//! Formatting / render helpers for the MCP tool surface: ack / recv /
//! loose-end / agent-meta reply shaping plus the retry annotation.
//! Stateless string builders, with one exception —
//! [`matrix_unread_summary`] queries the local matrix daemon socket
//! (best-effort) so `get_loose_ends` can prepend an unread-rooms entry.

/// Render the three identical failure arms every data-returning tool handler
/// repeats: a broker `Err` → `"{tool} failed: {m}"`, an unexpected `Ok` variant
/// → `"{tool} unexpected response: …"`, and a transport error → `"{tool}
/// transport error: …"`. Handlers match their own happy-path variant and route
/// everything else here via a catch-all arm (`other => reply_err(other, tool)`),
/// so the triplet lives in exactly one place.
pub(super) fn reply_err(resp: Result<hive_sh4re::Response, anyhow::Error>, tool: &str) -> String {
    match resp {
        Ok(hive_sh4re::Response::Err { message }) => format!("{tool} failed: {message}"),
        Ok(other) => format!("{tool} unexpected response: {other:?}"),
        Err(e) => format!("{tool} transport error: {e:#}"),
    }
}

/// Format helper for "send-like" tools (anything that expects an `Ok`).
/// `tool` and `ok_msg` only appear in the result string; they don't change
/// behavior.
#[must_use]
pub fn format_ack(
    resp: Result<hive_sh4re::Response, anyhow::Error>,
    tool: &str,
    ok_msg: String,
) -> String {
    match resp {
        Ok(hive_sh4re::Response::Ok) => ok_msg,
        other => reply_err(other, tool),
    }
}

/// Format helper for `recv`: renders zero, one, or many popped
/// messages. Empty list collapses to "(empty)" so claude doesn't go
/// hunting for content; when `waited` is set (the call parked on a
/// long-poll that timed out) the empty result also carries
/// [`IDLE_WAIT_HINT`] nudging the model toward other work. A single
/// message renders as the historical `from: X\n\nbody` block (banner
/// first if `redelivered`). A multi-message batch renders with a
/// `popped N message(s):` header and `---` separators between bodies
/// so the model can tell where one ends and the next begins;
/// per-message redelivery banners included.
#[must_use]
pub fn format_recv(resp: Result<hive_sh4re::Response, anyhow::Error>, waited: bool) -> String {
    match resp {
        Ok(hive_sh4re::Response::Messages {
            messages,
            remaining,
        }) => render_recv_messages(&messages, remaining, waited),
        // A graceful stop is pending — the inbox is fenced. Render a single
        // explicit directive (not an empty inbox, which claude's "park on recv"
        // habit would long-poll again, stalling the stop-checkpoint turn until
        // the drain wait times out into a hard stop) so every recv during the
        // stop unmissably tells claude to flush + end. `remaining` is forced
        // to 0 — the inbox is fenced, so a "N more pending" hint would be
        // misleading.
        Ok(hive_sh4re::Response::GracefulStop) => {
            render_recv_messages(&[graceful_stop_message()], 0, waited)
        }
        other => reply_err(other, "recv"),
    }
}

/// The synthetic single-message directive rendered for a fenced (graceful-stop)
/// inbox — see the `GracefulStop` arm of [`format_recv`].
fn graceful_stop_message() -> hive_sh4re::DeliveredMessage {
    hive_sh4re::DeliveredMessage {
        from: "graceful-stop".into(),
        body: "⛔ GRACEFUL STOP IN PROGRESS — the container shuts down as soon as this turn \
               ends. Flush anything worth keeping to your durable /state files, then END \
               YOUR TURN now. Do NOT call recv again: the inbox is fenced and recv will \
               only keep returning this same notice."
            .into(),
        id: 0,
        redelivered: false,
        in_reply_to: None,
    }
}

