zshrs 0.11.4

//! Daemon-presence detection + per-user config knob.
//!
//! **zshrs-original infrastructure — no C source counterpart.** C
//! zsh has no daemon process. Shell state lives in the running
//! interpreter and re-initializes on every launch. zshrs ships
//! `zshrs-daemon` as a separate binary that holds canonical
//! parameter/option/function state in shared memory; the shell
//! probes its socket at startup and decides whether to use the
//! cached state or fall back to vanilla full-init mode.
//!
//! Per the `zshrs ↔ zshrs-daemon = independent binaries` rule
//! (docs/DAEMON.md "Daemon lifecycle"), the shell does NOT spawn the
//! daemon. It probes once at startup and runs in one of three modes:
//!
//! | Mode             | Trigger                                       |
//! |------------------|-----------------------------------------------|
//! | DaemonPresent    | socket alive, daemon answered handshake       |
//! | DaemonAbsent     | no socket / connect refused; degraded vanilla |
//! | DaemonDisabled   | user set `[daemon] enabled = "off"` in config |
//!
//! Without the daemon: zshrs runs as a Rust-fast vanilla zsh — no
//! cache, no canonical state, every config re-evaluated per shell
//! launch ("rebuilding your house every morning"). With the daemon:
//! zshrs uses the cached canonical state for fast cold-start.
//!
//! The probe is single-shot at startup. Builtins / hooks check
//! `is_present()` before calling into the daemon client; on absent,
//! they noop or fall back to source-interp behavior.
//!
//! Config (`$ZSHRS_HOME/zshrs.toml` or `~/.zshrs/zshrs.toml`, all optional):
//!
//! ```toml
//! [daemon]
//! # "auto" (default) = probe at startup, use if alive
//! # "off"            = never probe; pure vanilla zsh mode
//! # "require"        = probe and warn if absent (no spawn either way)
//! enabled = "auto"
//!
//! [shell]
//! # "off"  (default) = always source .zshenv/.zprofile/.zshrc/.zlogin
//! # "auto"           = if daemon is present + has zshrs rows, skip
//! #                    every dotfile and apply canonical state
//! #                    from the daemon instead. ~10ms cold-start.
//! # "on"             = always skip dotfiles when the daemon is up;
//! #                    don't even check for zshrs rows. Strict mode.
//! skip_configs = "off"
//! ```
//!
//! Lives in `~/.zshrs/` alongside everything else (rkyv shards,
//! catalog.db, daemon.sock, zshrs-daemon.toml, log, …) — single
//! directory rule for all zshrs files. Survives OS cache eviction
//! (this is NOT cache-semantic state). `rm -rf ~/.zshrs/` is the
//! one-verb total reset.

use std::sync::atomic::{AtomicU8, Ordering};

/// Daemon-presence probe result.
/// zshrs-original — no C counterpart.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
pub enum Mode {
    /// Probe hasn't run yet.
    Unknown = 0,
    /// Socket connected; assume daemon is alive.
    Present = 1,
    /// Probe ran; daemon was not reachable. Shell runs in vanilla mode.
    Absent = 2,
    /// User opted out via `[daemon] enabled = "off"`. No probe attempted.
    Disabled = 3,
}

impl Mode {
    #[inline]
    fn from_u8(v: u8) -> Self {
        match v {
            1 => Self::Present,
            2 => Self::Absent,
            3 => Self::Disabled,
            _ => Self::Unknown,
        }
    }
}

static STATE: AtomicU8 = AtomicU8::new(Mode::Unknown as u8);

/// What the user said in `[daemon].enabled` (or the auto default).
/// zshrs-original — no C counterpart. C zsh has no daemon to enable.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ConfigSetting {
    /// Probe at startup; use the daemon if alive (default).
    Auto,
    /// Skip the probe entirely; never talk to the daemon.
    Off,
    /// Probe at startup; if the daemon isn't alive, log a warning
    /// (still doesn't spawn — that's the user's responsibility).
    Require,
}

