Readable XT2 downloader

do      --Readable XT downloader
    --Configs
    local inert=function()end;  --A function that does nothing. Use it to disable prints or read
    local cprint=print;         --Logs an info message
    local aprint=print;         --Prints an asking message, that the user must see to know what to input
    local cerr=printError;      --Prints an error in red, if possible
    local cread=read;           --Receives user input. If it returns "yes", answer is positive
    local xtpath="/xt";         --Where xt should be loaded and downloaded
    local autoupdate=true;      --Wether updates should always be checked, or just when necessary

    local lastver=false;
    local lastverpaste=false;
    local function checkForUpdate()
        if http then
            cprint("Checking for updates...");
            local lastverpage=http.get("http://www.pastebin.com/raw.php?i=BHpUQ8Hn");
            if lastverpage then
                lastver=tonumber(lastverpage.readLine());
                lastverpaste=lastverpage.readLine();
                lastverpage.close();
                if not lastver or not lastverpaste then
                    cerr("Update paste corrupted");
                    lastver=false;
                    lastverpaste=false;
                end
            else
                cerr("Cant check for updates");
            end
        else
            cerr("Cant check for updates, http disabled");
        end
    end

    local myver=false;
    local asktodelete=false;
    local loadedver=false;
    local mybestver=false;
    local function getMyVersion()
        if fs.isDir(xtpath) then
            cprint("\""..xtpath.."\" is a directory, not XT api");
            myver=false;
            asktodelete=true;
        elseif fs.exists(xtpath) then
            local handle=fs.open(xtpath,"r");
            local fline=handle.readLine();
            handle.close();
            if fline:sub(1,6)=="--XT V" and fline:sub(10)==" by negamartin" and tonumber(fline:sub(7,9)) then
                myver=tonumber(fline:sub(7,9));
                cprint("\""..xtpath.."\" is XT api V"..myver);
            else
                myver=false;
                asktodelete=true;
                cprint("\""..xtpath.."\" is a non-XT file");
            end
        else
            cprint("\""..xtpath.."\" does not exist");
            myver=false;
        end
        if xt then
            loadedver=xt.version;
            if type(loadedver)=="number" then
                cprint("XT V"..loadedver.." is already loaded");
            else
                loadedver=false;
            end
        else
            loadedver=false;
        end
        if myver then
            if loadedver then
                mybestver=math.max(myver,loadedver);
            else mybestver=myver; end
        else mybestver=loadedver; end
    end

    local function downloadXT()
        if lastver and lastverpaste then
            if http then
                cprint("Downloading XT V"..lastver.."...");
                local xtpage=http.get("http://www.pastebin.com/raw.php?i="..lastverpaste);
                if xtpage then
                    local handle=fs.open(xtpath,"w");
                    handle.write(xtpage.readAll());
                    handle.close();
                    xtpage.close();
                    myver=lastver;
                    return true;
                else
                    cerr("Cant download XT");
                end
            else
                cerr("Cant download XT, http disabled");
            end
        end
        return false;
    end

    getMyVersion();
    if autoupdate or not mybestver then
        checkForUpdate();
        if lastver then
            if mybestver then
                if mybestver<lastver then
                    local doit=true;
                    if asktodelete then
                        aprint("A non-XT file has been found in \""..xtpath.."\"");
                        aprint("Overwrite it? (\"yes\" or \"no\")");
                        if cread()=="yes" then
                            fs.delete(xtpath);
                        else
                            aprint("Remove the non-XT file if you wish to update");
                            doit=false;
                        end
                    end
                    if doit then
                        if downloadXT() then
                            cprint("Updated XT to V"..lastver);
                        else
                            cprint("Couldn't download XT, using offline version");
                        end
                    end
                else
                    cprint("XT up to date");
                end
            else
                if asktodelete then
                    aprint("A non-XT file has been found in \""..xtpath.."\"");
                    aprint("Overwrite it? (\"yes\" or \"no\")");
                    if cread()=="yes" then
                        fs.delete(xtpath);
                    else
                        aprint("Move the non-XT file and try again");
                        error();
                    end
                end
                if downloadXT() then
                    cprint("XT V"..lastver.." downloaded");
                else
                    cerr("Couldn't download xt");
                    error();
                end
            end
        else
            if mybestver then
                cprint("Couldn't update, using offline version");
            else
                cerr("Couldn't download xt, and no offline version");
                error();
            end
        end
    end
    if loadedver then
        if myver and myver>loadedver then
            dofile(xtpath);
        end
    else
        dofile(xtpath);
    end
end