//! Per-container HTTP UI. SPA shape: `GET /` returns a static shell;
//! `GET /static/*` serves CSS + JS; `GET /api/state` returns the page
//! state as JSON; the JS app renders. Live events stream on
//! `/events/stream`. Action POSTs (`/send`, `/login/*`) return either a
//! 303 Redirect (for browsers that submit the form normally) or just
//! 200 OK — the JS app re-fetches `/api/state` afterwards.

use std::convert::Infallible;
use std::net::SocketAddr;
use std::path::PathBuf;
use std::sync::{Arc, Mutex};

use anyhow::{Context, Result};
use axum::{
    Form, Router,
    extract::State,
    http::StatusCode,
    response::{
        IntoResponse, Response,
        sse::{Event, KeepAlive, Sse},
    },
    routing::{get, post},
};
use serde::{Deserialize, Serialize};
use tokio_stream::{Stream, StreamExt, wrappers::BroadcastStream};

use crate::client;
use crate::events::Bus;
use crate::login::LoginState;
use crate::login_session::{LoginSession, drop_if_finished};
use crate::mcp;
use crate::turn::TurnFiles;

/// Live login state for the web UI. The harness updates this in place as it
/// transitions between `NeedsLogin` and `Online`; the UI reads on each
/// render.
pub type LoginStateCell = Arc<Mutex<LoginState>>;

/// Shared turn lock. The serve loop acquires this (as an async mutex) for the
/// duration of every `drive_turn` call. The `/api/compact` handler tries
/// `try_lock()` and rejects immediately if a turn is in flight, preventing
/// concurrent access to the claude session.
pub type TurnLock = Arc<tokio::sync::Mutex<()>>;

#[derive(Clone)]
struct AppState {
    label: String,
    login: LoginStateCell,
    session: Arc<Mutex<Option<Arc<LoginSession>>>>,
    bus: Bus,
    socket: PathBuf,
    /// Same `TurnFiles` the harness's turn loop uses. Shared so
    /// `/api/compact` re-uses the exact MCP config / system prompt /
    /// settings claude saw on the last regular turn — keeps the
    /// session shape identical across compact + normal turns.
    files: TurnFiles,
    /// Prevents `/api/compact` from racing with an in-flight normal turn.
    turn_lock: TurnLock,
}

impl AppState {
    fn flavor(&self) -> Flavor {
        self.files.flavor
    }
}

/// Which wire protocol the per-agent UI's `/send` handler should speak.
/// Sub-agent → `AgentRequest::OperatorMsg`; manager →
/// `ManagerRequest::OperatorMsg`. Reuses the MCP-side enum so a
/// single value drives both the send protocol and (in
/// `post_compact`) the allowed-tools surface claude sees.
pub type Flavor = mcp::Flavor;

pub async fn serve(
    label: String,
    port: u16,
    login: LoginStateCell,
    bus: Bus,
    socket: PathBuf,
    files: TurnFiles,
    turn_lock: TurnLock,
) -> Result<()> {
    let state = AppState {
        label,
        login,
        session: Arc::new(Mutex::new(None)),
        bus,
        socket,
        files,
        turn_lock,
    };
    let app = Router::new()
        .route("/", get(serve_index))
        .route("/static/agent.css", get(serve_css))
        .route("/static/app.js", get(serve_app_js))
        .route("/static/hive-fr0nt.js", get(serve_shared_js))
        .route("/static/marked.js", get(serve_marked_js))
        .route("/api/state", get(api_state))
        .route("/events/stream", get(events_stream))
        .route("/events/history", get(events_history))
        .route("/send", post(post_send))
        .route("/login/start", post(post_login_start))
        .route("/login/code", post(post_login_code))
        .route("/login/cancel", post(post_login_cancel))
        .route("/api/cancel", post(post_cancel_turn))
        .route("/api/compact", post(post_compact))
        .route("/api/model", post(post_set_model))
        .route("/api/new-session", post(post_new_session))
        .route("/api/loose-ends", get(api_loose_ends))
        .route("/stats", get(serve_stats))
        .route("/static/stats.js", get(serve_stats_js))
        .route("/api/stats", get(api_stats))
        .with_state(state);
    let addr = SocketAddr::from(([0, 0, 0, 0], port));
    let listener = bind_with_retry(addr, "web UI").await?;
    tracing::info!(%port, "web UI listening");
    axum::serve(listener, app).await?;
    Ok(())
}

