//! Loose-ends aggregator. Walks the `approvals` + `operator_questions`
//! tables once per call and assembles a `Vec<OpenThread>` for either
//! a single agent (`for_agent`) or the whole hive (`hive_wide`). Both
//! `AgentRequest::GetOpenThreads` and `ManagerRequest::GetOpenThreads`
//! land here so the routing logic + age-seconds derivation stay in
//! one place.
//!
//! Call frequency is low (an agent doing self-introspection between
//! turns), so the sweep happens fresh every time — no caching, no
//! mutation events. If the sweep ever shows up in a profile, the
//! sqlite queries already filter on the same indexes
//! (`idx_approvals_pending` + `idx_operator_questions_pending`) that
//! the dashboard uses, so the bottleneck would be json
//! (de)serialisation, not the read.

use std::time::{SystemTime, UNIX_EPOCH};

use anyhow::Result;
use hive_sh4re::{MANAGER_AGENT, OpenThread};

use crate::coordinator::Coordinator;

/// Open threads pending against `agent`:
/// - pending approvals where this agent is the submitter (only ever
///   true for the manager — sub-agents don't submit approvals — but
///   we keep the rule per-agent so the manager's MCP surface gets
///   the same shape via a different code path);
/// - unanswered questions where `agent` is the asker (waiting on
///   someone) OR the target (owes a reply).
///
/// Newest-first within each kind, approvals before questions.
pub fn for_agent(coord: &Coordinator, agent: &str) -> Result<Vec<OpenThread>> {
    let now = now_unix();
    let mut out = Vec::new();
    // Approvals are only submitted by the manager today. When that
    // expands (e.g. sub-agents propose changes to their own configs),
    // teach the approvals table to track the submitter and filter
    // here on that column — for now MANAGER_AGENT == sole submitter.
    if agent == MANAGER_AGENT {
        for a in coord.approvals.pending()? {
            out.push(OpenThread::Approval {
                id: a.id,
                agent: a.agent,
                commit_ref: a.commit_ref,
                description: a.description,
                age_seconds: saturating_age(now, a.requested_at),
            });
        }
    }
    for q in coord.questions.pending_all()? {
        let role_match = q.asker == agent || q.target.as_deref() == Some(agent);
        if !role_match {
            continue;
        }
        out.push(OpenThread::Question {
            id: q.id,
            asker: q.asker,
            target: q.target,
            question: q.question,
            age_seconds: saturating_age(now, q.asked_at),
        });
    }
    Ok(out)
}

/// Hive-wide loose-ends view: EVERY pending approval + EVERY
/// unanswered question. Manager surface only; sub-agents can't see
/// each other's threads via the agent surface (`for_agent` filters
/// by name).
pub fn hive_wide(coord: &Coordinator) -> Result<Vec<OpenThread>> {
    let now = now_unix();
    let mut out = Vec::new();
    for a in coord.approvals.pending()? {
        out.push(OpenThread::Approval {
            id: a.id,
            agent: a.agent,
            commit_ref: a.commit_ref,
            description: a.description,
            age_seconds: saturating_age(now, a.requested_at),
        });
    }
    for q in coord.questions.pending_all()? {
        out.push(OpenThread::Question {
            id: q.id,
            asker: q.asker,
            target: q.target,
            question: q.question,
            age_seconds: saturating_age(now, q.asked_at),
        });
    }
    Ok(out)
}

fn saturating_age(now: i64, then: i64) -> u64 {
    let delta = now.saturating_sub(then);
    u64::try_from(delta).unwrap_or(0)
}

fn now_unix() -> i64 {
    SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .ok()
        .and_then(|d| i64::try_from(d.as_secs()).ok())
        .unwrap_or(0)
}

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

    #[test]
    fn saturating_age_handles_clock_back_step() {
        // `now` < `then`: caller's clock went backwards between rows.
        // We saturate to 0 rather than returning a negative or
        // wrapping around to ~u64::MAX (which would render as "27
        // billion years ago" in the wake prompt).
        assert_eq!(saturating_age(100, 200), 0);
    }

    #[test]
    fn saturating_age_normal_case() {
        assert_eq!(saturating_age(1_000_000, 999_990), 10);
    }

    #[test]
    fn saturating_age_zero_when_equal() {
        assert_eq!(saturating_age(42, 42), 0);
    }
}