use std::{
    collections::HashSet,
    fs::File,
    io::{BufRead, BufReader},
};

use directories::UserDirs;

use crate::{Session, SessionSource};

pub struct KnownHosts;

impl KnownHosts {
    pub fn new() -> Self {
        Self
    }
}

impl SessionSource for KnownHosts {
    type Error = std::io::Error;

    type Iter = Vec<Session>;

    fn sessions(&self) -> Result<Self::Iter, Self::Error> {
        let path = UserDirs::new()
            .ok_or(std::io::ErrorKind::NotFound)?
            .home_dir()
            .join(".ssh/known_hosts");

        let reader = BufReader::new(File::open(path)?);

        let sessions: Vec<Session> = reader
            .lines()
            .flatten()
            .filter_map(|s| s.split_whitespace().next().map(str::to_owned))
            .collect::<HashSet<String>>()
            .into_iter()
            .map(Session::from)
            .collect();

        Ok(sessions)
    }
}

impl Default for KnownHosts {
    fn default() -> Self {
        Self::new()
    }
}