//! systemctl + dpkg-query helpers for the FIPS daemon.
//!
//! Read-only queries (`is-active`, `--version`, `dpkg-query`) run as the
//! archipelago service user. Write operations (`unmask`, `start`, `stop`,
//! `restart`) go through `sudo`, matching the pattern established in
//! `src/vpn.rs` and `src/api/rpc/vpn.rs`. The sudoers rule shipped in the
//! ISO whitelists exactly these invocations.

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

/// `systemctl is-active <unit>` → "active" / "inactive" / "failed" / "masked"
/// / "unknown". Never errors; returns "unknown" on any failure.
pub async fn unit_state(unit: &str) -> String {
    match Command::new("systemctl")
        .args(["is-active", unit])
        .output()
        .await
    {
        Ok(out) => {
            let s = String::from_utf8_lossy(&out.stdout).trim().to_string();
            if s.is_empty() {
                "unknown".to_string()
            } else {
                s
            }
        }
        Err(_) => "unknown".to_string(),
    }
}

/// Whether the `fips` debian package is installed on the host.
pub async fn package_installed() -> bool {
    // dpkg-query -W -f='${Status}' fips → "install ok installed" when present.
    let out = Command::new("dpkg-query")
        .args(["-W", "-f=${Status}", "fips"])
        .output()
        .await;
    match out {
        Ok(o) if o.status.success() => {
            String::from_utf8_lossy(&o.stdout).contains("install ok installed")
        }
        _ => false,
    }
}

/// `fipsctl --version` output stripped of the "fipsctl " prefix if present.
pub async fn daemon_version() -> Result<String> {
    let out = Command::new("fipsctl")
        .arg("--version")
        .output()
        .await
        .context("fipsctl --version failed to launch")?;
    if !out.status.success() {
        anyhow::bail!("fipsctl exited with non-zero status");
    }
    let raw = String::from_utf8_lossy(&out.stdout).trim().to_string();
    Ok(raw
        .strip_prefix("fipsctl ")
        .map(|s| s.to_string())
        .unwrap_or(raw))
}

/// `sudo systemctl <verb> <unit>` — returns stderr on non-zero exit.
async fn sudo_systemctl(verb: &str, unit: &str) -> Result<()> {
    let out = Command::new("sudo")
        .args(["systemctl", verb, unit])
        .output()
        .await
        .with_context(|| format!("sudo systemctl {} {} failed to launch", verb, unit))?;
    if !out.status.success() {
        let stderr = String::from_utf8_lossy(&out.stderr).trim().to_string();
        anyhow::bail!("systemctl {} {}: {}", verb, unit, stderr);
    }
    Ok(())
}

/// Unmask + start + enable the FIPS service. Idempotent — safe to call
/// on every backend startup once the key is on disk.
pub async fn activate(unit: &str) -> Result<()> {
    // Order matters: unmask before enable/start, otherwise enable fails
    // on a masked unit.
    sudo_systemctl("unmask", unit).await?;
    sudo_systemctl("enable", unit).await?;
    sudo_systemctl("start", unit).await?;
    Ok(())
}

pub async fn stop(unit: &str) -> Result<()> {
    sudo_systemctl("stop", unit).await
}

pub async fn restart(unit: &str) -> Result<()> {
    sudo_systemctl("restart", unit).await
}

pub async fn mask(unit: &str) -> Result<()> {
    let _ = sudo_systemctl("stop", unit).await;
    let _ = sudo_systemctl("disable", unit).await;
    sudo_systemctl("mask", unit).await
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_unit_state_returns_string_for_bogus_unit() {
        // Nonexistent unit: systemctl returns "inactive" or "unknown" — we
        // just care that the helper doesn't panic and returns *something*.
        let s = unit_state("archipelago-bogus-test.service").await;
        assert!(!s.is_empty());
    }

    #[tokio::test]
    async fn test_package_installed_is_bool() {
        // Must not panic regardless of host state.
        let _ = package_installed().await;
    }
}