// ---------------------------------------------------------------------------
// Static assets + state snapshot
// ---------------------------------------------------------------------------

/// Bind a TCP listener with `SO_REUSEADDR` set, retrying on
/// `AddrInUse` for up to ~20s. nspawn restarts can race the previous
/// harness's socket release; `SO_REUSEADDR` lets us reclaim a port
/// still in `TIME_WAIT` from a clean previous exit, and the retry
/// covers the case where the previous process is genuinely still
/// alive (systemd restart-delay overlap).
async fn bind_with_retry(addr: SocketAddr, label: &str) -> Result<tokio::net::TcpListener> {
    let mut delay_ms = 250u64;
    let mut attempts = 0u32;
    loop {
        match try_bind(addr) {
            Ok(l) => return Ok(l),
            Err(e) if e.kind() == std::io::ErrorKind::AddrInUse && attempts < 12 => {
                tracing::warn!(
                    %addr, attempt = attempts + 1,
                    "{label}: AddrInUse, retrying in {delay_ms}ms"
                );
                tokio::time::sleep(std::time::Duration::from_millis(delay_ms)).await;
                attempts += 1;
                delay_ms = (delay_ms * 2).min(2000);
            }
            Err(e) => {
                return Err(e).with_context(|| format!("bind {label} on {addr}"));
            }
        }
    }
}

fn try_bind(addr: SocketAddr) -> std::io::Result<tokio::net::TcpListener> {
    let sock = match addr {
        SocketAddr::V4(_) => tokio::net::TcpSocket::new_v4()?,
        SocketAddr::V6(_) => tokio::net::TcpSocket::new_v6()?,
    };
    sock.set_reuseaddr(true)?;
    sock.bind(addr)?;
    sock.listen(1024)
}

async fn serve_index() -> impl IntoResponse {
    (
        [("content-type", "text/html; charset=utf-8")],
        include_str!("../assets/index.html"),
    )
}

async fn serve_css() -> impl IntoResponse {
    // Prepend the shared palette/typography so per-page styles only need
    // to declare what's actually page-specific. One HTTP request, no
    // per-asset cache to invalidate.
    let body = format!(
        "{}\n{}\n{}",
        hive_fr0nt::BASE_CSS,
        hive_fr0nt::TERMINAL_CSS,
        include_str!("../assets/agent.css"),
    );
    ([("content-type", "text/css")], body)
}

async fn serve_app_js() -> impl IntoResponse {
    (
        [("content-type", "application/javascript")],
        include_str!("../assets/app.js"),
    )
}

async fn serve_shared_js() -> impl IntoResponse {
    (
        [("content-type", "application/javascript")],
        hive_fr0nt::TERMINAL_JS,
    )
}

async fn serve_marked_js() -> impl IntoResponse {
    (
        [("content-type", "application/javascript")],
        hive_fr0nt::MARKED_JS,
    )
}

async fn serve_stats() -> impl IntoResponse {
    (
        [("content-type", "text/html; charset=utf-8")],
        include_str!("../assets/stats.html"),
    )
}

async fn serve_stats_js() -> impl IntoResponse {
    (
        [("content-type", "application/javascript")],
        include_str!("../assets/stats.js"),
    )
}

#[derive(Deserialize)]
struct StatsQuery {
    window: Option<String>,
}

async fn api_stats(
    State(_state): State<AppState>,
    axum::extract::Query(q): axum::extract::Query<StatsQuery>,
) -> axum::Json<crate::stats::Snapshot> {
    let window = crate::stats::Window::parse(q.window.as_deref().unwrap_or("24h"));
    axum::Json(crate::stats::snapshot_default(window))
}

