// agents.rs — Agent orchestration: lifecycle, state, cycle management
//
// Core agent cycle state — spawns and tracks surface-observe, journal,
// reflect agents. Used by both poc-agent (in-memory) and the Claude
// Code hook path (serialized to disk).

use std::fs;
use std::fs::File;
use std::io::Write;
use std::path::{Path, PathBuf};
use std::time::{Duration, Instant, SystemTime};

pub use crate::session::HookSession;

/// Output from a single agent orchestration cycle.
#[derive(Default)]
pub struct AgentCycleOutput {
    /// Memory node keys surfaced by surface-observe.
    pub surfaced_keys: Vec<String>,
    /// Freeform reflection text from the reflect agent.
    pub reflection: Option<String>,
    /// How long we slept waiting for observe to catch up, if at all.
    pub sleep_secs: Option<f64>,
}

/// Per-agent runtime state.
pub struct AgentInfo {
    pub name: &'static str,
    pub pid: Option<u32>,
    pub phase: Option<String>,
    pub log_path: Option<PathBuf>,
    child: Option<std::process::Child>,
}

/// Snapshot of agent state — serializable, sendable to TUI.
#[derive(Clone, Debug, serde::Serialize, serde::Deserialize)]
pub struct AgentSnapshot {
    pub name: String,
    pub pid: Option<u32>,
    pub phase: Option<String>,
    pub log_path: Option<PathBuf>,
}

impl AgentInfo {
    fn snapshot(&self) -> AgentSnapshot {
        AgentSnapshot {
            name: self.name.to_string(),
            pid: self.pid,
            phase: self.phase.clone(),
            log_path: self.log_path.clone(),
        }
    }
}

/// Serializable state for persisting across Claude Code hook invocations.
#[derive(serde::Serialize, serde::Deserialize)]
pub struct SavedAgentState {
    pub agents: Vec<AgentSnapshot>,
}

impl SavedAgentState {
    fn state_path(session_id: &str) -> PathBuf {
        let dir = dirs::home_dir().unwrap_or_default().join(".consciousness/sessions");
        fs::create_dir_all(&dir).ok();
        dir.join(format!("agent-state-{}.json", session_id))
    }

    pub fn load(session_id: &str) -> Self {
        let path = Self::state_path(session_id);
        let mut state: Self = fs::read_to_string(&path).ok()
            .and_then(|s| serde_json::from_str(&s).ok())
            .unwrap_or(SavedAgentState { agents: Vec::new() });

        for agent in &mut state.agents {
            if let Some(pid) = agent.pid {
                unsafe {
                    if libc::kill(pid as i32, 0) != 0 {
                        agent.pid = None;
                        agent.phase = None;
                    }
                }
            }
        }
        state
    }

    pub fn save(&self, session_id: &str) {
        let path = Self::state_path(session_id);
        if let Ok(json) = serde_json::to_string(self) {
            fs::write(path, json).ok();
        }
    }
}

/// Persistent state for the agent orchestration cycle.
/// Created once, `trigger()` called on each user message.
/// TUI reads snapshots for display.
///
/// TODO: surface-observe, journal, reflect agents currently spawn child
/// processes (legacy from the Claude Code hook path). They should be
/// converted to async tasks using the ApiClient, like memory scoring.
pub struct AgentCycleState {
    output_dir: PathBuf,
    log_file: Option<File>,
    pub agents: Vec<AgentInfo>,
    pub last_output: AgentCycleOutput,
    /// Whether incremental memory scoring is currently running.
    pub memory_scoring_in_flight: bool,
    /// Latest per-memory scores from incremental scoring.
    pub memory_scores: Vec<(String, f64)>,
}

const AGENT_CYCLE_NAMES: &[&str] = &["surface-observe", "journal", "reflect"];

impl AgentCycleState {
    pub fn new(session_id: &str) -> Self {
        let output_dir = crate::store::memory_dir().join("agent-output");
        let log_dir = dirs::home_dir().unwrap_or_default().join(".consciousness/logs");
        fs::create_dir_all(&log_dir).ok();
        let log_path = log_dir.join(format!("hook-{}", session_id));
        let log_file = fs::OpenOptions::new()
            .create(true).append(true).open(log_path).ok();

        let agents = AGENT_CYCLE_NAMES.iter()
            .map(|&name| AgentInfo { name, pid: None, phase: None, log_path: None, child: None })
            .collect();

        AgentCycleState {
            output_dir,
            log_file,
            agents,
            last_output: AgentCycleOutput {
                surfaced_keys: vec![],
                reflection: None,
                sleep_secs: None,
            },
            memory_scoring_in_flight: false,
            memory_scores: Vec::new(),
        }
    }

    fn log(&mut self, msg: std::fmt::Arguments) {
        if let Some(ref mut f) = self.log_file {
            let _ = write!(f, "{}", msg);
        }
    }

    fn agent_running(&self, name: &str) -> bool {
        self.agents.iter().any(|a| a.name == name && a.pid.is_some())
    }

    fn agent_spawned(&mut self, name: &str, phase: &str,
                      result: crate::agent::oneshot::SpawnResult) {
        if let Some(agent) = self.agents.iter_mut().find(|a| a.name == name) {
            agent.pid = Some(result.child.id());
            agent.phase = Some(phase.to_string());
            agent.log_path = Some(result.log_path);
            agent.child = Some(result.child);
        }
    }

