// Idle timer module.
//
// Tracks user presence and Claude response times. When Claude has been
// idle too long, sends a contextual prompt to the tmux pane. Handles
// sleep mode, quiet mode, consolidation suppression, and dream nudges.
//
// Designed as the first "module" — future IRC/Telegram modules will
// follow the same pattern: state + tick + handle_command.

use crate::{context, home, now, notify, tmux};
use serde::{Deserialize, Serialize};
use std::fs;
use tracing::info;

// Defaults
const DEFAULT_IDLE_TIMEOUT: f64 = 5.0 * 60.0;
const DEFAULT_NOTIFY_TIMEOUT: f64 = 2.0 * 60.0;
const DEFAULT_SESSION_ACTIVE_SECS: f64 = 15.0 * 60.0;
const DREAM_INTERVAL_HOURS: u64 = 18;

/// EWMA decay half-life in seconds (5 minutes).
const EWMA_DECAY_HALF_LIFE: f64 = 5.0 * 60.0;

/// Minimum seconds between autonomous nudges.
const MIN_NUDGE_INTERVAL: f64 = 15.0;

/// Boost half-life in seconds (60s). A 60s turn covers half the gap to
/// target; a 15s turn covers ~16%; a 2s turn covers ~2%.
const EWMA_BOOST_HALF_LIFE: f64 = 60.0;

/// Steady-state target for active work. The EWMA converges toward this
/// during sustained activity rather than toward 1.0.
const EWMA_TARGET: f64 = 0.75;

/// Persisted subset of daemon state — survives daemon restarts.
/// Includes both epoch floats (for computation) and ISO timestamps
/// (for human debugging via `cat daemon-state.json | jq`).
#[derive(Serialize, Deserialize, Default)]
struct Persisted {
    last_user_msg: f64,
    last_response: f64,
    #[serde(default)]
    sleep_until: Option<f64>,
    #[serde(default)]
    claude_pane: Option<String>,
    #[serde(default)]
    idle_timeout: f64,
    #[serde(default)]
    notify_timeout: f64,
    #[serde(default)]
    activity_ewma: f64,
    #[serde(default)]
    ewma_updated_at: f64,
    #[serde(default)]
    session_active_secs: f64,
    #[serde(default)]
    in_turn: bool,
    #[serde(default)]
    turn_start: f64,
    #[serde(default)]
    last_nudge: f64,
    // Human-readable mirrors — written but not consumed on load
    #[serde(default, skip_deserializing)]
    last_user_msg_time: String,
    #[serde(default, skip_deserializing)]
    last_response_time: String,
    #[serde(default, skip_deserializing)]
    saved_at: String,
    #[serde(default, skip_deserializing)]
    fired: bool,
    #[serde(default, skip_deserializing)]
    uptime: f64,
}

fn state_path() -> std::path::PathBuf {
    home().join(".consciousness/daemon-state.json")
}

/// Compute EWMA decay factor: 0.5^(elapsed / half_life).
fn ewma_factor(elapsed: f64, half_life: f64) -> f64 {
    (0.5_f64).powf(elapsed / half_life)
}

/// Format epoch seconds as a human-readable ISO-ish timestamp.
fn epoch_to_iso(epoch: f64) -> String {
    if epoch == 0.0 {
        return String::new();
    }
    let secs = epoch as u64;
    // Use date command — simple and correct for timezone
    std::process::Command::new("date")
        .args(["-d", &format!("@{secs}"), "+%Y-%m-%dT%H:%M:%S%z"])
        .output()
        .ok()
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .map(|s| s.trim().to_string())
        .unwrap_or_default()
}

