//! Runtime state + config shared between the host admin socket, the manager
//! socket, and the per-agent sockets: the broker, configured `agent_flake`,
//! and the map of registered agent sockets.

use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::{Arc, Mutex};

use anyhow::{Context, Result};
use tokio::sync::broadcast;

use crate::agent_server::{self, AgentSocket};
use crate::approvals::Approvals;
use crate::broker::Broker;
use crate::dashboard_events::DashboardEvent;
use crate::operator_questions::OperatorQuestions;

/// Capacity of the dashboard event channel. Slow browser subscribers
/// (idle tab, throttled connection) drop frames past this — that's
/// fine, the seq dedupe makes a reconnect resync safe.
const DASHBOARD_CHANNEL: usize = 256;

const AGENT_RUNTIME_ROOT: &str = "/run/hyperhive/agents";
const MANAGER_RUNTIME_ROOT: &str = "/run/hyperhive/manager";
/// Manager-editable per-agent config repos. Bind-mounted RW into the manager
/// container as `/agents/<name>/`. Hive-c0re only writes to these on first
/// spawn (initial commit); after that it's manager-only.
const AGENT_STATE_ROOT: &str = "/var/lib/hyperhive/agents";
/// Hive-c0re-only authoritative per-agent config repos. Containers build from
/// these. Manager has no filesystem access; the only way to update is via
/// `request_apply_commit` + user approval.
const APPLIED_STATE_ROOT: &str = "/var/lib/hyperhive/applied";

pub struct Coordinator {
    pub broker: Arc<Broker>,
    pub approvals: Arc<Approvals>,
    pub questions: Arc<OperatorQuestions>,
    /// URL of the hyperhive flake (no fragment). Inlined into per-agent
    /// `flake.nix` files as `inputs.hyperhive.url`.
    pub hyperhive_flake: String,
    /// TCP port the host's hive-c0re dashboard listens on. Inlined into
    /// each per-agent flake so the agent's web UI can build the right
    /// rebuild-button URL pointing back at the dashboard.
    pub dashboard_port: u16,
    /// Operator pronouns (free text) — `she/her` by default, set via
    /// the NixOS module option `services.hive-c0re.operatorPronouns`.
    /// Reaches each container as the `HIVE_OPERATOR_PRONOUNS` env var
    /// (injected into systemd.services.<harness>.environment by the
    /// meta flake); the harness substitutes it into the agent /
    /// manager system prompt at boot.
    pub operator_pronouns: String,
    agents: Mutex<HashMap<String, AgentSocket>>,
    /// Agents whose lifecycle action (currently just spawn) is in flight.
    /// Read by the dashboard to render a spinner; cleared when the action
    /// resolves (success or failure).
    transient: Mutex<HashMap<String, TransientState>>,
    /// Unified wire-facing event channel feeding the dashboard SSE
    /// stream. Carries broker messages (mirrored from `broker.subscribe`
    /// by the forwarder task in `main.rs`) and dashboard-only mutation
    /// events (approval added/resolved, question added/answered, etc.).
    /// Snapshot endpoints capture `event_seq` before reading state so
    /// the client can dedupe its buffered live traffic against the
    /// snapshot.
    dashboard_events: broadcast::Sender<DashboardEvent>,
    event_seq: AtomicU64,
}

/// Per-agent in-progress state that the dashboard surfaces between approve
/// click and container ready.
#[derive(Debug, Clone)]
pub struct TransientState {
    pub kind: TransientKind,
    pub since: std::time::Instant,
}

/// RAII handle returned by `Coordinator::transient_guard`. Cleared on
/// drop — including drop-via-cancellation, the path that bare
/// `set_transient` / `clear_transient` pairs leaked through. Holds an
/// `Arc<Coordinator>` so the guard is freely returnable / movable.
pub struct TransientGuard {
    coord: Arc<Coordinator>,
    name: String,
}

impl Drop for TransientGuard {
    fn drop(&mut self) {
        self.coord.clear_transient(&self.name);
    }
}

