//! The token lifetime of the agents' cert-auth roles that already exist.
//!
//! A role is written with its lifetimes only when an agent's certificate is
//! minted or renewed, and a role written before the lifetimes were set leaves
//! every login at the mount's default of 32 days, one store lease each. The
//! start pass in [`crate::read_policy`] calls [`bring_current`] so those roles
//! take [`swarm_secret_client::client::CERT_ROLE_TOKEN_TTL`] without waiting for
//! a renewal.
//!
//! Only the two lifetimes are written: the role's certificate, allowed names
//! and policies stay as they are, and no token or lease is revoked. Tokens
//! issued before expire on their own.

use swarm_secret_client::{client::DEFAULT_CERT_MOUNT, policy};

use crate::store::AccessStore;

/// What one pass did, one count per role.
#[derive(Debug, Default, PartialEq, Eq)]
pub struct Counts {
    pub rewritten: usize,
    pub already_current: usize,
    pub failed: usize,
}

/// Give every agent role among `roles`, a listing of the cert mount's roles,
/// the current token lifetimes, and log the counts once.
///
/// A role that cannot be read or written is named in a warning and skipped, so
/// it never stops the rest or the start. A role gone since the listing is
/// counted nowhere: there is nothing left to bring current.
pub async fn bring_current(store: &impl AccessStore, roles: &[String]) -> Counts {
    let mut counts = Counts::default();
    for agent in policy::agents_from_role_names(roles) {
        let Ok(role) = policy::agent_object_name(&agent) else {
            continue;
        };
        match bring_one(store, &role).await {
            Ok(Outcome::Rewritten) => counts.rewritten += 1,
            Ok(Outcome::AlreadyCurrent) => counts.already_current += 1,
            Ok(Outcome::Gone) => {}
            Err(e) => {
                counts.failed += 1;
                tracing::warn!(role, error = %e, "this agent role's token lifetime could not be brought current");
            }
        }
    }
    tracing::info!(
        rewritten = counts.rewritten,
        already_current = counts.already_current,
        failed = counts.failed,
        "agent role token lifetimes checked"
    );
    counts
}

enum Outcome {
    Rewritten,
    AlreadyCurrent,
    Gone,
}

async fn bring_one(
    store: &impl AccessStore,
    role: &str,
) -> Result<Outcome, swarm_secret_client::Error> {
    let Some(ttls) = store.cert_role_token_ttls(DEFAULT_CERT_MOUNT, role).await? else {
        return Ok(Outcome::Gone);
    };
    if ttls.is_current() {
        return Ok(Outcome::AlreadyCurrent);
    }
    store
        .set_cert_role_token_ttls(DEFAULT_CERT_MOUNT, role)
        .await?;
    Ok(Outcome::Rewritten)
}

#[cfg(test)]
mod tests {
    use swarm_secret_client::client::{CERT_ROLE_TOKEN_TTL_SECS, CertRoleTokenTtls};

    use crate::store::fake::{FakeAccess, FakeRole};

    use super::{Counts, bring_current};

    const CURRENT: CertRoleTokenTtls = CertRoleTokenTtls {
        token_ttl: CERT_ROLE_TOKEN_TTL_SECS,
        token_max_ttl: CERT_ROLE_TOKEN_TTL_SECS,
    };
    const STALE: CertRoleTokenTtls = CertRoleTokenTtls {
        token_ttl: 0,
        token_max_ttl: 0,
    };

    fn role(agent: &str, ttls: CertRoleTokenTtls) -> FakeRole {
        FakeRole {
            certificate: format!("CA-{agent}"),
            common_name: format!("hive-agent-{agent}"),
            policies: vec!["hive-agent".to_owned()],
            ttls,
        }
    }

    fn listing(agents: &[&str]) -> Vec<String> {
        agents.iter().map(|a| format!("hive-agent-{a}")).collect()
    }

