use std::fs::create_dir;
use std::io::{Result, ErrorKind};
use std::fs::File;
use crate::namespace::consts::{
    NET_NS_DIR,
    PROC_NS_DIR
};
use nix::mount::{
    mount,
    MsFlags
};

pub fn create_ns() -> Result<()> {
    create_ns_dir()?;
    let nsdir = format!("{}/{}",NET_NS_DIR,"fake-net");
    File::create(nsdir.clone())?;
    bind_ns_file(nsdir)?;
    Ok(())
}

fn create_ns_dir() -> Result<()> {
    match create_dir(NET_NS_DIR) {
        Err(e) if e.kind() != ErrorKind::AlreadyExists => {
            Err(e)
        },
        _ => {
            Ok(())
        },
    }
}

fn bind_ns_file(ns_file: String) -> Result<()> {
    match create_mount(ns_file) {
        Ok(_mount) => {
            Ok(())
        },
        Err(e) => Err(e),
    }
}

fn create_mount(ns_file: String) -> Result<()> {
    Ok(mount::<str, str, str, str>(Some(PROC_NS_DIR), ns_file.as_str(), None, MsFlags::MS_BIND, None)?)
}