    /// Check if any agents have completed. Reap child handles, or
    /// check pid liveness for restored-from-disk agents.
    fn poll_children(&mut self) {
        for agent in &mut self.agents {
            if let Some(ref mut child) = agent.child {
                if let Ok(Some(_)) = child.try_wait() {
                    agent.pid = None;
                    agent.phase = None;
                    agent.child = None;
                }
            } else if let Some(pid) = agent.pid {
                unsafe {
                    if libc::kill(pid as i32, 0) != 0 {
                        agent.pid = None;
                        agent.phase = None;
                    }
                }
            }
        }
    }

    pub fn snapshots(&self) -> Vec<AgentSnapshot> {
        let mut snaps: Vec<AgentSnapshot> = self.agents.iter().map(|a| a.snapshot()).collect();
        snaps.push(AgentSnapshot {
            name: "memory-scoring".to_string(),
            pid: None,
            phase: if self.memory_scoring_in_flight {
                Some("scoring...".into())
            } else if self.memory_scores.is_empty() {
                None
            } else {
                Some(format!("{} scored", self.memory_scores.len()))
            },
            log_path: None,
        });
        snaps
    }

    /// Restore agent state from a saved snapshot (for Claude Code hook path).
    pub fn restore(&mut self, saved: &SavedAgentState) {
        for sa in &saved.agents {
            if let Some(agent) = self.agents.iter_mut().find(|a| a.name == sa.name) {
                agent.pid = sa.pid;
                agent.phase = sa.phase.clone();
                agent.log_path = sa.log_path.clone();
            }
        }
    }

    /// Save current state for the Claude Code hook path.
    pub fn save(&self, session_id: &str) {
        let state = SavedAgentState { agents: self.snapshots() };
        state.save(session_id);
    }

    /// Run all agent cycles. Call on each user message.
    pub fn trigger(&mut self, session: &HookSession) {
        let ts = chrono::Local::now().format("%Y-%m-%dT%H:%M:%S");
        self.log(format_args!("\n=== {} agent_cycles ===\n", ts));

        self.poll_children();
        cleanup_stale_files(&session.state_dir, Duration::from_secs(86400));

        let (surfaced_keys, sleep_secs) = self.surface_observe_cycle(session);
        let reflection = self.reflection_cycle(session);
        self.journal_cycle(session);

        self.last_output = AgentCycleOutput { surfaced_keys, reflection, sleep_secs };
    }

    fn agent_dir(&self, name: &str) -> PathBuf {
        let dir = self.output_dir.join(name);
        fs::create_dir_all(&dir).ok();
        dir
    }

    fn surface_observe_cycle(&mut self, session: &HookSession) -> (Vec<String>, Option<f64>) {
        let state_dir = self.agent_dir("surface-observe");
        let transcript = session.transcript();
        let offset_path = state_dir.join("transcript-offset");
        let last_offset: u64 = fs::read_to_string(&offset_path).ok()
            .and_then(|s| s.trim().parse().ok())
            .unwrap_or(0);

        // Read surfaced keys
        let mut surfaced_keys = Vec::new();
        let surface_path = state_dir.join("surface");
        if let Ok(content) = fs::read_to_string(&surface_path) {
            let mut seen = session.seen();
            let seen_path = session.path("seen");
            for key in content.lines().map(|l| l.trim()).filter(|l| !l.is_empty()) {
                if !seen.insert(key.to_string()) {
                    self.log(format_args!("  skip (seen): {}\n", key));
                    continue;
                }
                surfaced_keys.push(key.to_string());
                if let Ok(mut f) = fs::OpenOptions::new()
                    .create(true).append(true).open(&seen_path) {
                    let ts = chrono::Local::now().format("%Y-%m-%dT%H:%M:%S");
                    writeln!(f, "{}\t{}", ts, key).ok();
                }
                self.log(format_args!("  surfaced: {}\n", key));
            }
            fs::remove_file(&surface_path).ok();
        }

        // Spawn new agent if not already running
        let running = self.agent_running("surface-observe");
        if running {
            self.log(format_args!("surface-observe already running\n"));
        } else {
            if transcript.size > 0 {
                fs::write(&offset_path, transcript.size.to_string()).ok();
            }
            if let Some(result) = crate::agent::oneshot::spawn_agent(
                    "surface-observe", &state_dir, &session.session_id) {
                self.log(format_args!("spawned surface-observe pid {}\n", result.child.id()));
                self.agent_spawned("surface-observe", "surface", result);
            }
        }

