Nginx rewrite parameter "p" to "page" using Lua

vhost.conf

server {
    ...

    rewrite_by_lua '
        -- get query args
        local args = ngx.req.get_uri_args()
 
        if args.p ~= nil then
            args.page = args.p
            args.p    = nil
             
            -- perform redirect
            -- @see http://wiki.nginx.org/HttpLuaModule#ngx.redirect
            -- @see http://wiki.nginx.org/HttpLuaModule#HTTP_status_constants
            ngx.redirect((ngx.var.uri or "/") .. (ngx.var.is_args or "") .. ngx.encode_args(args), ngx.HTTP_MOVED_PERMANENTLY)
         end
     ';

    ...
}