pub struct User {
    pub uid: u32,
    pub gid: u32,
    pub name: String,
}

pub struct UserDetail<'a> {
    pub user: &'a User,
    pub year: String,
    pub affilication: String,
}

impl<'a> UserDetail<'a> {
    pub fn new(user: &'a User) -> UserDetail {
        // e195730 -> 19
        let year = user.name.chars().skip(1).take(2).collect::<String>();
        // e195730 -> e19, tnal -> teacher
        let affilication = if year.parse::<u8>().is_ok() {
            user.name.chars().take(3).collect::<String>()
        } else {
            "teacher".to_string()
        };
        UserDetail {
            user,
            year,
            affilication,
        }
    }

    pub fn getpass(self) -> String {
        format!("{}/{}", self.affilication, &self.user.name)
    }
}

pub fn getlogin(uid: u32) -> String {
    use std::ffi::CStr;
    let user_passwd = unsafe { nix::libc::getpwuid(uid) };
    let c_str = unsafe { CStr::from_ptr((*user_passwd).pw_name) };
    c_str.to_str().unwrap().to_string()
}

pub fn getuid() -> u32 {
    let uid_struct = nix::unistd::getuid();
    uid_struct.into()
}

pub fn getgid() -> u32 {
    let gid_struct = nix::unistd::getgid();
    gid_struct.into()
}

const ROOT_ID: u32 = 0;

pub fn set_root_id() {
    if let Err(err) = nix::unistd::seteuid(nix::unistd::Uid::from_raw(ROOT_ID)) {
        panic!("failed seteuid {}", err)
    }
    if let Err(err) = nix::unistd::setegid(nix::unistd::Gid::from_raw(ROOT_ID)) {
        panic!("failed setedid{}", err)
    }
    if let Err(err) = nix::unistd::setuid(nix::unistd::Uid::from_raw(ROOT_ID)) {
        panic!("failed setuid {}", err)
    }
    if let Err(err) = nix::unistd::setgid(nix::unistd::Gid::from_raw(ROOT_ID)) {
        panic!("failed setdid{}", err)
    }
}