//! Thin async wrappers over `nixos-container`.

use std::path::Path;

use anyhow::{Context, Result, bail};
use tokio::process::Command;

pub const AGENT_PREFIX: &str = "hive-agent-";
pub const HIVE_PREFIX: &str = "hive-";

/// Mount point of the per-agent runtime directory inside the container.
pub const CONTAINER_RUNTIME_MOUNT: &str = "/run/hive";

pub fn container_name(name: &str) -> String {
    format!("{AGENT_PREFIX}{name}")
}

pub async fn spawn(name: &str, agent_flake: &str, agent_dir: &Path) -> Result<()> {
    let container = container_name(name);
    let bind = format!("{}:{CONTAINER_RUNTIME_MOUNT}", agent_dir.display());
    run(&["create", &container, "--flake", agent_flake, "--bind", &bind]).await?;
    run(&["start", &container]).await
}

pub async fn kill(name: &str) -> Result<()> {
    let container = container_name(name);
    run(&["stop", &container]).await
}

pub async fn rebuild(name: &str, agent_flake: &str) -> Result<()> {
    let container = container_name(name);
    run(&["update", &container, "--flake", agent_flake]).await
}

pub async fn list() -> Result<Vec<String>> {
    let out = Command::new("nixos-container")
        .arg("list")
        .output()
        .await
        .context("invoke nixos-container list")?;
    if !out.status.success() {
        bail!(
            "nixos-container list exited with status {}: {}",
            out.status,
            String::from_utf8_lossy(&out.stderr).trim()
        );
    }
    Ok(String::from_utf8_lossy(&out.stdout)
        .lines()
        .map(str::trim)
        .filter(|line| line.starts_with(HIVE_PREFIX))
        .map(str::to_owned)
        .collect())
}

async fn run(args: &[&str]) -> Result<()> {
    let status = Command::new("nixos-container")
        .args(args)
        .status()
        .await
        .with_context(|| format!("invoke nixos-container {}", args.join(" ")))?;
    if !status.success() {
        bail!("nixos-container {} exited with {status}", args.join(" "));
    }
    Ok(())
}