use std::{
    env,
    fs::{read_dir, DirEntry},
    io,
    path::PathBuf,
    process::{Command, Stdio},
};

use crate::fs::resolve_link;

pub fn handle_session() -> io::Result<()> {
    println!(">>> Activating environment <<<");
    let generation = env::var("NIXGREETY_GENERATION").unwrap();
    Command::new(format!("{}/activate", generation))
        .status()
        .expect("Failed to activate environment");

    println!(">>> Creating session <<<");
    Command::new(format!("{}/session/init", generation))
        .status()
        .expect("Failed to create session");

    println!(">>> Deactivating environment <<<");
    let home = env::var("HOME").unwrap();
    let profile_path = PathBuf::from(format!("{}/.local/state/nix/profiles/", home));
    let mut generations: Vec<DirEntry> = read_dir(profile_path)
        .expect("Failed to gather home-manager generations")
        .flatten()
        .collect();
    generations.sort_by_key(|entry| entry.file_name());
    let generation = generations
        .into_iter()
        .rev()
        .filter(|entry| {
            entry
                .file_name()
                .to_string_lossy()
                .starts_with("home-manager-")
        })
        .find(|entry| {
            let entry_path = entry.path();
            let resolved_path = resolve_link(&entry_path);
            let specialisation_path = resolved_path.join("specialisation");
            specialisation_path.exists()
        })
        .map(|entry| entry.path())
        .unwrap_or(PathBuf::from(""));
    Command::new(format!("{}/activate", generation.display()))
        .status()
        .unwrap();

    Ok(())
}