/// Render the popped-message payload of a successful `recv` (see `format_recv`
/// for the empty/single/batch shapes). `remaining` is the post-pop inbox
/// depth; when non-zero a shared "(N more pending …)" hint (identical to the
/// wake prompt's) is appended so an in-turn drain knows more is queued. The
/// empty path never carries the hint (nothing was popped).
fn render_recv_messages(
    messages: &[hive_sh4re::DeliveredMessage],
    remaining: u64,
    waited: bool,
) -> String {
    use std::fmt::Write as _;
    if messages.is_empty() {
        return if waited {
            format!("(empty){IDLE_WAIT_HINT}")
        } else {
            "(empty)".to_owned()
        };
    }
    let mut out = if messages.len() == 1 {
        let m = &messages[0];
        let banner = if m.redelivered { REDELIVERY_HINT } else { "" };
        format!("{banner}{}from: {}\n\n{}", msg_id_tag(m.id), m.from, m.body)
    } else {
        let n = messages.len();
        let mut out = format!("popped {n} message(s):\n\n");
        for (i, m) in messages.iter().enumerate() {
            if i > 0 {
                out.push_str("\n---\n\n");
            }
            let banner = if m.redelivered { REDELIVERY_HINT } else { "" };
            let _ = write!(
                out,
                "{banner}{}from: {}\n\n{}",
                msg_id_tag(m.id),
                m.from,
                m.body
            );
        }
        out
    };
    out.push_str(&crate::serve_common::pending_hint(remaining));
    out
}

/// `[msg #<id>] ` marker prefixed to each recv row so the agent knows
/// what to pass to `ack_until` when bulk-triaging a backlog. Transient
/// pings carry the sentinel id 0 (in-memory only, nothing in the
/// broker to ack) and render without the marker.
fn msg_id_tag(id: i64) -> String {
    if id > 0 {
        format!("[msg #{id}] ")
    } else {
        String::new()
    }
}

/// Header prepended to message bodies that were popped by a prior
/// harness session, never acked (turn crash / OOM / restart), and
/// resurfaced by `RequeueInflight` on this session's boot. Same
/// string surfaces in the wake prompt (see the bin loops) and the
/// in-turn `recv` tool result so claude sees the warning either way.
pub const REDELIVERY_HINT: &str = "[redelivered after harness restart — may already be handled]\n";

/// Appended to the `recv` empty result when the agent parked on a
/// long-poll (`wait_seconds > 0`) that timed out with nothing new.
/// Nudges the model to spend the idle time on other useful work
/// instead of immediately re-blocking on `recv`.
pub const IDLE_WAIT_HINT: &str = " — nothing arrived before the wait timed out. \
If you have other useful work (assigned issues, in-flight PRs, a docs sweep, \
notes to update), do that now rather than immediately parking on recv again.";

/// Inner renderer for a `Vec<LooseEnd>` already extracted from the socket
/// reply. Called by the `get_loose_ends` handler, which injects the
/// `UnreadMatrix` entry before formatting.
pub(super) fn render_loose_ends(loose_ends: &[hive_sh4re::LooseEnd]) -> String {
    use std::fmt::Write as _;
    if loose_ends.is_empty() {
        return "(no loose ends)".to_owned();
    }
    let mut out = format!("{} loose end(s):\n", loose_ends.len());
    for t in loose_ends {
        match t {
            hive_sh4re::LooseEnd::Approval {
                id,
                agent,
                commit_ref,
                description,
                age_seconds,
            } => {
                let desc = description
                    .as_deref()
                    .map(|d| format!(" — {d}"))
                    .unwrap_or_default();
                let _ = writeln!(
                    out,
                    "- approval #{id} ({agent} @ {commit_ref}, {age_seconds}s old){desc}"
                );
            }
            hive_sh4re::LooseEnd::Question {
                id,
                asker,
                target,
                question,
                age_seconds,
            } => {
                let to = target.as_deref().unwrap_or("operator");
                let _ = writeln!(
                    out,
                    "- question #{id} ({asker} → {to}, {age_seconds}s old): {question}"
                );
            }
            hive_sh4re::LooseEnd::Reminder {
                id,
                owner,
                message,
                due_at,
                age_seconds,
            } => {
                let _ = writeln!(
                    out,
                    "- reminder #{id} ({owner}, scheduled {age_seconds}s ago, due_at={due_at}): {message}"
                );
            }
            hive_sh4re::LooseEnd::PendingMessages { count } => {
                let _ = writeln!(
                    out,
                    "- {count} pending inbox message(s) — drain with recv (recv(max: {count}) to batch)"
                );
            }
            hive_sh4re::LooseEnd::UnreadMatrix { rooms, summary } => {
                let _ = write!(out, "- unread matrix messages in {rooms} room(s)");
                if summary.is_empty() {
                    let _ = writeln!(
                        out,
                        " — use list_rooms + read_room to view, mark_read to clear"
                    );
                } else {
                    let _ = writeln!(out, ":");
                    for line in summary.lines() {
                        let _ = writeln!(out, "  {line}");
                    }
                    let _ = writeln!(
                        out,
                        "  use list_rooms + read_room to view, mark_read to clear"
                    );
                }
            }
        }
    }
    out
}