#[derive(Serialize)]
struct StateSnapshot {
    /// Bus seq at the moment this snapshot was assembled. Clients dedupe
    /// their buffered SSE traffic against this value: events with
    /// `seq <= snapshot.seq` are already reflected (or pre-date the
    /// snapshot); `seq > snapshot.seq` is post-snapshot. Reset to 0 on
    /// harness restart — clients treat reconnect as a fresh world.
    seq: u64,
    label: String,
    dashboard_port: u16,
    /// `"online"` | `"needs_login_idle"` | `"needs_login_in_progress"`.
    status: &'static str,
    /// Present when `status == "needs_login_in_progress"`.
    session: Option<SessionView>,
    /// Last N messages addressed to this agent, newest-first. Pulled
    /// from the broker via the per-agent socket on each render.
    /// Empty on transport failure.
    inbox: Vec<hive_sh4re::InboxRow>,
    /// Authoritative turn-loop state from the harness and the unix
    /// timestamp the state was entered. The JS computes the age
    /// client-side off this rather than tracking it from SSE events.
    turn_state: crate::events::TurnState,
    turn_state_since: i64,
    /// Currently-active claude model name. Reflected on the page so
    /// the operator can see what they just switched to (and what's
    /// in flight). Mutable at runtime via `POST /api/model`.
    model: String,
    /// Last-inference token usage from the most recent completed
    /// turn — represents the current context-window size at turn-end.
    /// `null` until the first turn finishes.
    ctx_usage: Option<crate::events::TokenUsage>,
    /// Cumulative token usage across the most recent turn's inferences
    /// (cost signal). `null` until the first turn finishes.
    cost_usage: Option<crate::events::TokenUsage>,
}

#[derive(Serialize)]
struct SessionView {
    /// First `https://…` claude emitted on stdout, if any.
    url: Option<String>,
    /// Accumulated stdout + stderr.
    output: String,
    finished: bool,
    exit_note: Option<String>,
}

/// Proxy this agent's loose-ends list via the per-agent socket. The
/// web UI surfaces the result as a collapsible section in the page
/// so the operator can see at a glance what's pending against the
/// agent (questions asked by it, peer questions targeting it,
/// reminders it scheduled, approvals for the manager). Same data
/// the `mcp__hyperhive__get_loose_ends` tool sees from inside the
/// container.
async fn api_loose_ends(State(state): State<AppState>) -> Response {
    let loose_ends: Vec<hive_sh4re::LooseEnd> = match state.flavor() {
        Flavor::Agent => {
            match client::request::<_, hive_sh4re::AgentResponse>(
                &state.socket,
                &hive_sh4re::AgentRequest::GetLooseEnds,
            )
            .await
            {
                Ok(hive_sh4re::AgentResponse::LooseEnds { loose_ends }) => loose_ends,
                Ok(hive_sh4re::AgentResponse::Err { message }) => {
                    return error_response(&format!("get_loose_ends: {message}"));
                }
                Ok(other) => return error_response(&format!("unexpected response: {other:?}")),
                Err(e) => return error_response(&format!("transport: {e:#}")),
            }
        }
        Flavor::Manager => {
            match client::request::<_, hive_sh4re::ManagerResponse>(
                &state.socket,
                &hive_sh4re::ManagerRequest::GetLooseEnds,
            )
            .await
            {
                Ok(hive_sh4re::ManagerResponse::LooseEnds { loose_ends }) => loose_ends,
                Ok(hive_sh4re::ManagerResponse::Err { message }) => {
                    return error_response(&format!("get_loose_ends: {message}"));
                }
                Ok(other) => return error_response(&format!("unexpected response: {other:?}")),
                Err(e) => return error_response(&format!("transport: {e:#}")),
            }
        }
    };
    axum::Json(serde_json::json!({ "loose_ends": loose_ends })).into_response()
}

