claude-smart 0.2.9

//! Hook kill/stop — commit ordering + POSIX SIGTERM / Windows .stop flag IPC.
//!
//! # Commit ordering (§4b, mirrors `limit-switch.sh.j2` lines 384–425)
//!
//! 1. merge-sidecar `hop` (increment next_hop into `<sid>.json`)
//! 2. write `.relaunch` sentinel (atomic tmp+rename)
//! 3. noclobber-create `.switched` marker
//! 4. re-stamp `.last-switch`
//! 5. stop signal — LAST so the supervisor always finds a complete sentinel:
//!    - POSIX (`cfg(unix)`): `kill(pid, SIGTERM)` via nix
//!    - Windows (`cfg(windows)`): write `<sid>.stop` presence flag; supervisor polls
//!
//! # Managed-session gate
//!
//! We stop **only** a session this loop manages. Both conditions must hold:
//! - `<sid>.pid` exists and is parseable as `<pid> <born>`.
//! - The recorded PID is a live process whose exe basename ends in `claude` or `node`
//!   (case-insensitive, `.exe` stripped on Windows) — TOCTOU-tolerant via born check.
//!
//! If either gate fails the function returns `Ok(())` without stopping (notify already
//! emitted by the caller — this degrades to notify-only).

use std::path::Path;

use anyhow::Context as _;

/// The relaunch sentinel format is owned by `platform::relaunch` (the supervisor's
/// reader lives there too). Re-export it so the hook writes the EXACT same wire
/// format the supervisor reads — a single SSOT prevents silent field/format drift.
pub use crate::platform::relaunch::RelaunchSentinel;

/// Execute the full commit sequence and then stop the managed process.
///
/// `sid`            — session UUID string.
/// `target_profile` — profile name to switch to (stored in the sentinel).
/// `handoff`        — handoff prompt string forwarded to the resumed session.
/// `cwd`            — working directory from the hook input (not owner_dir).
/// `born`           — born epoch read from the PID file by classify().
/// `_owner_dir`     — CLAUDE_CONFIG_DIR of the owning profile (reserved for future use).
///
/// The commit ordering (§4b, mirrors `limit-switch.sh.j2` lines 384–425):
///   1. merge-sidecar hop
///   2. write .relaunch sentinel (atomic tmp+rename)
///   3. noclobber-create .switched marker
///   4. re-stamp .last-switch
///   5. stop signal LAST (POSIX SIGTERM / Windows .stop flag)
pub fn commit_and_stop(
    sid: &str,
    target_profile: &str,
    handoff: &str,
    cwd: &str,
    born: i64,
    _owner_dir: &Path,
) -> anyhow::Result<()> {
    use crate::paths;

    // ── Step 1: read current hop from sidecar, compute next_hop ──────────────
    // Shell: limit-switch.sh.j2 lines 394-395
    let current_hop = read_sidecar_hop(sid);
    let next_hop = current_hop + 1;

    // Merge next_hop back into the sidecar (merge-not-clobber: preserve other fields).
    // Shell: `"$HELPER" merge-sidecar "$session_id" hop "$next_hop"`
    merge_sidecar_hop(sid, next_hop)?;

    // ── Step 2: write .relaunch sentinel (atomic) ─────────────────────────────
    // Shell: `"$HELPER" write-relaunch ...` (limit-switch.sh.j2 lines 403-406)
    // born is passed from classify() (already read from the pidfile there).
    let actual_born = if born != 0 {
        born
    } else {
        read_pid_born(sid).unwrap_or(0)
    };

    let sentinel = RelaunchSentinel {
        session_id: sid.to_string(),
        target_profile: target_profile.to_string(),
        cwd: cwd.to_string(),
        handoff: handoff.to_string(),
        hop: next_hop,
        born: actual_born,
    };

    crate::platform::relaunch::write_relaunch(&paths::relaunch(sid), &sentinel)?;

    // ── Step 3: noclobber .switched marker ───────────────────────────────────
    let switched_path = paths::switched(sid);
    if !switched_path.exists() {
        let epoch = now_epoch();
        // Write epoch string; ignore EEXIST (noclobber semantics: first write wins).
        let _ = write_noclobber(&switched_path, &format!("{epoch}"));
    }

    // ── Step 4: re-stamp .last-switch ────────────────────────────────────────
    let epoch = now_epoch();
    std::fs::write(paths::last_switch(), format!("{epoch}"))
        .context("failed to write .last-switch")?;

    // ── Step 5: stop the managed process (LAST) ───────────────────────────────
    stop_managed_process(sid)?;