/// What the user said in `[shell].skip_configs`.
/// Explicit discriminants pin the AtomicU8 round-trip in
/// `skip_configs_setting()`.
/// zshrs-original — no C counterpart. C zsh always sources every
/// startup file (Src/init.c `source_home_file()` chain); the
/// canonical-state path that lets us skip those is unique to zshrs.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
pub enum SkipConfigs {
    /// Always source dotfiles (legacy / vanilla zsh behavior). Default.
    Off = 0,
    /// Skip dotfiles iff daemon is present AND has zshrs canonical
    /// rows. Falls back to dotfile sourcing otherwise. The recommended
    /// setting once the recorder has populated canonical state.
    Auto = 1,
    /// Always skip dotfiles when the daemon is up; don't bother
    /// checking for zshrs rows. Strict mode for users who know their
    /// daemon is fully populated.
    On = 2,
}

impl ConfigSetting {
    fn parse(s: &str) -> Option<Self> {
        match s {
            "auto" | "" => Some(Self::Auto),
            "off" | "false" | "no" | "0" => Some(Self::Off),
            "require" | "on" | "true" | "yes" | "1" => Some(Self::Require),
            _ => None,
        }
    }
}

impl SkipConfigs {
    fn parse(s: &str) -> Option<Self> {
        match s {
            "off" | "false" | "no" | "0" | "" => Some(Self::Off),
            "auto" => Some(Self::Auto),
            "on" | "true" | "yes" | "1" => Some(Self::On),
            _ => None,
        }
    }
}

/// Both knobs from `~/.zshrs/zshrs.toml`. Missing file / section
/// / key returns the safe defaults (`daemon=auto`,
/// `skip_configs=off`). Unrecognized values fall back with a log
/// warning.
/// zshrs-original — no C counterpart.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Config {
    pub daemon: ConfigSetting,
    pub skip_configs: SkipConfigs,
}

pub fn read_config_full() -> Config {
    let defaults = Config {
        daemon: ConfigSetting::Auto,
        skip_configs: SkipConfigs::Off,
    };
    let path = match config_file_path() {
        Some(p) => p,
        None => return defaults,
    };
    let body = match std::fs::read_to_string(&path) {
        Ok(s) => s,
        Err(_) => return defaults,
    };
    let parsed = match body.parse::<toml::Table>() {
        Ok(t) => t,
        Err(e) => {
            tracing::warn!(path = %path.display(), error = %e, "zshrs.toml: parse failed; using defaults");
            return defaults;
        }
    };
    let daemon = parsed
        .get("daemon")
        .and_then(|v| v.as_table())
        .and_then(|t| t.get("enabled"))
        .and_then(|v| v.as_str())
        .map(|s| {
            ConfigSetting::parse(s).unwrap_or_else(|| {
                tracing::warn!(value = s, "zshrs.toml: [daemon].enabled invalid; using auto");
                ConfigSetting::Auto
            })
        })
        .unwrap_or(ConfigSetting::Auto);
    let skip_configs = parsed
        .get("shell")
        .and_then(|v| v.as_table())
        .and_then(|t| t.get("skip_configs"))
        .and_then(|v| v.as_str())
        .map(|s| {
            SkipConfigs::parse(s).unwrap_or_else(|| {
                tracing::warn!(value = s, "zshrs.toml: [shell].skip_configs invalid; using off");
                SkipConfigs::Off
            })
        })
        .unwrap_or(SkipConfigs::Off);
    Config {
        daemon,
        skip_configs,
    }
}

/// Back-compat wrapper kept for callers that only need the daemon knob.
pub fn read_config() -> ConfigSetting {
    read_config_full().daemon
}

/// `[log] level` from `~/.zshrs/zshrs.toml` for the SHELL side
/// (zsh::log + zshrs-recorder). Same precedence model the daemon uses
/// for its own side: `$ZSHRS_LOG` env wins, then this directive, then
/// `"info"`. Caller hands the returned string straight to
/// `EnvFilter::try_new`. Errors / missing file / missing key all
/// resolve to "info" silently — a malformed directive produces a
/// useful "bad directive" message at the EnvFilter parse layer
/// instead.
pub fn read_log_directive() -> String {
    const DEFAULT: &str = "info";
    let path = match config_file_path() {
        Some(p) => p,
        None => return DEFAULT.into(),
    };
    let body = match std::fs::read_to_string(&path) {
        Ok(s) => s,
        Err(_) => return DEFAULT.into(),
    };
    let parsed = match body.parse::<toml::Table>() {
        Ok(t) => t,
        Err(_) => return DEFAULT.into(),
    };
    parsed
        .get("log")
        .and_then(|v| v.as_table())
        .and_then(|t| t.get("level"))
        .and_then(|v| v.as_str())
        .filter(|s| !s.is_empty())
        .map(str::to_string)
        .unwrap_or_else(|| DEFAULT.into())
}