async fn api_state(State(state): State<AppState>) -> axum::Json<StateSnapshot> {
    // Capture seq *before* any reads so the dedupe contract is
    // "events with seq > snapshot.seq are post-snapshot, never missed."
    let seq = state.bus.current_seq();
    drop_if_finished(&state.session);
    let login = *state.login.lock().unwrap();
    let session_snapshot = state.session.lock().unwrap().clone();
    let (status, session_view) = match (login, session_snapshot) {
        (LoginState::Online, _) => ("online", None),
        (LoginState::NeedsLogin, None) => ("needs_login_idle", None),
        (LoginState::NeedsLogin, Some(s)) => (
            "needs_login_in_progress",
            Some(SessionView {
                url: s.url(),
                output: s.output(),
                finished: s.finished(),
                exit_note: s.exit_note(),
            }),
        ),
    };
    let dashboard_port = std::env::var("HIVE_DASHBOARD_PORT")
        .ok()
        .and_then(|s| s.parse::<u16>().ok())
        .unwrap_or(7000);
    let inbox = recent_inbox(&state.socket, state.flavor()).await;
    let (turn_state, turn_state_since) = state.bus.state_snapshot();
    let model = state.bus.model();
    let ctx_usage = state.bus.last_ctx_usage();
    let cost_usage = state.bus.last_cost_usage();
    axum::Json(StateSnapshot {
        seq,
        label: state.label.clone(),
        dashboard_port,
        status,
        session: session_view,
        inbox,
        turn_state,
        turn_state_since,
        model,
        ctx_usage,
        cost_usage,
    })
}

/// Best-effort: pull the last 30 messages addressed to us via the
/// per-agent / manager socket. Empty list on any transport / decode
/// failure — the inbox section is decorative, not authoritative.
async fn recent_inbox(socket: &std::path::Path, flavor: Flavor) -> Vec<hive_sh4re::InboxRow> {
    const LIMIT: u64 = 30;
    match flavor {
        Flavor::Agent => {
            match client::request::<_, hive_sh4re::AgentResponse>(
                socket,
                &hive_sh4re::AgentRequest::Recent { limit: LIMIT },
            )
            .await
            {
                Ok(hive_sh4re::AgentResponse::Recent { rows }) => rows,
                _ => Vec::new(),
            }
        }
        Flavor::Manager => {
            match client::request::<_, hive_sh4re::ManagerResponse>(
                socket,
                &hive_sh4re::ManagerRequest::Recent { limit: LIMIT },
            )
            .await
            {
                Ok(hive_sh4re::ManagerResponse::Recent { rows }) => rows,
                _ => Vec::new(),
            }
        }
    }
}

// ---------------------------------------------------------------------------
// Action handlers
// ---------------------------------------------------------------------------

#[derive(Deserialize)]
struct SendForm {
    body: String,
}

async fn post_send(State(state): State<AppState>, Form(form): Form<SendForm>) -> Response {
    let body = form.body.trim().to_owned();
    if body.is_empty() {
        return error_response("send: `body` required");
    }
    let result = match state.flavor() {
        Flavor::Agent => match client::request::<_, hive_sh4re::AgentResponse>(
            &state.socket,
            &hive_sh4re::AgentRequest::OperatorMsg { body },
        )
        .await
        {
            Ok(hive_sh4re::AgentResponse::Ok) => Ok(()),
            Ok(hive_sh4re::AgentResponse::Err { message }) => Err(message),
            Ok(other) => Err(format!("unexpected response: {other:?}")),
            Err(e) => Err(format!("transport: {e:#}")),
        },
        Flavor::Manager => match client::request::<_, hive_sh4re::ManagerResponse>(
            &state.socket,
            &hive_sh4re::ManagerRequest::OperatorMsg { body },
        )
        .await
        {
            Ok(hive_sh4re::ManagerResponse::Ok) => Ok(()),
            Ok(hive_sh4re::ManagerResponse::Err { message }) => Err(message),
            Ok(other) => Err(format!("unexpected response: {other:?}")),
            Err(e) => Err(format!("transport: {e:#}")),
        },
    };
    match result {
        // 200 instead of 303 → the client doesn't refetch /api/state.
        // The operator message becomes a broker `Sent` (already shown
        // server-side in the dashboard); on the agent side, the
        // resulting `TurnStart` SSE event drives the terminal + the
        // inbox row gets consumed by the time `TurnEnd` fires the
        // existing turn-end refresh.
        Ok(()) => (axum::http::StatusCode::OK, "ok").into_response(),
        Err(e) => error_response(&format!("send failed: {e}")),
    }
}

