// idle.rs — Universal idle state machine
//
// Tracks user presence and response times. Manages sleep mode,
// quiet mode, activity EWMA, and notification thresholds.
// No Claude Code or tmux dependencies — pure state machine.
//
// The consciousness binary feeds events directly (key presses,
// turn completions). Claude Code feeds events via the daemon RPC.

use crate::thalamus::{home, now, notify};
use serde::{Deserialize, Serialize};
use std::fs;
use log::info;

// Defaults
pub const DEFAULT_IDLE_TIMEOUT: f64 = 5.0 * 60.0;
pub const DEFAULT_NOTIFY_TIMEOUT: f64 = 2.0 * 60.0;
pub const DEFAULT_SESSION_ACTIVE_SECS: f64 = 15.0 * 60.0;
pub 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.
pub const MIN_NUDGE_INTERVAL: f64 = 15.0;

/// Boost half-life in seconds (60s).
const EWMA_BOOST_HALF_LIFE: f64 = 60.0;

/// Steady-state target for active work.
const EWMA_TARGET: f64 = 0.75;

/// Persisted subset — survives restarts.
#[derive(Serialize, Deserialize, Default)]
struct Persisted {
    last_user_msg: f64,
    last_response: f64,
    #[serde(default)]
    sleep_until: Option<f64>,
    #[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
    #[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).
pub fn ewma_factor(elapsed: f64, half_life: f64) -> f64 {
    (0.5_f64).powf(elapsed / half_life)
}

/// Format epoch seconds as ISO timestamp.
pub fn epoch_to_iso(epoch: f64) -> String {
    if epoch == 0.0 {
        return String::new();
    }
    let secs = epoch as u64;
    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 sleep_until: Option<f64>,
    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,
            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;
                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.activity_ewma > 0.0 {
                    self.activity_ewma = p.activity_ewma;
                    self.ewma_updated_at = p.ewma_updated_at;
                }
                if p.session_active_secs > 0.0 {
                    self.session_active_secs = p.session_active_secs;
                }
                self.last_user_msg = p.last_user_msg;
                self.last_response = p.last_response;
                self.in_turn = p.in_turn;
                self.turn_start = p.turn_start;
                self.last_nudge = p.last_nudge;
                info!("loaded idle state");
            }
        }
    }

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

    pub fn decay_ewma(&mut self) {
        let t = now();
        let elapsed = t - self.ewma_updated_at;
        if elapsed > 0.0 {
            let factor = ewma_factor(elapsed, EWMA_DECAY_HALF_LIFE);
            self.activity_ewma *= factor;
            self.ewma_updated_at = t;
        }
    }

    pub fn boost_ewma(&mut self, turn_duration: f64) {
        self.decay_ewma();
        let gap = EWMA_TARGET - self.activity_ewma;
        let boost = gap * (1.0 - ewma_factor(turn_duration, EWMA_BOOST_HALF_LIFE));
        self.activity_ewma += boost.max(0.0);
    }

    /// Record user activity.
    pub fn user_activity(&mut self) {
        let t = now();
        self.last_user_msg = t;
        self.fired = false;
        if self.notifications.activity != notify::Activity::Focused {
            self.notifications.set_activity(notify::Activity::Focused);
        }
        self.save();
    }

    /// Record response activity.
    pub fn response_activity(&mut self) {
        let t = now();
        if self.in_turn {
            self.boost_ewma(t - self.turn_start);
        }
        self.last_response = t;
        self.in_turn = false;
        self.fired = false;
        self.save();
    }

    pub fn handle_afk(&mut self) {
        self.last_user_msg = 0.0;
        self.fired = false;
        self.save();
    }

    pub fn handle_session_timeout(&mut self, secs: f64) {
        self.session_active_secs = secs;
        self.save();
    }

    pub fn handle_idle_timeout(&mut self, secs: f64) {
        self.idle_timeout = secs;
        self.save();
    }

    pub fn handle_ewma(&mut self, value: f64) -> f64 {
        if value >= 0.0 {
            self.decay_ewma();
            self.activity_ewma = value;
            self.save();
        }
        self.activity_ewma
    }

    pub fn handle_notify_timeout(&mut self, secs: f64) {
        self.notify_timeout = secs;
        self.save();
    }

    pub fn handle_sleep(&mut self, until: f64) {
        if until == 0.0 {
            self.sleep_until = Some(0.0); // indefinite
        } else {
            self.sleep_until = Some(now() + until);
        }
        self.fired = false;
        self.notifications.set_activity(notify::Activity::Sleeping);
        self.save();
    }

    pub fn handle_wake(&mut self) {
        self.sleep_until = None;
        self.fired = false;
        self.notifications.set_activity(notify::Activity::Idle);
        self.save();
    }

    pub fn handle_quiet(&mut self, seconds: u32) {
        self.quiet_until = now() + seconds as f64;
        self.save();
    }

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

    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 }
    }

    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.user_present() {
            "user 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"
        }
    }

    /// Should we transition to idle? Call on every tick.
    pub fn should_go_idle(&self) -> bool {
        if self.sleep_until.is_some() { return false; }
        if now() < self.quiet_until { return false; }
        if self.consolidating { return false; }
        if self.dreaming { return false; }
        if self.user_present() { return false; }
        if self.in_turn { return false; }
        let reference = self.last_response.max(self.last_user_msg);
        if reference == 0.0 { return false; }
        self.since_activity() >= self.idle_timeout
    }

    pub fn debug_json(&self) -> String {
        let t = now();
        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": t - self.last_user_msg,
            "last_response": self.last_response,
            "last_response_ago": t - self.last_response,
            "since_activity": self.since_activity(),
            "activity_ewma": self.activity_ewma,
            "in_turn": self.in_turn,
            "user_present": self.user_present(),
            "fired": self.fired,
            "block_reason": self.block_reason(),
            "sleep_until": self.sleep_until,
            "quiet_until": self.quiet_until,
            "consolidating": self.consolidating,
            "dreaming": self.dreaming,
            "activity": format!("{:?}", self.notifications.activity),
            "pending_notifications": self.notifications.pending.len(),
        }).to_string()
    }
}

pub 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,
    };
    let end_str = end_str.replace('Z', "+00:00");
    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,
    }
}