//! 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, Redirect, 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};

/// 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>>;

#[derive(Clone)]
struct AppState {
    label: String,
    login: LoginStateCell,
    session: Arc<Mutex<Option<Arc<LoginSession>>>>,
    bus: Bus,
    socket: PathBuf,
    flavor: Flavor,
}

/// Which wire protocol the per-agent UI's `/send` handler should speak.
/// Sub-agent → `AgentRequest::OperatorMsg`; manager → `ManagerRequest::OperatorMsg`.
#[derive(Debug, Clone, Copy)]
pub enum Flavor {
    Agent,
    Manager,
}

pub async fn serve(
    label: String,
    port: u16,
    login: LoginStateCell,
    bus: Bus,
    socket: PathBuf,
    flavor: Flavor,
) -> Result<()> {
    let state = AppState {
        label,
        login,
        session: Arc::new(Mutex::new(None)),
        bus,
        socket,
        flavor,
    };
    let app = Router::new()
        .route("/", get(serve_index))
        .route("/static/agent.css", get(serve_css))
        .route("/static/app.js", get(serve_app_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))
        .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 {
    (
        [("content-type", "text/css")],
        include_str!("../assets/agent.css"),
    )
}

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

#[derive(Serialize)]
struct StateSnapshot {
    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,
}

#[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>,
}

async fn api_state(State(state): State<AppState>) -> axum::Json<StateSnapshot> {
    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();
    axum::Json(StateSnapshot {
        label: state.label.clone(),
        dashboard_port,
        status,
        session: session_view,
        inbox,
        turn_state,
        turn_state_since,
        model,
    })
}

/// 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 {
        Ok(()) => Redirect::to("/").into_response(),
        Err(e) => error_response(&format!("send failed: {e}")),
    }
}

async fn events_history(
    State(state): State<AppState>,
) -> axum::Json<Vec<crate::events::LiveEvent>> {
    axum::Json(state.bus.history())
}

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(
        "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 Redirect::to("/").into_response();
        }
    }
    match LoginSession::start() {
        Ok(session) => {
            *state.session.lock().unwrap() = Some(Arc::new(session));
            Redirect::to("/").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:#}"));
    }
    Redirect::to("/").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();
    }
    Redirect::to("/").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(format!(
        "operator: /model — claude model set to '{name}' for future turns"
    )));
    tracing::info!(%name, "operator set model");
    Redirect::to("/").into_response()
}

async fn post_compact(State(state): State<AppState>) -> Response {
    let bus = state.bus.clone();
    let socket = state.socket.clone();
    tokio::spawn(async move {
        bus.emit(crate::events::LiveEvent::Note(
            "operator: /compact — running on persistent session".into(),
        ));
        let settings = match crate::turn::write_settings(&socket).await {
            Ok(p) => p,
            Err(e) => {
                bus.emit(crate::events::LiveEvent::Note(format!(
                    "/compact failed: settings write — {e:#}"
                )));
                return;
            }
        };
        bus.set_state(crate::events::TurnState::Compacting);
        let r = crate::turn::compact_session(&settings, &bus).await;
        bus.set_state(crate::events::TurnState::Idle);
        if let Err(e) = r {
            bus.emit(crate::events::LiveEvent::Note(format!(
                "/compact failed: {e:#}"
            )));
        }
    });
    Redirect::to("/").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`.
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(note));
    Redirect::to("/").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()
}