async fn events_history(State(state): State<AppState>) -> axum::Json<serde_json::Value> {
    // Capture seq *before* the read so dedupe is "drop buffered events
    // you've already seen in history", never "lose an event that fired
    // between the read and the timestamp." Historical rows have no
    // per-row seq; only the high-water mark matters for the dedupe
    // window.
    let seq = state.bus.current_seq();
    let events = state.bus.history();
    axum::Json(serde_json::json!({ "seq": seq, "events": events }))
}

async fn events_stream(
    State(state): State<AppState>,
) -> Sse<impl Stream<Item = Result<Event, Infallible>>> {
    tracing::info!("sse: client subscribed");
    let rx = state.bus.subscribe();
    // Drop a "hello" note into the bus so every new subscriber sees at
    // least one event immediately and can clear the connecting placeholder.
    state.bus.emit(crate::events::LiveEvent::Note {
        text: "live stream attached".into(),
    });
    let stream = BroadcastStream::new(rx).filter_map(|res| {
        let ev = res.ok()?;
        let json = serde_json::to_string(&ev).ok()?;
        Some(Ok(Event::default().data(json)))
    });
    Sse::new(stream).keep_alive(KeepAlive::default())
}

async fn post_login_start(State(state): State<AppState>) -> Response {
    drop_if_finished(&state.session);
    {
        let guard = state.session.lock().unwrap();
        if guard.is_some() {
            return (axum::http::StatusCode::OK, "ok").into_response();
        }
    }
    match LoginSession::start() {
        Ok(session) => {
            *state.session.lock().unwrap() = Some(Arc::new(session));
            // Flip status from needs_login_idle → needs_login_in_progress
            // so the web UI's badge + polling kick in (polling is still
            // the right tool for the streaming session output during
            // the login flow itself; events drop the poll for
            // *everything else*).
            state.bus.emit_status("needs_login_in_progress");
            (axum::http::StatusCode::OK, "ok").into_response()
        }
        Err(e) => error_response(&format!("login start failed: {e:#}")),
    }
}

#[derive(Deserialize)]
struct CodeForm {
    code: String,
}

async fn post_login_code(State(state): State<AppState>, Form(form): Form<CodeForm>) -> Response {
    let session = state.session.lock().unwrap().clone();
    let Some(session) = session else {
        return error_response("no login session running");
    };
    if let Err(e) = session.submit_code(&form.code).await {
        return error_response(&format!("submit code failed: {e:#}"));
    }
    (axum::http::StatusCode::OK, "ok").into_response()
}

async fn post_login_cancel(State(state): State<AppState>) -> Response {
    let session = state.session.lock().unwrap().take();
    if let Some(session) = session {
        session.close_stdin().await;
        session.kill();
    }
    // Back to needs_login_idle (LoginState unchanged, session gone).
    state.bus.emit_status("needs_login_idle");
    (axum::http::StatusCode::OK, "ok").into_response()
}

/// Operator-initiated session compaction. Spawns `turn::compact_session`
/// in the background — the HTTP handler returns immediately so the
/// async-form spinner can clear. Output (claude's compaction stream,
/// the "/compact done" note) lands in the live event panel like any
/// other turn. If a regular turn is in flight, claude's own session
/// lock will reject this one and we surface the error as a Note.
#[derive(Deserialize)]
struct ModelForm {
    model: String,
}