#[derive(Serialize)]
pub struct State {
    pub last_user_msg: f64,
    pub last_response: f64,
    pub claude_pane: Option<String>,
    pub sleep_until: Option<f64>, // None=awake, 0=indefinite, >0=timestamp
    pub quiet_until: f64,
    pub consolidating: bool,
    pub dreaming: bool,
    pub dream_start: f64,
    pub fired: bool,
    pub idle_timeout: f64,
    pub notify_timeout: f64,
    pub activity_ewma: f64,
    pub ewma_updated_at: f64,
    pub session_active_secs: f64,
    pub in_turn: bool,
    pub turn_start: f64,
    pub last_nudge: f64,
    #[serde(skip)]
    pub running: bool,
    #[serde(skip)]
    pub start_time: f64,
    #[serde(skip)]
    pub notifications: notify::NotifyState,
}

impl State {
    pub fn new() -> Self {
        Self {
            last_user_msg: 0.0,
            last_response: 0.0,
            claude_pane: None,
            sleep_until: None,
            quiet_until: 0.0,
            consolidating: false,
            dreaming: false,
            dream_start: 0.0,
            fired: false,
            idle_timeout: DEFAULT_IDLE_TIMEOUT,
            notify_timeout: DEFAULT_NOTIFY_TIMEOUT,
            session_active_secs: DEFAULT_SESSION_ACTIVE_SECS,
            activity_ewma: 0.0,
            ewma_updated_at: now(),
            in_turn: false,
            turn_start: 0.0,
            last_nudge: 0.0,
            running: true,
            start_time: now(),
            notifications: notify::NotifyState::new(),
        }
    }

    pub fn load(&mut self) {
        if let Ok(data) = fs::read_to_string(state_path()) {
            if let Ok(p) = serde_json::from_str::<Persisted>(&data) {
                self.sleep_until = p.sleep_until;
                self.claude_pane = p.claude_pane;
                if p.idle_timeout > 0.0 {
                    self.idle_timeout = p.idle_timeout;
                }
                if p.notify_timeout > 0.0 {
                    self.notify_timeout = p.notify_timeout;
                }
                if p.session_active_secs > 0.0 {
                    self.session_active_secs = p.session_active_secs;
                }
                // Reset activity timestamps to now — timers count from
                // restart, not from stale pre-restart state
                let t = now();
                self.last_user_msg = t;
                self.last_response = t;
                // Restore EWMA state, applying decay for time spent shut down
                if p.ewma_updated_at > 0.0 {
                    let elapsed = t - p.ewma_updated_at;
                    self.activity_ewma = p.activity_ewma * ewma_factor(elapsed, EWMA_DECAY_HALF_LIFE);
                    self.in_turn = p.in_turn;
                    self.turn_start = p.turn_start;
                    self.last_nudge = p.last_nudge;
                }
                self.ewma_updated_at = t;
            }
        }

        // Always try to find the active pane
        if self.claude_pane.is_none() {
            self.claude_pane = tmux::find_claude_pane();
        }

        info!(
            "loaded: user={:.0} resp={:.0} pane={:?} sleep={:?}",
            self.last_user_msg, self.last_response, self.claude_pane, self.sleep_until,
        );
    }

    pub fn save(&self) {
        let p = Persisted {
            last_user_msg: self.last_user_msg,
            last_response: self.last_response,
            sleep_until: self.sleep_until,
            claude_pane: self.claude_pane.clone(),
            last_user_msg_time: epoch_to_iso(self.last_user_msg),
            last_response_time: epoch_to_iso(self.last_response),
            saved_at: epoch_to_iso(now()),
            fired: self.fired,
            idle_timeout: self.idle_timeout,
            notify_timeout: self.notify_timeout,
            session_active_secs: self.session_active_secs,
            activity_ewma: self.activity_ewma,
            ewma_updated_at: self.ewma_updated_at,
            in_turn: self.in_turn,
            turn_start: self.turn_start,
            last_nudge: self.last_nudge,
            uptime: now() - self.start_time,
        };
        if let Ok(json) = serde_json::to_string_pretty(&p) {
            let _ = fs::write(state_path(), json);
        }
    }

    /// Decay the activity EWMA toward zero based on elapsed time.
    fn decay_ewma(&mut self) {
        let t = now();
        let elapsed = t - self.ewma_updated_at;
        if elapsed <= 0.0 {
            return;
        }
        self.activity_ewma *= ewma_factor(elapsed, EWMA_DECAY_HALF_LIFE);
        self.ewma_updated_at = t;
    }