/// Per-room unread entry returned by `matrix_unread_summary`. Mirrors
/// `hive-matrix-mcp`'s `RoomUnread` but defined locally to avoid a
/// cross-crate dep on the matrix-sdk crate tree.
#[derive(Debug, serde::Deserialize)]
pub(super) struct MatrixRoomUnread {
    label: String,
    count: u32,
    last_body: Option<String>,
    last_sender: Option<String>,
}

/// Query the local matrix daemon for per-room unread summaries. Returns
/// `None` if the daemon socket is absent or the query fails. Best-effort:
/// agents without matrix configured are not penalised.
pub(super) async fn matrix_unread_summary() -> Option<Vec<MatrixRoomUnread>> {
    use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
    use tokio::net::UnixStream;
    let socket = std::env::var_os("HIVE_MATRIX_SOCKET").map_or_else(
        || std::path::PathBuf::from("/run/hive-matrix/socket"),
        std::path::PathBuf::from,
    );
    if !socket.exists() {
        return None;
    }
    let mut stream = UnixStream::connect(&socket).await.ok()?;
    stream
        .write_all(b"{\"method\":\"unread_summary\"}\n")
        .await
        .ok()?;
    let mut lines = BufReader::new(stream).lines();
    let line = lines.next_line().await.ok()??;
    let val: serde_json::Value = serde_json::from_str(&line).ok()?;
    // Response: {"kind":"ok","payload":[{label, count, last_body?, last_sender?}]}
    let arr = val.get("payload")?.as_array()?;
    serde_json::from_value(serde_json::Value::Array(arr.clone())).ok()
}

/// Format a `Vec<MatrixRoomUnread>` into a per-room summary string.
/// Single room / single message collapses to one line; multi-room
/// expands to a bulleted list. Returns an empty string for empty input.
pub(super) fn format_matrix_summary(rooms: &[MatrixRoomUnread]) -> String {
    use std::fmt::Write as _;
    if rooms.is_empty() {
        return String::new();
    }
    let mut out = String::new();
    for r in rooms {
        if r.count == 1
            && let (Some(body), Some(sender)) = (&r.last_body, &r.last_sender)
        {
            let _ = writeln!(out, "- {}: {sender}: {body}", r.label);
            continue;
        }
        let _ = writeln!(out, "- {}: {} unread", r.label, r.count);
    }
    // Remove trailing newline.
    if out.ends_with('\n') {
        out.pop();
    }
    out
}

/// Parse the user-facing `kind` string for `cancel_loose_end` into the
/// wire enum. Accepts a small alias set so claude doesn't have to
/// remember the exact spelling (`"q"` / `"r"` shorthand falls out
/// for free).
pub(super) fn parse_loose_end_kind(raw: &str) -> Result<hive_sh4re::CancelLooseEndKind, String> {
    match raw.trim().to_ascii_lowercase().as_str() {
        "question" | "q" => Ok(hive_sh4re::CancelLooseEndKind::Question),
        "reminder" | "r" => Ok(hive_sh4re::CancelLooseEndKind::Reminder),
        "approval" | "a" => Ok(hive_sh4re::CancelLooseEndKind::Approval),
        other => Err(format!(
            "cancel_loose_end: unknown kind '{other}' \
             (expected \"question\", \"reminder\", or \"approval\")"
        )),
    }
}