#[derive(Debug, Clone, Copy)]
pub enum TransientKind {
    /// `lifecycle::spawn` is running (nixos-container create + update + start).
    Spawning,
    /// `lifecycle::start` is running.
    Starting,
    /// `lifecycle::kill` is running.
    Stopping,
    /// `lifecycle::restart` is running.
    Restarting,
    /// `lifecycle::rebuild` is running (nixos-container update).
    Rebuilding,
    /// `actions::destroy` is running.
    Destroying,
}

impl Coordinator {
    pub fn open(
        db_path: &Path,
        hyperhive_flake: String,
        dashboard_port: u16,
        operator_pronouns: String,
    ) -> Result<Self> {
        let broker = Broker::open(db_path).context("open broker")?;
        let approvals = Approvals::open(db_path).context("open approvals")?;
        let questions = OperatorQuestions::open(db_path).context("open operator_questions")?;
        let (dashboard_events, _) = broadcast::channel(DASHBOARD_CHANNEL);
        Ok(Self {
            broker: Arc::new(broker),
            approvals: Arc::new(approvals),
            questions: Arc::new(questions),
            hyperhive_flake,
            dashboard_port,
            operator_pronouns,
            agents: Mutex::new(HashMap::new()),
            transient: Mutex::new(HashMap::new()),
            dashboard_events,
            event_seq: AtomicU64::new(0),
        })
    }

    /// Subscribe to the unified dashboard event channel. Used by the
    /// `/dashboard/stream` SSE handler and by the broker-to-dashboard
    /// forwarder task.
    pub fn dashboard_subscribe(&self) -> broadcast::Receiver<DashboardEvent> {
        self.dashboard_events.subscribe()
    }

    /// Stamp the next sequence number. Each emission of a
    /// `DashboardEvent` should fill its `seq` with `next_seq()` so the
    /// frame the wire carries is the one the client uses to dedupe.
    pub fn next_seq(&self) -> u64 {
        self.event_seq.fetch_add(1, Ordering::SeqCst) + 1
    }

    /// Current high-water seq. Snapshot endpoints read this *before*
    /// gathering state so the (snapshot.seq, snapshot) pair satisfies:
    /// any frame with `seq > snapshot.seq` is post-snapshot. The seq
    /// captured here may grow during snapshot construction — clients
    /// may double-apply such events, which renderers must tolerate.
    pub fn current_seq(&self) -> u64 {
        self.event_seq.load(Ordering::SeqCst)
    }

    /// Broadcast a freshly-built `DashboardEvent` (caller fills `seq`
    /// via `next_seq()`). Returns silently when there are no
    /// subscribers — the dashboard channel is best-effort presentation
    /// plumbing, not a delivery guarantee.
    pub fn emit_dashboard_event(&self, event: DashboardEvent) {
        let _ = self.dashboard_events.send(event);
    }

    /// Emit `ApprovalAdded` immediately after the row is inserted in
    /// sqlite. Caller passes the diff text it already computed (or
    /// `None` for spawn approvals which carry no diff).
    pub fn emit_approval_added(
        &self,
        id: i64,
        agent: &str,
        approval_kind: &'static str,
        sha_short: Option<String>,
        diff: Option<String>,
        description: Option<String>,
    ) {
        self.emit_dashboard_event(DashboardEvent::ApprovalAdded {
            seq: self.next_seq(),
            id,
            agent: agent.to_owned(),
            approval_kind,
            sha_short,
            diff,
            description,
        });
    }

