//! Each hive's sender account, `@hive-<hive>:`, on the swarm's homeserver:
//! created here with the **swarm's** appservice token and stored at
//! `swarm/hives/<hive>/matrix/sender-token`, where hive-c0re's matrix sweep
//! reads it under the hive's own store identity.
//!
//! Runs for every hive in the directory, local or remote, and decides the
//! same way [`super::agent_token`] does: a stored token that `whoami`
//! confirms as `@hive-<hive>:` is kept, so this writes only when the path is
//! empty or its token is dead.
//!
//! This is the only writer of that path: hive-c0re never mints, it takes
//! whatever the store holds.

use std::sync::Arc;

use anyhow::{Context, Result};
use swarm_matrix_client as homeserver;
use swarm_secret_client::matrix;

use super::agent_token::{Decision, Observed, appservice_token, classify, mint_at, plan, probe_at};

/// How often [`spawn`] re-checks every hive's sender token.
const RECONCILE_INTERVAL: std::time::Duration = std::time::Duration::from_mins(5);

/// Decide what to do about `hive`'s sender token from what the stored one is.
fn classify_hive(hive: &str, probe: &super::agent_token::Probe) -> Decision {
    classify(&matrix::hive_localpart(hive), probe)
}

/// Make sure `hive`'s sender account holds a live token in the store,
/// creating the account or logging in to it when it does not. The whole job
/// of the `MintHiveSenderToken` node.
///
/// # Errors
/// When the store or the homeserver refuses a step, the swarm appservice
/// token has not been published, or the new token authenticates as someone
/// else.
pub async fn ensure_hive_sender_token(base: &str, hive: &str) -> Result<()> {
    let store = crate::store::connect()
        .await
        .context("logging in to the swarm secret store")?;
    let as_token = appservice_token(&store).await?;
    let http = homeserver::client()?;
    let path = matrix::sender_token_path(hive)?;
    let reason = match classify_hive(hive, &probe_at(&store, &http, base, &path).await?) {
        Decision::Keep => {
            tracing::debug!(hive, "hive sender token is current; left as it is");
            return Ok(());
        }
        Decision::Mint(reason) => reason,
    };
    let localpart = matrix::hive_localpart(hive);
    mint_at(&store, &http, base, &localpart, &as_token, &path).await?;
    tracing::info!(hive, ?reason, %path, "hive sender token minted and stored");
    Ok(())
}

/// One pass: every hive in `hives`, observed.
///
/// Fails as a whole when the swarm appservice token is not published, for
/// the reason `agent_token`'s pass does.
async fn observe_all(base: &str, hives: &[String]) -> Result<Vec<(String, Observed)>> {
    let store = crate::store::connect()
        .await
        .context("logging in to the swarm secret store")?;
    appservice_token(&store).await?;
    let http = homeserver::client()?;
    let mut observed = Vec::with_capacity(hives.len());
    for hive in hives {
        let o = match matrix::sender_token_path(hive) {
            Ok(path) => match probe_at(&store, &http, base, &path).await {
                Ok(p) => Observed::Decided(classify_hive(hive, &p)),
                Err(e) => {
                    tracing::warn!(hive, error = %format!("{e:#}"), "hive sender token: read failed");
                    Observed::Unknown
                }
            },
            Err(e) => {
                tracing::warn!(hive, error = %e, "hive sender token: the hive name forms no store path");
                Observed::Unknown
            }
        };
        observed.push((hive.clone(), o));
    }
    Ok(observed)
}

/// Check every hive's sender token now and every [`RECONCILE_INTERVAL`]
/// after, and hand the hives that need one to `enqueue`, which inserts a
/// `MintHiveSenderToken` node for each.
///
/// The roster is the controller's hive directory. A pass that fails is
/// logged and retried on the next tick; it never stops the daemon.
pub fn spawn(base: Arc<str>, hives: Vec<String>, enqueue: impl Fn(Vec<String>) + Send + 'static) {
    tokio::spawn(async move {
        let mut ticker = tokio::time::interval(RECONCILE_INTERVAL);
        loop {
            ticker.tick().await;
            match observe_all(&base, &hives).await {
                Ok(observed) => {
                    let minting = plan(&observed);
                    if minting.is_empty() {
                        tracing::debug!(
                            checked = observed.len(),
                            "hive sender tokens: all current"
                        );
                    } else {
                        tracing::info!(
                            checked = observed.len(),
                            minting = minting.len(),
                            "hive sender tokens: queueing mints"
                        );
                        enqueue(minting);
                    }
                }
                Err(e) => tracing::warn!(
                    error = %format!("{e:#}"),
                    retry_in_s = RECONCILE_INTERVAL.as_secs(),
                    "hive sender tokens: pass failed; retrying next tick"
                ),
            }
        }
    });
}

#[cfg(test)]
mod tests {
    use super::super::agent_token::{MintReason, Probe};
    use super::*;
    use swarm_matrix_client::Whoami;

    fn user(id: &str) -> Probe {
        Probe::Whoami(Whoami::User(id.to_owned()))
    }

    #[test]
    fn a_live_token_for_the_hive_account_is_kept() {
        assert_eq!(
            classify_hive("pr1ma", &user("@hive-pr1ma:t.local")),
            Decision::Keep
        );
    }

    #[test]
    fn nothing_stored_mints() {
        // A hive whose homeserver is remote: nothing has ever written its path.
        assert_eq!(
            classify_hive("pr1ma", &Probe::NotStored),
            Decision::Mint(MintReason::NotStored)
        );
    }

    #[test]
    fn a_dead_token_mints() {
        // A token the homeserver revoked, or a device a manual login replaced.
        assert_eq!(
            classify_hive("pr1ma", &Probe::Whoami(Whoami::UnknownToken)),
            Decision::Mint(MintReason::Revoked)
        );
    }

    #[test]
    fn a_token_for_another_account_mints() {
        // The bare hive name is an agent's localpart, not the hive's account,
        // and another hive's account is not this one's.
        for other in ["@pr1ma:t.local", "@hive-beta:t.local", "@hive:t.local"] {
            assert_eq!(
                classify_hive("pr1ma", &user(other)),
                Decision::Mint(MintReason::OtherUser),
                "{other}"
            );
        }
    }

    #[test]
    fn an_outage_plans_nothing() {
        // A mint replaces the token the hive is running on, so a pass that
        // could not read must not mint for every hive.
        let observed = [
            ("alpha".to_owned(), Observed::Unknown),
            ("beta".to_owned(), Observed::Unknown),
        ];
        assert!(plan(&observed).is_empty());
    }

    #[test]
    fn the_published_path_is_the_one_the_hive_reads() {
        // hive-c0re's `stored_sender_token` resolves this path; the literal is
        // what the bao grant names.
        assert_eq!(
            matrix::sender_token_path("pr1ma").expect("a plain name is legal"),
            "swarm/hives/pr1ma/matrix/sender-token"
        );
    }
}