll()
        getmetatable("").fileName = name
        sleep(0.05)
        getmetatable("").targetFileID = nil
        getmetatable("").senderFileID = nil
        getmetatable("").fileContents = nil
        getmetatable("").fileName = nil
        getmetatable("").isServing = false
        return true
    else
        error(name .. ": file does not exist")
    end
end

if tArg[ 1 ] == nil then
    showControls()
    return false
else
    if tArg[ 1 ] == "about" then
        showAbout()
        return false
    else
        if tArg[ 1 ] == "update" then
            updateProgram(shell.dir())
            return true
        else
            if tArg[ 1 ] == "send" then
                if tArg[ 3 ] == nil then
                    send(tArg[ 2 ], -1)
                else
                    if tonumber(tArg[ 3 ]) < 0 then
                        send(tArg[ 2 ], -1)
                    else
                        send(tArg[ 2 ], tArg[ 3 ])
                    end
                end
            else
                if tArg[ 1 ] == "receive" then
                    if tArg[ 2 ] == nil then
                        receive(-1)
                    else
                        if tonumber(tArg[ 2 ]) >= 0 then
                            receive(tArg[ 2 ])
                        end
                    end
                else
                    if tArg[ 2 ] == nil then
                        send(tArg[ 1 ], -1)
                    else
                        if tonumber(tArg[ 2 ]) < 0 then
                            send(tArg[ 1 ], -1)
                        else
                            send(tArg[ 1 ], tArg[ 2 ])
                        end
                    end
                end
                return false
            end
        end
    end
end