    /// Emit `ApprovalResolved` after `mark_approved` / `mark_denied` /
    /// `mark_failed` lands. `resolved_at` is stamped from the system
    /// clock here so call sites don't repeat the conversion; if you
    /// already have an authoritative timestamp from the db update,
    /// the tiny skew between "row updated" and "event emitted" is
    /// presentation-only and doesn't matter to clients.
    pub fn emit_approval_resolved(
        &self,
        id: i64,
        agent: &str,
        approval_kind: &'static str,
        sha_short: Option<String>,
        status: &'static str,
        note: Option<String>,
        description: Option<String>,
    ) {
        let resolved_at = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .ok()
            .and_then(|d| i64::try_from(d.as_secs()).ok())
            .unwrap_or(0);
        self.emit_dashboard_event(DashboardEvent::ApprovalResolved {
            seq: self.next_seq(),
            id,
            agent: agent.to_owned(),
            approval_kind,
            sha_short,
            status,
            resolved_at,
            note,
            description,
        });
    }

    /// Emit `QuestionAdded` after an operator-targeted question is
    /// inserted. Peer-to-peer questions (those with a non-null
    /// `target` agent) never fire this — they don't surface on the
    /// dashboard at all. Caller is responsible for the
    /// `target.is_none()` guard.
    pub fn emit_question_added(
        &self,
        id: i64,
        asker: &str,
        question: &str,
        options: &[String],
        multi: bool,
        deadline_at: Option<i64>,
    ) {
        let asked_at = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .ok()
            .and_then(|d| i64::try_from(d.as_secs()).ok())
            .unwrap_or(0);
        self.emit_dashboard_event(DashboardEvent::QuestionAdded {
            seq: self.next_seq(),
            id,
            asker: asker.to_owned(),
            question: question.to_owned(),
            options: options.to_vec(),
            multi,
            asked_at,
            deadline_at,
        });
    }

    /// Emit `QuestionResolved` when an operator-targeted question
    /// transitions to answered (operator answer, peer override,
    /// cancel, or ttl watchdog). Caller filters on the original
    /// question's `target.is_none()` — peer questions are dashboard-
    /// invisible.
    pub fn emit_question_resolved(
        &self,
        id: i64,
        answer: &str,
        answerer: &str,
        cancelled: bool,
    ) {
        let answered_at = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .ok()
            .and_then(|d| i64::try_from(d.as_secs()).ok())
            .unwrap_or(0);
        self.emit_dashboard_event(DashboardEvent::QuestionResolved {
            seq: self.next_seq(),
            id,
            answer: answer.to_owned(),
            answerer: answerer.to_owned(),
            answered_at,
            cancelled,
        });
    }

    pub fn register_agent(self: &Arc<Self>, name: &str) -> Result<PathBuf> {
        // Idempotent: drop any existing listener so re-registration (e.g. on rebuild,
        // or after a hive-c0re restart cleared /run/hyperhive) gets a fresh socket.
        self.unregister_agent(name);
        let agent_dir = Self::agent_dir(name);
        std::fs::create_dir_all(&agent_dir)
            .with_context(|| format!("create agent dir {}", agent_dir.display()))?;
        let socket_path = Self::socket_path(name);
        // Hand the full Coordinator to the per-agent socket — it
        // needs broker + operator_questions to handle the agent-side
        // `ask` / `answer` tools, not just the broker.
        let socket = agent_server::start(name, &socket_path, self.clone())?;
        self.agents.lock().unwrap().insert(name.to_owned(), socket);
        Ok(agent_dir)
    }

    pub fn unregister_agent(&self, name: &str) {
        if let Some(socket) = self.agents.lock().unwrap().remove(name) {
            socket.handle.abort();
            let _ = std::fs::remove_file(&socket.path);
        }
    }
    pub fn list_agents(&self) -> Vec<String> {
        self.agents.lock().unwrap().keys().cloned().collect()
    }

    /// Mark an agent as in-progress (only one state per agent for now).
    ///
    /// Prefer `transient_guard` when possible — it auto-clears on drop
    /// even if the surrounding future is cancelled (HTTP request
    /// aborted, runtime shutdown mid-rebuild, panic between set and
    /// clear). The bare `set_transient` / `clear_transient` pair leaks
    /// the transient on any of those paths and the dashboard then
    /// shows the agent stuck in "rebuilding…" forever.
    pub fn set_transient(&self, name: &str, kind: TransientKind) {
        self.transient.lock().unwrap().insert(
            name.to_owned(),
            TransientState {
                kind,
                since: std::time::Instant::now(),
            },
        );
    }

    pub fn clear_transient(&self, name: &str) {
        self.transient.lock().unwrap().remove(name);
    }