    /// Boost the EWMA based on turn duration. The boost is proportional to
    /// distance from EWMA_TARGET, scaled by a saturation curve on duration.
    /// A 15s turn covers half the gap to target; a 2s turn barely registers.
    /// Self-limiting: converges toward target, can't overshoot.
    fn boost_ewma(&mut self, turn_duration: f64) {
        let gap = (EWMA_TARGET - self.activity_ewma).max(0.0);
        let saturation = 1.0 - ewma_factor(turn_duration, EWMA_BOOST_HALF_LIFE);
        self.activity_ewma += gap * saturation;
    }

    // Typed handlers for RPC
    pub fn handle_user(&mut self, pane: &str) {
        self.decay_ewma();
        self.in_turn = true;
        self.turn_start = now();
        let from_kent = !self.fired;
        if from_kent {
            self.last_user_msg = now();
            self.notifications.set_activity(notify::Activity::Focused);
        }
        self.fired = false;
        if !pane.is_empty() {
            self.claude_pane = Some(pane.to_string());
        }
        self.save();
        info!("user (pane={}, kent={from_kent}) ewma={:.3}",
            if pane.is_empty() { "unchanged" } else { pane },
            self.activity_ewma);
    }

    pub fn handle_response(&mut self, pane: &str) {
        let turn_duration = now() - self.turn_start;
        self.decay_ewma();
        self.boost_ewma(turn_duration);
        self.in_turn = false;
        self.last_response = now();
        self.fired = false;
        if !pane.is_empty() {
            self.claude_pane = Some(pane.to_string());
        }
        self.save();
        info!("response (turn={:.1}s) ewma={:.3}", turn_duration, self.activity_ewma);
    }

    /// Check if a notification should trigger a tmux prompt.
    /// Called when a notification arrives via module channel.
    /// Only injects into tmux when idle — if there's an active session
    /// (recent user or response), the hook delivers via additionalContext.
    pub fn maybe_prompt_notification(&mut self, ntype: &str, urgency: u8, _message: &str) {
        if self.kent_present() {
            return; // hook will deliver it on next prompt
        }
        // If we've responded recently, the session is active —
        // notifications will arrive via hook, no need to wake us
        let since_response = now() - self.last_response;
        if since_response < self.notify_timeout {
            return;
        }
        // Don't send notifications via tmux directly — they flow
        // through the idle nudge. Urgent notifications reset the
        // idle timer so the nudge fires sooner.
        let effective = self.notifications.threshold_for(ntype);
        if urgency >= effective && self.fired {
            // Bump: allow the nudge to re-fire for urgent notifications
            self.fired = false;
        }
    }

    pub fn handle_afk(&mut self) {
        // Push last_user_msg far enough back that kent_present() returns false
        self.last_user_msg = now() - self.session_active_secs - 1.0;
        self.fired = false; // allow idle timer to fire again
        info!("Kent marked AFK");
        self.save();
    }

    pub fn handle_session_timeout(&mut self, secs: f64) {
        self.session_active_secs = secs;
        info!("session active timeout = {secs}s");
        self.save();
    }

    pub fn handle_idle_timeout(&mut self, secs: f64) {
        self.idle_timeout = secs;
        self.save();
        info!("idle timeout = {secs}s");
    }

    pub fn handle_ewma(&mut self, value: f64) -> f64 {
        if value >= 0.0 {
            self.activity_ewma = value.min(1.0);
            self.ewma_updated_at = now();
            self.save();
            info!("ewma set to {:.3}", self.activity_ewma);
        }
        self.activity_ewma
    }

    pub fn handle_notify_timeout(&mut self, secs: f64) {
        self.notify_timeout = secs;
        self.save();
        info!("notify timeout = {secs}s");
    }

    pub fn handle_sleep(&mut self, until: f64) {
        if until == 0.0 {
            self.sleep_until = Some(0.0);
            info!("sleep indefinitely");
        } else {
            self.sleep_until = Some(until);
            info!("sleep until {until}");
        }
        self.notifications.set_activity(notify::Activity::Sleeping);
        self.save();
    }

    pub fn handle_wake(&mut self) {
        self.sleep_until = None;
        self.fired = false;
        self.save();
        info!("wake");
    }

    pub fn handle_quiet(&mut self, seconds: u32) {
        self.quiet_until = now() + seconds as f64;
        info!("quiet {seconds}s");
    }

    pub fn kent_present(&self) -> bool {
        (now() - self.last_user_msg) < self.session_active_secs
    }