/// Canonical user-facing label for a `CancelLooseEndKind` — used in
/// the success ack so the caller always sees `"question"` /
/// `"reminder"` instead of whatever alias they passed in (`"q"` /
/// `"r"`).
pub(super) fn loose_end_kind_label(kind: hive_sh4re::CancelLooseEndKind) -> &'static str {
    match kind {
        hive_sh4re::CancelLooseEndKind::Question => "question",
        hive_sh4re::CancelLooseEndKind::Reminder => "reminder",
        hive_sh4re::CancelLooseEndKind::Approval => "approval",
    }
}

/// Format helper for `get_agent_meta`: renders an agent's identity +
/// current status as a short human-readable block. `name`,
/// `hyperhive_rev`, and `running` are always shown; `status` only
/// appears when one is set, otherwise the line reads `status: <none>`.
/// When `running` is false the host has already cleared `status_text`
/// (it would be a stale snapshot from before the stop) so the status
/// line is implicitly `<none>` in that case — but the explicit
/// `running: no` line tells the caller WHY. See
/// `docs/turn-loop/mcp.md::Core tools` (`get_agent_meta`).
#[must_use]
pub fn format_agent_meta(resp: Result<hive_sh4re::Response, anyhow::Error>) -> String {
    match resp {
        Ok(hive_sh4re::Response::AgentMeta {
            name,
            running,
            hyperhive_rev,
            status_text,
            status_set_at,
            hive_name,
            swarm_name,
            matrix_accounts,
        }) => {
            let rev = hyperhive_rev.as_deref().unwrap_or("<unknown>");
            let run = if running { "yes" } else { "no" };
            let mut out = format!("name: {name}\nhyperhive_rev: {rev}\nrunning: {run}");
            // Surface hive + swarm display names only when set, so
            // single-hive deployments don't see noisy `<none>` lines.
            if let Some(hn) = hive_name.as_deref() {
                use std::fmt::Write as _;
                let _ = write!(out, "\nhive_name: {hn}");
            }
            if let Some(sn) = swarm_name.as_deref() {
                use std::fmt::Write as _;
                let _ = write!(out, "\nswarm_name: {sn}");
            }
            match status_text {
                None => out.push_str("\nstatus: <none>"),
                Some(s) => {
                    use std::fmt::Write as _;
                    let age = status_set_at.and_then(|ts| {
                        let now = std::time::SystemTime::now()
                            .duration_since(std::time::UNIX_EPOCH)
                            .ok()?
                            .as_secs();
                        // `ts` is a unix epoch second the agent itself
                        // sourced from `SystemTime` — always positive
                        // in normal operation. Clamp the negative
                        // (clock-skew) edge to 0 before the unsigned
                        // cast so the cast loses no real precision.
                        let ts_secs = u64::try_from(ts).unwrap_or(0);
                        let secs = now.saturating_sub(ts_secs);
                        Some(format_age_secs(secs))
                    });
                    // `write!` into the buffer instead of `push_str(&format!(…))` —
                    // avoids the intermediate allocation clippy::format_push_string
                    // flags. The infallible `String` writer makes this safe to
                    // `let _ =`-ignore.
                    match age {
                        Some(a) => {
                            let _ = write!(out, "\nstatus: {s} (set {a} ago)");
                        }
                        None => {
                            let _ = write!(out, "\nstatus: {s}");
                        }
                    }
                }
            }
            // Matrix identities the agent can act as (the `account` arg on
            // the matrix tools). Listed only when matrix is provisioned, so
            // non-matrix agents don't see an empty line.
            if !matrix_accounts.is_empty() {
                use std::fmt::Write as _;
                out.push_str("\nmatrix_accounts:");
                for acct in &matrix_accounts {
                    let uid = acct.user_id.as_deref().unwrap_or("?");
                    let _ = write!(out, "\n  {} ({uid}) on {}", acct.name, acct.homeserver);
                }
            }
            out
        }
        other => reply_err(other, "get_agent_meta"),
    }
}

