I have no clue where to start on this one. I would like to make a pastebin post and have a list of usernames and then somehow read it in-game. and if that player is on the list it will actually allow them to eg: open a GUI or anything like that.

I looked at the cape code awhile back but didn't see anything useful. I guess I'd be using an array and like ifplayername etc. I forgot the function. I am just getting back into modding so its all changed.

Pretty much:

Subscribe to events needed (GuiOpen event for example you provided).

Make event check if player has some permission, if not - cancel event.

Permission can be saved in some static Map<UUID, PlayerPermissions> where PlayerPermissions would be an object containing some perms that were read from file on server startup.

File can be a Forge Configuration or pretty much any other stream.

Since you (might) need interaction with permission on client-side, you will probably have to use packets to sync some of them via SimpleNetworkWrapper (google).

 

Note: You could also use IExtendedEntityProperties to save perms once player logs in. Would require some smart design since permission files should be read on startup and saved to memory (and during startup you don't have EntityPlayer so you have to still use some static map).

Just as an FYI:

If you plan on charging money for those features, in any way, it's illegal by Minecraft's EULA.

No no I won't be charging any money. its basically a mod with permissions. a private mod for a server so OP's can do only OP stuff with the mod.

The key point is that instead of using the players "name" you should use their UUID. That is more specific and persistent. After that, in your game have a map between UUIDs and functionality. And you can load information from a pastebin site using standard Java.

 

In Java, to read URLs you can do it this way (I would do it in a separate thread as shown because accessing files over internet could take time, also make sure to handle any errors):

 

public class PermissionChecker implements Runnable
{
    String fileContents = "";

    @Override
    public void run() 
    {
        InputStream in = null;
        try 
        {
            in = new URL("https:put_your_link_here").openStream();
        } 
        catch 
        (MalformedURLException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
        catch (IOException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        try 
        {
            fileContents = IOUtils.readLines(in).get(0); // toString(in);
        } 
        catch (IOException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
        finally 
        {
            IOUtils.closeQuietly(in);
        }
    }
    
    public String getFileContents()
    {
    	return fileContents;
    }
}

Then you need to write code to "parse" the string returned, and convert it to a map of UUID and permission levels. How you do that exactly is up to you.