//! The per-agent closure KV bucket: one key per agent, holding the latest
//! system closure the swarm builder built for it from the swarm meta flake.
//!
//! **swarm-controller is the only writer**, and creates the bucket on its first
//! write. It writes a key from a builder's `Built` reply and from nothing else,
//! so a failed build leaves the previous record in place. The builder holds no
//! grant on this bucket.
//!
//! Keyed by the agent alone, like [`crate::agent_limits`]: an agent can move
//! between hives, and its closure goes with it.

/// The KV bucket closures are recorded in, keyed by agent name.
pub const BUCKET: &str = "agent-closures";

/// The stream backing [`BUCKET`]. `create_key_value` prefixes `KV_`.
pub const STREAM: &str = "KV_agent-closures";

/// The subject `agent`'s entry is stored under.
#[must_use]
pub fn key_subject(agent: &str) -> String {
    format!("$KV.{BUCKET}.{agent}")
}

/// One agent's latest green build: the value under `BUCKET`/`<agent>`.
#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub struct AgentClosure {
    /// The `internal/meta` commit the closure was built from.
    pub meta_rev: String,
    /// The system closure's store path, in the builder host's store.
    pub store_path: String,
    /// The platform the closure was built for.
    pub system: String,
    /// When the controller recorded the build, in unix seconds.
    pub built_unix: i64,
}

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

    #[test]
    fn names_are_pinned() {
        assert_eq!(STREAM, format!("KV_{BUCKET}"));
        assert_eq!(key_subject("iris"), "$KV.agent-closures.iris");
    }

    #[test]
    fn the_record_serializes_as_pinned() {
        let value = AgentClosure {
            meta_rev: "abc".to_owned(),
            store_path: "/nix/store/x".to_owned(),
            system: "x86_64-linux".to_owned(),
            built_unix: 7,
        };
        let wire = serde_json::json!({
            "meta_rev": "abc",
            "store_path": "/nix/store/x",
            "system": "x86_64-linux",
            "built_unix": 7,
        });
        assert_eq!(serde_json::to_value(&value).expect("encodes"), wire);
        assert_eq!(
            serde_json::from_value::<AgentClosure>(wire).expect("decodes"),
            value
        );
    }
}