/// Cached `[shell].skip_configs` value. Set by `probe()`; read by the
/// shell-init path before sourcing dotfiles.
static SKIP_CONFIGS: AtomicU8 = AtomicU8::new(0);

/// Have we confirmed the daemon has zshrs canonical rows? Set during
/// the same probe pass so the `skip_configs` decision is one atomic
/// load on the hot path.
static SHOULD_SKIP_CONFIGS: AtomicU8 = AtomicU8::new(0);

/// Resolve `$ZSHRS_HOME/zshrs.toml` or `~/.zshrs/zshrs.toml`.
/// Single-directory rule: every zshrs file lives under one root.
/// Returns None if neither $ZSHRS_HOME nor $HOME is set, which is
/// rare enough to treat as "no config file".
fn config_file_path() -> Option<std::path::PathBuf> {
    let root = if let Some(custom) = std::env::var_os("ZSHRS_HOME") {
        std::path::PathBuf::from(custom)
    } else {
        std::path::PathBuf::from(std::env::var_os("HOME")?).join(".zshrs")
    };
    Some(root.join("zshrs.toml"))
}

/// Cheap probe — connect-only, no handshake — does the daemon
/// socket answer?
/// zshrs-original — no C counterpart. Sets the global state so
/// subsequent `is_present()` checks are O(1) atomic loads.
///
/// Honors `[daemon].enabled`:
///   - `Off` → state = Disabled, no probe
///   - `Auto` / `Require` → probe; state = Present or Absent
///
/// `Require` additionally logs a warning if the daemon isn't alive —
/// signal to the user that they configured the shell to expect a
/// daemon but didn't actually start one.
pub fn probe() -> Mode {
    let cfg = read_config_full();
    SKIP_CONFIGS.store(cfg.skip_configs as u8, Ordering::Relaxed);

    match cfg.daemon {
        ConfigSetting::Off => {
            tracing::info!("daemon: disabled in config ([daemon] enabled = \"off\")");
            STATE.store(Mode::Disabled as u8, Ordering::Relaxed);
            // Disabled daemon → no skip; dotfiles always source.
            SHOULD_SKIP_CONFIGS.store(0, Ordering::Relaxed);
            return Mode::Disabled;
        }
        ConfigSetting::Auto | ConfigSetting::Require => {}
    }

    let alive = probe_socket();
    let mode = if alive { Mode::Present } else { Mode::Absent };
    STATE.store(mode as u8, Ordering::Relaxed);

    if alive {
        tracing::info!("daemon: present (socket reachable)");
    } else {
        match cfg.daemon {
            ConfigSetting::Require => {
                tracing::warn!(
                    "daemon: absent — config requires it but socket is not reachable. \
                     Start it via `zshrs-daemon`, `systemctl --user start zshrs-daemon`, \
                     `launchctl load ~/Library/LaunchAgents/com.menketechnologies.zshrs-daemon.plist`, \
                     or `brew services start zshrs`. Falling back to vanilla mode."
                );
            }
            _ => {
                tracing::info!(
                    "daemon: absent (socket not reachable) — running in vanilla zsh mode"
                );
            }
        }
    }

    // Resolve [shell].skip_configs against daemon presence + zshrs-row
    // availability. Three settings collapse to a yes/no decision:
    //   Off  → never skip
    //   On   → skip iff daemon Present (don't even check rows)
    //   Auto → skip iff daemon Present AND has zshrs canonical rows
    let should_skip = match cfg.skip_configs {
        SkipConfigs::Off => false,
        SkipConfigs::On => mode == Mode::Present,
        SkipConfigs::Auto => mode == Mode::Present && daemon_has_zshrs_rows(),
    };
    SHOULD_SKIP_CONFIGS.store(if should_skip { 1 } else { 0 }, Ordering::Relaxed);
    if should_skip {
        tracing::info!(
            "shell: skip_configs active — bypassing /etc/zshenv + ~/.{{zshenv,zprofile,zshrc,zlogin}} and \
             applying canonical state from daemon"
        );
    } else if cfg.skip_configs != SkipConfigs::Off {
        tracing::info!(
            mode = ?cfg.skip_configs,
            daemon = ?mode,
            "shell: skip_configs configured but conditions not met — sourcing dotfiles normally"
        );
    }
    mode
}