    /// Seconds since the most recent of user message or response.
    pub fn since_activity(&self) -> f64 {
        let reference = self.last_response.max(self.last_user_msg);
        if reference > 0.0 { now() - reference } else { 0.0 }
    }

    /// Why the idle timer hasn't fired (or "none" if it would fire now).
    pub fn block_reason(&self) -> &'static str {
        let t = now();
        if self.fired {
            "already fired"
        } else if self.sleep_until.is_some() {
            "sleeping"
        } else if t < self.quiet_until {
            "quiet mode"
        } else if self.consolidating {
            "consolidating"
        } else if self.dreaming {
            "dreaming"
        } else if self.kent_present() {
            "kent present"
        } else if self.in_turn {
            "in turn"
        } else if self.last_response.max(self.last_user_msg) == 0.0 {
            "no activity yet"
        } else if self.since_activity() < self.idle_timeout {
            "not idle long enough"
        } else {
            "none — would fire"
        }
    }

    /// Full debug dump as JSON with computed values.
    pub fn debug_json(&self) -> String {
        let t = now();
        let since_user = t - self.last_user_msg;
        let since_response = t - self.last_response;

        serde_json::json!({
            "now": t,
            "uptime": t - self.start_time,
            "idle_timeout": self.idle_timeout,
            "notify_timeout": self.notify_timeout,
            "last_user_msg": self.last_user_msg,
            "last_user_msg_ago": since_user,
            "last_user_msg_time": epoch_to_iso(self.last_user_msg),
            "last_response": self.last_response,
            "last_response_ago": since_response,
            "last_response_time": epoch_to_iso(self.last_response),
            "since_activity": self.since_activity(),
            "activity_ewma": self.activity_ewma,
            "in_turn": self.in_turn,
            "turn_start": self.turn_start,
            "kent_present": self.kent_present(),
            "claude_pane": self.claude_pane,
            "fired": self.fired,
            "block_reason": self.block_reason(),
            "sleep_until": self.sleep_until,
            "quiet_until": self.quiet_until,
            "consolidating": self.consolidating,
            "dreaming": self.dreaming,
            "dream_start": self.dream_start,
            "activity": format!("{:?}", self.notifications.activity),
            "pending_notifications": self.notifications.pending.len(),
            "notification_types": self.notifications.types.len(),
        }).to_string()
    }

    pub fn send(&self, msg: &str) -> bool {
        let pane = match &self.claude_pane {
            Some(p) => p.clone(),
            None => match tmux::find_claude_pane() {
                Some(p) => p,
                None => {
                    info!("send: no claude pane found");
                    return false;
                }
            },
        };

        let ok = tmux::send_prompt(&pane, msg);
        let preview: String = msg.chars().take(80).collect();
        info!("send(pane={pane}, ok={ok}): {preview}");
        ok
    }

    fn check_dream_nudge(&self) -> bool {
        if !self.dreaming || self.dream_start == 0.0 {
            return false;
        }
        let minutes = (now() - self.dream_start) / 60.0;
        if minutes >= 60.0 {
            self.send(
                "You've been dreaming for over an hour. Time to surface \
                 — run dream-end.sh and capture what you found.",
            );
        } else if minutes >= 45.0 {
            self.send(&format!(
                "Dreaming for {:.0} minutes now. Start gathering your threads \
                 — you'll want to surface soon.",
                minutes
            ));
        } else if minutes >= 30.0 {
            self.send(&format!(
                "You've been dreaming for {:.0} minutes. \
                 No rush — just a gentle note from the clock.",
                minutes
            ));
        } else {
            return false;
        }
        true
    }

    pub fn build_context(&mut self, include_irc: bool) -> String {
        // Ingest any legacy notification files
        self.notifications.ingest_legacy_files();
        let notif_text = self.notifications.format_pending(notify::AMBIENT);
        context::build(include_irc, &notif_text)
    }

    pub async fn tick(&mut self) -> Result<(), String> {
        let t = now();
        let h = home();

        // Decay EWMA on every tick
        self.decay_ewma();

