//! Container-lifecycle request handlers (`Start` / `Restart` / `Kill` /
//! `Update` / `ListDescendants`), including the capability-gated
//! infra-container restart path. All are topology-guarded via
//! `super::require_descendant`.

use std::sync::Arc;

use hive_sh4re::AgentResponse;

use super::require_descendant;
use crate::coordinator::Coordinator;

/// `Start` — start a container, kicking its next turn. The caller must be an
/// ancestor of `name` in the topology (the root covers every agent).
pub(super) async fn handle_start(
    coord: &Arc<Coordinator>,
    agent: &str,
    name: &str,
) -> AgentResponse {
    if let Some(err) = require_descendant(agent, name, "start") {
        return err;
    }
    tracing::info!(%agent, %name, "start container");
    // Persist `wanted = Up` and submit the Start DAG; the submit layer
    // upgrades a stale-rev start to a full rebuild so the container
    // runs current nix derivations before it starts.
    crate::job_queue::submit::start(
        coord,
        name,
        crate::job_queue::Source::Manual,
        format!("agent `{agent}` start tool"),
    )
    .await;
    AgentResponse::Ok
}

/// `Restart` — enqueue a restart for a container. The caller must be an
/// ancestor of `name` in the topology. The infra-container branch is
/// orthogonal: it is gated on the `infra_admin` capability and audited, so it
/// stays ahead of the topology guard.
pub(super) async fn handle_restart(
    coord: &Arc<Coordinator>,
    agent: &str,
    name: &str,
) -> AgentResponse {
    // Infra-container restart: an agent holding the `infra_admin`
    // capability can restart a hive infrastructure container (hive-ci /
    // hive-gateway / hive-forge / hive-matrix) by passing its name to the
    // same restart tool. The `InfraContainer` enum parse both recognises
    // these (never agent children, so disjoint from the child path below)
    // and yields the typed value the restart path needs.
    if let Ok(container) = name.parse::<hive_priv_sock::InfraContainer>() {
        return handle_restart_infra(coord, agent, container).await;
    }
    if let Some(err) = require_descendant(agent, name, "restart") {
        return err;
    }
    tracing::info!(%agent, %name, "submit restart");
    crate::job_queue::submit::restart(
        coord,
        name,
        crate::job_queue::Source::Manual,
        format!("agent `{agent}` restart tool"),
    )
    .await;
    AgentResponse::Ok
}

/// Restart a hive infrastructure container on behalf of an agent that
/// holds the `infra_admin` capability. The `container` is already a valid
/// [`InfraContainer`] (the caller parsed it); this gates on the capability
/// and routes the systemctl restart through hive-priv. Direct, not
/// approval-gated.
async fn handle_restart_infra(
    coord: &Arc<Coordinator>,
    agent: &str,
    container: hive_priv_sock::InfraContainer,
) -> AgentResponse {
    let name = container.unit_name();
    // Record the attempt in the operator-visible privileged-action audit
    // trail, then emit a live `AuditEntryAdded` so the dashboard audit view
    // appends it off `/dashboard/stream`. Best-effort: `record` returns the
    // canonical row (or `None` on a sqlite blip), and we stream exactly that
    // row so the stored + streamed views can't drift. `action` is stable so
    // the dashboard can group/filter.
    let audit = |outcome: crate::audit_log::AuditOutcome, detail: Option<&str>| {
        if let Some(entry) = coord
            .audit_log
            .record(agent, "restart_infra", name, outcome, detail)
        {
            coord.emit_audit_entry(entry);
        }
    };
    if !crate::capabilities::has_cap(agent, hive_sh4re::Capability::InfraAdmin) {
        tracing::warn!(%agent, %name, "agent: infra restart denied (no infra_admin capability)");
        audit(
            crate::audit_log::AuditOutcome::Err,
            Some("denied: missing infra_admin capability"),
        );
        return AgentResponse::Err {
            message: format!(
                "restarting infra container `{name}` requires the `infra_admin` capability"
            ),
        };
    }
    tracing::info!(%agent, %name, "agent: restart infra container");
    match crate::priv_client::restart_infra_container(container).await {
        Ok(()) => {
            audit(crate::audit_log::AuditOutcome::Ok, None);
            AgentResponse::Ok
        }
        Err(e) => {
            let msg = format!("{e:#}");
            audit(crate::audit_log::AuditOutcome::Err, Some(&msg));
            AgentResponse::Err { message: msg }
        }
    }
}

/// `Kill` — kill a container, unregister it, notify the manager. The caller
/// must be an ancestor of `name` in the topology.
pub(super) async fn handle_kill(
    coord: &Arc<Coordinator>,
    agent: &str,
    name: &str,
) -> AgentResponse {
    if let Some(err) = require_descendant(agent, name, "kill") {
        return err;
    }
    tracing::info!(%agent, %name, "kill container");
    // Persist the intent even if the kill fails — otherwise the next
    // reconcile would restart the container.
    if let Err(e) = coord.power.set(name, crate::power::Wanted::Offline) {
        tracing::warn!(%name, error = ?e, "agent_power: set wanted=offline failed");
    }
    let result: anyhow::Result<()> = async {
        crate::lifecycle::kill(name).await?;
        coord.unregister_agent(name);
        Ok(())
    }
    .await;
    match result {
        Ok(()) => {
            coord.notify_manager(&hive_sh4re::HelperEvent::Killed {
                agent: name.to_owned(),
            });
            AgentResponse::Ok
        }
        Err(e) => AgentResponse::Err {
            message: format!("{e:#}"),
        },
    }
}

/// `Update` — enqueue a rebuild for a container. The caller must be an
/// ancestor of `name` in the topology.
pub(super) fn handle_update(coord: &Arc<Coordinator>, agent: &str, name: &str) -> AgentResponse {
    if let Some(err) = require_descendant(agent, name, "rebuild") {
        return err;
    }
    tracing::info!(%agent, %name, "submit rebuild");
    crate::job_queue::submit::rebuild(
        coord,
        name,
        crate::job_queue::Source::Manual,
        format!("agent `{agent}` update tool"),
    );
    AgentResponse::Ok
}

/// `ListDescendants` — every topological descendant of `agent` with
/// its running/stopped state, parents before children.
pub(super) async fn handle_list_descendants(agent: &str) -> AgentResponse {
    tracing::debug!(%agent, "agent: list descendants");
    // All containers known to nixos-container (running only).
    let running_set: std::collections::HashSet<String> = match crate::lifecycle::list().await {
        Ok(names) => names
            .into_iter()
            .filter_map(|c| {
                c.strip_prefix(crate::lifecycle::AGENT_PREFIX)
                    .map(str::to_owned)
            })
            .collect(),
        Err(e) => {
            return AgentResponse::Err {
                message: format!("list containers failed: {e:#}"),
            };
        }
    };
    // Walk the full topology and collect every descendant.
    let topo = crate::topology::read();
    let mut names: Vec<String> = topo
        .keys()
        .filter(|name| crate::topology::is_descendant_of(name, agent))
        .cloned()
        .collect();
    // Parents before children, then alpha within each tier.
    crate::auto_update::topology_sort(&mut names, &topo);
    let containers = names
        .into_iter()
        .map(|name| {
            let running = running_set.contains(&name);
            hive_sh4re::ContainerInfo { name, running }
        })
        .collect();
    AgentResponse::Containers { containers }
}