    /// Set a transient state and return a guard that clears it on drop.
    /// Use this from any path where the surrounding future could be
    /// cancelled or panic between set and clear (HTTP handlers, spawned
    /// tasks). The guard's `Drop` runs even on task cancellation, so
    /// the dashboard's spinner can't get pinned forever.
    pub fn transient_guard(self: &Arc<Self>, name: &str, kind: TransientKind) -> TransientGuard {
        self.set_transient(name, kind);
        TransientGuard {
            coord: self.clone(),
            name: name.to_owned(),
        }
    }

    pub fn transient_snapshot(&self) -> HashMap<String, TransientState> {
        self.transient.lock().unwrap().clone()
    }

    /// Drop a system message into the given agent's inbox. Wakes the
    /// turn loop with a "you were just (re)started" hint — operator
    /// caused the transition, agent picks up where it left off
    /// (notes are in the bind-mounted state dir, last turn is in
    /// --continue's session). Best-effort; broker errors are logged
    /// but don't propagate.
    pub fn kick_agent(&self, name: &str, reason: &str) {
        // Sub-agents bind their state at /agents/<name>/state. The
        // manager has both /state (legacy mount) and /agents
        // bind-mounted, so /agents/<name>/state resolves there too —
        // use that uniformly so the wake message has one canonical
        // path that works everywhere.
        let body = format!(
            "{reason}\n\nYou were just (re)started by the operator. \
             If you were mid-task, check `/agents/{name}/state/` for \
             your notes and pick up where you left off. claude's \
             `--continue` session is intact, so prior context is \
             still in your window."
        );
        if let Err(e) = self.broker.send(&hive_sh4re::Message {
            from: hive_sh4re::SYSTEM_SENDER.to_owned(),
            to: name.to_owned(),
            body,
        }) {
            tracing::warn!(error = ?e, %name, "kick_agent: broker.send failed");
        }
    }

    /// Push a `HelperEvent` into the manager's inbox. Encoded as JSON in
    /// `Message::body`; sender = `SYSTEM_SENDER`. The manager harness
    /// recognises the sender and parses the body. Best-effort: a serde or
    /// broker error is logged but does not propagate.
    pub fn notify_manager(&self, event: &hive_sh4re::HelperEvent) {
        self.notify_agent(hive_sh4re::MANAGER_AGENT, event);
    }

    /// Push a `HelperEvent` into an arbitrary agent's inbox. Encoded
    /// the same way as `notify_manager` (sender = `SYSTEM_SENDER`,
    /// body = JSON-encoded event). Used to route `QuestionAnswered`
    /// events back to the agent that called `ask`, `QuestionAsked`
    /// events to the target of a peer question, etc.
    pub fn notify_agent(&self, agent: &str, event: &hive_sh4re::HelperEvent) {
        let body = match serde_json::to_string(event) {
            Ok(s) => s,
            Err(e) => {
                tracing::warn!(error = ?e, "failed to encode helper event");
                return;
            }
        };
        if let Err(e) = self.broker.send(&hive_sh4re::Message {
            from: hive_sh4re::SYSTEM_SENDER.to_owned(),
            to: agent.to_owned(),
            body,
        }) {
            tracing::warn!(error = ?e, target = %agent, "failed to push helper event");
        }
    }

