use std::time::SystemTime;
use serde_json::Value;
use crate::secure;


const PERSIST_TIME:         u64 = 60 * 3;
const PERSIST_PATH:         &str = "/var/run/crab";


/// Returns true or false if a user is currently persisted from
/// a prior authentication. If the persist file had been tampered
/// with, or not trusted, it will be ignored, and return false.
/// #### Arguments
/// * `user` - The user to check if is persisted
/// #### Returns
/// * `true` - If the user is persisted
/// * `false` - If the user is not persisted, or if the persist file is not trusted
pub fn get_persist(user: &str) -> bool {
  let json = match get_persist_config() {
      Some(data) => data,
      None => return false
  };
  let timestamp = match json[user].as_u64() {
      Some(data) => data,
      None => return false
  };
  return now() - timestamp < PERSIST_TIME && timestamp - 1 < now();
}


/// Updates the current sessions persist file
/// #### Arguments
/// * `user` - The user to set persisted
pub fn set_persist(user: &str) {
  let mut json = match get_persist_config() {
      Some(data) => data,
      None => return
  };
  json[user] = Value::from(now());
  let session = match get_current_session() {
      Some(data) => data,
      None => return
  };
  match secure::write_file(PERSIST_PATH, &format!("{}", session), &json.to_string())  {
    Ok(_) => {},
    Err(e) => {
        eprintln!("crab: An Internal Has Error: {}", e);
    }
  };
}


/// Gets the current session that crab is running in
/// #### Returns
/// * `None` - If crab failed to get the current session
/// * `Some(i32)` - If the session is retrieved, returns the i32/pid_t session id
fn get_current_session() -> Option<i32> {
  let pid: i32 = match std::process::id().try_into() {
      Ok(data) => data,
      Err(_) => return None
  };
  let pid_stat = match procinfo::pid::stat(pid) {
      Ok(data) => data,
      Err(_) => return None
  };
  Some(pid_stat.session)
}


/// Gets the current persist file for the current session
/// #### Returns
/// * `None` - If the persist file is untrusted or doesnt exist
/// * `Some(Value)` - If the persist file is retrieved, returns the serde_json Value of the file
fn get_persist_config() -> Option<Value> {
  let session = match get_current_session() {
      Some(data) => data,
      None => return None
  };
  let data = match secure::read_file(PERSIST_PATH, &format!("{}", session)) {
      Some(data) => data,
      None => {
        "{}".to_string()
      }
  };
  let json: Value = match serde_json::from_str(&data) {
      Ok(data) => data,
      Err(_) => return None
  };
  Some(json)
}


// Gets the current time in seconds since the Unix Epoch
fn now() -> u64 {
  return SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
}