/// Format a duration in seconds as a human-readable age string.
fn format_age_secs(secs: u64) -> String {
    if secs < 60 {
        format!("{secs}s")
    } else if secs < 3600 {
        format!("{}m", secs / 60)
    } else if secs < 86400 {
        format!("{}h", secs / 3600)
    } else {
        format!("{}d", secs / 86400)
    }
}

/// Append a short note to a tool result when the underlying socket call
/// took retries to land. Lets claude distinguish "my request was wrong"
/// from "c0re flickered and the harness rode it out" — without the
/// hint, a tool result that took 30s to come back looks identical to a
/// content failure and the model would burn a turn retrying it.
#[must_use]
pub fn annotate_retries(mut s: String, retries: u32) -> String {
    if retries > 0 {
        use std::fmt::Write as _;
        let suffix = if retries == 1 { "retry" } else { "retries" };
        let _ = write!(
            s,
            "\n\n(note: hive socket connect needed {retries} {suffix} — c0re likely \
             restarted. Your request did succeed on the final attempt; no action needed.)"
        );
    }
    s
}

#[cfg(test)]
mod tests {
    use super::{IDLE_WAIT_HINT, format_recv};

    fn msg(id: i64, from: &str, body: &str) -> hive_sh4re::DeliveredMessage {
        hive_sh4re::DeliveredMessage {
            from: from.to_owned(),
            body: body.to_owned(),
            id,
            redelivered: false,
            in_reply_to: None,
        }
    }

    #[test]
    fn empty_recv_after_wait_appends_idle_hint() {
        let out = format_recv(
            Ok(hive_sh4re::Response::Messages {
                messages: vec![],
                remaining: 0,
            }),
            true,
        );
        assert!(out.starts_with("(empty)"));
        assert!(out.contains(IDLE_WAIT_HINT));
    }

    #[test]
    fn empty_recv_without_wait_has_no_hint() {
        let out = format_recv(
            Ok(hive_sh4re::Response::Messages {
                messages: vec![],
                remaining: 0,
            }),
            false,
        );
        assert_eq!(out, "(empty)");
    }

    #[test]
    fn single_recv_with_remaining_appends_pending_hint() {
        let out = format_recv(
            Ok(hive_sh4re::Response::Messages {
                messages: vec![msg(7, "alice", "hi")],
                remaining: 3,
            }),
            false,
        );
        assert!(out.starts_with("[msg #7] from: alice"));
        assert!(out.contains("3 more message(s) pending"));
        assert!(out.contains("max: 3"));
    }

    #[test]
    fn single_recv_no_remaining_has_no_pending_hint() {
        let out = format_recv(
            Ok(hive_sh4re::Response::Messages {
                messages: vec![msg(7, "alice", "hi")],
                remaining: 0,
            }),
            false,
        );
        assert!(!out.contains("more message(s) pending"));
    }

    #[test]
    fn batch_recv_with_remaining_appends_pending_hint_once() {
        let out = format_recv(
            Ok(hive_sh4re::Response::Messages {
                messages: vec![msg(7, "alice", "hi"), msg(8, "bob", "yo")],
                remaining: 9,
            }),
            false,
        );
        assert!(out.starts_with("popped 2 message(s):"));
        assert_eq!(out.matches("more message(s) pending").count(), 1);
        // `max` suggestion is clamped to the server-side recv cap.
        let batch = 9u64.min(u64::from(hive_sh4re::RECV_BATCH_MAX));
        assert!(out.contains(&format!("max: {batch}")));
    }
}