    /// Deliver `body` to every currently-registered agent, appending the
    /// standard broadcast hint. Returns a list of per-agent error strings
    /// for any that failed (empty = all ok). The sender's own inbox is
    /// included — the hint text tells agents to ignore if no action needed.
    pub fn broadcast_send(&self, from: &str, body: &str) -> Vec<String> {
        const HINT: &str =
            "\n\n⚠️ _hint: this was a broadcast and may not need any action from you_";
        let broadcast_body = format!("{body}{HINT}");
        let mut errors = Vec::new();
        for agent_name in self.list_agents() {
            if let Err(e) = self.broker.send(&hive_sh4re::Message {
                from: from.to_owned(),
                to: agent_name.clone(),
                body: broadcast_body.clone(),
            }) {
                errors.push(format!("{agent_name}: {e}"));
            }
        }
        errors
    }

    pub fn agent_dir(name: &str) -> PathBuf {
        PathBuf::from(format!("{AGENT_RUNTIME_ROOT}/{name}"))
    }

    pub fn socket_path(name: &str) -> PathBuf {
        Self::agent_dir(name).join("mcp.sock")
    }

    pub fn manager_dir() -> PathBuf {
        PathBuf::from(MANAGER_RUNTIME_ROOT)
    }

    pub fn manager_socket_path() -> PathBuf {
        Self::manager_dir().join("mcp.sock")
    }

    /// Ensure a runtime dir + (for sub-agents) per-agent socket exists. For
    /// the manager, `manager_server::start` owns the socket — just return
    /// the dir. For sub-agents this is `register_agent` (creates a fresh
    /// listener bound to `socket_path(name)`). Source directory of the
    /// `/run/hive/mcp.sock` bind that ends up in `set_nspawn_flags`.
    pub fn ensure_runtime(self: &Arc<Self>, name: &str) -> Result<PathBuf> {
        if name == crate::lifecycle::MANAGER_NAME {
            let dir = Self::manager_dir();
            std::fs::create_dir_all(&dir)
                .with_context(|| format!("create manager dir {}", dir.display()))?;
            return Ok(dir);
        }
        self.register_agent(name)
    }

    /// Per-agent state root (parent of `config/`, future `prompts/`, etc.).
    pub fn agent_state_root(name: &str) -> PathBuf {
        PathBuf::from(format!("{AGENT_STATE_ROOT}/{name}"))
    }

    /// Manager-editable proposed config repo. Bind-mounted into the manager
    /// container as `/agents/<name>/config/`.
    pub fn agent_proposed_dir(name: &str) -> PathBuf {
        Self::agent_state_root(name).join("config")
    }

    /// Per-agent Claude credentials dir. Bind-mounted RW into the agent
    /// container at `/root/.claude` so OAuth state survives container
    /// destroy/recreate. Each agent owns its own token lineage — sharing
    /// would break on the first refresh-token rotation.
    pub fn agent_claude_dir(name: &str) -> PathBuf {
        Self::agent_state_root(name).join("claude")
    }

    /// Per-agent durable knowledge dir. Bind-mounted RW into the agent
    /// container at `/state`. Survives destroy/recreate alongside the
    /// claude dir. Agents are told (via the system prompt) to write
    /// long-lived notes / scratch state here.
    pub fn agent_notes_dir(name: &str) -> PathBuf {
        Self::agent_state_root(name).join("state")
    }

    /// Authoritative applied config repo. Hive-c0re-only.
    pub fn agent_applied_dir(name: &str) -> PathBuf {
        PathBuf::from(format!("{APPLIED_STATE_ROOT}/{name}"))
    }

    /// Enumerate names that have a persistent state dir under
    /// `/var/lib/hyperhive/agents/` (i.e. config / claude creds /
    /// notes survive). Includes both currently-existing containers and
    /// destroyed-but-kept tombstones; callers filter the latter by
    /// subtracting `lifecycle::list()`.
    #[must_use]
    pub fn kept_state_names() -> Vec<String> {
        let Ok(rd) = std::fs::read_dir(AGENT_STATE_ROOT) else {
            return Vec::new();
        };
        let mut out: Vec<String> = rd
            .flatten()
            .filter(|e| e.file_type().is_ok_and(|t| t.is_dir()))
            .filter_map(|e| e.file_name().into_string().ok())
            .collect();
        out.sort();
        out
    }
}