/// Switch the model for future turns. The current turn (if any)
/// keeps its model; `/model <name>` applies starting with the next
/// `recv` cycle. Empty / whitespace-only inputs are rejected. No
/// claude-side validation — we just hand the string through to
/// `claude --model <name>`; an unknown model surfaces as a turn
/// failure in the live panel and the operator can revert.
async fn post_set_model(State(state): State<AppState>, Form(form): Form<ModelForm>) -> Response {
    let name = form.model.trim();
    if name.is_empty() {
        return error_response("model: name required");
    }
    state.bus.set_model(name);
    state.bus.emit(crate::events::LiveEvent::Note {
        text: format!("operator: /model — claude model set to '{name}' for future turns"),
    });
    tracing::info!(%name, "operator set model");
    (axum::http::StatusCode::OK, "ok").into_response()
}

async fn post_compact(State(state): State<AppState>) -> Response {
    // Clone the Arc before locking so the guard's lifetime is tied to the
    // clone (which we can move into the spawn) rather than to `state`.
    let lock = state.turn_lock.clone();
    // Reject immediately if a normal turn is in flight — concurrent access
    // to the claude session is unsafe and produces garbled output.
    let Ok(guard) = lock.try_lock_owned() else {
        return error_response("turn in flight — wait for it to finish before compacting");
    };
    let bus = state.bus.clone();
    let files = state.files.clone();
    tokio::spawn(async move {
        let _guard = guard; // keep lock alive for the duration of compaction
        bus.emit(crate::events::LiveEvent::Note {
            text: "operator: /compact — running on persistent session".into(),
        });
        bus.set_state(crate::events::TurnState::Compacting);
        let r = crate::turn::compact_session(&files, &bus).await;
        bus.set_state(crate::events::TurnState::Idle);
        if let Err(e) = r {
            bus.emit(crate::events::LiveEvent::Note {
                text: format!("/compact failed: {e:#}"),
            });
        }
    });
    (axum::http::StatusCode::OK, "ok").into_response()
}

/// Cancel the in-flight claude turn. Coarse-grained: shells out
/// `pkill -INT claude` since there's at most one claude per container.
/// SIGINT (not SIGTERM) so claude flushes anything in-flight and emits a
/// final result row. Emits a Note so the operator sees the cancel
/// landed; the actual state transition back to `idle` happens when
/// `run_claude` wakes up and the harness emits `TurnEnd`.
/// Arm a one-shot: the next claude turn drops `--continue`, starting a
/// fresh session. Subsequent turns resume normal `--continue`
/// behavior. Idempotent before the next turn fires — calling twice
/// still results in a single fresh start. Useful when the
/// session-resume context is poisoned (claude went off the rails,
/// hit an unrecoverable refusal, etc.) and a full reset is cheaper
/// than asking claude to forget mid-stream.
async fn post_new_session(State(state): State<AppState>) -> Response {
    state.bus.request_new_session();
    state.bus.emit(crate::events::LiveEvent::Note {
        text: "operator: new session armed — next turn runs without --continue".into(),
    });
    (axum::http::StatusCode::OK, "ok").into_response()
}

async fn post_cancel_turn(State(state): State<AppState>) -> Response {
    let out = tokio::process::Command::new("pkill")
        .args(["-INT", "claude"])
        .output()
        .await;
    let note = match out {
        Ok(o) if o.status.success() => "operator: /cancel — sent SIGINT to claude".to_owned(),
        Ok(o) if o.status.code() == Some(1) => {
            "operator: /cancel — no claude process to interrupt".to_owned()
        }
        Ok(o) => format!(
            "operator: /cancel — pkill exited {} stderr={}",
            o.status,
            String::from_utf8_lossy(&o.stderr).trim()
        ),
        Err(e) => format!("operator: /cancel — pkill failed: {e}"),
    };
    state.bus.emit(crate::events::LiveEvent::Note { text: note });
    (axum::http::StatusCode::OK, "ok").into_response()
}

fn error_response(message: &str) -> Response {
    // Plain text — JS app surfaces in `alert()`, HTML wrapping would just
    // be noise.
    (StatusCode::INTERNAL_SERVER_ERROR, message.to_owned()).into_response()
}