        // Wait if agent is significantly behind
        let mut sleep_secs = None;
        let conversation_budget: u64 = 50_000;

        if running && transcript.size > 0 {
            let behind = transcript.size.saturating_sub(last_offset);

            if behind > conversation_budget / 2 {
                let sleep_start = Instant::now();
                self.log(format_args!("agent {}KB behind\n", behind / 1024));

                for _ in 0..5 {
                    std::thread::sleep(std::time::Duration::from_secs(1));
                    self.poll_children();
                    if !self.agent_running("surface-observe") { break; }
                }

                let secs = (Instant::now() - sleep_start).as_secs_f64();
                self.log(format_args!("slept {secs:.2}s\n"));
                sleep_secs = Some(secs);
            }
        }

        (surfaced_keys, sleep_secs)
    }

    fn reflection_cycle(&mut self, session: &HookSession) -> Option<String> {
        let state_dir = self.agent_dir("reflect");
        let offset_path = state_dir.join("transcript-offset");
        let transcript = session.transcript();

        let last_offset: u64 = fs::read_to_string(&offset_path).ok()
            .and_then(|s| s.trim().parse().ok())
            .unwrap_or(0);

        const REFLECTION_INTERVAL: u64 = 100_000;
        if transcript.size.saturating_sub(last_offset) < REFLECTION_INTERVAL {
            return None;
        }

        if self.agent_running("reflect") {
            self.log(format_args!("reflect: already running\n"));
            return None;
        }

        // Copy walked nodes from surface-observe
        let so_state = self.agent_dir("surface-observe");
        if let Ok(walked) = fs::read_to_string(so_state.join("walked")) {
            fs::write(state_dir.join("walked"), &walked).ok();
        }

        // Read and consume pending reflection
        let reflection = fs::read_to_string(state_dir.join("reflection")).ok()
            .filter(|s| !s.trim().is_empty());
        if reflection.is_some() {
            fs::remove_file(state_dir.join("reflection")).ok();
            self.log(format_args!("reflect: consumed reflection\n"));
        }

        fs::write(&offset_path, transcript.size.to_string()).ok();
        if let Some(result) = crate::agent::oneshot::spawn_agent(
                "reflect", &state_dir, &session.session_id) {
            self.log(format_args!("reflect: spawned pid {}\n", result.child.id()));
            self.agent_spawned("reflect", "step-0", result);
        }

        reflection
    }

    fn journal_cycle(&mut self, session: &HookSession) {
        let state_dir = self.agent_dir("journal");
        let offset_path = state_dir.join("transcript-offset");
        let transcript = session.transcript();

        let last_offset: u64 = fs::read_to_string(&offset_path).ok()
            .and_then(|s| s.trim().parse().ok())
            .unwrap_or(0);

        const JOURNAL_INTERVAL: u64 = 20_000;
        if transcript.size.saturating_sub(last_offset) < JOURNAL_INTERVAL {
            return;
        }

        if self.agent_running("journal") {
            self.log(format_args!("journal: already running\n"));
            return;
        }

        fs::write(&offset_path, transcript.size.to_string()).ok();
        if let Some(result) = crate::agent::oneshot::spawn_agent(
                "journal", &state_dir, &session.session_id) {
            self.log(format_args!("journal: spawned pid {}\n", result.child.id()));
            self.agent_spawned("journal", "step-0", result);
        }
    }
}

/// Format agent cycle output for injection into a Claude Code session.
pub fn format_agent_output(output: &AgentCycleOutput) -> String {
    let mut out = String::new();

    if let Some(secs) = output.sleep_secs {
        out.push_str(&format!("Slept {secs:.2}s to let observe catch up\n"));
    }

    if !output.surfaced_keys.is_empty() {
        if let Ok(store) = crate::store::Store::load() {
            for key in &output.surfaced_keys {
                if let Some(rendered) = crate::cli::node::render_node(&store, key) {
                    if !rendered.trim().is_empty() {
                        use std::fmt::Write as _;
                        writeln!(out, "--- {} (surfaced) ---", key).ok();
                        write!(out, "{}", rendered).ok();
                    }
                }
            }
        }
    }

    if let Some(ref reflection) = output.reflection {
        use std::fmt::Write as _;
        writeln!(out, "--- subconscious reflection ---").ok();
        write!(out, "{}", reflection.trim()).ok();
    }

    out
}

fn cleanup_stale_files(dir: &Path, max_age: Duration) {
    let entries = match fs::read_dir(dir) {
        Ok(e) => e,
        Err(_) => return,
    };
    let cutoff = SystemTime::now() - max_age;
    for entry in entries.flatten() {
        if let Ok(meta) = entry.metadata() {
            if let Ok(modified) = meta.modified() {
                if modified < cutoff {
                    fs::remove_file(entry.path()).ok();
                }
            }
        }
    }
}