//! hive-ci Forgejo Actions runner registration, driven from hive-c0re.
//!
//! Moves the runner-registration forge round-trip OFF the container's
//! boot-critical path (it was a host-side `hive-ci-prefetch` oneshot that
//! gated `container@hive-ci` start — see `nix/host-modules/hive-ci.nix`).
//! hive-c0re holds the forge admin token; here it validates the runner's
//! existing credentials and, when they're absent or stale, mints a fresh
//! registration token and hands it to hive-priv, which writes it to the host
//! env-file the container bind-mounts read-only and restarts the in-container
//! runner. The admin token never enters the container — only the registration
//! token does, exactly as the prefetch did.

use anyhow::{Context as _, Result};
use serde_json::Value;

use super::forge_http_base;

/// Host path to the hive-ci runner's persisted credentials. The container is
/// non-ephemeral, so `.runner` survives restarts; a present file with a sane
/// `id` means the runner is already registered.
const RUNNER_FILE: &str = "/var/lib/nixos-containers/hive-ci/var/lib/gitea-runner/hive/.runner";

/// Whether the operator enabled the CI runner. The nix module sets
/// `HYPERHIVE_FORGE_CI_ENABLED=1` on `hive-c0re.service` when
/// `services.hyperhive.forge.ci.enable` is on; absent means CI is off and
/// there is no hive-ci container to register a runner for.
fn ci_enabled() -> bool {
    std::env::var("HYPERHIVE_FORGE_CI_ENABLED")
        .is_ok_and(|v| v == "1" || v.eq_ignore_ascii_case("true"))
}

/// Ensure the hive-ci runner is registered against the forge. Best-effort:
/// every failure is logged and swallowed so it never aborts the startup
/// sweep ([`super::ensure_all`]). No-op when CI is disabled or the runner
/// already holds valid credentials (so a healthy runner is never restarted).
pub(super) async fn ensure_ci_runner_registered(core_token: &str) {
    if !ci_enabled() {
        return;
    }
    // Existing creds still valid on the forge → nothing to do.
    if let Some(id) = existing_runner_id()
        && runner_valid(core_token, id).await
    {
        return;
    }
    // Absent or stale → mint a fresh registration token and hand it to
    // hive-priv (root) to write the env-file + restart the runner.
    match fetch_registration_token(core_token).await {
        Ok(token) => {
            if let Err(e) = crate::priv_client::register_ci_runner(&token).await {
                tracing::warn!(error = ?e, "ci runner: hive-priv register_ci_runner failed");
                crate::warnings::set_boot_warning(
                    "ci_runner_register",
                    "crit",
                    format!("ci runner: hive-priv register_ci_runner failed: {e}"),
                );
            } else {
                tracing::info!("ci runner: registered hive-ci runner with a fresh token");
            }
        }
        Err(e) => {
            tracing::warn!(error = ?e, "ci runner: fetch registration token failed");
            crate::warnings::set_boot_warning(
                "ci_runner_fetch_token",
                "crit",
                format!("ci runner: fetch registration token failed: {e}"),
            );
        }
    }
}

/// Parse the runner id from the persisted `.runner` JSON, if present and sane
/// (a `0` id is the gitea-runner "unregistered" sentinel).
fn existing_runner_id() -> Option<u64> {
    let raw = std::fs::read_to_string(RUNNER_FILE).ok()?;
    let json: Value = serde_json::from_str(&raw).ok()?;
    let id = json.get("id")?.as_u64()?;
    (id != 0).then_some(id)
}

/// `GET /admin/runners/{id}` — `true` iff the runner still exists on the forge
/// (HTTP 200). A 404 (deleted from the admin panel) or any other status means
/// re-registration is needed. A transport error (forge unreachable) is treated
/// as "keep the existing creds" so a network blip never wipes a valid runner.
async fn runner_valid(core_token: &str, id: u64) -> bool {
    let url = format!("{}/api/v1/admin/runners/{id}", forge_http_base());
    match reqwest::Client::new()
        .get(&url)
        .header("Authorization", format!("token {core_token}"))
        .send()
        .await
    {
        Ok(resp) => resp.status().is_success(),
        Err(e) => {
            tracing::warn!(error = ?e, "ci runner: validation request failed; keeping existing creds");
            true
        }
    }
}

/// `GET /admin/runners/registration-token` — mint a fresh registration token.
/// forgejo-api (0.11) doesn't wrap this endpoint, so this is a raw request
/// against the local HTTP forge ([`forge_http_base`]), mirroring the prefetch's
/// former curl; Forgejo accepts `Authorization: token <admin>`.
async fn fetch_registration_token(core_token: &str) -> Result<String> {
    let url = format!(
        "{}/api/v1/admin/runners/registration-token",
        forge_http_base()
    );
    let resp = reqwest::Client::new()
        .get(&url)
        .header("Authorization", format!("token {core_token}"))
        .send()
        .await
        .context("GET admin/runners/registration-token")?;
    let status = resp.status();
    let json: Value = resp
        .json()
        .await
        .context("parse registration-token response")?;
    if !status.is_success() {
        anyhow::bail!("registration-token HTTP {status}: {json}");
    }
    json.get("token")
        .and_then(Value::as_str)
        .map(str::to_owned)
        .context("registration-token response missing 'token' field")
}