/// Cheap probe: does the daemon have a recorder shard on disk for
/// shell_id "zshrs"? A `*-recorder.rkyv` file in `~/.zshrs/images/`
/// means the recorder ran at least once and we have canonical state to
/// apply. **No IPC** — this is a directory listing + filename match,
/// because the shell cold-start path can afford zero IPC roundtrips
/// (the architecture's whole speed thesis).
///
/// Returns false on any I/O error → caller falls through to vanilla
/// `source_startup_files()`.
#[cfg(feature = "daemon")]
fn daemon_has_zshrs_rows() -> bool {
    let paths = match crate::daemon::paths::CachePaths::resolve() {
        Ok(p) => p,
        Err(_) => return false,
    };
    let entries = match std::fs::read_dir(&paths.images) {
        Ok(it) => it,
        Err(_) => return false,
    };
    for entry in entries.flatten() {
        if let Some(s) = entry.file_name().to_str() {
            if s.ends_with("-recorder.rkyv") {
                return true;
            }
        }
    }
    false
}

#[cfg(not(feature = "daemon"))]
fn daemon_has_zshrs_rows() -> bool {
    false
}

/// Should the shell-init path skip every `/etc/zsh*` + `~/.zsh*`
/// dotfile and apply canonical state from the daemon instead? O(1)
/// atomic load — set by `probe()` at startup.
/// zshrs-original — no C counterpart. C zsh's Src/init.c always
/// sources every startup file unconditionally.
#[inline]
pub fn should_skip_configs() -> bool {
    SHOULD_SKIP_CONFIGS.load(Ordering::Relaxed) != 0
}

/// Read the cached `[shell].skip_configs` setting (verbatim from
/// config — independent of whether conditions to skip were met).
/// Mostly useful for diagnostics / `zshrs --doctor`.
pub fn skip_configs_setting() -> SkipConfigs {
    match SKIP_CONFIGS.load(Ordering::Relaxed) {
        1 => SkipConfigs::Auto,
        2 => SkipConfigs::On,
        _ => SkipConfigs::Off,
    }
}

/// Run the probe via the daemon-client crate's cheap is-alive helper.
/// Falls back to a manual socket check if the daemon feature is off
/// (which is the workspace's stub-mode build path).
#[cfg(feature = "daemon")]
fn probe_socket() -> bool {
    match crate::daemon::paths::CachePaths::resolve() {
        Ok(paths) => crate::daemon::client::Client::is_daemon_alive(&paths),
        Err(_) => false,
    }
}

#[cfg(not(feature = "daemon"))]
fn probe_socket() -> bool {
    false
}

/// O(1) read of the cached probe result. Returns `Unknown` until
/// `probe()` has run.
/// zshrs-original — no C counterpart.
#[inline]
pub fn current() -> Mode {
    Mode::from_u8(STATE.load(Ordering::Relaxed))
}

/// Did the probe see a live daemon? `false` for any other state
/// (`Unknown` / `Absent` / `Disabled`).
/// zshrs-original — no C counterpart.
#[inline]
pub fn is_present() -> bool {
    current() == Mode::Present
}

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

    #[test]
    fn config_setting_parses_common_aliases() {
        assert_eq!(ConfigSetting::parse("auto"), Some(ConfigSetting::Auto));
        assert_eq!(ConfigSetting::parse(""), Some(ConfigSetting::Auto));
        assert_eq!(ConfigSetting::parse("off"), Some(ConfigSetting::Off));
        assert_eq!(ConfigSetting::parse("false"), Some(ConfigSetting::Off));
        assert_eq!(ConfigSetting::parse("no"), Some(ConfigSetting::Off));
        assert_eq!(ConfigSetting::parse("0"), Some(ConfigSetting::Off));
        assert_eq!(ConfigSetting::parse("require"), Some(ConfigSetting::Require));
        assert_eq!(ConfigSetting::parse("on"), Some(ConfigSetting::Require));
        assert_eq!(ConfigSetting::parse("true"), Some(ConfigSetting::Require));
        assert_eq!(ConfigSetting::parse("garbage"), None);
    }

    #[test]
    fn mode_round_trips_through_atomic() {
        for m in [Mode::Unknown, Mode::Present, Mode::Absent, Mode::Disabled] {
            assert_eq!(Mode::from_u8(m as u8), m);
        }
    }
}