    Ok(())
}

// ─── sidecar hop helpers ─────────────────────────────────────────────────────

/// Read the `hop` field from `<sid>.json`, tolerating both String and Number forms.
/// Returns 0 on missing/corrupt sidecar (§6 compat: old zsh wrote hop as a JSON string).
/// Delegates to the single `Sidecar::hop_int` SSOT so the String/Number tolerance
/// rule lives in exactly one place (was triplicated across stop.rs/detect.rs/sidecar).
fn read_sidecar_hop(sid: &str) -> i64 {
    crate::sidecar::read_sidecar(&crate::paths::sidecar(sid))
        .map(|s| s.hop_int())
        .unwrap_or(0)
}

/// Merge `next_hop` into `<sid>.json` without clobbering other fields.
/// The hop field is written as a JSON **string** for sidecar compatibility (§6 compat:
/// `merge_sidecar` in the old zsh used `jq --arg` which always produces a string value).
fn merge_sidecar_hop(sid: &str, next_hop: i64) -> anyhow::Result<()> {
    use crate::paths;

    let path = paths::sidecar(sid);

    // Read existing sidecar or start from empty object.
    let mut val: serde_json::Value = match std::fs::read_to_string(&path) {
        Ok(content) => serde_json::from_str(&content).unwrap_or(serde_json::json!({})),
        Err(_) => serde_json::json!({}),
    };

    // Ensure val is an object; reset to {} on corrupt non-object.
    if !val.is_object() {
        val = serde_json::json!({});
    }

    // Write hop as a string (jq --arg compat).
    val["hop"] = serde_json::Value::String(next_hop.to_string());

    // Atomic tmp+rename.
    let tmp = path.with_extension("json.tmp");
    let json = serde_json::to_string(&val).context("failed to serialize sidecar")?;
    std::fs::write(&tmp, &json).context("failed to write sidecar tmp")?;
    std::fs::rename(&tmp, &path).context("failed to rename sidecar into place")?;

    Ok(())
}

// ─── pid helpers ─────────────────────────────────────────────────────────────

/// Read `<born>` from `<sid>.pid` (`<pid> <born>`). Returns None on missing/parse failure.
fn read_pid_born(sid: &str) -> Option<i64> {
    use crate::paths;
    let content = std::fs::read_to_string(paths::pid_file(sid)).ok()?;
    let mut parts = content.split_whitespace();
    let _pid: u32 = parts.next()?.parse().ok()?;
    let born: i64 = parts.next()?.parse().ok()?;
    Some(born)
}

/// Read `<pid>` from `<sid>.pid`. Returns None on missing/parse failure.
fn read_pid(sid: &str) -> Option<u32> {
    use crate::paths;
    let content = std::fs::read_to_string(paths::pid_file(sid)).ok()?;
    let pid: u32 = content.split_whitespace().next()?.parse().ok()?;
    Some(pid)
}

// ─── process stop ─────────────────────────────────────────────────────────────

/// Stop the managed process identified by `<sid>.pid`.
///
/// Managed-session gate: only stops if the PID in the file is a live claude/node process.
fn stop_managed_process(sid: &str) -> anyhow::Result<()> {
    let Some(pid) = read_pid(sid) else {
        // No pidfile — session unmanaged; skip (already notified).
        return Ok(());
    };

    if !is_live_claude_or_node(pid) {
        // PID is not a live claude/node — do not kill unrelated processes.
        return Ok(());
    }

    // Passed the managed-session gate: perform the platform-appropriate stop.
    platform_stop(pid, sid)
}

// ─── platform stop implementations ───────────────────────────────────────────

/// Public wrapper for detect.rs to call without reimplementing the check.
/// Returns true if `pid` is a live process whose exe basename ends with "claude" or "node"
/// (case-insensitive; `.exe` stripped on Windows).
///
/// Uses a targeted `sysinfo` refresh (never a full sweep) on every platform.
pub fn check_is_live_claude_or_node(pid: u32) -> bool {
    is_live_claude_or_node(pid)
}

fn is_live_claude_or_node(pid: u32) -> bool {
    // Cross-platform: `SysinfoProcCheck` does a single-process refresh + exe()
    // basename match (no `ps` spawn). Wired identically on macOS/Linux/Windows.
    use crate::platform::proc_check::ProcCheck;
    crate::platform::proc_check::SysinfoProcCheck::is_live_claude_or_node(pid)
}

// ─── cfg(unix) implementations ────────────────────────────────────────────────