    #[tokio::test]
    async fn a_stale_role_takes_the_ttl_and_keeps_its_certificate_names_and_policies() {
        let before = role("a", STALE);
        let store = FakeAccess::default().with_role("hive-agent-a", before.clone());
        let counts = bring_current(&store, &listing(&["a"])).await;
        assert_eq!(
            counts,
            Counts {
                rewritten: 1,
                ..Counts::default()
            }
        );
        assert_eq!(
            store.role("hive-agent-a"),
            Some(FakeRole {
                ttls: CURRENT,
                ..before
            })
        );
    }

    #[tokio::test]
    async fn a_role_with_a_lifetime_unset_or_different_is_rewritten() {
        let store = FakeAccess::default()
            .with_role(
                "hive-agent-a",
                role(
                    "a",
                    CertRoleTokenTtls {
                        token_ttl: CERT_ROLE_TOKEN_TTL_SECS,
                        token_max_ttl: 0,
                    },
                ),
            )
            .with_role(
                "hive-agent-b",
                role(
                    "b",
                    CertRoleTokenTtls {
                        token_ttl: 900,
                        token_max_ttl: 900,
                    },
                ),
            );
        let counts = bring_current(&store, &listing(&["a", "b"])).await;
        assert_eq!(counts.rewritten, 2);
        assert_eq!(store.role("hive-agent-a").expect("kept").ttls, CURRENT);
        assert_eq!(store.role("hive-agent-b").expect("kept").ttls, CURRENT);
    }

    #[tokio::test]
    async fn a_current_role_is_read_and_not_written() {
        let store = FakeAccess::default().with_role("hive-agent-a", role("a", CURRENT));
        let counts = bring_current(&store, &listing(&["a"])).await;
        assert_eq!(
            counts,
            Counts {
                already_current: 1,
                ..Counts::default()
            }
        );
        assert_eq!(store.calls(), ["cert_role_token_ttls hive-agent-a"]);
    }

    #[tokio::test]
    async fn a_role_that_fails_does_not_stop_the_others() {
        let store = FakeAccess::default()
            .with_role("hive-agent-a", role("a", STALE))
            .with_role("hive-agent-b", role("b", STALE))
            .with_role("hive-agent-c", role("c", STALE))
            .with_role("hive-agent-d", role("d", CURRENT))
            .with_unreadable_role("hive-agent-a")
            .with_unwritable_role("hive-agent-b");
        let counts = bring_current(&store, &listing(&["a", "b", "c", "d"])).await;
        assert_eq!(
            counts,
            Counts {
                rewritten: 1,
                already_current: 1,
                failed: 2,
            }
        );
        // The ones after the failures were still handled.
        assert_eq!(store.role("hive-agent-c").expect("kept").ttls, CURRENT);
        // The failed ones were left as they were.
        assert_eq!(store.role("hive-agent-a").expect("kept").ttls, STALE);
        assert_eq!(store.role("hive-agent-b").expect("kept").ttls, STALE);
    }

    #[tokio::test]
    async fn only_agent_roles_are_touched() {
        let store = FakeAccess::default()
            .with_role("hive-agent-a", role("a", STALE))
            .with_role("hive-pr1ma", role("pr1ma", STALE))
            .with_role("swarm-controller", role("c", STALE));
        let roles = vec![
            "hive-agent-a".to_owned(),
            "hive-pr1ma".to_owned(),
            "swarm-controller".to_owned(),
        ];
        let counts = bring_current(&store, &roles).await;
        assert_eq!(counts.rewritten, 1);
        assert_eq!(store.role("hive-agent-a").expect("kept").ttls, CURRENT);
        assert_eq!(store.role("hive-pr1ma").expect("kept").ttls, STALE);
        assert_eq!(store.role("swarm-controller").expect("kept").ttls, STALE);
    }

    #[tokio::test]
    async fn a_role_gone_since_the_listing_is_counted_nowhere() {
        let store = FakeAccess::default().with_role("hive-agent-b", role("b", STALE));
        let counts = bring_current(&store, &listing(&["a", "b"])).await;
        assert_eq!(
            counts,
            Counts {
                rewritten: 1,
                ..Counts::default()
            }
        );
        assert!(
            !store
                .calls()
                .contains(&"set_cert_role_token_ttls hive-agent-a".to_owned())
        );
    }
}