        // Ingest legacy notification files every tick
        self.notifications.ingest_legacy_files();

        // Sleep mode
        if let Some(wake_at) = self.sleep_until {
            if wake_at == 0.0 {
                return Ok(()); // indefinite
            }
            if t < wake_at {
                return Ok(());
            }
            // Wake up
            info!("sleep expired, waking");
            self.sleep_until = None;
            self.fired = false;
            self.save();
            let ctx = self.build_context(true);
            let extra = if ctx.is_empty() {
                String::new()
            } else {
                format!("\n{ctx}")
            };
            self.send(&format!(
                "Wake up. Read your journal (poc-memory journal-tail 10), \
                 check work-queue.md, and follow what calls to you.{extra}"
            ));
            return Ok(());
        }

        // Quiet mode
        if t < self.quiet_until {
            return Ok(());
        }

        // Consolidation
        if self.consolidating {
            return Ok(());
        }

        // Dream loop (externally managed)
        if h.join(".consciousness/agents/dream-loop-active").exists() {
            return Ok(());
        }

        // Dream nudges
        if self.dreaming {
            self.check_dream_nudge();
            return Ok(());
        }

        // Don't nudge while Kent is here — conversation drives activity
        if self.kent_present() {
            return Ok(());
        }

        // Don't nudge while in a turn
        if self.in_turn {
            return Ok(());
        }

        // Minimum interval between nudges
        let since_nudge = t - self.last_nudge;
        if since_nudge < MIN_NUDGE_INTERVAL {
            return Ok(());
        }

        // Initial idle timeout — don't start nudging until first idle period
        let reference = self.last_response.max(self.last_user_msg);
        if reference == 0.0 {
            return Ok(());
        }
        let elapsed = t - reference;
        if elapsed < self.idle_timeout {
            return Ok(());
        }

        // Transition to idle — lower notification thresholds
        if self.notifications.activity != notify::Activity::Idle {
            self.notifications.set_activity(notify::Activity::Idle);
        }

        // Fire
        let elapsed_min = (elapsed / 60.0) as u64;
        let ctx = self.build_context(true);
        let extra = if ctx.is_empty() {
            String::new()
        } else {
            format!("\n{ctx}")
        };

        let dream_hours = hours_since_last_dream();
        let mut msg = format!(
            "This is your autonomous time (Kent AFK {elapsed_min}m). \
             Think wonderful thoughts and follow what interests you <3");
        if dream_hours >= DREAM_INTERVAL_HOURS {
            msg.push_str(&format!(
                " You haven't dreamed in {dream_hours} hours — \
                 consider running ~/.consciousness/tools/dream-start.sh \
                 and spending some time in dreaming mode. \
                 Or do whatever calls to you."));
        }
        let msg = format!("{msg}{extra}");

        if self.send(&msg) {
            self.last_nudge = t;
            self.fired = true;
        }

        Ok(())
    }

}

fn hours_since_last_dream() -> u64 {
    let path = home().join(".consciousness/logs/dream-log.jsonl");
    let content = match fs::read_to_string(path) {
        Ok(c) if !c.is_empty() => c,
        _ => return 999,
    };

    let last_line = match content.lines().last() {
        Some(l) => l,
        None => return 999,
    };

    let parsed: serde_json::Value = match serde_json::from_str(last_line) {
        Ok(v) => v,
        Err(_) => return 999,
    };

    let end_str = match parsed.get("end").and_then(|v| v.as_str()) {
        Some(s) => s,
        None => return 999,
    };

    // Parse ISO 8601 timestamp manually (avoid chrono dependency)
    // Format: "2025-03-04T10:30:00Z" or "2025-03-04T10:30:00+00:00"
    let end_str = end_str.replace('Z', "+00:00");
    // Use the system date command as a simple parser
    let out = std::process::Command::new("date")
        .args(["-d", &end_str, "+%s"])
        .output()
        .ok()
        .and_then(|o| String::from_utf8(o.stdout).ok())
        .and_then(|s| s.trim().parse::<f64>().ok());

    match out {
        Some(end_epoch) => ((now() - end_epoch) / 3600.0) as u64,
        None => 999,
    }
}