#[cfg(unix)]
fn platform_stop(pid: u32, _sid: &str) -> anyhow::Result<()> {
    use nix::sys::signal::{kill, Signal};
    use nix::unistd::Pid;

    kill(Pid::from_raw(pid as i32), Signal::SIGTERM)
        .with_context(|| format!("failed to SIGTERM pid {pid}"))?;
    Ok(())
}

// ─── cfg(windows) implementations ─────────────────────────────────────────────

#[cfg(windows)]
fn platform_stop(pid: u32, sid: &str) -> anyhow::Result<()> {
    use crate::paths;
    // Windows IPC: write the <sid>.stop presence flag.
    // The supervisor polls for this file while claude.exe runs; on detection it
    // performs: delete flag → CTRL_BREAK_EVENT → grace → TerminateProcess fallback.
    let stop_path = paths::stop_flag(sid);
    std::fs::write(&stop_path, b"")
        .with_context(|| format!("failed to write stop flag for pid {pid}"))?;
    Ok(())
}

// ─── utility helpers ──────────────────────────────────────────────────────────

fn now_epoch() -> i64 {
    std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .unwrap_or_default()
        .as_secs() as i64
}

/// Write `content` to `path` only if the file does not already exist (noclobber semantics).
/// Returns Ok(()) regardless of whether the write happened.
fn write_noclobber(path: &Path, content: &str) -> anyhow::Result<()> {
    use std::fs::OpenOptions;
    use std::io::Write as _;

    // `create_new(true)` fails with AlreadyExists if the file exists — noclobber.
    match OpenOptions::new().write(true).create_new(true).open(path) {
        Ok(mut f) => {
            f.write_all(content.as_bytes())?;
        }
        Err(e) if e.kind() == std::io::ErrorKind::AlreadyExists => {
            // File exists — noclobber: first write wins, silently skip.
        }
        Err(e) => return Err(e.into()),
    }
    Ok(())
}

// ─── tests ────────────────────────────────────────────────────────────────────

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

    // The exe-basename name check (claude/node, case-insensitive, ends_with)
    // lives in `platform::proc_check` and is tested there; this module delegates
    // to `SysinfoProcCheck` rather than re-implementing it.

    /// write_noclobber: first write succeeds; second write is silently ignored.
    #[test]
    fn noclobber_first_write_wins() {
        let dir = TempDir::new().unwrap();
        let path = dir.path().join("marker");
        write_noclobber(&path, "first").unwrap();
        write_noclobber(&path, "second").unwrap(); // must not panic
        let content = std::fs::read_to_string(&path).unwrap();
        assert_eq!(content, "first");
    }

    /// RelaunchSentinel round-trips through serde_json with hop as a JSON number.
    #[test]
    fn relaunch_sentinel_hop_is_number() {
        let sentinel = RelaunchSentinel {
            session_id: "test-sid".to_string(),
            target_profile: "work".to_string(),
            cwd: "/tmp/cwd".to_string(),
            handoff: "resume".to_string(),
            hop: 1,
            born: 1718000000,
        };
        let json = serde_json::to_string(&sentinel).unwrap();
        // hop must be a JSON number (not a string) in .relaunch (§6 compat)
        assert!(
            json.contains("\"hop\":1"),
            "hop should be a JSON number in .relaunch: {json}"
        );
        let back: RelaunchSentinel = serde_json::from_str(&json).unwrap();
        assert_eq!(back.session_id, "test-sid");
        assert_eq!(back.hop, 1);
        assert_eq!(back.born, 1718000000);
    }

    /// merge_sidecar_hop writes hop as a JSON string (jq --arg compat for sidecar).
    #[test]
    fn sidecar_hop_serialized_as_string() {
        // Test the serde contract directly: sidecar hop must be a JSON string.
        let mut val = serde_json::json!({
            "sessionId": "abc",
            "permissionMode": "default"
        });
        val["hop"] = serde_json::Value::String(1_i64.to_string());
        let json = serde_json::to_string(&val).unwrap();
        // hop must be a JSON string in the sidecar (old zsh used jq --arg)
        assert!(
            json.contains("\"hop\":\"1\""),
            "hop should be a JSON string in sidecar: {json}"
        );
    }

    /// RelaunchSentinel hop is i64 (not a string), matching .relaunch format.
    #[test]
    fn relaunch_sentinel_born_and_hop_types() {
        let json = r#"{"session_id":"s","target_profile":"p","cwd":"/","handoff":"h","hop":2,"born":1234567890}"#;
        let s: RelaunchSentinel = serde_json::from_str(json).unwrap();
        assert_eq!(s.hop, 2i64);
        assert_eq!(s.born, 1234567890i64);
    }
}